Study On Pitting Corrosion Resistance Of 254SMo Austenitic Stainless Steel

Since the advent of austenitic stainless steel,because of its excellent corrosion resistance and comprehensive good performance and used in all walks of life,but the corrosion of metal is still inevitable,especially the local corrosion of metal alloys.At present,254SMo austenitic stainless steel is gradually replacing traditional austenitic stainless steel in harsh environment.Systematic study of its pitting corrosion resistance can provide theoretical basis for practical production.In this paper,the pitting corrosion resistance was studied by chemical and electrochemical methods.Among them,the electrochemical test results of 254SMo austenitic stainless steel in Na Cl solution by Zahner electrochemical workstation are as follows:(1)The polarization curves,cyclic polarization curves and electrochemical impedance spectra of 254SMo austenitic stainless steel in 0.01mol/L Na Cl,0.1mol/L Na Cl and0.6mol/L Na Cl solutions show that the pitting resistance of 254SMo decreases with the increase of chloride ion concentration.(2)The electrochemical test results of the 254SMo austenitic stainless steel soaked in the solution under the same test conditions for 2h,6h,12h,24h and 36h respectively show that the pitting corrosion resistance of the material decreases with the extension of soaking time.(3)The p H=3,p H=5,p H=9 and p H=11 respectively 0.6 mol/L Na Cl solution of the test results that 254SMo austenitic stainless steel in the p H=5 pitting corrosion resistance is better.The chemical test of 254SMo austenitic stainless steel in Fe Cl₃solution shows its pitting corrosion condition mainly through the establishment of the corrosion rate and the extended model of pitting pit.The results show that the corrosion rate of stainless steel is about 1.75g·m^-2·h^-1 at 25?and 9.667g·m^-2·h^-1 at 50?,indicating that the temperature has a great effect on the corrosion rate of stainless steel.Compared with the 316L stainless steel under the same experimental conditions,the corrosion rate of 254SMo austenitic stainless steel is much lower than that of 316L,whether at 25?or 50?,which also indicates that the pitting corrosion resistance of 254SMo austenitic stainless steel is better than that of ordinary stainless steel.When the approximate pitting morphology is simulated with an ellipsoid,with the extension of soaking time,the change rule of the depth and time of the pitting hole from the initiation of pitting corrosion isY(28)269.37x^{0.3 182}.