碳含量和组织类型对低合金钢耐蚀性的影响

 研究了碳含量不同和显微组织不同的低合金钢的耐腐蚀性能和腐蚀行为，并和商业耐候钢09CuPCrNi做了相应的比较。在碳含量比较低的情况下，组织类型对试验钢的耐蚀性影响不大；碳含量比较高时，单相贝氏体钢的耐蚀性优于由铁素体、渗碳体(珠光体)等构成的复相组织钢。轧后水冷时，不同碳含量的钢耐蚀性差别不大；轧后空冷时，碳含量低的钢的耐蚀性优于碳含量较高的钢。用扫描电镜对锈层进行观察，可以看出耐蚀性较好的试样在腐蚀后期形成了较致密的内锈层。碳的质量分数分别为0.03%和0.1%的钢水冷后的平均腐蚀速率相差很小，但从微观角度看其点蚀发展趋势不同。加速腐蚀5个周期后，w(C)为003%的水冷钢中蚀坑尺寸不再增加，而w(C)为01%的钢中蚀坑尺寸仍有增加趋势。

Effect of Carbon Content and Microstructure on Corrosion Resistance of Low Alloy Steels

The corrosion resistance and corrosion behavior of low alloy steels with different carbon content and different microstructure were investigated, and compared with a commercial weathering steel 09CuPCrNi. At low carbon content,the influence of microstructure on corrosion resistance of steels was not obvious. With higher carbon content, the single phase bainitic steel exhibited higher corrosion resistance than that of multi phase steel constituted by ferrite and cementite (pearlite). No marked distinction could be detected in corrosion resistance of steels with different carbon content water quenched after rolling, however,the steel with low carbon content air cooled after rolling exhibited higher corrosion resistance than that of steel with higher carbon content air cooled too. A compact inner rust layer was formed after 5 test cycles on the specimens with better corrosion resistance as observed by SEM. Though the general corrosion rate of 0.03wt%C water quenched steel was similar to that of 01wt%C water quenched steel, the trend of of pitting development was different. The growth of pitting was ceased after 5 test cycles in 0.03wt%C water quenched steel,but still increasing in the 0.1wt%C water quenched steel.