Tungsten Fabricated by Laser Powder Bed Fusion

Pietro Rebesan,Massimiliano Bonesso,Claudio Gennari,Maurizio Vedani,Adriano Pepato,Razvan Dima

doi:10.1007/s00501-021-01109-y

Abstract

Additive Manufacturing (AM) is the process that allows the production of complex geometry and lightweight components. Thanks to the high density of refractory metals, AM could be a possible solution for their application in the aerospace field and for biomedical or future nuclear fusion devices. Yet, Laser Powder Bed Fusion (LPBF) of refractory metals as Ta, Mo, and W faces some challenges due to their main properties: high melting point, heat conductivity, and susceptibility to cracks.The purpose of this study is to optimize the process parameters in order to produce high-density Tungsten parts by LPBF on an EOS M100 (maximum power of 170 W). The characterization is performed through physical properties measurements and microstructural analysis. Single Scan Tracks (SSTs) are produced on the top surfaces of Tungsten blocks to evaluate the process parameters that give regular-shape and continuous melt-pools. Both analytical and experimental optimizations of process parameters were performed. Micro-hardness measurements were done for dense bulk specimens. Finally, a description of susceptibility to cracks of additively manufactured Tungsten was performed.

Highlights

Refractory metals belong to the group of transition metals and are called “ultra-high temperature materials”
Tungsten is a promising candidate for nuclear fusion devices [2]; the proliferation of human osteoblast is much higher on tantalum compared to the most commonly used Ti-6Al-4V [3]; and for space and aerospace applications in order to increase the temperature capabilities of devices [4]
Single Scan Tracks (SSTs) studying allows to define the window of optimal laser power process parameters in order to produce intact contour, thin wall, and lattice structures

Summary

Introduction

Refractory metals belong to the group of transition metals and are called “ultra-high temperature materials”. In addition to the high melting temperatures, they have properties, like high density, high thermal conductivity, and excellent corrosion resistance, that make them suitable for many applications [1]. Tungsten is a promising candidate for nuclear fusion devices [2]; the proliferation of human osteoblast is much higher on tantalum compared to the most commonly used Ti-6Al-4V [3]; and for space and aerospace applications in order to increase the temperature capabilities of devices [4]. The traditional subtractive process for refractory metal tools is complicated and expensive, both for the waste of material that is removed and for the cost of tools suitable for hard metals, such as W, Ta, and Mo. For instance, the extremely high melting temperature, in addition to its high affinity towards oxygen at high temperatures, makes it difficult to process refractory metals components via conventional processing technologies like casting without a controlled atmosphere [5]

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