Hydrogen environment embrittlement of SCM440 steel in high-pressure hydrogen at room temperature

Abstract

Hydrogen environment embrittlement (HEE) of the heat-treated SCM440 steels was investigated at room temperature with the strain rate range from 4.2×10 -5 to 4.2×10 -2 s -1 by using specially designed testing equipment for materials under highpressure hydrogen of 70 MPa. Hydrogen showed marked effect on the tensile properties of SCM440 steel. The HEE of SCM440 steel increased with increasing hydrogen pressure and increased with decreasing strain rate. HEE increased from the annealed to the normalized and then to the quenched steel. HEE of the quenched-tempered SCM440 steel decreased with increasing the tempering temperture. It was observed that hydrogen causes quasi-cleavage fracture for annealed and normalized steel, and the mixture of the quasi-cleavage fracture and intergranular fracture for the quenched steel. © 2005 The Japan Institute of Metals.