不同比例保护气体的高强钢复合焊工艺特性及接头性能

Mechanical Properties of Welded Joint and the Hybrid Welding Technology Characteristics of High-strength Steel with Different Proportion Shielding Gas

对8.0mm厚低合金高强钢采用激光-MAG复合焊接,取5组不同比例保护气体(CO2+Ar),研究焊接工艺特性,对接头硬度、拉伸、弯曲、冲击性能进行分析,并从断口特征方面对其断裂原因和机制进行研究。结果表明,保护气体对工艺特性及硬度影响较大。焊接接头拉伸强度足够,均在母材处拉断,拉伸断口形貌为较为粗大的韧窝。正弯断口大多为细小韧窝,背弯断口大多为粗大韧窝和部分解理面。焊缝区冲击功低于热影响区,保护气体比例和冲击温度对接头冲击韧性影响较大。

Laser-MAG hybrid welding was used to weld 8.0 mm thick high strength steel. Five groups specimens of different proportion shielding gas （CO2 ＋Ar） were selected, the hardness, tensile, bend, impact properties of weld seam and the welding technology characteristics were analyzed respectively. Furthermore, the fracture mechanism was investigated through frac tography. The results show that the shielding gas have great influence on welding technology characteristics . The tensile test indicate that all specimens were fractured in base metal. The dimples in the fracture of weld seam are coarse. Most of bending fracture are fine dimple fracture, and most of back bending fracture are coarse dimple fracture and partial cleavage plane. The impact energy of weld area is lower than the HAZ. The proportion of shielding gas and impact temperature have an effect on impact toughness.