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

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 depo-sition 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 8 mu m throughout the built part. The me-chanical 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.

Automated summary

This study proposes the application of wire-arc-based directed energy deposition (DED) for building up three-dimensional structures of low-carbon steel. A classical trochoidal trajectory-based toolpath is used to rapidly build up structures with near homogeneous mechanical properties. The deposition process results in a uniform distribution of grains with degenerate pearlite phases, which is unusual for low-carbon steel. The built-up part exhibits improved mechanical properties, with uniform hardness and tensile strength, as well as enhanced elongation and wear resistance compared to the base material. The study presents a novel methodology for achieving near isotropic properties in arc-based DED process.