奥氏体不锈钢Cr15Mn9Cu2Ni1N连铸坯壳层的热塑性

为认识连铸坯壳层中热塑性的变化及其原因,从奥氏体不锈钢Cr15Mn9Cu2Ni1N连铸坯壳层不同深度区域及芯部制取小型试样,在热模拟试验机上进行高温拉伸试验.结果表明:变形温度高于1050℃时,表层试样断面收缩率较低,由表及里逐渐增加,在距壳层表面27 mm左右处达到最高;变形温度低于1050℃时,壳层各深度区域断面收...

Hot ductility of austenitic stainless steels Cr15Mn9Cu2Ni1N in slab shell

To understand the hot ductility of austenitic stainless steel Cr15Mn9Cu2Ni1N slab,small tensile specimens were cut from the slab core and shell,and high temperature tensile tests were carried out on THERMORESTOR-W machine.Results show that,when deformation temperature is higher than 1050 ℃,the reduction of area(RA) of specimens from shell surface is low,and gradually increases from surface to inside;when deformation temperature is lower than 1050 ℃,the RA doesn’t change apparently.According to the microstructures of the slab,it is found that the cooling rate of shell surface during solidification is so high that δ-ferrite don’t solidify as primary phase entirely in liquid phase and then transform austenite,instead,the austenite is solidified directly from retained liquid phase between dendrites.This change of solidification mode is very obvious in the shell surface,which decreases its hot ductility.Owing to coarse equiaxed structures in core,the hot ductility is lower than that in shell.