低合金高强钢焊缝熔敷金属强韧化机理

Mechanism of high strength and high toughness of HSLA weld deposited metal

关键词:  焊缝  针状铁素体  低温  韧性  低合金钢

Key words:  weld  acicular ferrite  low temperature  toughness  high strength low alloy steel

摘要:

向焊缝熔敷金属过渡微量的Ti-B和稀土元素,可以有效地抑制先共析铁素体的析出,使焊缝获得细小、均匀的针状铁素体组织。从而提高了焊缝的低温冲击韧性。通过透射电镜观察,发现焊缝中合金元素能形成细小、难溶的非金属夹杂物,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,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,这相当于进一步细化了晶粒,是提高焊缝熔敷金属低温韧性微观原因。

Abstract:

It was effective to resist precipitation of grain boundary ferrite and make fine homogeneous acicular ferrite formation by transferring suitable amount of Ti-B elements and suitable amount of rare earth elements so that it increased low temperature toughness of weld deposited metal.It had been found that weld alloy elements could be the nucleating-centers of acicular ferrite as long as they formed fine non-metallic inclusions which were difficult to dissolve by the investigation of transmitted electron microscope.Titanium could form such fine combination nucleus(TiO) which spreaded in the weld metal and was acicular ferrite nucleus forming.Acicular ferrite consisted of a lot of substructure,and it was the microstructural reason to improve the low temperature toughness of weld deposited metal.