RESEARCH ON REPAIR PROCESS AND PERFORMANCE OF U71Mn RAIL BASED ON LASER CLADDING

Laser cladding technology has received more and more attention in the field of rail repair in response to the wear and tear problems that occur after long-term use of rails. One of the keys to apply laser cladding technology to the field of rail repair is to study whether the martensitic organization in the heat-affected zone is completely eliminated. In this paper, the effects of laser power, scanning speed and powder feeding volume on the geometrical characteristics (width, height and depth) of single-pass, single-layer cladding layers on rails were firstly investigated. It can be concluded from the experimental results that the two key parameters affecting the geometric dimensions of the cladding layer are scanning speed (for width) and powder feed rate (for height). It was laser power that had the most substantial impact on the depth of the cladding layer. Subsequently, a lap ratio of 40% was determined under the optimal process parameters. In the multi-pass, multi-layer fusion cladding experiments, martensitic organization was generated in the heat affected zone and was completely eliminated by 4 passes of 10 layers of fusion cladding, which transformed it into tempered martensitic. In conclusion, through a series of corrosion resistance and wear resistance assessments, multi-pass multi-layer laser cladding technology is proven to be applicable to rail repair engineering.