大气腐蚀在低合金钢显微组织中的发生与发展

采用光学金相技术结合交流阻抗测量,分析了三种低合金钢在模拟的沿海大气环境中的初期腐蚀行为.实验发现,显微组织直接决定钢的初期腐蚀行为并间接影响长期腐蚀行为.在腐蚀初期,铁素体钢中的大角晶界易于被择优腐蚀,而贝氏体内的小角晶界的择优腐蚀趋势较弱,铁素体+珠光体钢的择优腐蚀集中于珠光体及其边界.铁素体裸钢有较强的耐腐蚀性,但其锈层电阻随腐蚀时间增加产生的增量较小;贝氏体与铁素体+珠光体裸钢的耐腐蚀性较差,但其锈层电阻随腐蚀时间增加产生的增量较大,长期腐蚀性能更优.这些结果表明,在适当合金化后,贝氏体作为新型低成本高强度耐候钢的基本组织极具应用潜力.

Incubation and development of atmospheric corrosion in the microstructures of low alloy steels

Initial corrosion behaviors of three low alloy steels in simulative marine atmosphere were analyzed by optical microscopy along with electrochemical impedance spectra. It is found that the microstructures of the steels not only affect the initial corrosion behaviors directly, but also influence the long term corrosion behavior indirectly. In the early stages of corrosion, large-angle boundaries in ferrite are easy to be corroded, on the contrary, low-angle boundaries in bainite are difficult to be corroded,...