高速列车支撑槽用6005A-T6铝合金腐蚀疲劳裂纹扩展行为研究

Corrosion fatigue crack propagation behavior of 6005A-T6 aluminum alloy for high speed train supporting groove components

通过微观组织分析、裂纹扩展路径及断口表面形貌分析,研究了高速列车支撑槽用6005A-T6铝合金在3.5%NaCl溶液中的腐蚀疲劳裂纹扩展行为。结果表明:6005A-T6铝合金在3.5%NaCl溶液中的疲劳裂纹扩展速率较空气环境中快3倍左右;腐蚀环境中疲劳裂纹呈沿晶扩展,扩展过程中出现较多的沿晶二次裂纹。6005A-T6铝合金中较高腐蚀电位的第二相促进周围α-Al基体在3.5%NaCl溶液中的腐蚀,并在腐蚀过程中同时释放H2,氢和腐蚀环境的联合作用促进了6005A-T6铝合金在3.5%NaCl溶液中的疲劳裂纹扩展。

In combination with microstructure analysis,crack propagation path and fracture surface morphology analysis,the corrosion fatigue crack propagation behavior of 6005A-T6 aluminum alloy used for manufacturing high speed train support trough in 3.5%Na⁃Cl solution was studied.The results show that the fatigue crack growth rate in 3.5%NaCl solution was 3 times faster than that in air.The corrosion fatigue crack propagated along grain boundary and many intergranular secondary cracks could be observed.The precipi⁃tation phases in 6005A-T6 aluminum alloy exhibited higher corrosion potential than theα-Al matrix,which enhanced the corrosion rate of theα-Al matrix near the precipitation phases.As a result,H2 released during the corrosion reaction,the combined action of hy⁃drogen and corrosive environment promoted the fatigue crack propagation of 6005A-T6 aluminum alloy in 3.5%NaCl solution.