硫化氢环境下两种不锈钢的应力腐蚀开裂行为

用U形弯试样浸泡和慢应变速率拉伸实验研究了3Cr17Ni7Mo2SiN和00Cr22Ni5Mo3N(2205)不锈钢在硫化氢介质中的应力腐蚀开裂(SCC)行为.2205不锈钢的SCC萌生孕育期较长,在pH较低的饱和H₂S溶液中具有明显的SCC敏感性,其SCC敏感性随溶液pH值的升高或H₂S含量的降低而迅速降低.3Cr17Ni7Mo2SiN的SCC孕育期均低于2205不锈钢,在pH ≤ 4.5、H₂S的质量浓度 ≥ 10³mg·L^-1的H₂S介质中均具有明显的SCC敏感性,其SCC敏感性受pH值和H₂S含量变化影响较小.3Cr17Ni7Mo2SiN的SCC以沿晶裂纹萌生,扩展后转变为穿晶应力腐蚀开裂;2205不锈钢近表面处首先发生奥氏体-铁素体相间氢致开裂,并促进SCC萌生,其SCC为穿晶应力腐蚀开裂.

Stress corrosion cracking behaviour of two stainless steels in hydrogen sulfide environment

Stress corrosion cracking (SCC) of 3Cr17Ni7Mo2SiN and 00Cr22Ni5Mo3N (2205) stainless steels in acidic hydrogen sulfide solutions was investigated by slow strain rate tensile test and U-bent specimen immersing test. The time to SCC failure of 2205 stainless steel was much longer than that of 3Cr17Ni7Mo2SiN stainless steel. 2205 stainless steel was highly susceptible to SCC at a lower pH level in saturated H₂S solution, and its SCC susceptibility sharply decreased with increasing pH value or decreasing H₂S concentration in solution. 3Cr17Ni7Mo2SiN stainless steel showed a high susceptibility to SCC in solution with a HES concentration higher than 10³ mg·L^-1 and pH≤4.5. However, the susceptibility varied slightly with the change of pH value and H₂S concentration. SCC of 3Cr17Ni7Mo2SiN stainless steel initiated in an intergranular mode, which transformed into transgranular cracking as the SCC propagated further. For 2205 stainless steel, SCC originated at the place where hydrogen-induced cracking (HIC) occurred along the ferrite/austenite matrix boundaries firstly, and then propagated transgranularly.