Microstructure and Mechanical Properties of Fe-Cr-Ni Alloy Cladding Layer on EA4T Steel by Laser Cladding

EA4T steel surface of damaged axles was repaired by laser cladding. The microstructure of the laser cladding was analyzed by using optical microscopy, scanning electron microscopy and X -ray. The binding properties between matrix and cladding layer and the residual stresses of the laser cladding were examined by universal testing machine and stress testing instrument. The results shows that the microstructures of laser cladding layers are mainly composed of γ-Fe solid solution, BNi₃, M₇C₃ and Fe₃C. The microstructure of the heat affected zone is composed of fined bainite and network ferrite. The binding region is mainly formed by Crystal, columnar crystals and dendrites. The microstructures of top region of cladding layer are mainly cross dendrite crystals. After laser cladding, the tensile strength of EA4T steel increases, while the yield strength and U -notch impact properties at room temperature decrease. Residual tensile stress exists in cladding layer and residual stress in the substrate is compressive stress.