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超级马氏体不锈钢(SMSS)在较高温度下具有良好的力学性能,并具有高的应力腐蚀断裂抗力和良好的可焊性,因此其在苛刻环境下的应用正日趋广泛.用于石油勘探的材料要求其具有优良的综合性能,双相不锈钢和超级双相不锈钢尽管价格昂贵,但仍在该领域得到了广泛应用,而具有技术和经济优势的SMSS能取代上述两种钢在石油勘探领域获得应用.通常,SMSS在许多加工行业也有望得到应用.本文研究了添加与未添加Nb或Ti的SMSS的点蚀机制和形貌.添加Nb和Ti是为了使敏化的影响减至最小,促进晶粒细化,并研究其对钢在海水中点蚀的影响,重点在于点蚀的形貌和腐蚀电位.添加与未添加Nb和Ti的钢具有相近的显微硬度和类似的回火马氏体组织.阳极极化曲线表明,用Nb微合金化的钢的腐蚀电位高于其他钢.对不同电位下点蚀的形成和扩展进行了重复试验,并采用光学显微镜进行观察.在工业用钢中,添加Ti的钢显示出了最佳的耐蚀性能--具有最高的腐蚀电位和较低的点蚀电位.添加Nb的钢尽管腐蚀电位较高,但其点蚀电位比未添加Nb的钢低.“,”Supermartensitic stainless steel(SMSS) show increasing use,being used in harsh environments due to its good mechanical properties at higher temperature,high stress corrosion cracking resistance and good weldability.Applications in oil exploration demand steels with superior combination of properties,and both duplex and superduplex stainless steels have found wide application in this area, despite their high costs.The SMSS consist of a technical and economical alternative to the use of those steels.They are also promising applications in various processing industries in general.This work presents investigations of pitting corrosion mechanism and the morphology of the pitting formed on SMSS with and without Nb or Ti additions to SMSS base steel.Additions of Nb and Ti were made in order to minimize the effect of sensitizing,to promote the grains refining and study their effect in the pitting corrosion in seawater,focusing their morphologies and their potential.The steels with Nb and Ti additions and without addition,showed similar microhardness values and tempered martensitic microstructures.The anodic polarization curves obtained for Nb microalloyed steel,presented hgher corrosion potential than other steels.The formation and evolution of pits in various potentials were accompanied by repeated testing and photographed using optical microscope.The steel with Ti addition showed the best corrosion performance,with the highest corrosion potential and lower pitting potential,among the steels in study.The steel with Nb,although presented higher corrosion potential,in comparison with steels without additions,had a pitting potential lower than other steels.