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采用冲击试验研究了-40～20℃温度范围内550 MPa级手工焊条电弧焊焊缝金属冲击韧性,利用金相显微镜、扫描电镜表征了焊缝金属的显微组织与断口形貌。结果表明,焊缝金属显微组织由先共析铁素体和针状铁素体构成。焊缝金属冲击功随着测试温度的降低而减小,冲击断口中塑性区域所占面积也相应减少。添加Ni、Mo元素,降低Mn、Si含量的焊缝金属在所测试温度范围内具有更高的冲击韧性。
Impact test was used to study the metal impact toughness of 550 MPa SMAW weld metal in the temperature range of -40 ~ 20 ℃. The microstructure and fracture morphology of the weld metal were characterized by metallographic microscope and scanning electron microscopy. The results show that the weld metal microstructure consists of pro-eutectoid ferrite and acicular ferrite. The weld metal impact energy decreases as the test temperature decreases, and the area occupied by the plastic zone in the impact fracture decreases accordingly. Weld metals with Ni and Mo additions and lower Mn and Si contents have higher impact toughness over the tested temperature range.