X70管线钢电化学充氢后的力学行为研究

应用拉伸试验和慢拉伸试验，研究X70管线钢电化学充氢后材料拉伸性能的变化．结果表明：电化学充氢对X70管线钢的强度没有显著的影响，主要降低了材料的塑性，从而降低了材料的断裂延性和断裂强度．在静态电化学充氢条件下，材料的塑性随充氢时间的增加，依次降低．在慢拉伸条件下，动态电化学充氢显著降低材料的塑性．断口分析表明：静态电化学充氢后的断口以韧窝为主要特征，但韧窝直径变小；慢拉伸的动态电化学充氢断口出现准解理断裂．

AN INVESTIGATION ON MECHANICAL BEHAVIORS OF PIPELINE STEEL X70 AFTER ELECTROCHEMICAL HYDROGEN CHARGING

Tensile tests and slow strain rate tests (SSRT) are used to investigate the mechanical behaviors of X70 pipeline steel after electrochemical hydrogen charging.The experimental results show that hydrogen charging has little influence on the tensile strength of X70 steel and decreases the plasticity of X70 steel,thereby the fracture ductility and the fracture strength reduce considerably.After static electrochemical charging with hydrogen,the plastic properties successively decrease with the increase of pre-charging time.At the slow strain rate tension(SSRT) condition,dynamic electrochemical charging with hydrogen decreases the plasticity of X70 pipeline steel considerably.Analysis on the fracture morphology by SEM indicates that the fractograph exhibits typical ductile dimple fracture pattern after static electrochemical charging,and the diameter of dimple becomes smaller compared to the uncharging specimen.The fractograph of dynamic electrochemical charging during the SSRT displays with a quasi-cleavage mode.