Surface modification of mild steel via heterogeneous double-wire arc directed energy deposition: Microstructure and performance of cladding layer

The applications of mild steel in harsh service environments are limited due to its poorer mechanical properties and less favorable corrosion resistance. In this work, a martensitic stainless steel cladding layer is manufactured on the surface of the mild steel via heterogeneous double-wire arc directed energy deposition (DED). Two gas metal arc (GMA) torches are used, with heterogeneous metal wires of ER316L and ER70-G as raw materials. The wires, with wire feed speeds of 5.6 m/min and 2.4 m/min, respectively, melt together to form a common molten pool, which solidifies to create a cladding layer. The formation characteristics, microstructure, mechanical properties, and corrosion resistance of the cladding layer are investigated. The results reveal a well-formed cladding layer without macroscopic defects. The microstructure of the cladding layer is composed of martensite and austenite. Compared with the mild steel substrate, the cladding layer exhibits a 170 % increase in microhardness, a 160 % increase in strength, and a 1070 % increase in corrosion resistance. The results of this work contribute to the high-efficiency and low-cost preparation of a high-strength, high-hardness, and corrosionresistant Fe-based cladding layer (F-BCL) on mild steel.