321和304不锈钢在含硫污水中的应力腐蚀开裂行为研究

Stress Corrosion Cracking Behavior of Austenitic Stainless Steel in Sulfur Containing Waste Water

采用C型环暴露实验、应力环暴露实验及慢应变速率拉伸(SSRT)实验对321和304不锈钢在含硫污水中的应力腐蚀开裂(SCC)行为进行了研究。结果表明,含硫污水环境下发生SCC的风险并没有达到很高的程度,但是经过浸泡的试样表面有明显点蚀产生,并且随着浸泡时间的延长,点蚀程度加剧。加载应力最大的C型环321试样在浸泡3个月后可以观察到有腐蚀沟壑和少量裂纹出现,因此不能排除发生SCC的风险。304不锈钢试样在NH_4Cl溶液中的开裂敏感性并没有随Cl^-浓度的增加而单调增加,当Cl^-浓度处于50～100 mg/L时,pH值(25℃)处于6左右时,开裂敏感性最高。

The stress corrosion cracking（SCC） of 321, 304 stainless steel should be paid enough attention,since large amount of stainless steel was used in sulfur containing waste waters. This article studied the stress corrosion cracking（SCC） behavior of 321 and 304 stainless steel in the sour water through the c-ring exposure experiment, stress ring exposure experiment and slow strain rate tensile test（SSRT）. Results showed that the risk of SCC in sour water environment did not reach a high degree, but the surface of specimen has obvious pitting after soaking, and the degree of pitting became more and more serious with the increase of soaking time. Ravine-like corrosion with little corrosion cracks could be observed for the c-ring 321 sample with the largest load stress after 3 months of immersion, therefore,the risk of SCC can not be ruled out. The cracking sensitivity of 304 stainless steel samples in the NH4Cl solution did not increase monotonously with the increase of the concentration of chloride ion, the cracking sensitivity is highest when the concentration of Cl^- is between 50 and 100 mg/L, the pH value at 25 ℃ is about 6.