The Effect of Deep Cryogenic Treatment on Microstructure, Hardness and Wear Behavior of INDRA 5 Cold Work Tool Steel

Abstract

In this study, the effect of cryogenic treatment on microstructure, hardness and wear behavior of cold work tool steel containing 5 wt. % Cr used in the production of cold rollers was investigated. For this purpose, the starting and finishing temperatures of the martensite transformation were determined by dilatometer test (234 °C and -102 °C, respectively). Then, quenched-tempered heat treatment (QT) and quenched-cryogenic heat treatment for 24 hours-temper (DCT) were performed on the samples. In the next phase, microstructure of the samples was evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and their hardness and wear behavior were studied by pin-on- disk wearing machine. In order to determine the wear mechanisms, the level of the wear effect was investigated by SEM. The obtained results showed that in deep cryogenic treatment compared to the quenched-tempered treatment, due to the<br />transformation of retained austenite to martensite, precipitation of fine carbides, increased volume fraction of carbides and more appropriate distribution of these carbides, led to an increase in hardness and wear resistance to 3HRC and 30%, respectively. The study of the worn- out surface and its products showed that the wear mechanism was adhesive wear along with tribochemical wear. Deep cryogenic treatment reduced the amount of adhesive wear.