du.sePublikationer
Ändra sökning
Avgränsa sökresultatet
1 - 7 av 7
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • chicago-author-date
  • chicago-note-bibliography
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Nilsson, Maria
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Tribology in Metal Working2012Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis focuses on the tribological performance of tool surfaces in two steel working operations, namely wire drawing and hot rolling. In all forming operations dimensions and surface finish of the products are of utmost importance. Forming basically includes three parts – forming conditions excluded – that may be changed; work material, tool and (possibly) lubricant. In the interface between work material and tool, the conditions are very aggressive with – generally or locally – high temperatures and pressures. The surfaces will be worn in various ways and this will change the conditions in the process. Consequently, the surface finish as well as the dimensions of the formed product may change and in the end, the product will not fulfil the requirements of the customer. Therefore, research and development in regard to wear, and consequently tribology, of the forming tools is of great interest.

    The investigations of wire drawing dies focus on coating adhesion/cohesion, surface characteristics and material transfer onto the coated steel both in laboratory scale as well as in the wire drawing process. Results show that it in wire drawing is possible to enhance the tribological performance of drawing dies by using a lubricant together with a steel substrate coated by a polished, dual-layer coating containing both hard and friction-lowering layers.

    The investigations of hot rolling work rolls focus on microstructure and hardness as well as cracking- and surface characteristics in both laboratory scale and in the hot strip mill. Results show that an ideal hot work roll material should be made up of a matrix with high hardness and a large amount of complex, hard carbides evenly distributed in the microstructure. The surface failure mechanisms of work rolls are very complex involving plastic deformation, abrasive wear, adhesive wear, mechanical and thermal induced cracking, material transfer and oxidation.

    This knowledge may be used to develop new tools with higher wear resistance giving better performance, lower costs and lower environmental impact.

  • 2.
    Nilsson, Maria
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    An investigation of worn work roll materials used in the finishing stands of the hot strip mill for steel rolling2012Konferensbidrag (Refereegranskat)
    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.

  • 3.
    Nilsson, Maria
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    An investigation of worn work roll materials used in the finishing stands of the hot strip mill for steel rolling2013Ingår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology, ISSN 1350-6501, E-ISSN 2041-305X, Vol. 227, nr 8, s. 837-844Artikel i tidskrift (Refereegranskat)
    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.

  • 4.
    Nilsson, Maria
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik. 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 rolling2013Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 307, nr 1-2, s. 209-217Artikel i tidskrift (Refereegranskat)
    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.

  • 5.
    Nilsson, Maria
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    On the possibility to replace cemented carbide with CVD and PVD coated steel in wire drawing dies – A tribological investigation2009Ingår i: Wear of Materials, Las Vegas, 2009Konferensbidrag (Övrigt vetenskapligt)
    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.

  • 6.
    Nilsson, Maria
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Tribological Testing of Some Potential PVD and CVD Coatings for Steel Wire Drawing Dies2010Ingår i: Nordtrib 2010, Storforsen, 2010Konferensbidrag (Refereegranskat)
    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.

  • 7.
    Nilsson, Maria
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Olsson, Mikael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Tribological testing of some potential PVD and CVD coatings for steel wire drawing dies2011Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 273, nr 1, s. 55-59Artikel i tidskrift (Refereegranskat)
    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).

1 - 7 av 7
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • chicago-author-date
  • chicago-note-bibliography
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf