Experimental Study On The Sensitization Behavior Of High Purity Ferritic Stainless Steel

High purity ferritic stainless steel with total carbon and nitrogen content below 300×10-6 is the important developing trends in the stainless steel industry.Systematic study on the tendency to intergranular corrosion of high purity ferritic stainless steel holds guiding significance to the production,processing and application of high purity ferritic stainless steel.The present study focuses on the sensitization behavior of stainless steel and the high purity ferritic stainless steel is chosen as the research object.With the EPR,oxalic acid etching experiments,SEM-EDS analysis and TEM analysis,the sensitization process of high purity ferritic stainless steel at different temperature was investigated.The conclusions can be summarized as following:(1)As the temperature increases from 600 ? to 1000?,the reactivation rate of high purity ferritic stainless steel reduces.The depth and width of the grain boundaries decrease which reveals that the susceptibility to intergranular corrosion is suppressed.Since the reactivation rate achieves its maximum value at 600 ?,the sensitization temperature of high purity ferritic stainless steel should be 600 ?.(2)When the sensitization processed at 600?,the reactivation rate of high purity ferritic stainless steel is closely related to the concentration of Nb.The increasing Nb content can improve the susceptibility to intergranular corrosion of high purity ferritic stainless steel.(3)As the grain size of high purity ferritic stainless increases,the ratio of grain boundary with low grain boundary energy increases,resulting in the weakness of susceptibility to intergranular corrosion.