X80管线钢不同电化学充氢状态下的断裂特性

Fracture Toughness of X80 Pipeline Steel after Electrochemical Hydrogen Charging in Different States

采用拉伸和慢拉伸试验,研究了X80管线钢在静态充氢与慢拉伸动态充氢条件下的断裂特性。结果表明:在静态充氢条件下,当充氢电流密度小于12.5 mA/cm2时,材料的断裂韧性随电流密度的增加而增加,当电流密度大于该值时,随电流密度增加,材料的断裂韧性呈下降趋势;在慢拉伸动态充氢条件下,随电流密度的增加,材料的断裂韧性显著降低,并满足一定的函数关系。静态充氢试样断口主要呈韧窝特征,但与未充氢试件比较,韧窝的尺寸变小,数量变多;慢拉伸动态充氢试样断口呈现解理形貌。

The fracture toughness of X80 pipeline steel after static electrochemical hydrogen charging and dynamic electrochemical hydrogen charging was investigated by tensile tests and slow strain rate tests（SSRT）.The experimental results indicate that under the static hydrogen charging condition,the fracture toughness increased with the increase of current density when current density was lower than 12.5 mA/cm2.Otherwise,the effect of current density on fracture toughness was opposite.Under the SSRT condition,dynamic electrochemical hydrogen charging decreased the fracture toughness of X80 pipeline steel considerably and followed a certain function relationship with the current density of hydrogen charging.The fractograph of the X80 pipeline steel after static hydrogen charging exhibited typical ductile dimple fracture pattern,the size and depth of which was smaller than those without hydrogen charging.The fractograph showed areas of cleavage under SSRT condition with dynamic hydrogen charging.