材料期刊网

针对焊接接头不能通过落锤检验问题，对钢轨母材和焊接接头进行取样，采用SEM、硬度、冲击、拉伸等分析方法，对比母材和焊接接头相同部位的断口微观形貌、金相组织、硬度、冲击性能和拉伸性能；采用网格法对夹杂物进行计量分析。结果发现，母材基体存在元素偏析，母材和焊态钢轨里存在大量分布极不均匀的非金属夹杂物；母材硬度波动大、冲击性能低、强度高、韧性差；采用正常焊接工艺所得到的接头力学性能有所提高，但品质不稳定；局部夹杂缺陷是引起钢轨断裂的本质原因。

To identify reasons for engineering problem that the welding joints still can not pass the drop hammer test in a project, the mother material and the welding joints are sampled respectively. Then SEM, hardness, shock test, tensile test, etc. analysis methods are employed to comparatively analysis the same parts of the mother material and welding joint’s fracture microcosmic appearance, microstructure, hardness, impact and tensile properties. Also the inclusions are measured. The results show that the microsegregation exists in the mother material, a large quantity of non-inclusions distribute extremely uneven in the mother rail and welding joints. The mother material has the properties of unsteady hardness, low impact, high strength and poor toughness. Normal welding process can improve the joints’ mechanical performance, but the quality is unstable. Local inclusion defect is the essence reason that causes the rail’s fracture.