| 31. |
- Olsson, Mikael
(författare)
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Tribologi i samband med pulverkompaktering
- 2011
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Ingår i: Stålforskningsdagar 2011 : materialteknik vid Högskolan Dalarna. - Borlänge.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 32. |
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| 33. |
- Olsson, Mikael
(författare)
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Tråddragningens tribologi
- 2015
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Ingår i: Nordisk Trådteknisk Förening. - : NTTF.
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 34. |
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| 35. |
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| 36. |
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| 37. |
- Saketi, Sara
(författare)
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Investigation of topography, adhesion and diffusion in sliding contacts during steel and titanium alloy machining
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the present thesis work is to increase the fundamental knowledge of the tribological contact between the cutting tool and the work material in three different cutting operations, i.e. hard milling of cold work tool steels, turning in 316L stainless steel and turning in Ti6Al4V alloy, respectively. The influence of cutting parameters and tool surface topography on the initial material transfer tendency and resulting wear and wear mechanisms were investigated under well controlled cutting conditions. High resolution scanning electron microscopy (SEM) and surface analysis, including energy dispersive X-ray spectroscopy (EDS), Auger electron spectroscopy (AES) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), were used in order to characterize the worn cutting tools on a sub-µm scale and deepen the understanding of the wear mechanisms prevailing at the tool / work material interface. The characterization work includes the analysis of worn tool surfaces as well as cross-sections of these. Also, the back side of collected chips were analysed to further understand the contact mechanisms between the tool rake face and chip.The results show that the transfer tendency of work material is strongly affected by the surface topography of the rake face and that an appropriate pre- and post-coating treatment can be used in order to reduce the transfer tendency and the mechanical interaction between the mating surfaces. The continuous wear mechanisms of the cutting tools were found to be dependent on the work materials and the cutting parameters used. In hard milling of cold work tool steels, polycrystalline cubic boron nitride shows a combination of tribochemical wear, adhesive wear and mild abrasive wear. In the turning of 316L stainless steel and Ti6Al4V alloy, using medium to high cutting speeds/feeds, the wear of cemented carbide is mainly controlled by diffusion wear of the WC phase. Interestingly, the diffusion wear processes differ between the two work materials. In contact with 316L stainless steel crater wear is controlled by atomic diffusion of W and C into the passing chip. In contact with Ti6Al4V crater wear is controlled by the diffusion of C into a transfer work material layer generating a W-rich and TiC interfacial layer which repeatedly is removed by the passing chip. The experimental work and results obtained illustrates the importance of in-depth characterization of the worn surfaces in order to increase the understanding of the degradation and wear of tool materials and coatings in metal cutting operations.
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| 38. |
- Surreddi, Kumar Babu, 1977-, et al.
(författare)
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Characterization of surface degradation and wear damage Of cemented carbide in rock drilling
- 2018
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Ingår i: The 18th Nordic Symposium on Tribology – NORDTRIB 2018.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this work, worn top hammer drill bit buttons after underground drifting in Granodiorite are analysed using scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and electron backscatter diffraction (EBSD) to understand the dominant surface failure and wear mechanisms on the flank wear land region, i.e. the outer side of the gauge row cemented carbide buttons. SEM shows that the worn surface of the flank wear land is partly covered with islands of a thin rock material transfer layer and that the exposed cemented carbide show deformed, cracked and fragmented WC grains. AES gives that the transferred rock material is mainly located on the surface but may penetrate into cemented carbide microstructure to a depth of 1-2 WC grain diameters. Finally, EBSD reveals that the deformation of the cemented carbide in the flank wear land region is located to a thin zone, about ~10 μm in depth.
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| 39. |
- Surreddi, Kumar Babu, 1977-, et al.
(författare)
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Wear of cemented carbide nibs in steel wire drawing
- 2018
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Ingår i: The 18th Nordic Symposium on Tribology – NORDTRIB 2018.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The tribological interaction between a cemented carbide drawing die and a steel wire under lubricated wire drawing conditions has been characterized using 3D optical surface profilometry, scanning electron microscopy and energy dispersive X-ray spectroscopy. The results show that wear of the cemented carbides mainly is located to three different wear zones, i) at the entrance of the reduction zone, ii) at the exit of the reduction zone/ entrance of the bearing zone and iii) at the exit of the bearing zone. In the first wear zone, wear of the cemented carbide occurs on a WC grain size level and is controlled by plastic deformation, cracking and fragmentation of individual WC grains. In the second wear zone, wear of the cemented carbide is controlled by chipping of small WC/Co composite fragments resulting in craters, ~ 10μm in diameter.
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| 40. |
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