环境诱导氢致断裂的非比例过载效应

THE EFFECT OF NON-PROPORTIONAL OVERLOADING ON ENVIRONMENTAL HYDROGEN INDUCED FRACTURE

研究连续充氢条件下短时非比例过载对４２ＣｒＭｏ钢／０．５ｍｏｌ／ＬＨ２ＳＯ４体系氢致断裂（ＨＩＦ）寿命的影响。结果表明：短时非比例过载对于ＨＩＦ的影响较之比例过载更为严重。究其原因，从非比例过载引起裂纹偏折、残余压应力、位错屏蔽和过载损伤等方面进行了分析与讨论。

he effect of short period non-proportional overloading on environmental hydrogen induced fracture life of 42CrMo steel in 0.5 mol/L H2SO4solution was studied under continuous hydrogen charging condition.A weight loading system was employed in the study. Experimental results showed that non-proportional overloading might cause more severe retardation than proportional one. The mechanisms responsible for retardation of subsequent crack growth were discussed. The influence of overloading was dependent on integral effect of the following faCtors: (1) crack branching,which decreassed significantly the crack growth driving force; (2) residual compressive stresses existing in the overloading plastic zone, which reduced effective stress intensity factors; (3) effect of dislocation shielding on retarding hydrogen transportation as well as accumulation; and (4) overloading damage, which might shorten HIF life.