固溶处理对304不锈钢晶界特征及腐蚀性能的影响

Effect of solid solution on grain boundary character distribution and corrosion resistance of 304 stainless steel

研究了固溶处理工艺对304不锈钢试样在乙二酸中的晶间腐蚀敏感性和不同硝酸体系中的耐腐蚀性的影响。结果表明：在试验条件下,固溶温度升高,得到的试样晶粒尺寸增大,晶界处腐蚀倾向降低,晶间腐蚀后的试样表面属于双重结构,即除台阶外,晶粒边界处有一些沟槽,但无被完全环绕的晶粒;适当升高固溶温度有利于增强不锈钢表面的耐蚀性能,较快的冷却方式（水冷）更有利于得到耐电化学腐蚀性能更好的试样。另外,随着硝酸溶液温度升高,不锈钢表面自腐蚀电流（I（corr））增大,腐蚀更易发生;在较高浓度（10%～12.5%）的硝酸溶液中,虽然氢离子浓度较大,但由于不锈钢形成了更加坚固的钝化膜,抑制阳极反应的发生,降低了腐蚀倾向,具有更好的抗点蚀能力。

Effect of solid solution treatment on the susceptibility to intergranular corrosion and electrochemical corrosion of 304 stainless steel was studied. The results show that with the solution temperature rises,the grain size of the steel increases and the intergranular corrosion tendency decreases. After corrosion,it exhibits a step microstructure and grooves at grain boundary on surface of the steel. The corrosion resistance of the steel can be improved by means of properly increasing the solution temperature and choosing a faster cooling way such as water quenching. Besides,with the nitric acid solution temperature rises,the corrosion current （I（corr）） increases,in which pitting corrosion is more likely to happen. Moreover,in high concentration （10%-12. 5%） of nitric acid,a stability passive film can be formed on the surface of 304 stainless steel,which prevents the reaction of the anode,lowers the corrosion,and shows a better anti-corrosive ability.