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Bexell, Ulf
Publications (6 of 6) Show all publications
Saketi, S., Östby, J., Bexell, U. & Olsson, M. (2019). A methodology to systematically investigate the diffusion degradation of cemented carbide during machining. Materials, 12(14), Article ID 2271.
Open this publication in new window or tab >>A methodology to systematically investigate the diffusion degradation of cemented carbide during machining
2019 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 14, article id 2271Article in journal (Refereed) Published
Abstract [en]

Using Ti6Al4V as a work material, a methodology to systematically investigate the diffusion degradation of cemented carbide during machining is proposed. The methodology includes surface characterization of as-tested worn inserts, wet etched worn inserts, metallographic cross-sectioned worn inserts as well as the back-side of the produced chips. Characterization techniques used include scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Auger electron spectroscopy (AES) and time of flight secondary ion mass spectroscopy (ToF-SIMS).

The results show that the characterization of wet etched worn inserts give quick and useful information regarding the diffusion degradation of cemented carbide, in the present work the formation of a fine crystalline W layer (carbon depleted WC layer) at the tool / work material interface. The present study also illuminates the potential of AES analysis when it comes to analyzing the degradation of cemented carbide in contact with the work material during machining. The high surface sensitivity in combination with high lateral resolution makes it possible to analyze the worn cemented carbide surface on a sub-µm level. Especially AES sputter depth profiling, resulting in detailed information of variations in chemical composition across interfaces, is a powerful tool when it comes to understanding diffusion wear. Finally, the present work illustrates the importance of analyzing not only the worn tool but also the produced chips. An accurate characterization of the back-side of the chips will give important information regarding the wear mechanisms taking place at the tool rake face / chip interface. Surface analysis techniques such as AES and ToF-SIMS are well suited for this type of surface characterization.

Keywords
Turning, Ti6Al4V, Wear, Tool, Chip, SEM, AES, ToF-SIMS
National Category
Materials Engineering
Research subject
Steel Forming and Surface Engineering
Identifiers
urn:nbn:se:du-29661 (URN)10.3390/ma12142271 (DOI)000480454300059 ()31311114 (PubMedID)2-s2.0-85070464240 (Scopus ID)
Available from: 2019-03-15 Created: 2019-03-15 Last updated: 2019-08-29Bibliographically approved
Saketi, S., Bexell, U., Östby, J. & Olsson, M. (2019). On the diffusion wear of cemented carbide in the turning of 316L austenitic stainless steel. Wear, 430-431, 202-213
Open this publication in new window or tab >>On the diffusion wear of cemented carbide in the turning of 316L austenitic stainless steel
2019 (English)In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 430-431, p. 202-213Article in journal (Refereed) Published
Abstract [en]

The present study focuses on the wear and wear mechanisms of three different cemented carbide grades during orthogonal turning of 316L austenitic stainless steel at different cutting speeds. The influence of WC grain size and cutting speed on the resulting crater and flank wear was evaluated by optical surface profilometry and scanning electron microscopy (SEM). The mechanisms behind the crater and flank wear were characterized on the sub-micrometer scale using high resolution SEM, energy dispersive X-ray spectroscopy (EDS), Auger electron spectroscopy (AES) and time of flight secondary ion mass spectrometry (ToF-SIMS) of the worn cutting inserts and the produced chips.

The results show that the wear rate of cemented carbide drastically increases with increasing cutting speed and that the wear is dependent on the WC grain size; i.e. the crater wear decreases with increasing WC grain size while the flank wear increases with increasing WC grain size. High resolution SEM, AES and ToF-SIMS analysis of the worn cemented carbide within the crater and flank wear regions reveal that the degradation of cemented carbide at higher cutting speeds is mainly controlled by diffusion wear of the WC-phase. This is confirmed by ToF-SIMS analysis of the back-side of stainless steel chips which reveals the presence of a 10 nm thin W-containing oxide film. The results are discussed and interpreted in the light of the conditions prevailing at the tool-chip interface.

Keywords
Cemented carbide, 316 L austenitic stainless steel, turning, diffusion wear, SEM, AES, ToF-SIMS
National Category
Materials Engineering
Research subject
Steel Forming and Surface Engineering
Identifiers
urn:nbn:se:du-29660 (URN)10.1016/j.wear.2019.05.010 (DOI)000471597300021 ()
Available from: 2019-03-15 Created: 2019-03-15 Last updated: 2020-06-01Bibliographically approved
Saketi, S., Östby, J., Bexell, U. & Olsson, M. (2018). Wear behaviour of two different cemented carbide grades in turning 316 L stainless steel. Paper presented at THERMEC 2018. Materials Science Forum, 941, 2367-2372
Open this publication in new window or tab >>Wear behaviour of two different cemented carbide grades in turning 316 L stainless steel
2018 (English)In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 941, p. 2367-2372Article in journal (Refereed) Published
Abstract [en]

Cemented carbides are the most common cutting tools for machining various grades of steels. In this study, wear behavior of two different cemented carbide grades with roughly the same fraction of binder phase and carbide phase but different grain size, in turning austenitic stainless steel is investigated. Wear tests were carried out against 316L stainless steel at 180 and 250 m/mincutting speeds. The worn surface of cutting tool is characterized using high resolution scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), Auger electron spectroscopy (AES) and 3D optical profiler.The wear of cemented carbide in turning stainless steel is controlled by both chemical and mechanical wear. Plastic deformation, grain fracture and chemical wear is observed on flank and rake face of the cutting insert. In the case of fine-grained, the WC grains has higher surface contact with the adhered material which promotes higher chemical reaction and degradation of WC grains, so chemical wear resistance of the composites is larger when WC grains are larger. The hardness of cemented carbide increase linearly by decreasing grain size, therefore mechanical wear resistance of the composites is larger when WC grains are smaller.

Keywords
Cemented carbide, Turning, Stainless steel, Chemical wear, plastic deformation
National Category
Materials Engineering
Research subject
Steel Forming and Surface Engineering
Identifiers
urn:nbn:se:du-29312 (URN)10.4028/www.scientific.net/MSF.941.2367 (DOI)000468152500390 ()2-s2.0-85064069653 (Scopus ID)
Conference
THERMEC 2018
Available from: 2019-01-20 Created: 2019-01-20 Last updated: 2019-06-10Bibliographically approved
Saketi, S., Bexell, U. & Olsson, M. (2018). Wear mechanism of cemented carbide cutting tool in the turning of 316L stainless steel. In: : . Paper presented at The 18th Nordic Symposium on Tribology – NORDTRIB 2018 18-21 June 2018, Uppsala University, Uppsala, Sweden.
Open this publication in new window or tab >>Wear mechanism of cemented carbide cutting tool in the turning of 316L stainless steel
2018 (English)Conference paper, Published paper (Refereed)
Keywords
Cemented carbide; stainless steel 316 L; turning; SEM; AES
National Category
Engineering and Technology
Research subject
Steel Forming and Surface Engineering
Identifiers
urn:nbn:se:du-28052 (URN)
Conference
The 18th Nordic Symposium on Tribology – NORDTRIB 2018 18-21 June 2018, Uppsala University, Uppsala, Sweden
Available from: 2018-06-29 Created: 2018-06-29 Last updated: 2019-03-27Bibliographically approved
Rehnlund, D., Lindgren, F., Böhme, S., Nordh, T., Zou, Y., Pettersson, J., . . . Nyholm, L. (2017). Lithium trapping in alloy forming electrodes and current collectors for lithium based batteries. Energy & Environmental Science, 10(6), 1350-1357
Open this publication in new window or tab >>Lithium trapping in alloy forming electrodes and current collectors for lithium based batteries
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2017 (English)In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 10, no 6, p. 1350-1357Article in journal (Refereed) Published
Abstract [en]

Significant capacity losses are generally seen for batteries containing high-capacity lithium alloy forming anode materials such as silicon, tin and aluminium. These losses are generally ascribed to a combination of volume expansion effects and irreversible electrolyte reduction reactions. Here, it is shown, based on e.g. elemental analyses of cycled electrodes, that the capacity losses for tin nanorod and silicon composite electrodes in fact involve diffusion controlled trapping of lithium in the electrodes. While an analogous effect is also demonstrated for copper, nickel and titanium current collectors, boron-doped diamond is shown to function as an effective lithium diffusion barrier. The present findings indicate that the durability of lithium based batteries can be improved significantly via proper electrode design or regeneration of the used electrodes. © The Royal Society of Chemistry 2017.

National Category
Materials Engineering
Research subject
Steel Forming and Surface Engineering
Identifiers
urn:nbn:se:du-25634 (URN)10.1039/c7ee00244k (DOI)000403320300006 ()2-s2.0-85021990496 (Scopus ID)
Funder
Swedish Energy AgencySwedish Research Council, 2012-4681Swedish Research Council, 2015-04421
Available from: 2017-07-25 Created: 2017-07-25 Last updated: 2017-08-21Bibliographically approved
Rhenlund, D., Lindgren, F., Böhme, S., Nordh, T., Zou, Y., Pettersson, J., . . . Leif, N. (2016). Improved Cycling Stability of Conversion and Alloying Anodes through the use of Nanomaterials. In: : . Paper presented at The 18th International Meeting on Lithium Batteries, IMLB 2016, Chicago, USA, 19 – 24 June, 2016.
Open this publication in new window or tab >>Improved Cycling Stability of Conversion and Alloying Anodes through the use of Nanomaterials
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2016 (English)Conference paper, Poster (with or without abstract) (Refereed)
National Category
Other Chemical Engineering
Research subject
Steel Forming and Surface Engineering
Identifiers
urn:nbn:se:du-23802 (URN)
Conference
The 18th International Meeting on Lithium Batteries, IMLB 2016, Chicago, USA, 19 – 24 June, 2016
Available from: 2016-12-30 Created: 2016-12-30 Last updated: 2017-01-01Bibliographically approved
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