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  • 51.
    Harlin, Peter
    et al.
    Sandvik Materials Technology.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Influence of surface topography of arc-deposited TiN and sputter-deposited WC/C coatings on the initial material transfer tendency and friction characteristics under dry sliding contact conditions2009In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 203, no 13, p. 1748-1755Article in journal (Refereed)
    Abstract [en]

    The influence of surface topography of PVD coatings on the initial material transfer tendency and friction characteristics in dry sliding contact conditions has been investigated. A modified scratch test was used to evaluate the material transfer tendency between ball bearing steel and two different PVD coatings, TiN and WC/C, under dry sliding contact conditions. Post test characterisation of the contact surfaces was performed using SEM/EDS and AES in order to map the initiation points and mechanisms for material transfer. The results show that the resulting topography of the PVD coated surfaces is strongly dependent on both the substrate material topography and the topography induced by the coating deposition process used. In sliding contact with a softer surface the coating topography results in a significant material pick-up tendency of the PVD coated surfaces. The material pick-up is mainly controlled by the abrasive action of hard coating asperities and as a result a polishing post treatment of the as-deposited PVD coatings significantly reduces the material pick-up tendency. For the WC/C coating, showing intrinsic low friction properties, the post treatment inhibits the material pick-up and results in a low and stable friction coefficient (mu similar to 0.1). For the TiN coating, that lacks intrinsic low friction properties, the post treatment reduces the material pick-up tendency but has no significant influence on the friction characteristics. This is mainly due to the presence of metallic Ti originating from the macroparticles on the TiN coating which results in a reactive surface that promotes a strong adhesion between the mating surfaces.

  • 52.
    Harlin, Peter
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Carlsson, Per
    Dalarna University, School of Technology and Business Studies, Material Science.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Influence of surface roughness of PVD coatings on tribological performance in sliding contacts2006In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 201, no 7, p. 4253-4259Article in journal (Refereed)
    Abstract [en]

    The influence of surface roughness on the tribological performance, i.e. friction, wear and material pick-up tendency, of two different commercial PVD coatings, TiN and WC/C, in sliding contact with ball bearing steel has been evaluated using two different types of sliding wear laboratory tests. Post-test characterisation using SEM/EDS, AES, ToF-SIMS and XPS was used to evaluate the prevailing friction and wear. The results show that the surface roughness of the coating is of importance in order to control the initial material pick-up tendency and thus the friction characteristics in a sliding contact. Once initiated, the material pick-up tendency will increase, generating a tribofilm at the sliding interface. For steel–TiN sliding couples a FeO-based tribofilm is generated on the two surfaces and FeO/FeO becomes the sliding interface (interfilm sliding) resulting in a high friction coefficient. For steel–WC/C sliding couples the WC/C displays a pronounced running-in behaviour which generates a WO3-based tribofilm on the steel surface while a carbon rich surface layer is formed on the WC/C surface, i.e. WO3/C becomes the sliding interface (interface sliding) resulting in a low friction coefficient.

  • 53.
    Harlin, Peter
    et al.
    Sandvik Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Abrasive wear resistance of starch consolidated and sintered high speed steel2009In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 267, no 9-10, p. 1482-1489Article in journal (Refereed)
    Abstract [en]

    The abrasive wear resistance of starch consolidated (SC) and super solidus liquid phase sintered (SLPS) M3/2 high speed steel (HSS) samples have been evaluated by a two-body micro-abrasion test (low stress abrasion), using 6 µm diamond abrasive particles, and a three-body abrasion test (high stress abrasion), using significantly larger abrasive particles of blast furnace slag (600 HV) and silicon carbide (2400 HV), respectively. In the tests a commercial powder metallurgical (PM) HSS was used as a reference material. The results show that the microstructure of the SC and SLPS HSS samples is strongly dependent on the sintering temperature used. With increasing temperature the microstructure ranges from a porous (5% porosity) relatively fine grained low temperature sintered microstructure to a fully dense relatively coarse grained high temperature sintered microstructure with eutectic carbides/carbide networks. However, despite the pronounced microstructural differences displayed by the as-sintered HSS microstructures these show a relatively high abrasive wear resistance, comparable with that of a HIPed HSS reference, both under low and high stress abrasion contact conditions. The characteristic features of the low and high temperature sintered microstructures, i.e. the pores and coarse eutectic carbides/carbide networks, only show a limited impact on the wear rate and the wear mode (dominant wear mechanism). The results obtained imply that near net shaped components manufactured by starch consolidation and super solidus liquid phase sintering might be of interest in tribological applications.

  • 54.
    Harlin, Peter
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Starch consolidation of M3/2 high speed steel - Influence of sintering temperature on mechanical properties2007In: Powder Metallurgy, ISSN 0032-5899, E-ISSN 1743-2901, Vol. 50, no 3, p. 232-238Article in journal (Refereed)
  • 55.
    Harlin, Peter
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Starch consolidation of M3/2 high speed steel powder: influence of process parameters on resulting microstructure2007In: Powder Metallurgy, ISSN 0032-5899, E-ISSN 1743-2901, Vol. 50, no 4, p. 345-353Article in journal (Refereed)
    Abstract [en]

    The possibility to produce near net shape high speed steel components with an adequate microstructure by the combination of starch consolidation (SC) and super solidus liquid phase sintering (SLPS) has been evaluated using a gas atomised M3/2 high speed steel (HSS) powder. Characterisation of the green body and as sintered microstructures using light optical microscopy (LOM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) reveals that both the SC and SLPS processes strongly influence the resulting microstructure and thus the properties of the high speed steel material. The results obtained show that the morphology and distribution of starch to a high extent affect the green body surface strength and that the large pores remaining after sintering originates from entrapped air introduced in the fabrication process of the green body. The results illuminate the possibility to combine SC and SLPS to produce HSS components with fully dense microstructures and retained green body geometry from a powder with particle size distribution 50 - 150 mu m.

  • 56. Hatami, S.
    et al.
    Armada, S.
    Laurent, A.
    Nyborg, L.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Tribological properties of powder metallurgical tool steels used in powder compaction pressing dies2011In: Lubrication Science, ISSN 0954-0075, E-ISSN 1557-6833, Vol. 23, no 3, p. 139-152Article in journal (Refereed)
    Abstract [en]

    The tribological properties of two powder metallurgical (PM) tool steels, high and low nitrogen containing, are investigated by means of three different wear tests: ball-on-disc, rubber wheel and scratch test. The ball-on-disc tests showed two distinct friction curves corresponding to each material. In order to simulate the tribosystem existing in metal powder compaction dies, the rubber wheel and the scratch test were modified. The rubber wheel test was performed using ferrous powder instead of sand, and scratch testing was carried out by sliding a powder compact over the tool steels. The scratch tests indicated a higher steady-state coefficient of friction for the low nitrogen containing PM steel as compared with the high nitrogen containing alloy. Additionally, the results from the rubber wheel tests were in agreement with industrial experiences, showing the low nitrogen containing tool steel to suffer from severe galling.

  • 57.
    Heinrich, Jannica
    et al.
    Tribomaterials Group, The Ångström Laboratory, Uppsala University.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology. Tribomaterials Group, The Ångstrom Laboratory, Uppsala University.
    Jenei, Istvan Zoltan
    Instrumentation Physics, Stockholm University.
    Jacobson, Staffan
    Tribomaterials Group, The Ångström Laboratory, Uppsala University.
    Transfer of titanium in sliding contacts: new discoveries and insights revealed by in situ studies in the SEM2014In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 315, no 1-2, p. 87-94Article in journal (Refereed)
    Abstract [en]

    Titanium and its alloys generally display poor tribological properties in sliding contacts due to their high chemical activity and strong adhesion to the counter surface. The strong adhesion causes a high tendency to transfer and ultimately galling or build-up edge formation, resulting in severe surface damage. As a result, forming and machining of titanium and its alloys are generally associated with significant problems such as high friction, rapid tool wear and poor surface finish of the formed/machined surface.

    In the present study, in situ tests in a scanning electron microscope have been performed to increase the understanding of the mechanisms controlling the initial transfer of titanium (Grade 2) in sliding contact with tool surfaces. Tool materials included cover cold work tool steel, cemented carbide, CVD deposited Al2O3and PVD deposited DLC. In these tests, a relatively sharp tip, representing the titanium work material, slides against a flat surface, representing the tool. The contact conditions result in plastic deformation of the work material against the tool surface, thereby simulating forming or machining. The limited and well-defined contact, along with the possibility to study the sliding in the SEM, makes it possible to correlate local surface variations to transfer of work material and frictional response. Post-test characterization of the contact surfaces was performed by high-resolution SEM, TEM, EDS and EELS.

    The initial friction was low and stable against all tested materials, but then gradually escalated against all surfaces except the DLC. The friction escalation was associated to increasing levels of transfer, while the DLC stayed virtually free from transfer. From these very initial sliding tests DLC is a promising tool coating in forming and machining of titanium.

  • 58. Heinrichs, J.
    et al.
    Norgren, S.
    Jacobson, S.
    Yvell, Karin
    Dalarna University, School of Information and Engineering, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Information and Engineering, Materials Technology.
    Influence of binder metal on wear initiation of cemented carbides in sliding contact with granite2021In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 470-471, article id 203645Article in journal (Refereed)
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  • 59. Heinrichs, J.
    et al.
    Norgren, S.
    Jacobson, S.
    Yvell, Karin
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Influence of cemented carbide binder type on wear initiation in rock drilling – Investigated in sliding wear against magnetite rock2019In: International journal of refractory metals & hard materials, ISSN 0263-4368, Vol. 85, article id 105035Article in journal (Refereed)
  • 60.
    Heinrichs, J
    et al.
    Uppsala Universitet.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Jacobson, S
    Uppsala Universitet.
    Influence of tool steel microstructure on initial material transfer in metal forming: in situ studies in the SEM2013In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 302, no 1-2, p. 1249-1256Article in journal (Refereed)
    Abstract [en]

    Metal forming constitutes a group of industrially important processes to form metallic components to net shape. When forming aluminium and other materials that tend to stick to the tools, problems associated with material transfer, e.g. galling, may occur. In a previous study by the present authors, in situ observations of aluminium transfer during sliding contact in the SEM revealed that the surface topography and chemical composition of the tool steel counter surface have a strong impact on the initial material transfer tendency. Even if carefully polished to a very smooth surface (Ra<50 nm), transfer of aluminium was found to immediately take place on a very fine scale and preferentially to the surface irregularities presented by the slightly protruding M(C,N) particles (height 15 nm) in the tool steel. In contrast, the less protruding M6C carbides, as well as the martensitic steel matrix exhibited very little initial transfer. The mechanism behind the preferential pick-up tendency displayed by the M(C,N) particles was not fully understood and it was not possible to determine if the decisive mechanism operates on the microstructural scale, the nanoroughness scale or the chemical bonding scale. In the present study, these mechanisms have been further investigated and analysed by comparing the very initial stages of material transfer onto different types of tool steels in sliding contact with aluminium in the SEM. The tool steels investigated cover conventional ingot cast and powder metallurgy steel grades, selected to possess a range of different types, amounts and sizes of hard phase particles, including MC, M(C,N), M7C3 and M6C. The transfer mechanisms are investigated using high resolution SEM, and the differences between the different microstructures and carbide types are carefully analysed. The implications for real metal forming are discussed.

  • 61.
    Heinrichs, J
    et al.
    Uppsala Universitet.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Jacobson, S
    Uppsala Universitet.
    Initial deformation and wear of cemented carbides for rock drilling as evaluated by a sliding wear test2015In: Proceedings of International Tribology Conference 2015, 2015Conference paper (Refereed)
  • 62. Heinrichs, J.
    et al.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Jacobson, S.
    Initial deformation and wear of cemented carbides in rock drilling as examined by a sliding wear test2017In: International journal of refractory metals & hard materials, ISSN 0263-4368, Vol. 64, p. 7-13Article in journal (Refereed)
    Abstract [en]

    Due to a combination of high hardness and toughness, resulting in excellent wear resistance, cemented carbides are commonly used as the rock crushing component in rock drilling. The present paper presents a unique study where the very initial stages of deformation and wear of cemented carbide in sliding contact with rock are followed in small incremental steps. After each step, a pre-determined area within the wear mark is characterized using high resolution SEM and EDS. This facilitates analysis of the gradual deformation, material transfer, degradation and wear. The deterioration mechanisms found in this sliding test are similar to those observed in actual rock drilling. Cemented carbide grades with different microstructures show significant differences, where a higher amount of Co and a larger WC grain size both are associated to more wear. 

  • 63.
    Heinrichs, J
    et al.
    Uppsala Universitet.
    Olsson, Mikael
    Jacobson, S
    Uppsala Universitet.
    Initiation of Galling in Metal Forming: Differences Between Aluminium and Austenitic Stainless Steel Studied In Situ in the SEM2013In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 50, no 3, p. 431-438Article in journal (Refereed)
    Abstract [en]

    High friction and transfer of work material to tool surfaces constitute important industrial problems in forming of many metals and alloys. However, it is very hard to gain a deeper understanding of these phenomena by studying real forming operations. In this paper, we have tried to gain fundamental understanding by avoiding as much as possible of the complexity of real forming. This has been realised by studying the friction and material transfer between well-defined tool material surfaces; uncoated and DLC-coated tool steel, and a needle shaped austenitic stainless steel tip, in situ in the SEM. The tool materials were tested in two conditions; well polished and well polished with local intentional scratches. It was found that work material was immediately transferred to the tool steel surface. When passing an intentional scratch, the local transfer was on a much larger scale, and the friction was higher, but the effect was mostly local. For the polished DLC-coated surface, almost no work material was transferred and the friction was low. An intentional scratch in the polished DLC surface barely influenced the galling behaviour. The present results are discussed in the light of previously published results from an analogous study with aluminium as work material.

  • 64.
    Heinrichs, J.
    et al.
    Uppsala universitet.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology. Uppsala universitet.
    Jacobson, S.
    Uppsala universitet.
    Surface degradation of cemented carbides in scratching contact with granite and diamond: the roles of microstructure and composition2015In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 342, p. 210-221Article in journal (Refereed)
    Abstract [en]

    Cemented carbides are composite materials comprising metal carbide grains in a more ductile metallic binder. This microstructure results in a combination of high hardness and toughness, making them commonly used as rock crushing parts in rock drilling, where they usually show wear on a very fine scale. The hardness and toughness can ultimately be tuned for the application by adjusting the carbide grain size, binder fraction and composition.In the present investigation, the initial micro-scale deformation and wear of polished cemented carbide surfaces is studied by micro scratching with diamond and granite styli, and also by instrumented micro and nanoindentation. The deformation and wear is evaluated on the sub-micrometer scale using high resolution FEG-SEM and FIB cross sectioning. The selected microstructures include besides four cemented carbide grades that are commonly used in rock drilling also binderless and Ni containing grades. This wider range of cemented carbides is used to gain fundamental insights into the relations between microstructure and micro-scale deformation and wear. The results are discussed with respect to their significance for wear of cemented carbides in rock drilling operations.

  • 65.
    Heinrichs, J
    et al.
    Uppsala Universitet.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Jenei, I. Z,
    Stockholms Universitet.
    Jacobson, S
    Uppsala Universitet.
    Transfer of titanium in sliding contacts – New discoveries and insights revealed by in situ studies in the SEM2013In: Proceedings of World Tribology Congress 2013, Torino, Italy, September 8 – 13, 2013, 2013Conference paper (Refereed)
  • 66. Heinrichs, J.
    et al.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology. Uppsala University.
    Yvell, Karin
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Jacobson, S.
    On the deformation mechanisms of cemented carbide in rock drilling: Fundamental studies involving sliding contact against a rock crystal tip2018In: International journal of refractory metals & hard materials, ISSN 0263-4368, Vol. 77, p. 141-151Article in journal (Refereed)
    Abstract [en]

    Cemented carbide is a composite material, most commonly consisting of tungsten carbide grains in a metallic matrix of cobalt. The combination of a hard ceramic phase in a ductile metallic matrix combines high hardness and ability to withstand plastic deformation with toughness to avoid cracking and fracturing. Since these properties are very important in rock drilling, cemented carbides are frequently used in such applications. In earlier work, it was found that granite in sliding contact with considerably harder cemented carbides not only results in plastic deformation of the cemented carbide composite, but also in plastic deformation of some of the individual WC grains. The latter observation is remarkable, since even the two hardest granite constituents (quartz and feldspar) are significantly softer than the WC grains. This tendency to plastic deformation of the WC grains was found to increase with increasing WC grain size. The present investigation aims to increase the understanding of plastic deformation of cemented carbides in general, and the individual WC grains in particular, in a situation representative for the rock drilling application. The emphasis is put on explaining the seemingly paradoxical fact that a nominally softer counter material is able to plastically deform a harder constituent in a composite material. The experimental work is based on a scratch test set-up, where a rock crystal tip slides against a fine polished cemented carbide surface under well-controlled contact conditions. The deformation and wear mechanisms of the cemented carbide are evaluated on the sub-micrometer scale; using high resolution FEG-SEM, EDS, EBSD, BIB and FIB cross-sectioning. The size of the Co-pockets, together with the shape and size of WC grains, turned out to be decisive factors in determining the degree of carbide deformation. The results are discussed with respect to their industrial importance, including rock drilling.

  • 67.
    Heinrichs, J
    et al.
    Uppsala Universitet.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Yvell, Karin
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Jacobson, S
    Uppsala Universitet.
    Soft rock scratches hard cemented carbide2015In: Proceedings of Wear of Materials, 2015Conference paper (Refereed)
  • 68.
    Heinrichs, J
    et al.
    Uppsala Universitet.
    Yvell, Karin
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology. Uppsala universitet.
    Jacobson, S
    Uppsala Universitet.
    Influence of hardness and microstructure on the mechanisms of deformation and wear of cemented carbides for rock drilling2014In: Proceedings of 16th Nordic Conference on Tribology, Aarhus, Denmark, June 10-13, 2014, 2014Conference paper (Refereed)
  • 69. Heinrichs, Jannica
    et al.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology. Uppsala universitet.
    Almqvist, Bjarne
    Jacobson, Staffan
    Initial surface failure and wear of cemented carbides in sliding contact with different rock types2018In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 408-409, p. 43-55Article in journal (Refereed)
    Abstract [en]

    The initial wear, deformation and degradation of cemented carbide in contact with different rock types are studied using a crossed cylinder sliding test. The sliding distance is limited to centimetres at a time, interrupted by successive SEM analysis. This allows for careful studies of the gradually changing microstructure of the cemented carbide during the test. Five different rock types are included; granite, metal sulphide ore, mica schist, quartzite and marble. All rock types are very different in microstructure, composition and properties. The cemented carbide grade used for the evaluation contains 6 wt% Co and fine (~ 1 µm) WC grains, a grade commonly used in rock drilling. The results show that the cemented carbide microstructure becomes altered already during the very first contact with rock. The initial wear rate and wear character is highly influenced by the rock type. The initial wear of the cemented carbide is highest against quartzite and lowest against marble.

  • 70.
    Heinrichs, Jannica
    et al.
    Uppsala University.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Jacobson, Staffan
    Uppsala University.
    Initial wear of cemented carbides in sliding contact with different rock types2016In: Proceedings of the 17th Nordic Symposium on Tribology - Nordtrib 2016, 2016Conference paper (Refereed)
  • 71. Heinrichs, Jannica
    et al.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Jacobson, Staffan
    Mechanisms of material transfer studied in situ in the SEM: explanations to the success of DLC coated tools in aluminium forming2012In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 292, p. 49-60Article in journal (Refereed)
    Abstract [en]

    Metal forming constitutes a group of industrially important processes to form metallic components to net shape. When forming aluminium and other materials that tend to stick to the tools, problems occur. The transferred work material increases the friction, which increases the forming forces. Additionally, the transferred work material becomes hardened and then scratches the softer work material in subsequent forming. This process, known as galling, compromises the surface finish of the next pieces to be formed. This paper employs a newly developed technique to investigate the initial stages of transfer at high resolution in situ in the SEM. We show that the complex microscale processes involved can be distinguished into three classes: primary transfer, secondary transfer and damage activated transfer. The damage activated transfer constitutes a new fundamental tribological phenomenon, involving the activation and healing of a soft metal in sliding contact with a harder surface. Damage activation leads to transfer onto surfaces such as the polished DLC in this investigation, which would otherwise not see any transfer. These processes are important when forming aluminium, but are expected to be of general tribological significance, in sliding involving non-perfect lubricant films, especially for soft metals with protective surface oxides. (C) 2012 Elsevier B.V. All rights reserved.

  • 72. Heinrichs, Jannica
    et al.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Jacobson, Staffan
    New understanding of the initiation of material transfer and transfer layer build-up in metal forming: in situ studies in the SEM2012In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 292, p. 61-73Article in journal (Refereed)
    Abstract [en]

    The tribological mechanisms behind the initiation of material transfer and build-up of transfer layers in aluminium forming have been studied in situ in the SEM where a tip of aluminium is put into contact with a tool steel surface under controlled sliding contact conditions. By combining in situ observations with post-test high resolution FEG-SEM studies of the contacting surfaces we have shown that aluminium is immediately transferred onto the fine polished tool steel. It was also confirmed that the initial transfer occurs on a very fine scale and is localised to the surface irregularities presented by the slightly protruding carbonitrides. In contrast, the less protruding M6C carbides, as well as the martensitic steel matrix exhibit very little initial transfer. Intentionally made scratches (roughly 5 mu m wide and 2 mu m deep) across the tool surface immediately result in larger scale transfer, which grows upon further passages of work material causing a high coefficient of friction. The study illuminates the extreme value of combining the in situ technique with high-resolution scanning electron microscopy using low acceleration voltage as a mean to detect the very thin initial transfer layers. With the higher acceleration voltages normally used, the transferred aluminium becomes transparent and can hardly be detected. (C) 2012 Elsevier B.V. All rights reserved.

  • 73. Hörnström, S. -E
    et al.
    Karlsson, E.
    Losch, A.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Bay, N.
    Forming of high-strength steels using a hot-melt dry lubricant2010In: 17th International Colloquium Tribology 2010 - Solving Friction and Wear Problems, 2010, Vol. 2, p. 958-971Conference paper (Refereed)
    Abstract [en]

    The increasing use of high strength steels in a variety of mechanical engineering applications has illuminated problems associated with galling in sheet metal forming operations. Galling is a tribological phenomenon associated with transfer of material from the steel sheet to the tool surface during forming resulting in seizure of the tool/steel sheet contact and extensive scratching of the steel sheet surface. As a result, a number of concepts have been developed in order to reduce the tendency to galling in metal forming, including the development of new dry lubricants, new forming tool steel grades and improved surface engineering treatments such as the deposition of low friction CVD and PVD coatings. In the present study the performance of a hot-melt dry lubricant in the forming of hot and cold rolled and hot-dip galvanized high strength steel has been evaluated and compared with a conventional rust protection oil using five different tests methods, i.e. a strip reduction test, a bending under tension test, a stretch-forming test, a pin-on disc test and a strip drawing test. In these tests, two different cold work tool steels, a conventional steel grade and a nitrogen alloyed PM steel grade were evaluated. The results show that the different tests used give consistent results and valuable information concerning the galling tendency of the steel sheet, tool steel and lubricant combinations investigated and when combined can be used to rank the galling resistance of lubricants and tool steels. The results clearly show that the dry lubricant provides better lubrication and generates less galling than the rust protection oil. Also, the nitrogen alloyed PM steel grade shows a significantly higher galling resistance as compared with the conventional steel grade and can, in combination with a dry lubricant, preferably be used in sheet metal forming operations to further improve the galling resistance.

  • 74. Hörnström, Sven-Erik
    et al.
    Karlsson, Erik
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Bay, Niels
    Losch, Achim
    Forming of high strength steels using a hot-melt lubricant2008In: Best in Class Stamping, IDDRG, Olofström, Sweden, 2008Conference paper (Refereed)
  • 75.
    Jacobson, S
    et al.
    Uppsala Universitet.
    Beste, U
    Uppsala Universitet.
    Heinrichs, J
    Uppsala Universitet.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Wiklund, U
    Uppsala Universitet.
    On the nature of cemented carbide wear in rock drilling2014In: Hard Rock Tribology Course and Seminar, Tampere, Finland, November 4-5, 2014, 2014Conference paper (Other academic)
  • 76.
    Jacobson, S
    et al.
    Uppsala Universitet.
    Heinrichs, J
    Uppsala Universitet.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    New experimental findings on the role of initial material transfer in determining friction and surface damage,2013In: Proceedings of World Tribology Congress 2013, Torino, Italy, September 8 – 13, 2013, 2013Conference paper (Refereed)
  • 77.
    Jayamani, Jayaraj
    et al.
    Dalarna University, School of Information and Engineering, Materials Technology.
    Elo, Robin
    Uppsala University.
    Surreddi, Kumar Babu
    Dalarna University, School of Information and Engineering, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Information and Engineering, Materials Technology.
    Electrochemical and passivation behavior of a corrosion-resistant WC-Ni(W) cemented carbide in synthetic mine water2023In: International journal of refractory metals & hard materials, ISSN 0263-4368, Vol. 114, article id 106227Article in journal (Refereed)
    Abstract [en]

    Two different grades, WC-20 vol.% Ni and WC-20 vol.% Co cemented carbides, respectively were systematically investigated concerning their microstructure, binder composition, and corrosion behavior. SEM-EBSD analysis verified that both grades have similar WC grain sizes (0.9–1.1 μm). AES analysis confirmed that the binder phase of the respective grade is an alloy of Ni-W and Co-W and that the concentration of W in the Ni- and Co-binder is 21 and 10 at. %, respectively. In synthetic mine water (SMW), the EIS behavior of WC-Ni(W) at the open circuit potential (OCP) conditions was studied for different exposure periods (up to 120 h). The EIS data fitting estimates low capacitance and high charge transfer resistance (Rct) values, which indicate that the passive film formed on WC-Ni(W) is thin and exhibits high corrosion resistance. At the OCP and potentiostatic-passive conditions, SEM investigations confirm the uncorroded microstructure of the WC-Ni(W). The AR-XPS studies confirmed the formation of an extremely thin (0.25 nm) WO3 passive film is responsible for the high corrosion resistance of WC-Ni(W), at OCP conditions. However, above the transpassive potential, the microstructure instability of WC-Ni(W) was observed, i.e., corroded morphology of both WC grains and Ni(W) binder. The electrochemical parameters, Rct, corrosion current density, and charge density values, confirmed that the WC-Ni(W) is a far better alternative than the WC-Co(W) for application in SMW.

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  • 78.
    Jayamani, Jayaraj
    et al.
    Dalarna University, School of Information and Engineering, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Information and Engineering, Materials Technology.
    Effect of tribo-layer on the corrosion behavior of WC-Co and WC-Ni cemented carbides in synthetic mine water2021In: International journal of refractory metals & hard materials, ISSN 0263-4368, Vol. 100, article id 105621Article in journal (Refereed)
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  • 79. Johansson, M
    et al.
    Samuelsson, J
    Sundell, P.-E
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Radiation Induced Polymerization of Monomers From Renewable Resources2003In: Polymer Preprints, ISSN 0551-4657, Vol. 44, no 1, p. 19-20Article in journal (Refereed)
  • 80.
    Karlsson, P
    et al.
    Karlstads Universitet.
    Eriksson, Jenny
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Gaard, A
    Karlstads Universitet.
    Krakhmalev, P
    Karlstads Universitet.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Bergstrom, J
    Karlstads Universitet.
    Galling resistance evaluation of tool steels by two different laboratory test methods for sheet metal forming2012In: Lubrication Science, ISSN 0954-0075, E-ISSN 1557-6833, Vol. 24, no 6, p. 263-272Article in journal (Refereed)
    Abstract [en]

    Adhesive accumulation of work material on the tool surface is today a major problem in many sheet metal-forming applications. Different laboratory test methods are used to investigate galling with respect to different tool materials, lubricants and process conditions. In the present study, the galling resistance of a modern nitrogen-alloyed powder metallurgy tool steel and an conventional ingot cast D2 type tool steel was evaluated under lubricated sliding against ferritic stainless steel sheets using a commercial pin-on-disc (POD) and an in-house made slider-on-flat-surface (SOFS) tribotester. The investigated tool steels ranked similarly in terms of galling resistanc in both test methods. However, sliding distances to galling were longer for the SOFS equipment due to continuous sliding on new lubricated sheet surface. Best performance was demonstrated by the powder metallurgy tool steel treated to 65?HRC. Differences in friction behaviour and galling initiation were analysed on the basis of the two different working conditions, i.e. open (SOFS) and closed (POD) tribosystems. Copyright (c) 2012 John Wiley & Sons, Ltd.

  • 81.
    Lindgren, Lars-Erik
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Carlsson, Per
    Dalarna University, School of Technology and Business Studies, Material Science.
    Simulation of hydroforming of steel tube made of metastable stainless steel2010In: International journal of plasticity, ISSN 0749-6419, E-ISSN 1879-2154, Vol. 26, no 11, p. 1576-1590Article in journal (Refereed)
    Abstract [en]

    The Olson-Cohen model for strain-induced deformation, further developed by Stringfellow and others, has been calibrated together with a flow stress model for the plastic deformation of metastable stainless steel. Special validation tests for checking one of the limitations of the model have also been carried out. The model has been implemented into a commercial finite element code using a staggered approach for integrating the stress-strain relations with the microstructure model. Results from a thermo-mechanical coupled simulation of hydroforming of a tube have been compared with corresponding experiments. The agreement between experimental results of radial expansion and martensite fraction and the corresponding computed results is good. 

  • 82. Mahade, S.
    et al.
    Björklund, S.
    Govindarajan, S.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Joshi, S.
    Novel wear resistant carbide-laden coatings deposited by powder-suspension hybrid plasma spray: Characterization and testing2020In: Surface and Coatings Technology, ISSN 0257-8972, Vol. 399, article id 126147Article in journal (Refereed)
  • 83.
    Nilsson, Maria
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    An investigation of worn work roll materials used in the finishing stands of the hot strip mill for steel rolling2012Conference paper (Refereed)
    Abstract [en]

    The surface failure characteristics of different work roll materials, i.e. High Speed Steel, High Chromium Iron and Indefinite Chill Iron, used in the finishing stands of a hot strip mill have been investigated using stereo microscopy, 3D optical profilometry, scanning electron microscopy and energy dispersive X-ray spectroscopy. The results show that the surface failure mechanisms of work rolls for hot rolling are very complex, involving plastic deformation, abrasive wear, adhesive wear, mechanical and thermal induced cracking, material transfer and oxidation. Despite the differences in chemical composition and microstructure, the tribological response of the different work roll materials was found to be strongly dependent on the material microstructure and especially the presence and distribution of microstructural constituents, such as the different carbide phases and graphite (in the case of Indefinite Chill Iron). Cracking and chipping of the work roll surfaces, both having a negative impact on work roll wear, are strongly influenced by the presence of carbides, carbide networks and graphite in the work roll surface. Consequently, the amount of carbide forming elements as well as the manufacturing process must be controlled in order to obtain an optimised microstructure and a predictable wear rate.

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    An investigation of worn work roll materials used in the finishing stands of the hot strip mill for steel rolling
  • 84.
    Nilsson, Maria
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    An investigation of worn work roll materials used in the finishing stands of the hot strip mill for steel rolling2013In: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 227, no 8, p. 837-844Article in journal (Refereed)
    Abstract [en]

    The surface failure characteristics of different work roll materials, i.e. High Speed Steel, High Chromium Iron and Indefinite Chill Iron, used in the finishing stands of a hot strip mill have been investigated using stereo microscopy, 3D optical profilometry, scanning electron microscopy and energy dispersive X-ray spectroscopy. The results show that the surface failure mechanisms of work rolls for hot rolling are very complex, involving plastic deformation, abrasive wear, adhesive wear, mechanical and thermal induced cracking, material transfer and oxidation. Despite the differences in chemical composition and microstructure, the tribological response of the different work roll materials was found to be strongly dependent on second phase constituents such as the size, morphology and distribution of different carbide phases and graphite (in the case of Indefinite Chill Iron) which was found to promote cracking. Cracking and chipping of the work roll surfaces, both having a negative impact on work roll wear, are strongly influenced by the presence of carbides, carbide networks and graphite in the work roll surface. Consequently, the amount of carbide forming elements as well as the manufacturing process must be controlled in order to obtain an optimised microstructure and a predictable wear rate.

  • 85.
    Nilsson, Maria
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology. Tribomaterials group, The Ångström Laboratory, Uppsala University, Sweden.
    Microstructural, mechanical and tribological characterisation of roll materials for the finishing stands of the hot strip mill for steel rolling2013In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 307, no 1-2, p. 209-217Article in journal (Refereed)
    Abstract [en]

    The microstructure, mechanical and tribologicalproperties for three different materials, High Speed Steel, High Chromium ironand Indefinite Chill iron, used for hot strip mill work rolls have beenevaluated. Microstructural characterisation was performed using light opticalmicroscopy, scanning electron microscopy and energy dispersive X-rayspectroscopy. The mechanical and tribological properties were evaluated usingmicro Vickers indentation and scratch testing in combination with post-testmicroscopy. The microstructures of the investigated materials were found to berather complex with a number of secondary phases andalso materials with similar nominal composition display significant differenceswith respect to distribution, size and morphology of carbides. Scratch testing,including detection of friction coefficient, acoustic emission and penetrationdepth, gives valuable information concerning the mechanical and tribologicalresponse on a microscopic level of the investigated materials. Type,amount, distribution, size and morphology of the secondary phases in thematerials have a strong impact on the surface deformation and wear mechanismsduring scratching. Cracking and chipping are frequently observed in connectionto the ridges surrounding the scratches. However, cross-sectional analyses ofthe scratched microstructures reveal that cracking of the brittle carbidephases may extend to significant depths, >100 µm, reducing the mechanicalstrength of the material. Based on the results, it is believed that a moreisotropic microstructure, e.g. obtained via a powder metallurgy process, withfiner carbides would result in improved properties and performance in a hotrolling application.

  • 86.
    Nilsson, Maria
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    On the possibility to replace cemented carbide with CVD and PVD coated steel in wire drawing dies – A tribological investigation2009In: Wear of Materials, Las Vegas, 2009Conference paper (Other academic)
    Abstract [en]

    Cemented carbide is today the most frequently used drawing die material in steel wire drawing applications. This is mainly due to the possibility to obtain a broad combination of hardness and toughness thus meeting the requirements concerning strength, crack resistance and wear resistance set by the wire drawing process. However, the increasing cost of cemented carbide in combination with the possibility to increase the wear resistance of steel through the deposition of wear resistant CVD and PVD coatings have increased the interest for steel wire drawing dies during the last years. In the present study, the possibility to replace cemented carbide wire drawing dies with CVD and PVD coated steel drawing dies have been investigated by i) tribological testing, i.e. pin-on-disc and scratch testing, in combination with post-test observations of the tribo surfaces using scanning electron microscopy, energy dispersive X-ray spectroscopy and 3D surface profilometry and ii) steel wire drawing under full scale industrial conditions. In the tests a sodium stearate based soap was used as a lubricant. Of the CVD and PVD coatings evaluated in the tribological tests, a CVD TiC and a PVD CrC/C coating displayed the most promising results, i.e. a combination of high wear resistance and low friction in contact with the steel wire material and consequently these coatings were selected for the steel wire drawing tests. Post-test examination of the worn drawing dies showed that the CrC/C coating displayed a high wear rate while the TiC coating showed a low wear rate but also signs of local cracking and chipping. However, the overall best performance was displayed by a TiC – CrC/C dual layer coating which displayed a limited cracking and chipping tendency although the top CrC/C coating showed a high wear rate. Based on the results obtained, CVD and PVD coatings aimed to provide improved tribological performance of steel wire drawing dies should display a smooth surface topography, a high wear resistance, a high fracture toughness (i.e. a high cracking and chipping resistance) and intrinsic low friction properties in contact with the wire material. Also, the steel substrate used must display a sufficient load carrying capacity and resistance to thermal softening.

  • 87.
    Nilsson, Maria
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Tribological Testing of Some Potential PVD and CVD Coatings for Steel Wire Drawing Dies2010In: Nordtrib 2010, Storforsen, 2010Conference paper (Refereed)
    Abstract [en]

    Cemented carbide is today the most frequently used drawing die material in steel wire drawing applications. This is mainly due to the possibility to obtain a broad combination of hardness and toughness thus meeting the requirements concerning strength, crack resistance and wear resistance set by the wire drawing process. However, the increasing cost of cemented carbide in combination with the possibility to increase the wear resistance of steel through the deposition of wear resistant CVD and PVD coatings have enhanced the interest to replace cemented carbide drawing dies with CVD and PVD coated steel wire drawing dies. In the present study, the possibility to replace cemented carbide wire drawing dies with CVD and PVD coated steel drawing dies have been investigated by tribological characterisation, i.e. pin-on-disc and scratch testing, in combination with post-test observations of the tribo surfaces using scanning electron microscopy, energy dispersive X-ray spectroscopy and 3D surface profilometry. Based on the results obtained, CVD and PVD coatings aimed to provide improved tribological performance of steel wire drawing dies should display a smooth surface topography, a high wear resistance, a high fracture toughness (i.e. a high cracking and chipping resistance) and intrinsic low friction properties in contact with the wire material. Also, the steel substrate used must display a sufficient load carrying capacity and resistance to thermal softening. Of the CVD and PVD coatings evaluated in the tribological tests, a CVD TiC and a PVD CrC/C coating displayed the most promising results.

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  • 88.
    Nilsson, Maria
    et al.
    Dalarna University, School of Technology and Business Studies, Material Science.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Tribological testing of some potential PVD and CVD coatings for steel wire drawing dies2011In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 273, no 1, p. 55-59Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate the possibility to replace cemented carbide wire drawing dies with CVD or PVD coated steel dies. Material pick-up tendency, friction and wear characteristics of four different commercial coatings – CVD TiC and PVD (Ti,Al)N, CrN and CrC/C – in sliding contact with ASTM 52100 bearing steel were evaluated using pin-on-disc testing. The load bearing capacity of the coating/substrate composites was evaluated using scratch testing. The results show that the friction characteristics and material pick-up tendency of the coatings to a large extent is controlled by the surface topography of the as-deposited coatings which should be improved by a polishing post-treatment in order to obtain a smooth surface. Based on the results obtained in this study, three different coatings – CrC/C, TiC and dual-layer TiC/CrC/C – are recommended to be evaluated in wire drawing field tests. CrC/C and TiC are recommended due to their intrinsic low friction properties and material pick-up tendency in sliding contact with steel. The dual-layer is recommended in order to combine the good properties of the two coatings CrC/C (low shear strength) and TiC (high hardness).

  • 89.
    Olovsjö, S
    et al.
    Atlas Copco.
    Johanson, R
    Atlas Copco.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    On the understanding of cemented carbide degradation in rock drilling: the importance of metallographic sample preparation2012In: Proceedings of Euro PM 2012 Congress & Exhibition Vol. 2, 2012Conference paper (Refereed)
  • 90.
    Olovsjö, S
    et al.
    Atlas Copco.
    Johanson, R
    Atlas Copco.
    Falsafi, M
    Atlas Copco.
    Bexell, Ulf
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Surface failure and wear of cemented carbide rock drill buttons: the importance of sample preparation and optimized microscopy settings2013In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 302, no 1-2, p. 1546-1554Article in journal (Refereed)
    Abstract [en]

    The combination of suitable mechanical properties and wear resistance makes cemented carbide one of the most interesting engineering composite materials for tribological applications, such as in rock drilling. Despite the fact that cemented carbide buttons have been used in rock drilling applications for a long time the detailed understanding of the prevailing wear mechanisms is far from complete and wear and breakage of rock drill buttons are still one of the lifetime-limiting factors for rock drill bits. Consequently, further research in this area, including detailed characterization of worn drill button surfaces and sub-surface regions, is needed in order to support the future development of new cemented carbide grades with improved failure and wear resistance. In the present paper, high resolution scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Auger electron spectroscopy (AES) have been used to characterize the wear and failure mechanisms of worn drill buttons and samples exposed to well controlled impact and scratch tests performed in the laboratory. The most important mechanisms of surface failure and wear were found to be severe plastic deformation, cracking, crushing of individual WC grains and mechanical/tribochemical degradation of the Co binder phase including Co depletion. Fracture cross-sectioning under tensile stress-state was found to be the best method for achieving large and reliable sub-surface cross-sections within a short time and to a low cost. The importance of optimized microscopy and spectroscopy settings for enhanced surface sensitivity for the examination of small-scale tribological phenomena is illuminated and discussed.

  • 91.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    A new test method for measuring the galling resistance between metal powders and die tool materials in powder compaction2010In: 14th Nordtrib Conference, Storforsen, Sweden, 2010Conference paper (Refereed)
    Abstract [en]

    The friction characteristics and galling resistance between metal powder and die tool material in metal powder compaction is of outmost importance since they will influence the porosity and surface quality of the green body and consequently the porosity, tolerances and surface quality of the final sintered product. In the present study, a new test method for evaluating the tribological performance of die tool materials aimed for powder compaction is presented. The test method is based on controlled scratch testing using a commercial scratch tester but instead of the commonly used Rockwell C diamond stylus a sample holder with a small green body of compacted powder particles is drawn over the surface in a well controlled multi pass linear reciprocating sliding contact. The capability of the test method was evaluated for different types of tool materials including two PVD coatings in contact with different types of metal powders to determine the friction characteristics and the adhesion and material transfer tendency at the sliding interface. Post-test examination of the tool surfaces using FEG-SEM, EDS and 3D surface profilometry were performed in order to evaluate the mechanisms controlling the friction behavior and the material transfer tendency.

  • 92.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    A new test method for measuring the galling resistance between metal powders and die tool materials in powder compaction2011In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 273, no 1, p. 49-54Article in journal (Refereed)
    Abstract [en]

    The friction characteristics and galling resistance between metal powder and die tool material in metal powder compaction is of outmost importance since they will influence the porosity and surface quality of the green body and consequently the porosity, tolerances and surface quality of the final sintered product. In the present study, a new test method for evaluating the tribological performance of die tool materials aimed for powder compaction is presented. The test method is based on controlled scratch testing using a commercial scratch tester but instead of the commonly used Rockwell C diamond stylus a sample holder with a small green body of compacted powder particles is drawn over the surface in a well controlled multi pass linear reciprocating sliding contact. The capability of the test method was evaluated for different types of tool materials including two PVD coatings in contact with different types of metal powders to determine the friction characteristics and the adhesion and material transfer tendency at the sliding interface. Post-test examination of the tool surfaces using FEG-SEM and EDS were performed in order to evaluate the mechanisms controlling the friction behavior and the material transfer tendency. The results show that the proposed test is a simple and fast method to obtain relevant data regarding the friction and galling characteristics of die tool materials in metal powder compaction. The mechanisms prevailing at the green body/die tool material interface, e.g. cold welding, can easily be monitored by the friction and acoustic emission signals. Of the die tool materials investigated the low friction PVD a-C:Cr coating displayed the lowest friction and highest galling resistance.

  • 93.
    Olsson, Mikael
    Dalarna University, School of Information and Engineering, Materials Technology.
    Characterization of hot-rolled and annealed oxides on 2507 stainless steel – Microstructure, chemical composition, mechanical properties and pickling characteristics2021Report (Other academic)
    Abstract [en]

    The surface characteristics of samples of the 2507 super duplex stainless steel with three different surface conditions, i.e. after hot rolling, annealing and blasting plus pickling, respectively, have been investigated. High resolution scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and scratch testing have been used to characterize the oxide scales with respect microstructure, chemical composition, and mechanical properties.

    SEM and EDS-analysis of the oxide scales formed on hot rolled and hot rolled plus annealed samples, show an outer Fe-rich oxide layer and an inner Cr-rich oxide layer close to the interface. While the hot rolled oxide scale displays a relatively porous oxide composed of oxide particles, the hot rolled plus annealed oxide scale displays a more dense, “sintered”, microstructure, i.e. the high temperature during the annealing step promotes a densification of the oxide scale microstructure.

    The outer porous Fe-rich layer shows poor cohesive strength and poor adhesion to the underlying Cr-rich layer. In contrast, the inner more dense Cr-rich layer shows strong adhesion towards the 2507 duplex stainless steel. The dense microstructure and strong adhesion of the inner Cr-rich layer is believed to significantly influence the blasting and pickling characteristics.

  • 94.
    Olsson, Mikael
    Dalarna University, School of Information and Engineering, Materials Technology.
    Characterization of oxide layers formed on pilot plant Steckel rolled 304 stainless steel samples2021Report (Other academic)
    Abstract [en]

    The evolution of oxide scales on 304 austentic stainless steel during Steckel mill rolling has been investigated by performing pilot trials at Swerim Luleå. The influence of Steckel furnace conditions, i.e. temperature, time and excess oxygen, at reheating between subsequent roll passes have been evaluated and the resulting surface structures have been characterized.

    High resolution scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to characterize the oxide scales with respect microstructure and chemical composition. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to analyze the chemical composition at the stainless steel / oxide interface region.

    In common for all Steckell rolled samples investigated was a pronounced rough surface morphology and the surface roughness was found to increase with more iterations of rolling. Also, the amount of oxides in the rolled surface tends to increase with longer heating times and more iterations of rolling. 

    Surface areas, less distorted by the rolling contact, displayed an oxide scale with an outer rather well-defined oxide layer with relatively large grains and an inner, less well defined, oxide layer. EDS-analysis show that the outer oxide mainly consists of Fe2O3, whereas the inner oxide layer corresponds to a chromium rich (Cr,Fe)2O3 oxide combined with areas of partly oxidized stainless steel. ToF-SIMS analysis of the stainless steel / oxide interface region show the presence of B, Ca and Cu in connection to the oxides.

  • 95.
    Olsson, Mikael
    Dalarna University, School of Information and Engineering, Materials Technology.
    Influence of annealing on hot-rolled oxides on 2507 stainless steel2021Report (Other academic)
    Abstract [en]

    The influence of annealing on the oxide scale characteristics of hot rolled samples of 2507 super duplex stainless steel have been investigated using well controlled lab scale annealing experiments. High resolution scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to characterize the oxide scales with respect microstructure and chemical composition.

    SEM and EDS-analysis of the oxide scales after annealing show an outer Fe-rich oxide layer and an inner Cr-rich oxide layer close to the interface. While the hot rolled oxide scale displays a relatively porous oxide composed of oxide particles, the hot rolled plus annealed oxide scale displays a more dense, “sintered”, microstructure.

    The annealing peak temperature was found to have a strong impact on the oxide scale microstructure. The higher peak temperature, 1150 °C, resulted in a significantly denser microstructure with more pronounce, larger grains, as compared with the lower peak temperature, 1100 °C, which resulted in a less dense microstructure. In contrast, the influence of annealing atmosphere, was found to be relatively small.

  • 96.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Influence of tool steel microstructure on the prevailing wear mechanisms in metal powder compaction2011In: Proceednings of the 18th International Conference on Wear of Materials, Philadelphia, USA, 2011Conference paper (Other academic)
  • 97.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    On the use of scratch testing as a model experiment for evaluating the initial wear of cemented carbidein rock drilling2013Conference paper (Refereed)
  • 98.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Surface and wear characteristics of electrical discharge machined (EDM) cemented carbide drawing dies2014In: Jernkontorets Forskning, ISSN 0280-2481Article, review/survey (Other academic)
  • 99.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Material Science.
    Tribologi i samband med pulverkompaktering2011In: Stålforskningsdagar 2011 : materialteknik vid Högskolan Dalarna / [ed] Storck, Joakim, Borlänge, 2011Conference paper (Other academic)
  • 100.
    Olsson, Mikael
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Tribological aspects of conventional wire drawing - A case study2014In: Jernkontorets Forskning, ISSN 0280-2481Article, review/survey (Other academic)
123 51 - 100 of 145
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