Effect of Layer Thickness in Cold Metal Transfer Cladding of Fe-Based ER70S-6 Alloy on AA 6061-T6 Aluminum Alloy

Abstract

This study explores the effectiveness of the cold metal transfer (CMT) technique in producing thick cladding without significantly heating substrate materials. Fe-based alloy cladding with thicknesses of 1, 2, and 3 mm were obtained by deposition on AA 6061-T6 alloy and post-machining. The dilution, bead contact angle and surface roughness were the least in 1 mm thick cladding layer due to enhanced cooling rate. In the 1 mm thick cladding layer, the grain size was relatively small with an average size of 40 μm. The porosity, microhardness, Lancaster wear coefficient and shear bond strength were 1.75%, 282 HV, 0.88 × 10⁻⁵ mm³/N m and 88 MPa, respectively. The corresponding values were 2.69%, 249 HV, 1.03 × 10⁻⁵ mm³/N m and 77 MPa for 3 mm thick cladding. Improved properties of 1 mm thick cladding are attributed to enhanced low angle grain boundaries, higher dislocation density and dense martensitic structure. However, tripling the cladding layer thickness from 1 to 3 mm does not deteriorate the properties in that proportion. Hence, in applications like additive manufacturing, an optimum layer thickness can be chosen for providing the best trade-off between properties and production rate.