含Ti铸造双相不锈钢组织与耐腐蚀性能研究

Study on Microstructure and Corrosion Resistance of Ti-Cast Duplex Stainless Steel

运用电化学实验测试含Ti铸造双相不锈钢的耐腐蚀性能,并与不含Ti铸造双相不锈钢进行对比;为了探究Ti的作用,对含Ti铸造双相不锈钢进行金相组织观察以及碳化物定量定性分析,并利用布氏硬度计测定硬度;采用扫描电镜(SEM)和能谱分析(EDS)对含Ti铸造双相不锈钢未腐蚀和腐蚀试样表面形貌观察。试验结果表明,含Ti铸造双相不锈钢中碳化物类型主要是Cr_(23)C_6和(Ti,Nb)C,Ti能减少铸造双相不锈钢中Cr_(23)C_6以及富Cr区形成,提高其耐腐蚀性能;含Ti铸造双相不锈钢中奥氏体为弱相,奥氏体中富Cr区附近以及铁素体和奥氏体相界处是含Ti铸造双相不锈钢腐蚀发生的主要区域。

In this paper, the corrosion resistance of Ti-cast duplex stainless steel was investigated by electrochemical test, and compared with non-Ti-cast duplex stainless steel. In order to explore the effect of Ti element, the microstructure of Ti-cast duplex stainless steel was observed and the qualitative analysis of carbides was carried out. The hardness was measured by Brinell hardness tester. Scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS） were used to observe the surface morphology of non-corrosion and corrosion samples. The results show that the types of carbides in Ti-cast duplex stainless steel are Cr23C6 and （Ti, Nb） C, Ti can reduce the formation of Cr23C6 and Cr-rich phase in the cast duplex stainless steel, and improve the performance of corrosion resistance. The austenite was weak phase in Ti-cast duplex stainless steel, pitting mainly occurred in the vicinity of the Cr-rich area in the austenite and at the phase boundary of ferrite and austenite.