409 Cr-Mo 鋼の焼戻脆化と水素脆化

概要

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A large 3.5 inch thick compact tension specimens (CT) were hydrogen charged in an extra high capacity autoclave and long time crack growth tests were conducted in the air to simulate the hydroprocessing reactor at shutdown. It was confirmed that the hydrogen charged large specimen held such enough hydrogen content for a long time that is enough to determine a slow stable crack growth rate or delayed fracture behavior. The recent generation steel with high purity, less temper embrittlement susceptibility, showed sub-critical flaw growth over 10days. On the other hand, temper embrittled, old generation steel showed fast fracture phenomenon at very low stress intensity factor (=K_<IC-H>) which is below the fracture toughness without hydrogen chraged condition (=K_<IC->). This fast fracture phenomenon occurred at about 10% of the K_<IC> at room temperature and about 50% of the K_<IC> at 86℃. The threshold stress intensity factor for crack growth (=K_<IH>) made no difference between old generation steel and recent generation steel above 20℃.
一般社団法人日本機械学会の論文
2002-10-05