退火温度对00Cr12NiTi不锈钢组织和性能的影响

Effect of annealing temperature on microstructure and properties of 00Cr12NiTi stainless steel

对10 mm厚的00Cr12NiTi不锈钢热轧态钢板在750~950℃之间进行退火试验,并通过拉伸试验机、硬度计、OM和SEM进行力学性能和硬度测定以及显微组织观察。试验结果表明:850℃以前,00Cr12NiTi不锈钢随着退火温度的提高,抗拉强度和屈服强度均呈现缓慢下降趋势,而伸长率呈增加趋势;在850℃后,抗拉强度和屈服强度均呈现增加趋势,而伸长率呈下降趋势;表面硬度随退火温度的升高,在800℃附近发生转折,呈现'抛物线'形态变化;在低温退火时00Cr12NiTi不锈钢铁素体基体中出现大量细小等轴晶和点状析出物;随着温度的升高铁素体晶粒发生变化,点状析出物消失;850℃后随退火温度升高奥氏体比例增加,空冷后在铁素体晶粒晶界出现大量板条状马氏体,在实现'第二相'强化的同时,也使铁素体晶粒再一次细化。

Annealing test of as-hot-rolled 00Cr12NiTi stainless steel sheet with the thickness of 10 mm was carried out in the range of 750-950℃.The mechanical properties,hardness and microstructure of the hot-rolled steel sheet were measured by means of tensile tester,hardness tester,OM and SEM.The results show that the tensile and yield strength of 00Cr12NiTi stainless steel are decreased slowly with the increase of annealing temperature before 850℃,while the elongation is increased.With the increase of annealing temperature,the surface hardness turns around 800℃and changes to the form of'parabola'.At low annealing temperature,a large number of fine equiaxed grains and point precipitates appear in the ferrite matrix of 00Cr12NiTi stainless steel.With the increase of temperature,ferrite grains are changed and point precipitates are disappeared,and then austenite proportion is increased at high temperature after 850℃.After air cooling,a large number of lath martensite appear at the grain boundary of ferrite grains,which makes the ferrite grains is refined while the'second phase'strengthening is realized.