Effect of Laser Power on the Microstructure and Mechanical Properties of High-Speed Laser-Cladded Coating on 27SiMn Steel

Abstract

A single-factor variable method was adopted to investigate the effect of laser power on repairing hydraulic support steel (27SiMn) via laser cladding and identify the optimal power for superior cladding performance. Key parameters, including scanning speed (65 mm·s⁻¹), powder feed rate (13.6 g·min⁻¹), defocus distance, and spot diameter (3 mm), were held constant while laser powers of 1900, 2000, 2100, and 2200 W were assessed. Results indicate that the microhardness of the cladding layer increased and then decreased with the increase in laser power, and the average hardness of the 2000 W specimen reached 709.2 HV_0.5, and the average hardness of the 2000 W specimen reached 709.2 HV_0.5, which was the highest; the mechanical properties of Fe5Z-1 Fe-based alloy cladding on 27SiMn steel improve and then decline with increasing power. The best performance occurred at 2000 W, yielding a microstructure with uniform cellular, columnar, and isometric crystals; this cladding layer displayed the highest elongation (~18.5%), and the fracture of the tensile specimen is characterized by toughness, and the plasticity of the fused cladding specimen at this power is the strongest among the fused cladding specimens. Considering cross-sectional morphology, microstructure, microhardness, mechanical properties, and fracture behavior, 2000 W was the ideal power for achieving a well-bonded, ductile cladding layer.