Coaxial powder feeding laser cladding of high-nitrogen austenitic stainless steel cladding layer on low-carbon steel: microstructure, hardness, and corrosion resistance

High-nitrogen austenitic stainless steel cladding layers are successfully produced on low-carbon steel by coaxial powder feeding laser cladding technology and found to be well metallurgically bonded with low carbon steel. The study analyzed the effects of laser scanning speed on the cladding layer. The microstructure, hardness, and corrosion resistance of the cladding layer were further examined at optimized scanning speed. The results show that the cladding layer exhibits the fewest pores and no cracks at 10 mm/s. The cladding layer is composed of austenite with a minor ferrite. The microstructure of the cladding layer includes equiaxed grains at the top, dendritic grains in the middle, and columnar grains at the bottom. Compared with the substrate (158.53 HV, E_corr = − 0.594 V and I_corr = 31.49 μA·cm⁻²), the cladding layer has excellent hardness (245.71 HV) and corrosion resistance (E_corr = − 0.175 V, I_corr = 2.24 μA·cm⁻²). The excellent resistance to chloride-induced pitting corrosion and mechanical properties of high-nitrogen austenitic stainless steel cladding layer demonstrate great potential to prolong the service life of low-carbon steel, presenting a new strategy for corrosion protection in marine environments.