时效处理工艺对海工用高氮不锈钢耐蚀性的影响

Effect of aging treatment process on corrosion resistance of high nitrogen stainless steel for marine engineering

海工用不锈钢需要长时间浸泡在海水当中,而海水自身是一种良好的电解质,具有含盐量高、电阻率小等特点,对不锈钢的耐腐蚀性是一种较大的考验。主要以18Cr15.5Mn1.4MoN系高氮奥氏体不锈钢为研究对象,通过固溶后的时效处理,分析时效第二相析出行为对试验钢耐蚀性能的影响。对试验钢进行盐雾腐蚀试验,计算其失重率和腐蚀速率,并测定试验钢动电位极化曲线。试验结果表明,不同时效处理后的试验钢耐蚀性能差距较大,600℃时效0.5 h试验钢耐蚀性能最佳,失重率和腐蚀速率分别为1.157%、4.608×10^(-5)g/(cm^(2)·h);800℃时效2 h耐蚀性能最差,失重率和腐蚀速率分别为3.737%、1.502×10^(-4)g/(cm^(2)·h);而316L不锈钢耐蚀性能介于两者之间,失重率和腐蚀速率分别为1.423%、6.751×10^(-5)g/(cm^(2)·h);当第二相Cr2N大量析出时,会严重降低试样钢耐蚀性能。通过观察海工用高氮不锈钢第二相析出和溶解行为,阐明第二相析出行为与高氮不锈钢耐蚀性之间的关系,为后续分析高温下第二相析出物对金属材料性能影响提供理论依据。

Stainless steel for marine engineering needs to be soaked in seawater for a long time,and seawater itself is good electrolyte with high salt content and low resistivity,which is big test for the corrosion resistance of stainless steel.18Crl5.5Mnl.4MoN high nitrogen austenitic stainless steel was taken as the research object,and the effect of aging second phase precipitation behavior on the corrosion resistance of test steel was analyzed through aging treatment after solid solution.The salt spray corrosion test was carried out on test steel,the weight loss rate and corrosion rate were calculated,and the potentiodynamic polarization curve of test steel was determined.The results show that the corrosion resistance of test steel after different aging treatments is quite different,and the corrosion resistance of test steel aged at 60o℃ for 0.5 h is the best,the weight loss rate and corrosion rate are 1.157% and 4.608×10^(-5)g/(cm^(2)·h),respectively.Test steel aged at 800 C for 2 h has the worst corrosion resistance,and the weight loss rate and corrosion rate are 3.737%and 1.502×10^(-4)g/(cm^(2)·h),respectively.The corrosion resistance of 316L stainless steel is between the two,and the weight loss rate and corrosion rate are 1.423% and 6.751 X10^(-5) g/(cm^(2)·h),respectively.When the second phase Crz N precipitates in a large amount,it will seriously reduce the corrosion resistance of sample steel performance.By observing the second phase precipitation and dissolution behavior of high nitrogen stainless steel used in marine engineering,the relationship between the second phase precipitation behavior and the corrosion resistance of high nitrogen stainless steel is elucidated,providing theoretical basis for subsequent analysis of effect for secondary phase precipitation on properties of metal materials at high temperatures.