S690高强钢腐蚀疲劳裂纹扩展行为拘束效应

S690高强钢由于其良好的综合力学性能广泛用于海洋平台中. 海洋平台结构易产生腐蚀疲劳失效，海水腐蚀、循环载荷和结构本身的拘束水平对裂纹扩展有重要的影响. 通过空气中和海水环境中的S690高强钢疲劳裂纹扩展试验，结合显微断口分析，研究了拘束水平对S690高强钢腐蚀疲劳裂纹扩展行为的影响. 结果表明，在阳极溶解和氢致开裂的共同作用下，海水环境对S690高强钢疲劳裂纹扩展具有明显的加速作用. 同时随着裂纹的不断扩展，拘束水平对S690高强钢腐蚀疲劳裂纹的影响不断增加，且裂纹扩展速率与裂纹扩展前后的拘束水平增量和结构本身的拘束水平均密切相关.

Constraint effect of corrosion fatigue crack growth behavior in S690 high strength steel

S690 high strength steel was widely used in offshore platforms because of its comprehensive mechanical properties. Corrosion fatigue fracture was easily formed at the offshore platforms, while corrosion fatigue crack growth behavior was significantly affected by seawater corrosion, cyclic loading and constraint effect of the structure. Therefore, the fatigue crack growth rate tests in air and seawater, combining with fracture morphologies analysis, were conducted to investigate the constraint effects of the corrosion fatigue crack growth behavior in S690 high strength steel. The results indicated that the fatigue crack growth rate in seawater was dramatically accelerated by anodic dissolution and hydrogen induced cracking. Meanwhile, the constraint effect on the corrosion fatigue crack growth rate increased with the crack growth. The corrosion fatigue crack growth rate was closely related to the constraint increment before and after the crack growth and the constraint of the structure.