固溶温度对316L奥氏体不锈钢δ铁素体转变的影响

Effect of Solution Temperature on Transformation ofδ-ferrite in 316L Austenitic Stainless Steel

对含有残余铁素体的316L奥氏体不锈钢进行不同温度的固溶处理,使用SEM、EBSD、TEM和显微硬度等技术分析试验样品的微观组织、织构和析出相。结果表明:奥氏体不锈钢在900~1100℃固溶处理30min后水淬,存在奥氏体、铁素体和Sigma三相。在900~1000℃范围内生成Sigma相,Sigma相会提高基体硬度。Sigma相主要由残余δ铁素体分解生成,{001}<110>和{001}<100>取向的δ铁素体优先向Sigma相转变。且随着温度的升高,Sigma含量降低,奥氏体平均晶粒尺寸增加,硬度呈逐渐下降趋势。固溶温度超过1050℃后,Sigma相完全固溶进奥氏体中,奥氏体平均晶粒尺寸显著长大,硬度值快速降低,残余铁素体中{001}<110>和{001}<100>织构重新增强。1100℃固溶处理后,残余铁素体含量降低至0.2%。

The 316L austenitic stainless steel samples containing residualδferrite were solution treated at different temperatures.The SEM,EBSD,TEM and hardness tester were applied to investigate the microstructure,texture,hardness and precipitate phase characterization of the experimental samples.The results show that there are three phases of austenite,ferrite and sigma in austenitic stainless steel after solution treatment at 900~1100℃for 30 min.The sigma phase forms in the range of 900~1000℃,which also enhances the hardness of the matrix.Sigma phase is mainly formed by decomposition of residualδferrite.The{001}<110>and{001}<100>orientedδferrite preferentially transforms to sigma phase.With the increase of temperature,the content of sigma phase decreases,the average grain size of austenite increases,and the hardness decreases gradually.After 1050℃,sigma phase is completely dissolved into austenite,and the average grain size of austenite grows significantly.This results in the rapid decrease of hardness.Meanwhile,{001}<110>and{001}<100>textures ofδferrite are re-enhanced.After solution treatment at 1100℃,the content of residualδferrite decreases to 0.2%.