Influence of build direction and heat treatment on the microstructure and tensile characteristics of cold metal transfer based wire arc additive manufactured SS 304L

Abstract

Wire arc additive manufacturing has gained a noble position in the field of manufacturing metallic structures. This paper aims to evaluate the effect of build direction and heat treatment on the tensile behaviour along three different orientations: transverse (T), longitudinal (L), and diagonal (D). Microstructural investigations have been conducted to identify the microstructural features caused by CMT-based WAAM and its relation to mechanical properties. The results revealed a fine microstructure with austenite and ferrite phases and the formation of ferrite morphologies. For the untreated and treated specimens, respectively, the ferrite percentage was greater in the middle of the samples and is 12.29% and 11.21%. The WAAM components exhibited good tensile properties with a clear indication of anisotropic behaviour with respect to building direction. The diagonal specimen from WAAM and heat-treated WAAM resulted in better tensile properties. Additionally, it demonstrates a significant rise in Young's modulus value compared to the standard value for SS304L and other directional specimens in both treated and untreated circumstances. The percentage of anisotropy in WAAM and heat-treated specimen ranges from 6.42% to 57.76%. Fine microstructure creation and directional grain growth have produced resistance to slip movement in different orientations in different ways, resulting in the anisotropic behaviour of WAAM fabricated components.