Comparison of Tribological Behavior of Deep Cryogenic Treated Hot Work Tool Steel at Room and High Temperature

Abstract

<span>The deep cryogenic treatment is a complementary operation that is done on a variety of tool steels aimed at improving their abrasion resistance and hardness. In the case of the H13 hot-work steel, which is widely used at high temperatures as a hot-deformation tool, we need to determine the efficiency of subzero treatment on it at the working temperature. In this regard, this paper is focused on effect of deep cryogenic treatment on the wear behavior of H13 hot-work steel at the working temperature. We compared two types of quench-tempered and quenched-subzero-tempered samples in this study. The microstructure of the samples was determined by scanning electron microscopy and their structure was determined by X-ray diffraction device after the cryogenic treatment. The wear test was performed at work temperature of 600 °C (die temperature in the iron-based alloys forging process). The results indicated that the highest hardness rate has occurred in the quenched-subzero-tempered conditions, which amount is about 26% higher than that of the quenched-tempered in the oil. Applying quenched-subzero-tempered operations has reduced the percentage of residual austenite by 10%. Also, the fine, dispersed, and uniform sediments in this sample are more observed than the quenched-tempered samples. The improved weight lose were respectively achieved by 50% and 44% at temperatures of 25 and 600 °C. The evaluation of the wear surfaces indicates that the abrasion dominant mechanism is close-fitting and tribochemical.</span>