Effects of Tempering Temperature on Wear Resistance and Surface Roughness of a High Speed Steel Roll

Abstract

The effects of tempering temperature on wear resistance and surface roughness of a high speed steel (HSS) roll manufactured by centrifugal casting method were investigated in this study. Hot-rolling simulation test was carried out using a high-temperature wear tester capable of controlling speed, load, and temperature. The test results revealed that the peak-tempered roll specimen showed the best wear resistance because of its hard matrix. However, its surface roughness deteriorated as the scratching wear proceeded, thereby leading to increase in friction coefficient. In the over-tempered specimens containing numerous fine spherical carbides in the matrix, the abrasive wear occurred predominantly as fine carbides were fallen off from the matrix, and thus the surface roughness was enhanced by the homogeneous wear of both matrix and carbides. These findings suggested that the tempering treatment at temperatures slightly past the peak hardness point would be more desirable in order to improve the wear resistance with consideration of the surface roughness of the HSS roll.