在金相检验工作中发现, 由于相关标准中无焊接熔深上限值的规定, 很多零部件在焊接时出现无节制地加大熔深的现象, 导致母材过热而引发断裂失效。通过控制焊接电流、电压等工艺参数, 对不同厚度的钢板进行二氧化碳气体保护焊得到焊接组合体。通过万能电子拉力试验机、显微维氏硬度计、光学显微镜进行力学性能测试与金相检验, 讨论了熔深对焊接体抗拉强度、硬度及显微组织的影响。研究结果表明: 当焊接熔深控制在大于0.2 mm且小于板厚的0.6倍范围内时, 既可保证足够的抗拉强度, 同时又可避免因过热导致的断裂失效。对于不能用拉伸试验进行验证的焊接件, 可以用金相测量法测定熔深进行验证判定。

In metallographic testing, it was found that most components were increased weld penetration immoderately because of lacking the upper limit of weld penetration values in the relating test standards. And most components fractured because base metal for welding were overheat. In order to get different welding body, carbon dioxide gas shielded arc welding was used for welding the different thickness of low carbon steel plate by controling the welding parameters, including welding current, welding voltage, etc. The mechanical properties and microstructures of the weldments were investigated by means of universal tensile testing machine, micro hardness tester and optical microscopy. The effects of weld penetration on tensile strength, hardness, microstructure of weldments were examined and the optimum range of weld penetration values was determined. The results showed that when the penetration values were not only greater than 0.2 mm but also smaller than 0.6 times of the thickness,the weldments had sufficient tensile strength and the fracture failure because of base metal overheat could be avoid. So without tensile test, the weldment could be judged from weld penetration values.