Abstract: The σ-phase precipitation rule in four kinds of typical ultra-low-carbon dual phase stainless steel 00Cr21Ni2Mn5N, 00Cr22Ni5Mo3N, 00Cr25Ni7Mo3N and 00Cr27Ni7Mo5N solid-solution-treaded at 1 050 ~ 1 120 °C and aged at 500 ~ 1 100 °C and the effect of σ-phase content on pitting corrosion potential of four kinds of ultra-low-carbon dual phase stainless steel are analyzed and studied by Thermo-Calc thermodynamic calculation, metallurgraphy and electrochemical method. Results show that with increasing ageing temperature the a-phase precipitation amount increases at earlier and decreases later, and with chromium-molybdenum content (/% ) in ultra-low-carbon dual phase stainless steel increasing progressively in order of 20. 98-0. 03, 22. 41-3. 16, 25. 30-3. 46 and 26. 69-4 74, the peak amount of σ- phase precipitation increases progressively in order of 4. 9% , 22. 5% , 27. 0% and 40. 5% , while the σ-phase complete dissolution temperature increases in order of 660 °C , 950°C, 1 060 °C and 1 100 °C ； the more amount of σ- phase precipitation, the lower the pitting corrosion resistance of ultra-low-carbon dual phase stainless steel, and the corresponding E_b100 value to σ- phase precipitation peak of four kinds of steel is in order of -94. 0 mV, 100. 1 mV, 260. 2 mV and 117. 7 mV.

摘要： 通过Thermo-Calc热力学计算、金相和电化学方法分析和研究了1 050~1120℃固溶的00Cr21Ni2Mn5N、00Cr22Ni5Mo3N、00Cr25Ni7Mo3N、00Cr27Ni7Mo5N四种典型超低碳双相不锈钢在5001~100℃时效后σ相的析出规律和σ相含量对四种双相不锈钢点蚀电位的影响。结果表明,σ相析出量随着时效温度的升高呈现先增加后减小的趋势,并且随着双相不锈钢中铬-钼含量（/%）依次20.98-0.03,22.41-3.16,25.30-3.46,26.69-4.74递增时,σ相析出量峰值递增,依次为4.9%,22.5%,27.0%,40.5%,同时σ相完全溶解温度提高,依次为660,950,1 060,1100℃;σ相析出量越大超低碳双相不锈钢耐点蚀性能越低,4种钢的σ相析出峰值对应的E_b100值依次为-94.0,100.1,260.2,117.7 mV。

关键词: 超低碳双相不锈钢, Cr , Mo , σ-相, 析出行为, 点蚀电位