Evaluation of the plastic deformation behavior of modified 100Cr6 steels with increased fractions of retained austenite using cyclic indentation tests

Abstract

Abstract In highly loaded components, such as roller bearings, early failures may occur due to microstructural defects. Thus, a higher defect tolerance of the material can improve the fatigue lifetime. To produce steels with high defect tolerance, innovative alloying concepts, and a sound knowledge of the influence of heat treatment parameters on the resultant mechanical properties is indispensable. Consequently, two bearing steels based on 100Cr6 with different silicon contents were investigated to achieve relatively high retained austenite (RA) fractions, which are assumed to increase the defect tolerance at cyclic loading. To understand the relation between bainitic heat treatment and mechanical characteristics, the resultant RA fractions, Vickers hardness, microhardness, and cyclic hardening exponent CHT eII, which correlates to defect tolerance of metallic materials, were determined for differently heat-treated conditions. Based on the statistical design of experiments and measurements obtained with X-ray diffraction and cyclic indentation testing, regression calculations were conducted. Pertaining to the results of the regression analyses, the heat treatment parameterizations of these steels were specifically determined for certain desired property combinations within the boundaries investigated. Therefore, the temperatures used in the austenitizing and bainitizing procedures have shown the highest influence on the mechanical characteristics and the RA fraction of both steels.