冷轧低碳钢板闪光焊HAZ的显微特性

MICROSTRUCTURE CHARACTERISTICS OF FLASH WELDED HAZ OF COLD ROLLED LOW CARBON SHEETS

研究了两种成分的钢 (钢A和钢B)的冷轧低碳钢板闪光焊接HAZ的显微组织、焊接热影响区 (HAZ)各区段的显微硬度分布和显微宽度。结果表明 :钢A和钢B冷轧低碳钢板焊接HAZ具有相同的显微组织特征 ,但铁素体晶粒大小不同。根据显微硬度的变化 ,将焊接HAZ分为五个区段。从焊接HAZ熔合区到母材 ,随着距熔合区距离的增大 ,显微特性发生明显的变化。钢A冷轧低碳钢板HAZ的显微宽度较宽 ,显微硬度与母材相比降低幅度较大 ,所受“约束强化”作用降低 ,在HAZ产生软化现象 ,钢B则与钢A相反 ,没有产生软化现象。

The microstructure,subregion micro-hardness distribution and microwidth of flash welded HAZ of cold rolled low carbon sheets having different composition (steel A and B) were investigated. The results obtained show the microstructure characteristics of the welded HAZ of the cold rolled low carbon sheets (steel A and B) are same,but the ferrite grain sizes are different.On the basis of the microhardness variation,the HAZ is divided into five subregions. The microstructure characteristics change obviously from the fusion zone of the welded HAZ to the basis material with far away from the fusion zone. Compared with the steel B,the HAZ microwidth of the steel A is wider,but the microhardness is lower in contrast to the basis material. Therefore,the role of “restrain strengthening” reduces, the softening takes place in the HAZ. In contrast to steel A, the softening doesn't take place in the HAZ of the steel B.