强度匹配对HG785钢焊接接头力学性能影响的研究

Effect of Strength Matching on Mechanical Properties of HG785 Steel Welded Joints

通过熔化极气体保护焊的方法,分别采用等强匹配和低强匹配焊丝对HG785钢进行对接焊,并对焊接接头拉伸、弯曲、冲击、硬度等力学性能进行了检测。结果表明,低强匹配接头抗拉强度在810 MPa左右,断裂位置均位于焊缝,接头背弯出现裂纹;等强匹配接头抗拉强度在840 MPa左右,断裂位置均位于HAZ,接头正弯、背弯均合格,接头塑性良好;低强匹配接头低温冲击韧性均优于等强匹配接头,随着试验温度降低,低强匹配接头焊缝冲击韧性降低速度小于等强匹配接头,说明采用低强匹配对于提高低温冲击韧性有利;低强匹配焊缝一定程度上减小了熔合线附近硬度的波动,使得焊缝和热影响区硬度趋于均匀分布,有利于降低接头应力集中。

Through the gas metal arc welding （GMAW） method, the equal strength matching and the low strength matching welding wires were used for the butt welding of HG785 steel, and the mechanical properties including tensile, bending, impact toughness and hardness were tested. The results show that, the tensile strength is about 810MPa for the low strength matching joints, the fracture position is located in the weld, and the crack appears at the root bend test specimen.The tensile strength is about 840MPa for the equal strength matching joints, the fracture position is located in HAZ, face and root bend are qualified, and the joint plastic property is good.The low temperature impact toughness of the low strength matching joints is better than that of the equal strength matching joints, and with the test temperature decreasing, the impact toughness drop velocity of the weld metal of the low strength matching joints is also much slower than that of the equal strength matching joints, which indicates that the low strength matching is good for the low temperature impact toughness. The low strength matching weld can reduce the hardness fluctuation near the fusion line to a certain extent, homogenize the weld and HAZ hardness distribution and reduce stress concentration of the welded joints.