Martensite transformation characteristics in the heat affected zone of laser cladding on rail

This paper studied the macroscopic morphology and properties of the heat affected zone (HAZ) in multi-layer multi-track cladding layers on rail. The results showed that in the two-layer laser cladding, there are martensitic structures and cracks in the HAZ. With the increase of the number of laser cladding layers, the tempering structure in the HAZ expands gradually from the bottom to the top, from the middle to the edge, and no cracks appear in the HAZ. At ten-layer laser cladding, the martensitic structure has been completely eliminated and transformed into tempered sorbite. Finally, the hardness test shows that the hardness of cladding layer, HAZ and substrate are basically the same, which meets the performance requirements of rail repair.