3.3 Wear results from G65 and CT test
The wear results from both G65 tests and CT tests are shown in Table 3. In Fig. 13, the wear results have been normalized by the volume loss of the tool steel and multiplied by a factor of 100 For both wear tests, the lowest volume loss was observed in case of the PM steel. In the G65 test, a low wear rate is accomplished by the distribution of small V and Cr carbides which impede selective removal of the matrix. In the CT test, the combination of small V and Cr carbides is not completely able to avoid microcutting of the microstructure, but the volume of removed material is lower compared to the other materials. The ranking of the tool steel and the cast iron is different for the two wear tests. In the G65 test, the tool steel exhibits a higher wear resistance than the cast iron, but the opposite result is found by CT testing. The cast iron, having large Cr carbides, suffers from micro-cracking in case of elevated contact pressures. Such failures of the Cr carbides are, however, not reflected by the measured volume loss as the CT test principle is not a continuous wear process. As the carbides fracture in the sub-surface, one would expect that wear accelerate with time as broken carbides become exposed and removed. Higher wear rates of the cast iron would, therefore, be expected in case the CT testing was to be extended on individual samples.
3.3 Wear results from G65 and CT test
The wear results from both G65 tests and CT tests are shown in Table 3. In Fig. 13, the wear results have been normalized by the volume loss of the tool steel and multiplied by a factor of 100 For both wear tests, the lowest volume loss was observed in case of the PM steel. In the G65 test, a low wear rate is accomplished by the distribution of small V and Cr carbides which impede selective removal of the matrix. In the CT test, the combination of small V and Cr carbides is not completely able to avoid microcutting of the microstructure, but the volume of removed material is lower compared to the other materials. The ranking of the tool steel and the cast iron is different for the two wear tests. In the G65 test, the tool steel exhibits a higher wear resistance than the cast iron, but the opposite result is found by CT testing. The cast iron, having large Cr carbides, suffers from micro-cracking in case of elevated contact pressures. Such failures of the Cr carbides are, however, not reflected by the measured volume loss as the CT test principle is not a continuous wear process. As the carbides fracture in the sub-surface, one would expect that wear accelerate with time as broken carbides become exposed and removed. Higher wear rates of the cast iron would, therefore, be expected in case the CT testing was to be extended on individual samples.
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