锈层损伤对低碳贝氏体钢在含C1^-环境中腐蚀行为的影响

EFFECT OF DAMNIFICATION IN RUST LAYER ON CORROSION BEHAVIORS OF LOW CARBON BAINITIC STEEL IN THE ENVIRONMENT CONTAINING C1^-

利用电化学、金相、能谱等方法.研究了低碳贝氏体钢在表面锈层受到不同程度的损伤后,在含Cl^-环境中的继续腐蚀行为.实验发现,低碳贝氏体钢和作为对比材料的低碳钢试样的表面锈层受损伤后,在继续腐蚀过程中均能很快得到修复.在损伤程度与继续腐蚀时间相同的条件下,低碳贝氏体钢的锈层电阻与损伤修复率均高于低碳钢.低碳贝氏体钢基体/锈层界面的断裂韧性高于锈层本身.在受外界作用时,锈层不会沿基体/锈层界面彻底脱落从而在基体表面保存残留锈层.残留锈层能明显促进新锈层在损伤部位的形成,原有锈层与损伤部位新形成的锈层中Cu和Cr含量接近,并与钢基体的含量相当.

The weatherability of weathering steel layers on its surface. However, the compact rust layers depends on the protection of the compact rust might be damaged when they were subject to external actions, for example, collision and scrape etc., which will influence the protective effect on steel base. It is deserved to put attention on further corrosion behavior of the samples with damaged rust layer, which will determine the long term corrosion property. In the present study, electrochemical measurement, metallographie observation and energy disperse spectrum analysis were employed to investigate the further corrosion behaviors of a low carbon bainitic steel in the environment containing Cl^-, after its original rust layers had been damaged on different degrees. It was found that the damnification of rust layers on both the low carbon bainitic steel and low carbon steel as a contrast could be rapidly self repaired in the further corrosion process. When damnification degree and further corrosion time are the same, the resistance and the repair ratio of damaged rust layers on the low carbon bainitic steel are higher than those of the low carbon steel. The fracture toughness of the steel base/rust layer interface of the low carbon bainitic steel is higher than that of the rust layers, so the rust layers would not be abscised thoroughly from the interface and some residual rust would be remained when the steel is subjected to applied actions. The formation of new rust at the damaged sites can be significantly promoted by the residual rust. The contents of Cu and Cr in the original rust layers are close to those in the newly formed rust layers, and both of them are equivalent to those in the steel base. These results indicate that low carbon bainitic steel with excellent mechanical properties and weld ability is a potential candidate for novel weathering steels with higher strength.