低碳Ti-Nb系列钢焊后显微组织和性能

The Microstructure and Toughness of HAZ in Low Carbon Ti-Nb Series Steels after Welding

摘要: 研究了焊接热模拟工艺参数中,冷却时间t_8/5对Ti-N和Ti-Nb-N两种成分系列钢热影响区(HAZ)显微组织和冲击韧性的影响。用光学显微镜和电子显微镜(SEM,TEM)观察了不同试样的HAZ中,铁素体(F)和粒贝组织的特征,特别是M-A组元的形态、数量和分布,分析了不同冷却速度产生的显微组织与冲击韧度的关系,探讨了微量合金元素Ti、Nb、N的添加对焊后试样HAZ组织和韧性所起的作用。结果表明,随t_8/5趋缓,Ti-N系列钢中F数量增加,粒贝数量减少,M-A组元由长条状变为方块状,韧性相应大幅提高。而Nb的添加抑制了F的生成,有利于产生侧板条状粒贝,对韧性的改善不利。

Abstract: Effects of cooling rate (t_8/5) during simulated welding thermal cycle on the microstructures and toughness of HAZ in two series Ti-Nb steels were studied. The morphology, numbers and distribution of ferrite and granular bainite, especially M-A constituent in HAZ at different cooling rate (t_8/5) were observed by optical and electron microscopes. The relation between microstructures and impact toughness in different cooling rates was analysised. The actions of added microalloying elements Ti, Nb and N on improving microstructures and toughness of HAZ in specimens was discussed.