Mechanical and Tribological Behaviors of U75VG Rail Flash−Butt Welded Joint

Flash−butt welded rail is widely used in railway transportation; however, the joint vulnerable after a long time of service, and its damage mechanism controversial. Here, tensile reciprocating friction tests were carried out to analyze mechanical tribological behaviors between base metal U75VG rail. The results show that flash−butt welding promotes pearlite transform into ferrite, leading relatively low hardness value but high plasticity. In addition, yielding strength all−weld−metal specimen are 385 MPa 1090 MPa, respectively, which about 24.51% 7.63% lower than specimen. It worth noting elongation 57.1% higher specimen, more dimples tearing ridges can be detected on fracture morphology while filled with shallow cleavage planes. Moreover, weld has COF (coefficient friction), fluctuation amplitude 1.25 times metal, due rougher worn surface. Furthermore, introduction changes wear from adhesive oxidation fatigue slight oxidation, ultimately leads serious damage.