Ti-V-Nb微合金钢第二相粒子在焊接热循环过程中的变化规律

利用萃取复型技术，对Ti-V-Nb微台金钢母材、焊缝及模拟粗晶区中第二相粒子进行了研究结果表明，母材中的粒子为含有Ti，V，Nb的碳氮化台物复合粒子，其尺寸均在100nm以下；粒子的形状不规则，不同粒子具有不同的成分．焊接过程中，溶池中的碳氮化合物粒了绝大部分发生溶解，溶解到溶池中的Ti通过冶金反应生成TiO，TiO与溶池中的其它脱氧(脱硫)产物结合成尺寸较大的夹杂物；而溶解到溶池中的Nb及V未重新忻出．分析表明，TiO位于夹杂物的表面，且其附近一般有MnAl2O4相，两者具有相同晶体位向．焊接热循环旨，焊接粗晶区中仍保留了较多的粒子，但粒子尺寸显著增大，粒子的形状由母材中的不规则状变为方形，粒子的Ti含量显著提高。

Response of Second Phase Particles in Ti-V-Nb Microalloyed Steel During Weld Thermal Cycles

By using carbon extraction replica technology and welding thermal simulation, the second phase particles in parent metal, weld metal and simulated coarse grain heat affected zone (CGHAZ) of Ti-V-Nb microalloyed steel were investigated. Experiment results and analysis show that the particle sizes in the steel are less than 100 nm, and the relative content of Ti in particles increases with increasing particle size. During welding, most of carbonitride particles in welding pool dissolved, the dissolved Ti takes part in deoxidation reaction producing TiO, TiO combined with the other deoxidation or desulfuration products to form large inclusion, dissolved Nb and V did not re-precipitated. TiO and MnAl2O4 formed at the surface of inclusions have cubic coherent relationship. A large quantity of carbonitride particles remained in CGHAZ after welding thermal cycle, the shape of particles changed from irregular shape to cubic one, the mean particle size increased and all of these particles are rich in Ti.