Microstructure and Mechanical Property Characterization of Wire Arc Additively Manufactured SS308L Built Part: Study of Heat Interaction Phenomena

In the present work, CMT-based robotic MIG welding is carried out for wire arc additive manufacturing of SS308L part. Commercially available SS308L-T1 wire is used as feedstock material. Studies of direction-specific microstructure evolution and mechanical property characterization of as-built specimens are carried out. WAAMed SS308L exhibits a typical microstructure consisting of grain boundary δ ferrite with varied morphologies (vermicular/skeletal and lathy) within γ austenite dendrites. The amount of δ ferrite along with its morphology is observed to be varied from location to location, within the as-deposited specimen. Such variation diminishes after the heat treatment. The average ultimate tensile strength of horizontally cut specimens supersedes than that of vertically cut specimens. Heat treatment causes reduction in microhardness value of WAAMed SS308L. Additionally, temperature data as recorded by the thermocouple (tacked with the substrate plate) are utilized to understand various heat interaction phenomena during the WAAM process. Effect of post-deposition heat treatment is also studied.