高、低匹配对G115/T92异种钢接头组织与力学性能的影响

Effect of Overmatching and Undermatching on Microstructure and Mechanical Properties of G115/T92 Dissimilar Steel Joint

分别采用高、低匹配焊接材料对G115钢和T92钢进行了异种钢焊接,研究了高、低匹配对这两种接头显微组织和力学性能的影响。结果表明:两种接头的焊缝和热影响区组织均为典型的回火马氏体,高匹配接头中T92钢侧熔合线附近的δ-铁素体含量高于低匹配接头中的,平均体积分数均低于0.3%;高匹配接头T92钢侧、低匹配接头G115钢侧熔合区均存在钨、钴、钼、铜元素稀释现象;两种接头的截面显微硬度均呈"W"形分布,高匹配焊缝的硬度波动较大;低匹配接头的室温和650℃抗拉强度、屈服强度高于高匹配接头的,两种接头焊缝处的冲击韧性均最差;高匹配接头焊缝的冲击断裂机制为准解理断裂机制,低匹配接头焊缝的为微孔聚集断裂和准解理断裂的混合断裂机制。

The dissimilar steel welding was conducted on G115 steel and T92 steel with overmatching and undermatching welding materials,respectively.The effects of overmatching and undermatching on the microstructure and mechanical properties of the two joints were investigated.The results show that the microstructures in weld and heat-affected zone of the two joints consisted of typical tempered martensite.The content ofδ-ferrite near the fusion line at T92 steel side in the overmatching joint was higher than that in the undermatching joint.The average volume fractions ofδ-ferrite were both less than 0.3%.The dilution of W,Co,Mo and Cu was observed in the fusion zone at T92 steel side in overmatching joint and at G115 steel side in undermatching joint.The microhardness profile on cross-section of the two joints was W-shaped,and the hardness fluctuation in the overmatching weld was relatively large.The tensile strength and yield strength at room temperature and at 650℃ of the undermatching joint were higher than those of the overmatching joint.The impact toughness in the weld of the two joints was the poorest.The impact fracture of the weld in overmatching joint showed a quasi-cleavage fracture mechanism and that of the weld in undermatching joint showed a microvoid coalescence/quasi-cleavage mixed fracture mechanism.