铌含量对17%Cr超纯铁素体不锈钢组织与高温强度的影响

来源期刊：钢铁2011年第1期

论文作者：谷宇 孙铭山 范光伟

文章页码：70 - 74

关键词：超纯铁素体不锈钢； 高温强度； 析出强化； Nb-Ti双稳定

Key words：superferritic stainless steel； high temperature strength； precipitate strengthen； Nb-Ti dual stabilization

摘    要：随着汽车行业的发展,汽车排气系统热端用铁素体不锈钢的使用温度越来越高,高温性能成为限制其发展的关键性能。研究铌含量对铁素体不锈钢组织与高温性能的影响可以指导钢种设计和工业化生产。选取了2种17%Cr超纯铁素体不锈钢进行高温时效试验,结果表明:铌的质量分数为0.2%时,铌没有明显的强化作用,950℃高温下晶粒迅速长大,高温强度迅速降低;铌的质量分数为0.4%时,在950℃高温下时效,材料中析出弥散第二相粒子Fe2Nb,阻止晶粒长大,提高强度,防止高温引起的材料软化。材料的高温强度是由固溶铌以及铌析出物的共同作用引起的,当固溶铌析出形成析出物时,固溶铌含量减少引起的强度降低以及析出引起强度升高的竞争导致了材料的强度变化。

Abstract: High temperature properties have been key properties as the work temperature of ferritic stainless steels used at hot end of automotive exhaust system increases.To study the effect of Nb content on microstructure and high temperature properties would help the design of steel grades and production.High temperature age tests were performed for two 17%Cr ferritic stainless steels.The results show that the strengthen effect of Nb is not obvious for stainless steel and with 0.2% Nb content and grain size increases quickly at 950 ℃.When the steels with 0.4% Nb content were aged at 950 ℃,second phase Fe2Nb particles precipitated at grain boundary or inside blocked grain growth,improved high temperature strength.The high temperature strength is affected by solutionizing Nb and Nb precipitations.The change of high temperature strength is induced by the competition between strength decrease caused by decrease of solutionizing Nb and strength increase caused by Nb precipitating.