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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。
Super martensitic stainless steels (SMSS) have good mechanical properties at elevated temperatures, high stress corrosion cracking resistance and good weldability, making them extremely versatile for use in harsh environments. Materials for oil exploration require excellent overall performance, and duplex and super duplex stainless steels, though expensive, are still widely used in this area, while technically and economically advantageous SMSS can replace both steels Obtained in the field of oil exploration. In general, SMSS is also expected to be used in many processing industries. In this paper, the pitting mechanism and morphology of SMSS with or without addition of Nb or Ti were investigated. The addition of Nb and Ti is intended to minimize the effects of sensitization, promote grain refinement, and study its effect on pitting of steel in seawater, with emphasis on pitting morphology and corrosion potential. Add similar microhardness and similar tempered martensite structure to those of Nb and Ti-free steels. Anodic polarization curve shows that the corrosion resistance of Nb microalloyed steel is higher than that of other steels. The formation and propagation of pitting corrosion under different potentials were repeated and observed by optical microscope. In industrial steels, Ti-added steels show the best corrosion resistance - with the highest corrosion potential and the lower pitting potential. Steel with Nb addition has a higher corrosion potential but a lower pitting potential than steel with no addition of Nb.