极化电位对GC-4钢腐蚀疲劳裂纹扩展特性的影响

THE EFFECT OF POLARIZATION POTENTIAL ON CORROSION FATIGUE CRACK PROPAGATION IN GC-4 STEEL

研究了极化电位对贝氏体与马氏体GC-4钢腐蚀疲劳(CF)裂纹扩展特性的影响。结果表明,强阴极极化(-1240mV,SCE)显著促进贝氏体钢的CF裂纹扩展,强阳极极化(-480mV)显著阻滞低△K区贝氏体钢的CF裂纹扩展,而较弱阴极极化(-1170mV),与较弱阳极极化(-520mV)对贝氏体钢CF裂纹扩展影响不大。对马氏体GC-4钢,弱阴极极化(-1170mV)与较弱阳极极化(-520mV)对中△K区CF裂纹扩展影响不大,但显著影响低△K区CF裂纹扩展。多数情况下,马氏体GC-4钢的CF裂纹扩展速率大于贝氏体GC-4钢的。试验结果支持氢促CF裂纹扩展的观点。

The effects of polarization potential on corrosion fatigue (CF) crack propagation behaviour of GC-4(40CrMnSiMoVA) steel in 3.5% NaCl solution were experimentally investigated. Test results show that CF crack propagation of GC-4 steel with bainite structure is significantly accelerated by intensive cathodic polarization(—1240mV SCE) but decelerated by intensive anodic polarization (—480mV). However,the weak cathodic polarization (—1170mV) and weak anodic polarization (—529mV) have only little effect. For GC-4 steel with martensite strcture,cathodic polarization at —1170mV and anodic polarization at — 520mV have little effect on CF crack propagation in medium △K region of da/dN vs △K curves,but have greater effect in low △K region. In most cases,CF crack propagation rate of martensitie GC-4 steel is greater than that of bainitic GC-4 steel. Test results support the viewpoint of hydrogen accelerated CF crack propagation of high strength steel in aqueous solution.