Effect of Deep Cryogenic Treatment on Microstructure, Mechanical Properties, and Residual Stress of AISI 52100 Bearing Steel
Abstract
This study covers tensile, fatigue, and material characterization tests on AISI 52100 material. In this study, the effects of deep cryogenic treatment (DCT) applied to the material at different holding hours on the mechanical properties (macro-hardness, micro-hardness, yield and tensile strength), microstructure, change in residual austenite volume ratio and residual stress values were examined. Five different holding times (12, 24, 36, 48 and 60h) were employed to the bearing steel to compare the effect of holding time in the deep cryogenic temperature. The metallographic findings showed that the deep cryogenic treatment (DCT) decreased the retained austenite and hence improved the micro-hardness, due to more homogenized carbide distribution and the elimination of the retained austenite, compared with the conventional heat treatment (CHT). The improvements in the maximum tensile strength of DCT specimens were 5.2%, 3.6%, 3.35%, 2.9% and 1.7% for DCT-36, DCT-48, DCT-60, DCT-24 and DCT-12, respectively. The highest value in macro and micro-hardness was obtained with the DCT-36 sample. It was observed that the best fatigue performance was obtained with the DCT-12 sample. In addition, the fatigue life of DCT-12, DCT-36, DCT-24, DCT-48 and DCT-60 samples increased by 122%, 108%, 100%, 40% and 12%, respectively, compared to the CHT sample. The lowest stress values for both axial and circumferential tensile residual stresses were obtained in the DCT-12 sample.
