X80管线钢电化学充氢后的断裂特性研究

Study of fracture toughness of X80 pipeline steel after electrochemical hydrogen charging

采用3点弯曲试样,研究了X80管线钢在0.5mol/L H2SO4溶液中,经不同电流密度充氢后的断裂特性。结果表明:X80管线钢在0.5mol/L H2SO4溶液中充氢时,材料中可扩散氢的质量分数随电流密度增大而增加。以小于12.5mA/cm2的电流密度充氢时,X80管线钢的断裂韧性随电流密度的增大而增加,当电流密度大于该值时,材料的断裂韧性随电流密度增加呈下降趋势。断口分析表明:电化学充氢试件断口仍以韧窝为主要特征,但与未充氢试件相比,韧窝的尺寸变小、变浅,且数量增多,韧窝的分布也接近均匀。

The fracture toughness of X80 pipeline steel after electrochemical hydrogen charging in 0.5 mol/L H2SO4 solution with different current density is investigated by three point bending specimen in this paper. The experimental results indicate: the concentration of diffusible hydrogen shows up tendency with the increase of current density during X80 pipeline steel hydrogen charging in 0.5mol/LH2SO4 solution. When current density is lower than 12.5 mA/cm2, the fracture toughness can increase with the increase of current density. Otherwise, the effect of current density to fracture toughness is opposite. The analysis of the fracture indicates: the fractograph of the X80 pipeline steel after hydrogen charging exhibits typical ductile dimple fracture pattern, the size and depth of which are smaller than those without hydrogen charging.