Influence of TIG-WAAM Process Parameters on Delta Ferrite Morphology and Mechanical Response in AM-۳۱۶ Stainless Steel

This research investigates the influence of the TIG-Wire Arc Additive Manufacturing (TIG-WAAM) process on the evolution of ۸-ferrite phase morphology in ۳۱۶ stainless steel, aiming to clarify how process parameters and alloying elements govern solidification behavior and resultant properties. The study focuses on correlating deposition conditions such as deposition rate, heat input, inter-layer pauses, and alloy content with microstructural characteristics of ۸-ferrite and their impact on mechanical performance. Austenitic ۳۱۶ stainless steel fabricated by additive manufacturing exhibited a two-phase microstructure comprising y-austenite and ۸-ferrite, with phase stability directly linked to alloying elements including chromium, nickel, molybdenum, and nitrogen, which influence ferrite and austenite stabilization during solidification. Such phase relationships control solidification pathways and result in distinct microstructures. The elemental composition of the samples was quantified using Energy Dispersive X-Ray Spectroscopy (EDAX), while ۸-ferrite morphologies were examined using optical microscopy (OM) and image analysis tools. The results demonstrated the formation of diverse ۸-ferrite morphologies including lathy, skeletal, vermicular, and acicular structures whose evolution was found to be substantially affected by deposition rate and heat flow. These morphological variations significantly influenced phase distribution and microstructural features, thereby affecting mechanical behavior, particularly microhardness and strength. The findings confirm that TIG-WAAM processing conditions can be tailored to control ۸-ferrite morphology, enabling optimization of both mechanical properties and microstructure for demanding structural applications. Enhanced understanding of these relationships supports refined process strategies for additive manufacturing of austenitic stainless steels.

کلیدواژه ها:

TIG-WAAM ، ۳۱۶ stainless-steel ، Delta-ferrite