Microstructure and mechanical properties of double-wire feed GTA additive manufactured 308L stainless steel

• Published in: Rapid prototyping journal Vol. 26; no. 9; pp. 1503 - 1513
• Main Authors: Ke, Yang, Xiong, Jun
• Format: Journal Article
• Language: English
• Published: Bradford Emerald Publishing Limited 30-09-2020; Emerald Group Publishing Limited
• Subjects: Accumulation; Additive manufacturing; Aluminum alloys; Cooling; Cooling rate; Gamma phase; Grains; Intermetallic compounds; Mechanical properties; Microhardness; Microstructure; Phase composition; Rapid prototyping; Raw materials; Single wires; Stainless steel; Stainless steels; Tensile strength; Titanium alloys; Tungsten; Wire; Mechanical properties; Microstructure; GTA; 308L stainless steel; Double-wire feed additive manufacturing
• ISSN: 1355-2546; 1758-7670
• DOI: 10.1108/RPJ-09-2019-0238

Purpose
This paper aims to introduce a novel concept of a double-wire feed (DWF) to alleviate heat accumulation and improve the cooling rate of the molten pool in gas tungsten arc (GTA)-based additive manufacturing (AM), in which the former wire is fed into the arc and the latter wire is melt by the molten pool.
Design/methodology/approach
The microstructure, phase composition and mechanical properties of 308 L stainless steel components built by single-wire feed (SWF) AM and DWF-AM are compared, and the differences are analyzed in detail.
Findings
The microstructures for both wire feeding modes include δ and γ phases. Compared with the SWF-AM, the sample fabricated in the DWF-AM exhibits finer microstructure, and the microstructure in the middle region is transformed from columnar grains to cellular grains. Microhardness of the sample produced in the DWF-AM is higher than the SWF-AM. In comparison to the SWF-AM, the tensile strength of the specimen fabricated using the DWF-AM reaches 571 MPa and increases by 16.14%.
Originality/value
This study proposes a novel concept of the DWF-AM to reduce heat accumulation as well as enhance the cooling rate of the molten pool, and improved mechanical properties of the 308 L stainless steel component are obtained.