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用扫描电子显微镜及能谱仪对重轨钢接触焊接断口进行了观察分析。发现断裂起源于硫化物薄膜缺陷,该薄膜产生于焊接工艺掌握不当,使材料中原有的少量MnS、FeS夹杂在高温下熔融,而后又快冷,排挤到枝晶间隙形成薄膜,造成焊缝区的内部缺陷。在断口上表现为硫化物薄膜区与解理断裂相混杂,从硫的面分布照片清楚显示其分布状态。金相观察证实该薄膜是沿晶分布的。 用能谱分析技术,改变加速电压,由卡斯坦公式对薄膜厚度进行了定量计算。结果表明,膜厚在1～3μm范围,计算结果与金相双察相符,表明这是一种计算复盖层厚度(不同于其体元素)的简易方法。
Scanning electron microscopy and energy dispersive spectrometer were used to observe and analyze the welding contact of heavy rail steel. Found that the fracture originated in the sulfide film defects, the film produced in the welding process is not properly controlled, so that a small amount of material in the original small amount of MnS, FeS inclusions melt at high temperatures, and then quickly cold, squeezed into the dendrite gap film, resulting weld zone Internal defects. In the fracture on the performance of the sulfide film area and cleavage fracture mixed phase sulfur distribution photos clearly show the distribution. Metallographic observation confirmed that the film is distributed along the crystal. Using energy spectrum analysis technique, the accelerating voltage was changed, and the film thickness was calculated by the method of Castane formula. The results show that the film thickness is in the range of 1 ~ 3μm and the calculated result is in agreement with the metallographic examination, indicating that this is a simple method for calculating the thickness of the caprock (different from its bulk element).