<p>Due to its remarkable strength and toughness, 42CrMo steel finds extensive application in shipbuilding as well as various industrial sectors. Nevertheless, it exhibits inadequate surface corrosion resistance and is prone to damage from prolonged exposure within marine environments. In order to improve its surface corrosion resistance, multi-pass nickel–aluminum bronze (NAB) alloy deposition layers were prepared on the surface of 42CrMo steel using wire arc additive manufacturing (WAAM) technology, and the effect of overlap rate on the microstructure and properties of the deposition layers was investigated thoroughly. The results show that the CuAl8Ni2/42CrMo bimetallic deposition exhibits excellent metallurgical bonding and properties. The deposited layer contains various phase structures of α-Cu phase, β/β′&#xa0;phase, and weak κ phase. With the increase in overlap rate, the microstructure of the overlap region changes with the increase in iron-rich dendrites and coarse columnar crystals, and the increase of element diffusion at the interface. The microhardness of the deposited layer peaks at 40% overlap rate (159.5 HV), and the highest tensile strength (628.8&#xa0;MPa) appears in the parallel weld direction of the sample at 30% overlap rate. 40% overlap rate also exhibits the best corrosion resistance, with a corrosion current density (<i>I</i>_corr) of 6.559 μA/cm², and the corrosion rate decreases to 0.0341&#xa0;mm/y after 27&#xa0;days of static immersion, which is attributable to the formation of Al₂O₃ and Cu₂O protective films formed on the surface effectively mitigated the corrosion.</p> Graphical abstract <p></p>