Evolution of near homogenous mechanical and microstructural properties in wire-arc based directed energy deposition of low carbon steel following trochoidal trajectory toolpath

Abstract

In the present work, the application of wire-arc-based directed energy deposition (DED) for the building up of three-dimensional structures of low-carbon steel (ER70S6) is proposed. The classical trochoidal-trajectory-based toolpath is employed to rapidly build up the structures with near homogeneous mechanical properties of the built. A robust as well as simple methodology has been developed, which is capable of building up thick walls of height 5 − 6 mm and width ∼ 20 − 22 mm in a single pass. During the deposition process, a uniform and fine distribution of grains with degenerate pearlite phases revealed, which is not usual in the layer-by-layer deposition of low-carbon steel. The trochoidal trajectory of the toolpath leads to the reheating of the deposition layer at 900 K and results in the formation of degenerate pearlite. The Electron Back Scatter Diffraction (EBSD) analysis confirms the formation of homogeneous and equiaxed grains of size 8μm throughout the built part. The mechanical properties of the built-up part improved with a uniform hardness of ∼174 HV and tensile strength of ∼ 494 MPa. Even, 40% elongation and 48.7% better wear resistance with respect to the base material are achieved for the deposited wall in different directions. This work presents a novel methodology to achieve near isotropic propery of arc-based DED process.