固溶温度及时间对高氮不锈钢耐蚀性能的影响

Effect of solution treatment temperature and time on corrosion resistance of high nitrogen stainless steel

使用真空感应炉+电渣重熔炉在0.08 MPa下制备了氮含量0.54%的高氮无镍奥氏体不锈钢,热轧后分别在800、900、1000、1100、1200℃下保温不同时间,研究在不同固溶工艺下试验钢的显微组织和耐蚀性。采用动电位极化曲线研究不同固溶工艺下高氮不锈钢在3.5%NaCl溶液中的耐蚀性能,并在6%FeCl_(3)溶液中浸泡8 d后计算其质量损失率和腐蚀速率。结果表明,固溶对高氮不锈钢组织及耐蚀性能的影响很大,经1000、1100℃热处理后的试验钢为单一的奥氏体组织;未经热处理和经800、900℃热处理的试验钢组织中存在析出相Cr_(2)N;经1200℃热处理的试验钢从奥氏体中析出了铁素体组织;1100℃下保温1 h的试验钢耐蚀性最好,腐蚀速率仅为1.35×10^(-5)g·cm^(-2)·h^(-1);800℃保温3 h后试验钢的耐蚀性最差,腐蚀速率高达8.18×10^(-4)g·cm^(-2)·h^(-1);而316L不锈钢的耐蚀性能介于两者之间,腐蚀速率为1.24×10^(-4)g·cm^(-2)·h^(-1)。

High nitrogen nickel-free austenitic stainless steel with 0.54%N was prepared by vacuum induction furnace+electroslag remelting furnace under 0.08 MPa.After hot rolling,the tested steel was solution treated at 800,900,1000,1100 and 1200℃for different time,respectively.The microstructure and corrosion resistance of the tested steel were studied with different solution treatment processes,in which the corrosion resistance was studied in 3.5%NaCl solution by potentiodynamic polarization curve,and the mass loss ratio and corrosion rate were calculated after soaking in 6% FeCl_(3) solution for 8 days.The results show that solution treatment has a great influence on microstructure and corrosion resistance of the high nitrogen stainless steel.The tested steel after solution treatment at 1000℃and 1100℃has a single austenite structure.The precipitation phase Cr_(2)N exists in the microstructure of the tested steel without heat treatment and in that solution treated at 800℃and 900℃.In the tested steel solution treated at 1200℃,the ferrite structure is precipitated from the austenite.The tested steel heated at 1100℃for 1 h has the best corrosion resistance,and the corrosion rate is only 1.35×10^(-5)g·cm^(-2)·h^(-1).While the corrosion resistance of the tested steel heated at 800℃for 3 h is the worst,the corrosion rate is as high as 8.18×10^(-4)g·cm^(-2)·h^(-1).The corrosion resistance of 316 L stainless steel is somewhere in between,and the corrosion rate is 1.24×10^(-4)g·cm^(-2)·h^(-1).