Investigation on High Temperature Wear Resistance of Cryotreated Hot Work Tool Steel

Deep sub-zero treatment is a complementary operation performed on all types of tool steels, carbonized and high-speed steels to improve wear resistance and hardness. among these tool steels, h13 is a hot work tool steel that have an extended application in industry as a hot deforming tool. this paper investigates the wear behavior of deep cryogenic treated h13 hot work steel at operating temperature. two quench-tempered and quench-subzero-tempered samples are compared. the microstructures of the specimens were determined by scanning electron microscopy, and the structures were determined by x-ray diffraction. vickers hardness used for determining hardness after each treatment. the wear test was carried out at 250°c (mold temperature on forging of copper base alloys). finally, the wear surface was examined by scanning electron microscope equipped with eds analyzer. the results show that the highest hardness was in quench-subzero-tempered condition which is about 26% higher than the quench-tempered in oil conditions. this is due to the formation of fine, dispersed and uniform precipitates and higher martensite percentage in quench-subzero-tempered sample compared to quench-tempered sample. quench-subzero-temper operation reduced the residual austenite percentage by 10% and improved the wear properties by 36% at 250° c. examination of wear surfaces indicates the presence of oxidized surfaces adhered to the wear surface in the form of abrasive particles. these oxide levels were lower in quench-subzero-tempered sample than quench-tempered sample.