2 1/4Cr-1Mo 鋼の水素脆性に及ぼす焼もどし脆化の影響

概要

論文の詳細を見る
The effect of temper embrittlement on hydrogen embrittlement was investigated on 2 1/4Cr-1Mo steel for high-temperature and high-pressure vessels. The threshold stress intensity, K_<IH>, for hydrogen-stress cracking (HSC) was determined by immersing modified 1T-WOL specimens with and without step-cooling heat treatment into a H_2S-saturated 0.5% acetic acid solution. The results obtained are summarized as follows : (1) Temper embrittlement enhances the susceptibility to hydrogen embrittlement of grain boundary. (2) The K_<IH> value decreases with increase of fracture surface transition temperature, νTrs(℃), grain size, d(mm), and hydrogen content, C(ppm). (3) The K_<IH> value has a good correlation with the hydrogen embrittlement susceptibility factor, Φ, denoted by Φ=0.05d^<-1/5>(νTrs+133)+4(logd^2+C^<1/3>) (4) On the basis of the relation between K_<IH> and Φ and some diagrams to determine the maximum residual hydrogen content in a pressure vessel wall, a safety estimation method for preventing HSC during hydrostatic test of pressure vessels after the service was proposed.
1984-02-01