摘要
研究了钛微合金化SQ700MCD高强钢焊接热影响区的软化机理。采用显微组织分析与透射电镜分析相结合，考查了母材及热模拟粗晶热影响区的组织形态与第二相粒子的溶解再析出行为。结果表明，随着焊接热输入的增大，粗晶热影响区显微组织由以板条状马氏体为主逐渐向粒状贝氏体为主转变；母材第二相粒子为含有钛和铌的碳氮化物，平均尺寸在10nm以下，且弥散分布；经模拟焊接热循环后，粗晶热影响区中绝大部分碳氮化合物粒子发生了回溶现象，但在冷却过程中，未完全回溶粒子的尺寸随着t8/5的延长而增大，第二相粒子的形状由母材中的方形变为圆形。
The softening mechanism of the heat affected zone in weld SQ700MCD, a Ti microalloyed high strength steel, was presented in this paper. Welding thermal simulation were performed to analyze the behavior of dissolution and reprecipitation of the second phase particles in parent metal and in simulated coarse grain heat affected zone （CGHAZ） by microstructure analysis and TEM analysis. The results indicated that the microstructure in CGHAZ, with the increase of heat input, transformed gradually from lath martensite to granular bainite. Carbonitride particles in the parent metal contained the component of Ti and Nb, whose average size were less than 10 nm and distributed uniformly. Most of those particles in CGHAZ dissolved after the simulated welding thermal cycling. However, the size of remanent particles increased along with t8/5 uring the cooling process and in the same time, the shape of the second phase particles changed from cubic to circular.
出处
《首钢科技》
2011年第4期13-18,共6页
Shougang Science and Technology
