材料期刊网

将Ｘ７０管线钢单边预裂纹试件在０．５ ｍｏｌ/Ｌ Ｈ２ＳＯ４溶液中充氢至饱和，然后在空气中拉伸至断裂，获得裂纹体的条件断裂韧性。当固溶氢含量 ＜ ０．９７８×１０－４ ｍａｓｓ％时，氢使裂纹体断裂韧性提高１１．８％；固溶氢含量 ＞ ０．９７８×１０－４ ｍａｓｓ％时，裂纹体断裂韧性随氢含量线性降低；断裂特征为典型的韧窝断口，但韧窝直径随氢含量的增加逐渐变小。在动态充氢条件下进行慢应变速率拉伸实验，氢使裂纹体断裂韧性显著降低，裂纹体断裂韧性随充氢电流密度Ｉ的幂函数而线性降低，断裂特征为典型的准解理断口。

The pre-cracking specimens of X70 pipeline steel were pre-charged with hydrogen in 0.5mol/L H2SO4 solution,and then extended in air to fracture in order to obtain the fracture roughness of the cracking bodies. When the hydrogen concentration was less than 0.978×10-4 mass%,the hydrogen made the fracture roughness in?鄄crease 11.8%. When the hydrogen concentration was more than 0.978×10-4 mass%, the hydrogen made the frac?鄄ture roughness decrease according to the linear relationship of the hydrogen concentration.The fracture surfaces were characteristic of the dimple and the diameter of the dimple varied smaller with the gradual increase of the hydrogen concentration. On the slow strain rate tension tests with dynamically charging with hydrogen in 0.5mol/L H2SO4 solution,the fracture roughness decreased considerably.The fracture roughness for hydrogen-induced cracking decreased linearly with exponential function of charging current density. The hydrogen-induced fracture had appearance of the quasi-cleavage.