加热温度对308L奥氏体不锈钢铸坯组织及高温热塑性的影响

Effect of heating temperature on microstructure and high temperature ductility of 308L austenitic stainless steel casting billets

采用EBSD、金相拼图、高温拉伸试验和扫描电镜断口形貌观察等方法,研究了不同加热温度对308L奥氏体不锈钢铸坯组织及高温热塑性的影响。结果表明:铸坯中树枝状的高温铁素体分布在基体奥氏体上,铁素体面积百分比为10.07%。试样在1100~1250℃的温度范围加热,随着加热温度升高,树枝状铁素体出现溶解现象,组织中高温铁素体面积百分比逐渐减小,同时高温拉伸断面收缩率不断增加,断口中韧窝数量逐渐增多,尺寸和深度逐渐均匀。温度继续升高到1300℃时,出现相反的规律。为保证308L奥氏体不锈钢好的热塑性,铸坯加热温度应该设定在1200~1250℃。

The effect of heating temperature on the microstructure and high temperature ductility of 308L austenitic stainless steel casting billets was investigated by electron backscatter diffraction(EBSD),metallographic mosaic,thermal tensile test and fracture morphology observation by scanning electron microscope(SEM).The results show that theδferrite with dendritic morphology is distributed on the matrix of austenite,the area percentage ofδferrite is 10.07%.When the sample is heated in the temperature range of 1100-1250℃,with the increase of heating temperature,the dendritic ferrite dissolves and the area percentage ofδferrite decreases gradually.At the same time,the area reduction increases,the number of dimples in fracture increases gradually and the size and depth of dimples gradually become uniform.When the temperature continues to rise to 1300℃,the opposite rule appears.To ensure the good high temperature ductility of 308L austenitic stainless steel,the heating temperature of casting billets should be set at 1200-1250℃.