Effect of Applied Stress on Temper Embrittlement of 21/4Cr-1Mo Steel

Effect of applied stress on the temper embrittlement was studied using aboratory heats of normalized and tempered 21/4Cr-1Mo steel. Charpy impact tests and tensile tests were performed to assess the embrittlement and scanning electron microscopy and Auger electron spectroscopy were conducted for the analysis of fracture surface. Applied stress and ageing time dependences of the embrittlement at 450°C were investigated. The results showed that applied stress enhanced the embrittlement when the material contained a substantial amount of residual phosphorus which was believed to cause the temper embrittlement.