| A study was made of the effects of carbon and chromium addition on microstructural factors and wear properties of five high speed steel(HSS) rolls manufactured by centrifugal casting method. Based on the basic chemical composition of Fe-2.0C-5.0V-3.0Mo-1.5W-6.2Cr-0.75Si-0.35Mn(wt.%), the rolls were made with varying additions of carbon and chromium in order to examine their respective effects. They were then austenitized at 1050℃, air cooled, and double-tempered at the temperature range from 470℃ to 600℃. A simulation test was carried out using a high-temperature wear tester capable of controlling speed, load, and temperature. The test results revealed that the HSS roll containing a smaller amount of chromium showed the best wear resistance because it contained a number of hard MC carbides. However, it showed a very rough roll surface because of the preferential removal of the matrix and the sticking of the rolled material to the roll surface during the wear process, thereby leading to increase in friction coefficient and rolling force. In order to improve wear resistance with consideration of the roll surface roughness, the increase in the chromium content, i.e., the increase the amount of M_7C₃ carbides which can give good surface roughness, was suggested. |
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