U71Mn钢轨气压焊焊接接头滚动磨损与损伤性能研究

研究了U71Mn钢轨气压焊焊接接头上各区域的组织与性能，并利用MMS-2A轮轨滚动磨损与接触疲劳试验机对焊接接头材料进行试验，分析了各区域的磨损与损伤特性. 结果表明:焊接接头组织为珠光体，但晶粒大小及渗碳体形态和大小存在差异. 焊缝中珠光体晶粒较小，渗碳体呈细小片层状及细小颗粒状，因此硬度高且塑性变形能力强. 在1×105和2×105循环次数时耐磨性优于母材，在3×105循环次数时，焊缝磨损量大于母材磨损量，且焊缝表面损伤较母材严重. 在焊缝两侧各有1个区域(软化区)，组织为粒状珠光体和少量片层状珠光体，颗粒大小和片层厚度不均匀，硬度较小，磨损量较大，塑性变形层较厚，表面损伤最严重. 

Research on Rolling Wear and Damage Properties of Gas Pressure Welding Joint of U71Mn rail

The structure and properties of the Gas Pressure welding joint of U71Mn rail were studied. The MMS-2A wheel-rail rolling wear and contact fatigue testing machine was used to test the joint material and the parent material. The wear and damage characteristics of the joint and the parent material were studied. The results showed that the microstructure of the joint was pearlite, but the size of grain and the shape and size of cementite were different. The pearlite grain of the weld bead was smaller than that of the parent metal, and the shape of cementite was fine lamellar and fine granular, so the hardness and the plastic deformation ability were higher. At 1×105 and 2×105, the wear resistance was better than that of the parent material; at 3×105, the wear loss of the weld bead was larger than that of the parent material, and the surface damage was more serious. On both sides of the weld, there were two areas (softened zones) which were composed of granular cementite and a small amount of lamellar cementite. The grain size and the thickness of the lamellar of cementite were not uniform, so the hardness was the lowest. Moreover, the wear, cracks and plastic deformation were aggravated.