冶金因素对低合金钢点蚀扩展过程的影响

Effect of metallurgical factors on pitting propagation process of low alloy steels

通过室内间浸挂片与模拟闭塞腐蚀电池试验对4种常用N i-Cr系与Mn系低合金钢的点蚀扩展速率作了比较,研究了4种钢的腐蚀行为,从冶金因素上分析探讨了引起点蚀扩展速率差异的机理.结果表明:短期内N i-Cr系钢的点蚀扩展速率小于Mn系钢,而在模拟长期挂片的OCC试验中N i-Cr系钢的点蚀扩展速率却大于Mn系钢.初步分析认为钢中的夹杂物对钢的点蚀扩展有促进作用;Cr在点蚀扩展初期尚未完全活化对提高钢的点蚀扩展阻力有利,在中后期Cr的活化促进了点蚀的扩展.

Pitting propagation rates of four low alloy steels were compared by indoor hanging plate tests and simulating occluded corrosion cell tests. Their corrosion behavior was studied. The mechanism that caused the difference in pitting propagation rates were analyzed. The effect of metallurgical factors on pitting propagation process were initially found. The results indicated that the rates of pitting propagation of nickel - chromium steels were slower than those of manganese steels in early pit propagation stage. However, the reverse result was found when simulating long -term immersion corrosion test. Preliminary analysis was that inclusions promote pitting propagating. Chromium in nickel -chromium steels improved the resistance to pitting propagation in earlier stage. However, it accelerated pitting propagation in the later.