Abstract
A twin disk-rolling-sliding contact machine was used to investigate the cold wear property of the tool materials, SKD11, Cast-HSS (High Speed Steel), and HIP-HSS. According to the test results, HIP-HSS, which was harder and had smaller carbide particles, showed better wear resistance than the other two materials. A strong correlation was seen between cold wearing, hardness and microstructure, especially carbide size. Through the observations of the wear surface and cross section, the cold wearing mechanism is assumed as follows. Under heavy load conditions, plastic deformation occurs and microcracks initiate from the near-surface material where the carbide particles have broken. Cracks then propagate and finally the near-surface material disintegrate into flakes. Based on these phenomena, new steel pipe reforming rolls were produced using HIP-HSS, which demonstrated four times longer life than conventional SKD11 rolls.
