铋元素对316L奥氏体不锈钢高温塑性的影响

Effect of Bismuth Element on Hot Ductility of 316L Austenitic Stainless Steel

通过高温锻造和Gleeble高温拉伸实验研究了含铋316L奥氏体不锈钢的高温塑性变形性能,并结合OM和SEM-EDS分析了铋元素影响其高温塑性的作用机理。结果表明,铋元素在实验钢中主要以微米级和纳米级尺寸铋金属夹杂物的形式存在,提高钢的可切削加工性能。含铋实验钢在高温锻造和高温拉伸过程中易于发生晶界开裂,高温塑性较差,850~1000℃实验温度断面收缩率均在40%以下。分析原因,这主要与铋的晶界偏聚有关,高温下晶界偏聚的铋颗粒将以液态的形式存在,显著降低了晶界结合力,进而导致沿晶脆性断裂。

The hot ductility deformation ability of 316L austenitic stainless steel containing bismuth was investigated by high temperature forging and high temperature tensile test with Gleeble machine.The effect mechanism of bismuth on the hot ductility was analyzed by OM and SEM-EDS.The results show that bismuth element mainly exists in the form of bismuth metal inclusions with micron and nanometer sizes in the experimental steel,which can improve the machinability of the steel.The experimental steel containing bismuth is prone to crack at grain boundaries and has poor plasticity at high temperature during forging and stretching at high temperature.The reduction of area at 850-1000℃is less than 40%.The reason is mainly related to the grain boundary segregation of bismuth.At high temperature,the grain boundary segregated bismuth particles exist in the form of liquid,which can significantly reduce the grain boundary binding force and lead to intergranular brittle fracture.