Cr、Mo对超低碳双相不锈钢的σ-相析出行为和耐点蚀性能的影响

Effect of Cr and Mo on σ-Phase Precipitation Behavior and Pitting Corrosion Resistance Properties of Ultra-Low-Carbon Dual Phase Stainless Steel

通过Thermo-Calc热力学计算、金相和电化学方法分析和研究了1 0501120℃固溶的00Cr21Ni2Mr5N、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Eb100值依次为-94.0,100.1,260.2,117.7 mV。

The cr-phase precipitation rule in four kinds of typical ultra-low-carbon dual phase stainless steel00Cr21Ni2Mn5 N,00Cr22Ni5Mo3N,00Cr25Ni7Mo3 N and 00Cr27Ni7Mo5 N solid-solution-treaded at 1 050 1 120 ℃ and aged at 500 1 100 ℃ and the effect of cr-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 cr-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 a- phase precipitation increases progressively in order of 4.9%,22.5%,27.0%and 40.5%,while the cr-phase complete dissolution temperature increases in order of 660 ℃,950 ℃,1 060 ℃ and 1 100 ℃;the more amount of σ- phase precipitation,the lower the pitting corrosion resistance of ultra-low-carbon dual phase stainless steel,and the corresponding Eb100 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.