The Effect of Carburizing Variables on Residual Stresses in Hardened Chromium Steel

By calculating the cooling rate during quenching and calculating Ms temperatures from measured carbon contents and carbide quantities in depth, curves indicating the time at which transformation began in cylindrical specimens were determined. Using these curves, measured residual stress distributions were analyzed. Transformation started at a depth near the carburized case-core boundary, determined by the carbon gradient and cooling rate. It then proceeded out to the case and into the core, generating high internal stresses in these areas. The sequence of transformation was responsible for oscillations in the final residual stress distribution, with maximum compression occurring outside the case-core boundary.