不同焊丝MAG焊接新型超高强度钢接头的显微组织及性能  

Microstructure and Property of New Ultra-high Strength Steel Joint Welded by MAG Welding using Different Welding Wires

作　　者：江卓俊 李敬勇[1] 齐彦昌[2] 崔冰[2] 马成勇[2] 

机构地区：[1]江苏科技大学材料科学与工程学院,镇江212003 [2]钢铁研究总院先进钢铁流程及材料国家重点实验室,北京100081

出　　处：《机械工程材料》2017年第4期33-38,43,共7页Materials For Mechanical Engineering

基　　金：国家重点基础研究发展计划项目(2010CB630800)

摘　　要：分别采用镍-铬-钼系和镍-钼系焊丝,在相同热输入条件下对一种新型超高强度钢进行了熔化极活性气体保护电弧焊(MAG焊),对比研究了两种接头的显微组织及力学性能;通过斜Y型坡口焊接裂纹试验评定了两种焊丝焊接接头的抗裂倾向。结果表明:镍-铬-钼系焊丝焊接接头焊缝组织主要为粗大的板条马氏体和少量贝氏体,镍-钼系焊丝焊接接头焊缝组织为细小的针状铁素体及少量的块状先共析铁素体;两种焊丝MAG焊都可以实现此钢的高强度连接,且镍-钼系焊丝焊接接头的韧性明显优于镍-铬-钼系焊丝焊接的,但焊接接头都在回火区出现了软化现象;镍-钼系焊丝焊接接头的抗开裂性能优于镍-铬-钼系焊丝的,两种焊丝斜Y型坡口焊接试样的冷裂纹断裂模式均以沿晶断裂为主,穿晶断裂为辅。A new ultral-high strength steel was welded by metal active gas （MAG） welding with Ni-Cr-Mo and Ni-Mo welding wires, respectively, under the same heat input. The microstructures and mechanical properties of the two welded joints were compared and studied. The anti-crack sensitivity of two joints welded with the two welding wires was assessed by the Y-groove cracking test. The results show that weld microstructure of the welded joint with Ni-Cr-Mo welding wire mainly consisted of coarse lath martensite and small amount of bainite, while that with Ni-Mo welding wire as composed of fine acicular ferrite anct small amount of block proeutectoid ferrite. The high strength joint of the steel can been obtain by the MAG welding with the two welding wires. But the toughness of the welded joint with Ni-Mo welding wire was better than that with Ni-Cr-Mo welding wire and the softening phenomenon in tempering zone was observed in both welded joints. The crack resistance of the welded joint with Nb Mo welding wire was better than that with Ni-Cr-Mo welding wire, and the cold crack fracture patterns of Y-groove welded samples with the two welding wires were mainly intergranular fracture and little transgranular fracture.

关 键 词：超高强度钢 MAG焊 显微组织 抗裂性 冷裂纹 

分 类 号：TG406[金属学及工艺—焊接]