Wire and Arc Additive Manufacturing of High-Strength Al–Zn–Mg Aluminum Alloy

Xuewei Fang,Guopeng Chen,Ke Huang,Jiannan Yang,Yang Xie,Bingheng Lu

doi:10.3389/fmats.2021.656429

Abstract

High-strength 7xxx series aluminum alloys are of great importance for the aerospace industries. However, this type of aluminum alloys has poor processability for most additive manufacturing techniques. In this paper, a newly designed Al–Zn–Mg alloy was used as a feeding wire to fabricate thin wall-shaped samples using the wire and arc additive manufacturing (WAAM) technique. These samples were fabricated based on the cold metal transfer (CMT) process with four different types of arc modes, that is, CMT, CMT-incorporated pulse (CMT + P), CMT-incorporated polarity (CMT + A), CMT-incorporated pulse and polarity (CMT + PA). The optical microscopy, x-ray computed tomography, and scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD) were employed to characterize the microstructure and phase constitution. The results clearly reveal that the porosity varies with the arc modes, and the densest sample with porosity of 0.97% was obtained using the CMT + P mode. The mechanical properties of the fabricated samples are also dependent on the arc modes. The tensile strength and yield strength of the sample manufactured by the CMT + PA arc mode are the highest. In terms of anisotropy, the strength differences in horizontal and vertical direction of the samples made by CMT + PA, CMT + A, and CMT modes are all large, which is mainly ascribed to the pores distributed at the interlayer region.

Highlights

Additive manufacturing process is an efficient technique to manufacture complex, large-scale parts (DebRoy et al, 2018)
The Al–Zn–Mg alloy was successfully fabricated without a hot crack by wire and arc additive manufacturing (WAAM)
The following conclusion can be drawn: The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author/s

Summary

Introduction

Additive manufacturing process is an efficient technique to manufacture complex, large-scale parts (DebRoy et al, 2018). There are only a limited number of materials that exhibit good weldability, e.g., Ti6Al4V, Inconel 718, and AlSi10Mg (Kuo et al, 2017; Aboulkhair et al, 2019; Liu and Shin, 2019). Among these alloys, aluminum alloys are widely used in aerospace, aircraft, and automotive fields because of their good combination of light weight, high strength, and good ductility. AlSi10Mg is, currently, the most suitable aluminum alloy for laser-based additive manufacturing process (Rosenthal et al, 2014; Girelli et al, 2019).

Results

Discussion

Conclusion