Effects of Deep Cryogenic Treatment on Wear Resistance and Structure of GB 35CrMoV Steel

Wear resistance of metallic materials can be effectively improved by the deep cryogenic treatment. In this study, different deep cryogenic treatment conditions were considered, with different soaking durations between quenching and tempering. The main objective is investigating the effects of deep cryogenic treatment and exploring the relationship between the mechanical properties and the microstructure of GB 35CrMoV steel. Hardness and relative wear ratios of samples were evaluated by the Vickers-hardness test and the pin-on-disk wear test, respectively. Worn surface was characterized by a non-contact optical surface profiler. Microstructures were studied by scanning electron microscope (SEM) and X-ray diffraction (XRD). Significant improvements in hardness and wear resistance are observed for higher cryogenic soaking times; the root mean square deviation (RMS) parameter (Sq) was employed to evaluate the effect of deep cryogenic treatment on the worn surface roughness; the improvements were ascribed to the precipitated carbides. The mechanism can be interpreted not only as the promoted effect of deep cryogenic treatment in the decomposition kinetics of martensite, but also as the acceleration on the Ostwald ripening process