Comparison of the mechanical properties of Grade 5 and Grade 23 Ti6Al4V for wire-arc additive manufacturing

L Mashigo,H Möller,C Gassmann

doi:10.17159/2411-9717/1498/2021

Abstract

SYNOPSIS Wire-arc additive manufacturing (WAAM) is a directed-energy deposition technology that uses arc welding procedures to produce computer-aided designed parts, such as three-dimensional printed metal components. A challenge of additive manufacturing is the anisotropy. Interstitial elements play a significant role in the mechanical properties of Ti6Al4V of different grades. In this research, the mechanical properties of Grade 5 and Grade 23 Ti6Al4V were compared for this application. Samples were extracted from WAAM-produced Ti6Al4V walls in different directions (horizontal and vertical) and at different positions (top and bottom). The samples were subjected to optical microscopy and tensile and hardness tests. Grade 5 Ti6Al4V samples were found to have greater strength, greater hardness, and lower ductility, owing to the higher content of interstitial elements compared with Grade 23. The bottom samples had higher strength than the top samples, which is attributed to thermal cycling during manufacturing, resulting in different microstructures. Keywords: Ti6Al4V, wire-arc additive manufacturing, anisotropy, heat accumulation, interstitial elements.

Highlights

Additive manufacturing has been growing exponentially in the fabrication industry since its inception in the 1980s
The horizontal XY plane had higher tensile strength than the vertical ZX plane for both grades. This was influenced by the build direction (Z) of the walls, ZX being in the plane in which the walls were built and XY perpendicular to the build planes
The results show that samples taken from different positions in the walls exhibited different tensile strengths: the bottom layers had higher tensile strength than the top layers

Summary

Introduction

Additive manufacturing has been growing exponentially in the fabrication industry since its inception in the 1980s. Subtractive fabrication has been more broadly utilized, in which raw material is subjected to a machining process to remove unwanted material to produce the designed component (Li et al, 2019). In contrast, has the advantage of decreasing the cost and time of manufacturing because it directly produces the designed component without wasting any material (Antonysamy, 2012). WAAM is a directed-energy deposition procedure that employs arc welding to produce components using a three-dimensional (3D) metal printer (AMFG, 2018). A metal wire is melted onto a substrate using an electric arc as the heat source, and the component is manufactured in a layer-by-layer deposition process. WAAM-manufactured components have a high surface roughness and contain residual stresses and distortion because of the relatively high heat input (AMFG, 2018)

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