Page 125 - 摩擦学学报2025年第5期

第 5 期 徐昆宇, 等: 3种珠光体钢轨焊接接头滚动磨损与损伤性能研究 759

Abstract: High-speed passenger transport and heavy haul freight transportation have gradually become the development
direction of railway transportation. As one of the weakest parts in the track structure, the damage of rail welded joints
increases rapidly, the cost of line maintenance increases greatly, and even affects the safety of train operation. The wear
and damage of rail welded joints are related to their microstructure. The microstructure and mechanical properties of
each region on the rail welded joints of three different pearlite materials were studied. In this study, the MJP-30A tester
was used to carry out rolling sliding wear experiments of the materials at the joints. This machine allowed two discs to
run against each other with controlled normal and tangential forces to simulate the rolling-sliding contact between wheel
and rail. The experiments were carried out under dry conditions and at the room temperature, and simulated axle load
was 25 t. The contact stress was calculated to be 1 215 MPa by Hertz contact theory. The wheel speed was 500 r/min, the
rail speed was 495 r/min, and the creep rate was 1%, and the number of cycles was 100 000 cycles. Each group was
repeated during the test. During the test, the wear and damage characteristics of the joints were studied from the aspects
the hardness values, the microstructure, the adhesion coefficient, the wear rate, the macro morphology of the wear
surface and the profile damage. The results showed that the fusion line in the center of the weld was a white bright area
under the optical microscope. As the carbon content of the three welded joints decreased, the pearlite lamellar spacing
increased, the content of pro-eutectoid ferrite increased, resulting in a decrease in hardness. The hardness of the three
welded joints was low at the center of the weld, the microstructure of the heat affected zone was refined, and the
hardness was increased. The wear rate decreased with the increase of average hardness, and the surface damage of the
weld zone was more serious than that of the heat affected zone. The surface damage at the rail weld was characterized by
large spalling. Compared with the weld zone, the surface cracks in the heat affected zone were short and the number
increased, mainly manifested as ratchet failure and slight peeling. The plastic deformation layer of the weld zone was
bigger than that of the heat affected zone, which was about 12%~15% thicker. The plastic deformation of rail 2# was the
most serious, and the thickness was 286 μm in the weld zone. In the heat affected zone, the thickness was 243 μm. The
fatigue cracks in the weld zone were characterized by multi-layer cracks, and different degrees of breakage occurred
inside the material. The heat affected zone showed short and shallow single cracks. The crack length and depth of the
weld zone awere larger than that of the heat affected zone, and the crack angle was smaller than that of the heat affected
zone. In the weld zone, the average crack length and crack depth of rail 2# were the biggest, reaching 317.1 μm and 23.6
μm, respectively. The fatigue crack was in line with the plastic deformation. With the increase of pearlite lamellar
spacing, the damage degree of rail increased firstly and then decreased, and the crack angle decreased. With the increase
of pearlite lamellar spacing, the degree of rail damage increased sharply and then decreased slightly, and the crack angle
decreased. The pearlite lamellar spacing of rail 1# was the smallest and the damage degree was the smallest. The pearlite
lamellar spacing of rail 3# was bigger than that of rail 2#, but the damage degree was reduced. With the increase of the
interlayer spacing, the resistance of the crack in the rail decreased, which made it easier to expand, and it was also easier
to break and remove, so the wear rate increased and the damage was reduced. Based on the above results, it could be
found that the rolling wear and contact fatigue behavior of the welded and the heat affected zone of the welded joints of
different materials were consistent. The hardness of the welded center was lower than that of the heat affected zone, and
the damage and plastic deformation of the welded were more serious than that of the heat affected zone. The text results
could provide a theoretical basis for improving the welded process and improving the welded joint performance.
Key words: rail welded joint; microstructure; wear; plastic deformation; damage

铁路运输逐渐向高速客运和重载货运发展，列车 重，焊缝疲劳损伤的种类也越来越多，出现不同程度的
[1]
运行速度和轴重的增加对轮轨关系的考验愈发严峻 . 龟裂、压溃、剥离、侧磨和断裂等疲劳损伤 [5-7] . 丁韦等 [8]
作为轨道线路的薄弱环节，钢轨焊接接头的安全稳定 对重载线路钢轨焊接接头和母材的磨耗进行对比，发
[2]
就显得尤为重要 . 在钢轨焊接过程中，因焊接热的影 现接头处的磨耗与钢轨母材有密切关系，两者硬度差
[9]
响造成材料不均匀，材料性能梯度变化，导致在运行 异越大，接头处磨耗越严重. 陆鑫等 对断裂闪光焊接
过程中轨道不平顺. 同时焊接可能存在缺陷，使钢轨 头进行分析，发现断裂原因是循环载荷的作用，并在
[10]
在焊接接头处的损伤更为严重，影响列车运行的安全 接头轨底脚处发现呈黑色的裂纹源. 许鑫等 对我国
和舒适性 [3-4] . 部分铁路钢轨焊接接头断裂原因汇总分析，发现断裂
经现场调查发现，钢轨焊接接头损伤问题日趋严 起源多来自于轨底，大部分断裂均是焊接缺陷导致.