Effects of Hydrogen and Stress on Temper Embrittlement of 2.25Cr-1Mo Steel Using Series Electrochemical Hydrogen Charging Method

A series electrochemical hydrogen charging method was developed, which could be effectively carried out with several samples at the same time. The new method could availably resolve the problem of uneven hydrogen concentration in the sample charged by the previous method of electrochemical hydrogen charging. 2.25Cr-1Mo steel samples in 4 kinds of state, i.e., temper embrittlement for 200 h, temper embrittlement for 200 h under stress, hydrogen charging after temper embrittlement for 200 h and hydrogen charging after temper embrittlement for 200 h under stress were prepared. Before the sample preparation, a 2.25Cr-1Mo block had been put in the running hydrogenation reactor for 100 000 h and then the de-brittled steel was embrittled at 468 ℃ for 200 h. Impact tests and Auger electron spectroscopy were performed for the 4 states of samples. The results show that stress could reduce the degree of temper embrittlement of the 2.25Cr-1Mo steel, while hydrogen charging could accelerate it. The reason was phosphous segregation.