摘要
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缩率变化不大.除表层外,壳层的断面收缩率均高于芯部.结合铸坯各区域微观组织分析认为,由于高的冷却速度,壳层形成时液相不能全部以初始析出相为δ铁素体而后转变为奥氏体的方式凝固,而从枝晶间的剩余液相中直接析出奥氏体.这种凝固模式的改变在壳层表层最为严重,使得其热塑性有所降低;由于铸坯芯部为粗大的等轴晶,其热塑性低于壳层.
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.
出处
《材料科学与工艺》
EI
CAS
CSCD
北大核心
2011年第1期91-94,共4页
Materials Science and Technology
基金
国家自然科学基金资助项目(50775105)
关键词
奥氏体不锈钢
铸坯壳层
热塑性
冷却速度
austenitic stainless steel
slab shell
hot ductility
cooling rate
