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利用恒电位临界点蚀温度测试法和微观组织观察法研究了时效温度对LDX 2404双相不锈钢的微观组织演变和点蚀行为的影响。结果表明,1050℃固溶时点蚀优先在奥氏体相内萌生,此时样品的奥氏体相为弱相。在600~950℃时效15 min后LDX 2404双相不锈钢铁素体和奥氏体相界处有大量σ相、Cr_2N和M_(23)C_6等二次相析出。随时效温度的升高,虽然Cr_2N和M_(23)C_6的析出量不再继续增加,但σ相的析出量急剧增加并在850℃达到最大值。当温度升到950℃后,二次析出相在基体中重新溶解。850℃为LDX 2404双相不锈钢点蚀抗力最低的鼻尖时效温度。
The effect of aging temperature on the microstructure evolution and pitting corrosion of LDX 2404 duplex stainless steel was studied by means of potentiostatic critical pitting temperature test and microstructure observation. The results show that pitting preferentially occurs in the austenite phase at 1050 ℃ and the austenite phase is weak phase. After aging at 600-950 ℃ for 15 min, a large amount of σ phases and secondary phases such as Cr_2N and M_ (23) C_6 were precipitated in the interface of ferrite and austenite of LDX 2404 duplex stainless steel. With the increase of aging temperature, although the amount of Cr 2 N and M 23 C 6 precipitates no longer increases, the amount of σ phase precipitates sharply and reaches the maximum at 850 ℃. When the temperature rose to 950 ° C, the secondary precipitates re-dissolved in the matrix. 850 ℃ is the lowest pitting corrosion resistance of LDX 2404 duplex stainless steel tip temperature.