钢轨闪光焊灰斑缺陷及其非金属夹杂物相关性分析

Correlation Analysis of Flat Spot Defect and Non-metallic Inclusion in Rail Flash Butt Welding

通过观察钢轨闪光焊接头断口灰斑缺陷的宏观和微观特征,结合灰斑缺陷非金属夹杂物组织、成分定量分析,采用统计方法对影响灰斑缺陷的不同元素含量进行了相关性分析。结果发现:钢轨闪光焊灰斑缺陷与断口基体间存在明显界限,且造成落锤自然砸断的灰斑多出现于钢轨轨底部位,宏观形貌多呈块状、椭圆形或圆形,轨底露头灰斑明显降低接头抗落锤性能。微观形貌上钢轨断口基体属于解理断裂,而灰斑属于韧性断裂,灰斑组织由韧窝加弥散分布于其中的非金属夹杂物组成,非金属夹杂物主要成分为锰、氧、硅元素。基于大量灰斑非金属夹杂物化学成分统计的假设检验分析结果发现,灰斑非金属夹杂物中锰、氧含量存在显著的线性相关性,钢轨母材中的锰含量对接头灰斑缺陷的产生几率存在显著的影响。

Combined with the overall performance test of rail flash butt welding joint,the characteristics and composition of the flat spot defects affecting the joint performance were studied.The composition and content of non-metallic inclusions in the flat spot were statistically analyzed.The results showed that there was an obvious boundary between the flat spot and fracture matrix.In addition,the flat spots causing the natural breaking of the falling hammer mostly appear at the rail bottom,and the macroscopic morphology is mostly lumpy,elliptical or circular.The exposed flat spots at the rail bottom significantly reduce the hammer impact test resistance of the joint.The fracture matrix of steel rail was cleavage fracture,while the flat spot belonged to ductile fracture,The flat spot structure was composed of dimples and non-metallic inclusions.Moreover,there was a significant linear correlation between manganese content and oxygen content in flat spot non-metallic inclusions,and the manganese content in rail base metal had a significant impact on the occurrence probability of flat spot defects.