Additive manufacturing of dense WE43 Mg alloy by laser powder bed fusion

Holden Hyer, Le Zhou, George Benson, Brandon McWilliams, Kyu Cho, Yongho Sohn

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Abstract

WE43 is a high-strength, corrosion-resistant Mg-alloy containing rare earths such as Y and Nb, and has potential for many lightweight structural or bioresorbable prosthetic applications. In this study, additive manufacturing of dense WE43 alloy by laser powder bed fusion (LPBF) from gas atomized powders has been accomplished through studies involving single track scan of wrought WE43, parametric variation of LPBF, microstructural analysis and mechanical testing, both in compression and tension. The Archimedes method and image analyses from optical micrographs were employed to document the LPBF of dense (>99 % relative density) WE43 using optimum parameters of 200 W laser power, 1100 mm/sec scan speed, 0.13 mm hatch spacing, and 0.03 mm slice thickness. Moreover, the LPBF processing window for dense (>99 %) WE43 alloy was observed to exist for a range of power, 100 ∼ 250 W, using an energy density range of 32−37 J/mm3. The as-built microstructure consisted of fine (<10 μm) α-Mg (hcp) grains with globular β1 -Mg3Nd precipitates and (Y,Zr)2O3 oxides. After the heat treatment, which consisted of solutionizing at 536 °C for 24 h and subsequent ageing at 205 °C for 48 h, the globular β1 -Mg3Nd precipitates were observed to have dissolved and re-precipitate into thin sheets. The (Y,Zr)2O3 oxides were not found to dissolve or coalesce, but were agglomerated within α-Mg (hcp) matrix. Under compression, the as-built LPBF WE43 had, on average, yield strength of 224 MPa, compressive strength of 417 MPa and strain at failure of 9.5 %. In tension, the as-built LPBF WE43 had, on average, yield strength of 215 MPa, tensile strength of 251 MPa and strain at failure of 2.6 %. After the heat treatment, the LPBF WE43 had yield strength of 219 MPa, tensile strength of 251 MPa and strain at failure of 4.3 %. These values are comparable to those of WE43 design data specified by Magnesium Elektron.

Original languageEnglish
Article number101123
JournalAdditive Manufacturing
Volume33
DOIs
StatePublished - May 2020
Externally publishedYes

Funding

This research was sponsored by the U.S. Army Research Laboratory under a cooperate agreement contract, W911NF1720172. The views, opinions and conclusions made in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the U.S. Army Research Laboratory or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein.

FundersFunder number
Army Research LaboratoryW911NF1720172

    Keywords

    • Additive manufacturing
    • Laser powder bed fusion
    • Mg alloy
    • WE43

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