DP1000超高强度双相钢激光对接焊工艺研究

Research on Laser Butt Welding Process of DP1000 Ultra High Strength Dual Phase Steel

对DP1000超高强度双相钢进行了激光对接焊试验,并测试分析了焊后试样的显微组织和机械性能。结果表明,DP1000超高强度双相钢焊缝接头熔合区组织为粗大的板条状马氏体,还存在少量的贝氏体、残余奥氏体以及先共析铁素体组织。焊接区域依次分为:过热区、部分相变区、回火区。过热区的组织为板条状马氏体,其他两个区域组织均为回火马氏体和铁素体,同时导致焊接接头显微硬度降低,出现了软化。热影响区的显微硬度最低,拉伸试验结果显示,断裂往往出现在热影响区。DP1000超高强度双相钢的最佳焊接工艺参数为:激光功率1.7 kW,焊接速度6~10 mm/s,保护气体流量20 L/min。

Laser butt welding experiments were conducted on DP1000 ultra high strength dual phase steel,and the microstructure and mechanical properties of the welded specimens were analyzed and tested.The results showed that the fusion zone structure of DP1000 ultra high strength dual phase steel welded joint was coarse lath martensite,with a small amount of bainite,residual austenite and proeutectoid ferrite.The welding area was sequentially divided into overheating zone,partial phase transformation zone and tempering zone.The microstructure of the overheating zone was lath martensite,and the microstructure of the other two areas was tempered martensite and ferrite.At the same time,the microhardness of the welded joint decreased and softening occured.The microhardness of the heat-affected zone was the lowest,and the tensile test results showed that the fracture often occured in the heat-affected zone.The optimal welding process parameters for DP1000 ultra high strength dual phase steel were laser power of 1.7 kW,welding speed of 6 to 10 mm/s and shielding gas flow rate of 20 L/min.