含稀土高铌钢的等温弛豫行为

Isothermal Relaxation Behavior of High Niobium Steel Containing Rare Earth

使用Gleeble-1500D型热模拟试验机对含稀土高铌钢进行了900℃等温弛豫试验,采用激光共焦显微镜、扫描电子显微镜和维氏硬度计等研究了试验钢弛豫淬火后的显微组织、含铌第二相的析出行为和硬度。结果表明:试验钢等温弛豫时的应力松弛过程分为三个阶段,分别为析出相的形核、长大和粗化阶段,第二相析出开始和结束时间分别为10s和433s;随着等温弛豫时间的延长,贝氏体板条束的尺寸逐渐减小,板条组织得到了明显的细化,析出相为均匀分布的球状颗粒物;试验钢硬度随弛豫时间的延长先升高后降低。

The isothermal relaxation experiments of the high niobium steels containing rare earth were conducted at 900 ℃ using Gleeble-1500 Dsimulator.The microstructures,precipitation behavior of second niobium containing phase and hardness of the steel after isothermal relaxation followed by quenching were studied using laser confocal microscopy,scanning electron microscopy and Vickers hardness tester.The results show that the stress relaxation process of the experimental steel was divided into three stages of precipitation nucleation,growth and coarsening.The start and end time of second phase precipitation was 10 sand 433srespectively.With the increase of the isothermal relaxation time,the bainite lath size decreased gradually and the lath microstructure was refined significantly.The precipitations consisted of evenly distributed spherical particles.The hardness of the experimental steel first increased then decreased with the increase of the relaxation time.