低合金高强钢焊缝针状铁素体形核问题的探讨

研究结果表明 ,通过向焊缝金属过渡微量的Ti B和稀土元素 ,可以使焊缝获得细小、均匀的针状铁素体组织 .通过透射电镜观察发现 :焊缝中合金元素如果能形成细小、难溶的非金属夹杂物 ,就可以成为针状铁素体的形核核心 ;Ti能形成细小、难溶而弥散分布的化合物 (TiO )质点 ,因而对针状铁素体的形核更为有利 ;针状铁素体由许多亚结构组成 .

Formation of Acicular Ferrite Nucleus in Welds of Low Alloy High Strength Steel

The addition of suitable amount of Ti*.B and rare earth elements could prevent precipitation of grain boundary ferrite and yield fine homogeneous acicular ferrite (AF) formation. Observation from transmission electron microscope shows that if the weld alloy elements could form fine non-metallic inclusions then they are the likely sites of a AF nucleation. Ti could form TiO nuclei that are difficult to dissolve; it could also enhance the formation of AF nuclei. The multi-structured character of AF tends to improve the toughness of weld metal at low temperature.