钢轨闪光焊接头损伤分析

Destructive Analysis of Rail Flash Welded Joint

对钢轨闪光焊接头进行超声探伤,发现在焊缝轨顶部位存在反射回波。对焊接接头进行静力弯曲试验,轨顶断口呈现解理穿晶断裂特征,轨顶面部位存在异常条状缺陷。对断口裂纹源区进行取样,电镜分析确认存在微孔洞样貌,能谱分析表明氧、铝、硅、碳等元素富集,金相分析观察到存在大量网状二次渗碳体。通过分析确认,在钢轨闪光焊过程中,轨头、轨腰、轨底的焊接端面温度分布不均匀,轨头的焊接端面温度过高,最终形成缺陷组织残留于焊缝中。

Ultrasonic flaw detection was carried out on the rail flash welded joint,and it was found that there was a reflected echo at the top of the welded rail.The static bending test of the welded joint was carried out,and the fracture of the rail top showed the cleavage transgranular fracture feature and there were abnormal strip defects on the top surface of the rail.The source area of the fracture was sampled.Electron microscope analysis confirmed the existence of micro-voids.Energy spectrum analysis showed that oxygen,aluminum,silicon,carbon and other elements were enriched.Metallographic analysis observed the existence of a large number of reticulated secondary cementite.Through analysis,it was confirmed that in the process of rail flash welding,the temperature distribution of the welding end faces of the rail head,rail waist and rail bottom was uneven,and the temperature of the welding end face of the rail head was too high,resulting in the formation of defective structures remaining in the weld seam.