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采用CO_2气体保护焊对3.0 mm厚SAHP400热轧钢进行了焊接,研究了工艺参数对焊缝成形、接头力学性能和显微组织的影响,并得到了优化的焊接工艺参数。结果表明:当焊接速度一定时,随着焊接电流的增大,焊缝熔宽逐渐增大,且焊缝表面的黄色结晶产物增多。当焊接电流一定时,随着焊接速度的增大,焊缝熔宽减小,且焊缝表面黄色结晶物减少。当焊接速度较大时,焊缝易出现气孔,焊缝中心为柱状枝晶。当焊接速度较小时,焊缝热影响区组织为针状铁素体,而焊缝中心为片状铁素体和少量等轴晶。当焊接电流为175 A,焊接速度为50 cm/min时,接头抗拉强度最大,达到471 MPa。
The hot rolled steel of 3.0 mm thick SAHP400 was welded by CO2 gas shielded welding. The influence of technological parameters on the formation of weld, the mechanical properties of joints and the microstructure was studied. The optimized welding parameters were obtained. The results show that when the welding speed is constant, as the welding current increases, the weld bead width increases gradually, and the yellow crystalline product on the weld surface increases. When the welding current is constant, as the welding speed increases, the weld bead melting width decreases, and the weld surface yellow crystal decreases. When the welding speed is large, the weld prone to stomatal, weld center columnar dendrite. When the welding speed is small, the HAZ of the weld is acicular ferrite, and the center of the weld is platelet ferrite and a small amount of equiaxed grains. When the welding current is 175 A and the welding speed is 50 cm / min, the tensile strength of the joint is the highest, reaching 471 MPa.