Microstructure and Mechanical Properties of AlSi7Mg0.6 Aluminum Alloy Fabricated by Wire and Arc Additive Manufacturing Based on Cold Metal Transfer (WAAM-CMT)

Qingfeng Yang; Cunjuan Xia; Yaqi Deng; Xianfeng Li; Haowei Wang

doi:10.3390/ma12162525

Microstructure and Mechanical Properties of AlSi7Mg0.6 Aluminum Alloy Fabricated by Wire and Arc Additive Manufacturing Based on Cold Metal Transfer (WAAM-CMT)

Materials (Basel). 2019 Aug 8;12(16):2525. doi: 10.3390/ma12162525.

Authors

Qingfeng Yang^{1

2}, Cunjuan Xia^{3

4}, Yaqi Deng^{1

2}, Xianfeng Li^{1

2}, Haowei Wang^{1

2}

Affiliations

¹ School of Materials Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan, Shanghai 200240, China.
² The State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China.
³ School of Materials Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan, Shanghai 200240, China. xiacunjuan@sjtu.edu.cn.
⁴ The State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China. xiacunjuan@sjtu.edu.cn.

Abstract

Wire and arc additive manufacturing based on cold metal transfer (WAAM-CMT) has aroused wide public concern in recent years as one of the most advanced technologies for manufacturing components with complex geometries. However, the microstructure and mechanical properties of the parts fabricated by WAAM-CMT technology mostly are intolerable for engineering application and should be improved necessarily. In this study, heat treatment was proposed to optimize the microstructure and enhance mechanical properties in the case of AlSi7Mg0.6 alloy. After heat treatment, the division between coarse grain zone and fine grain zone of as-deposited samples seemed to disappear and the distribution of Si and Mg elements was more uniform. What is more, the yield strength and ultimate tensile strength were improved significantly, while the ductility could be sustained after heat treatment. The improvement of strength is attributed to precipitation strengthening, and the shape change of Si phase. No reduction in ductility is due to the higher work hardening rate caused by nanostructured precipitate. It is proved that heat treatment as an effective method can control the microstructure and enhance comprehensive mechanical properties, which will boost rapid development of WAAM industrial technology.

Keywords: AlSi7Mg0.6; cold metal transfer; mechanical properties; microstructure; wire and arc additive manufacturing.