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Modeling and Simulation for Material Selection and Mechanical Design Part 12

Tham khảo tài liệu 'modeling and simulation for material selection and mechanical design part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | and the workpiece under test to the short-time tensile yield strength of the softer contact body at the test temperature. The value of t is simply a measure of the resistance of the joint to shear. The friction condition at the surface of a cutting tool will be similar to that for which the value of t was measured. The results of the wear resistance tests are given in Fig. 6. As can be seen the wear resistance of HSS tools is 2.0-3.5 times lower than that of DCPM tools. This reduction was associated with a significantly lower friction parameter of DCPM compared to HSS Fig. 7 and a broadening of the range of normal friction Fig. 6 . Within the normal friction range the rate of wear for DCPM is much lower than that for HSS Fig. 6 curves 1-3 . While the hardness and heat resistance values of the HSS T15 and DCPM are similar the wear resistance of the latter is significantly higher Table 3 . In our opinion the lower wear intensity of the DCPM-tool material is related to the presence of titanium carbides in the structure and their subsequent transformation to oxygen-rich compounds during cutting. When studied by secondary ion mass spectroscopy SIMS the analysis of typical wear craters revealed the formation of oxygen-containing phases. The data in Fig. 8 demonstrate that the transformation of titanium carbide into an oxygen-containing phase starts in the initial stage of wear during the running-in process Fig. 8a . With further operation there is increased surface oxide formation at the bottom of the wear crater. This process is accompanied by stabilization of the wear processes Fig. 6 and 8b c and an expansion of the normal friction range. Evidently this is determined by the phenomenon of self-organization that is connected with the emergence of secondary structures titanium-oxygen compounds which play the role of stable solid lubricants 25 . Figure 6 The dependence of the flank wear value of cutting tools on the cutting time 1 HSS M2 2 HSS T15 3 DCPM. Turning test .