Effect of solution-treated temperature on hydrogen embrittlement of 17-4 PH stainless steel

The effect of solution-treated temperature on hydrogen embrittlement of 17-4 PH stainless steel is investigated. Electrochemical hydrogen charging and slow strain rate tensile tests were used to calculate the index of susceptibility to hydrogen embrittlement. Fracture morphology and microstructure of the steel were observed by scanning electron microscope, optical microscope and transmission electron microscope. The results show that as the solution-treated temperature increases from 890°C to 1090°C, the susceptibility to hydrogen embrittlement of the steel firstly decreases and then increases. Based on the experimental results, it is deemed that the susceptibility to hydrogen embrittlement is determined by the result of a combined effect of the prior austenite grain size and copper precipitation. In addition, hydrogen permeation test result reveals that hydrogen-induced cracking of 17-4 PH steel is closely related to the diffusion behavior of hydrogen in alloys.