Impact Wear Properties of Hypereutectic Rail Joints Welded by Two Welding Processes
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摘要: 为研究闪光焊、铝热焊两种焊接工艺下过共析钢轨焊接接头的冲击损伤演变行为以及性能差异，在自制的冲击磨损试验机上对过共析钢轨焊缝、热影响区软化部位及母材进行了不同冲击次数下的模拟实验. 研究结果表明：随着冲击次数的增加，钢轨焊接接头的冲击磨损均经历着塑性变形、点蚀破坏和疲劳剥落的过程，冲击损伤是疲劳磨损和氧化磨损共同作用的结果；由于焊接工艺导致的接头组织结构和力学性能的差异，热影响区软化部位冲击时塑性变形最严重，磨损体积和磨损率最大，抗冲击性能最差；由于对闪光焊焊接接头进行了焊后正火热处理，其组织结构及抗冲击性能明显优于铝热焊；硬度对焊接接头的抗冲击性能有显著影响，硬度越高，抗冲击性能越好，疲劳剥落出现的时间越晚.Abstract: In order to study the impact damage evolution behavior and the impact performance difference of the hypereutectic rail welding joints welded by flash welding and aluminothermic welding, the impact simulation experiments of the hypereutectoid rail welding seam, the softening part of heat-affected zone and the base metal under different impact cycles were carried out by using a self-made impact wear tester. The results show that the impact wear of the rail welded joints underwent the processes of plastic deformation, pitting failure and fatigue spalling with the increasing impact cycles, and the impact damage is the result of combined action of fatigue wear and oxidation wear. Due to the differences in joint microstructure and mechanical properties caused by different welding processes, the softening part of the heat-affected zone exhibited the most severe plastic deformation, the largest wear volume and wear rate, and the worst impact resistance. The microstructure and impact resistance of the flash welding joint are better than those of the aluminothermic welding joint because of the normal heat treatment after welding. Hardness has a significant effect on the impact resistance of welded joints. The higher the hardness, the better the impact resistance and the later the fatigue spalling.
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Key words:
- hypereutectoid rail /
- flash welding /
- aluminothermic welding /
- impact wear /
- spalling fatigue
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图 5 焊接接头在不同冲击次数下典型的二维磨痕轮廓
Figure 5. Typical two-dimensional wear profile of welded joint under different impact times
图 6 冲击试验前焊接接头典型OM、SEM照片
Figure 6. Typical OM and SEM photographs of welded joints before impact test
图 7 不同冲击次数下焊接接头典型的SEM照片
Figure 7. Typical SEM photos of welded joints under different impact times
图 8 母材M磨痕剖面典型的SEM照片
Figure 8. Typical SEM photos for the cross section of the base metal
表 1 钢轨材料化学成分质量分数
Table 1. Chemical composition of rail materials (mass fraction )
% C Si Mn P Cr V 0.850～
1.0000.100～
0.8000.400～
1.300≤ 0.025 ≤ 0.700 ≤ 0.120 
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表 2 不同冲击次数下的磨损结果
Table 2. Wear results under different impact times
次数/
（ × 105 次）磨损结果 M SR SH LR LH 1 磨损深度/μm 4.4 10 7.4 11.2 7.0 3 4.8 13.1 7.5 13.2 8.0 5 4.8 13.2 8.2 14.3 9.8 10 9.1 18.7 9.2 21.0 10.7 1 磨损体积/cm3 0.42 1.57 0.82 2.30 0.96 3 0.47 2.83 0.89 2.99 1.22 5 0.51 2.98 0.99 3.03 1.38 10 1.07 3.75 1.32 5.25 2.04 1 磨损率/（μm3•次−1） 4.24 15.79 8.23 23.04 9.65 3 0.24 6.25 0.33 3.44 1.27 5 0.19 0.78 0.49 0.20 0.80 10 1.12 1.52 0.66 4.45 1.31
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