Cryogenic Process Optimization for Medium Carbon Spring Steels

Abstract

Spring steels are extensively used in load bearing elements of road and railway vehicles. The basic microstructure of these parts, which are subjected to high cycle fatigue, is tempered martensite. The improvement of the mechanical properties of these steels can only be achieved by modifying the material microstructure. In the microstructure of steel parts produced in different diameters, the formation of retained austenite and residual stresses is inevitable. For spring steels operating under heavy load, it is very important to remove the residual austenite form. Although the cryogenic treatment process is applied as a standard process for high alloyed and high carbon steels, it is not optimized for low alloy and medium carbon steels. In this study, different types of cryogenic treatment (Deep Cryogenic Treatment (DCT) / Shallow Cryogenic Treatment (SCT)) and tempering applications were carried out on spring steels with different alloying levels. With the outputs obtained from these experiments, optimization of cryogenic process parameters for medium carbon spring steels is aimed.