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

Abstract

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.

Citation

Ke, Y. and Xiong, J. (2020), "Microstructure and mechanical properties of double-wire feed GTA additive manufactured 308L stainless steel", Rapid Prototyping Journal, Vol. 26 No. 9, pp. 1503-1513. https://doi.org/10.1108/RPJ-09-2019-0238