采用挂片试验和浸泡试验考察了S32304、S31803、S32750三种双相不锈钢在硝酸环境中的耐蚀性。结果表明：三种固溶态双相不锈钢在硝酸环境中的腐蚀速率均较低，耐蚀性良好，经敏化处理后，三者的腐蚀速率依次增大，且敏化态S32750试样出现了明显的选择性腐蚀。随着双相钢中Cr、Mo元素含量的增大，敏化过程中会在相界析出更多的σ相，并向铁素体内部发展长大，同时伴随有次生奥氏体的生成。在硝酸环境中，敏化态S32750双相不锈钢更容易发生选择性腐蚀，其中的次生奥氏体首先发生腐蚀，而后蔓延至奥氏体相，并最终剩余铁素体相。

The corrosion resistance of S32304, S31803 and S32750 duplex stainless steels in nitric acid environment was investigated by coupon test and immersion test. The results show that the three kinds of duplex stainless steels in solid solution state had low corrosion rate and good corrosion resistance in nitric acid environment. After sensitization treatment, the corrosion rates of the three steels were increased in turn, and the sensitized S32750 sample showed obvious selective corrosion. With the increase of the content of Cr and Mo in the dual-phase steels, more σ phase would precipitate at the phase boundary during the sensitization process, and it would grow into the interior of the ferrite, accompanied by the generation of secondary austenite. In the nitric acid environment, the sensitized S32750 duplex stainless steel was more susceptible to selective corrosion, in which corrosion occurred in the secondary austenite first and then spread to the austenite phase, and finally the ferrite phase remained.