钢轨闪光对焊接头中灰斑的形成机制

Formation mechanism of gray spot in flash-butt welding joint of rail steel

通过对钢轨闪光对焊的预热阶段和烧化阶段进行分析,研究这两个阶段所形成的夹杂物和氧化物的情况,并结合对第三唇中的夹杂物分布及成分的分析,给出灰斑的形成机制。研究发现,焊缝区硅酸盐夹杂物的出现大致有两个主要原因,首先是融化后的金属层中形成的夹杂物的含量,其次是夹杂物在表层区形成之后,被不断爆破飞溅的液态金属流动区一层层覆盖,成为更深层的夹杂物,这些较深层的金属中形成的夹杂物很难挤出。硅酸盐夹杂物在顶锻不能被完全挤出而残留在焊缝中,是导致钢轨闪光对焊接头中出现灰斑的根本原因。

The preheating stage and burn- off stage in flash- butt welding of rail steel were analyzed by experiments,the inclusions and oxides formed in these two stages were study,the formation mechanism of gray spots was concluded by analyzing the inclusion distribution and component analysis in the third lip.It can be found that there are two main reasons about the emergence of the silicate inclusions in the weld zone.One is the inclusion contents formed in the melted metal layer,and the other is that after the inclusions formed in the surface area,which would be covered by blasting splashes of liquid metal flow layers,become deeper inclusions,which is hard to squeeze.If the Silicate inclusions are in the deep place,it's difficult to completely extruded in the next upset stage and remain in the weld zone,which is the root cause of gray spots.