Microstructure Evolution and Mechanical Property Anisotropy of Wire and Arc-Additive-Manufactured Wall Structure Using E
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Microstructure Evolution and Mechanical Property Anisotropy of Wire and Arc-Additive-Manufactured Wall Structure Using ER2319 Welding Wires Mingye Dong, Yue Zhao, Quan Li, Yunjun Fei, Tianyi Zhao, Fude Wang, and Aiping Wu Submitted: 15 April 2020 / Revised: 1 October 2020 / Accepted: 24 October 2020 ER2319 welding wires were used to fabricate a wall structure using CMT-PAdv-based wire and arc additive manufacturing (WAAM). Heat treatment was used after the WAAM process. The microstructure and mechanical property anisotropy before and after the heat treatment were studied. There were three areas with different grain morphology along building direction in the as-deposited wall structure. Microstructure difference was clear between interlayer regions and intra-layer regions both in as-deposited and heattreated state. Netlike second phases became discontinuous after heat treatment, but pores and Fe-rich phases basically unchanged. Mechanical property presented isotropy before heat treatment because a-Al with lower Cu content had low resistance on crack initiation or growth and crack mainly grew via netlike second phases which had no directionality. Mechanical property presented anisotropy after heat treatment because a-Al was strengthened and brittle Fe-rich phases which concentrated in interlayer regions played a leading role in crack initiation. Moreover, the tensile loading force along the building direction was perpendicular to interlayer regions. Thus, mechanical properties in building direction were lower than that in deposition direction. Keywords
Al alloy, heat treatment, mechanical property anisotropy, microstructure, wire and arc additive manufacturing
1. Introduction Wire and arc additive manufacturing (WAAM) has attracted attention in large-scale complex metal structures because of high efficiency and low cost (Ref 1-3). Gas metal arc welding (GMAW), gas tungsten arc welding (GTAW), plasma arc welding (PAW) and cold metal transfer (CMT) are four main supporting methods used in WAAM (Ref 4-7). CMT was regarded as the promising one, and there are four droplet transfer modes which are conventional CMT, CMT pulse (CMT-P), CMT advanced (CMT-Adv) and CMT pulse advanced (CMT-PAdv) in the CMT welding machine. CMTPAdv mode adds pulse and variable polarity based on conventional CMT mode, and it can provide better arc strike
Mingye Dong, Yunjun Fei, and Tianyi Zhao, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China; Yue Zhao, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China; and Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Tsinghua University, Beijing 100084, China; Quan Li and Fude Wang, Capital Aerospace Machinery Corporation Limited, Beijing 100076, China; Aiping Wu, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China; Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Tsinghua University, Beijing 100084, China; and
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