Study of flow stress and spall strength of additively manufactured Ti-6-4 alloy

Vitaly Paris,Shmuel Osovsky,Arnon Yosef-Hai,Refael Hevroni,Eli Gudinetsky,Shmuel Samuha,Eitan Tiferet,Amitai Cohen,E Buzaud,E Cadoni,H Couque,A Cosculluela

doi:10.1051/epjconf/201818303003

Abstract

The use of additive manufacturing (AM) by Electron Beam Melting (EBM) or Selective Laser Melting (SLM) has extensively grown in the past few years. A major goal in AM is to manufacture materials with mechanical properties at least as good as traditionally manufactured materials. In this work we present the results of planar impact tests and Split Hopkinson Pressure Bar tests (SHPB) on Ti-6Al-4V manufactured by EBM and LSM techniques. Stress strain curves based on SHPB measurements at strain rate of about 1500 s-1 display similar plastic flow stresses for SLM and EBM processed Ti-6Al-4V alloys, and about 15% higher than reported for commercial Ti-6Al-4V alloy. Results of planar impact tests on SLM samples display slightly higher spall strength than EBM while the stress at Hugoniot elastic limit (HEL) is practically the same. Hugoniot elastic limit and spall strength estimates for EBM-and SLM-processed Ti-6Al-4V alloys are at least as high as values obtained for conventionally-processed alloys. The results of post mortem SEM analysis of the spall fracture have demonstrated significant differences in the spall fracture characteristics between the AM-processed and commercial Ti-6Al-4V alloys.

Highlights

The use of additive manufacturing (AM) print-like technique in manufacturing of metal components increased considerably in last ten years [1, 2]
The temperature differences of the powder bed in Selective Laser Melting (SLM) compared to Electron Beam Melting (EBM) affect the solidification rate and the directional growth, which eventually affects the mechanical properties of the material
The current study focuses on dynamic mechanical characterization of Ti-6Al-4V alloy manufactured by SLM and EBM techniques, while samples from conventionally processed Ti-6Al-4V rod were used for comparison

Summary

Introduction

The use of AM print-like technique in manufacturing of metal components increased considerably in last ten years [1, 2]. This trend is driven by the fact that almost nearly any complex geometry can be processed from a 3D computer modelling using the 3D - printing or AM [3]. The temperature differences of the powder bed in SLM compared to EBM affect the solidification rate and the directional growth, which eventually affects the mechanical properties of the material. The current study focuses on dynamic mechanical characterization of Ti-6Al-4V alloy manufactured by SLM and EBM techniques, while samples from conventionally processed Ti-6Al-4V rod were used for comparison. The measured spall strength is practically the same for EBM, SLM and conventionally-processed Ti-6Al-4V alloy

Materials and Experimental Methods

Results

Conclusions