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采用混合气体(80%Ar+20%CO2)保护焊,对一种Ti-Nb微合金化控轧控冷高强钢板进行了焊接强度实验研究。通过微观组织特征分析,阐述了焊接接头热影响区(HAZ)的软化行为,综合分析了回火态HAZ的脆化机理。结果表明,随焊接热输入增加,粗晶热影响区(CGHAZ)晶粒长大,内部析出相粒子发生回溶现象,接头强度降低;焊接接头回火态强度有所提高,但随回火温度上升,CGHAZ的冲击韧性严重降低,其原因主要与原始组织遗传及碳化物沿晶界析出有关。
A new type of Ti-Nb microalloyed controlled rolling controlled cold rolled high strength steel was tested by using a mixed gas (80% Ar + 20% CO2) for welding. Through the analysis of microstructure characteristics, the softening behavior of heat-affected zone (HAZ) of welded joints was expounded, and the embrittlement mechanism of tempering HAZ was comprehensively analyzed. The results show that with the increase of welding heat input, the grains of CGHAZ grow up, the precipitated phase of the precipitated particles return to solution and the strength of the joint decreases. The strength of the welded joint increases with the increase of tempering temperature Rise, the impact toughness of CGHAZ severely reduced, mainly due to the original genetic and carbide precipitation along the grain boundary.