PSI - Issue 71

Ganesan G et al. / Procedia Structural Integrity 71 (2025) 438–444

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3. Results and Discussion The heterogeneous steel alloys fabricated using the multi-wire GTAW-based WAAM process demonstrated remarkable enhancements in mechanical properties, including increased ultimate tensile strength and hardness. These improvements were attributed to the effective blending of distinct material characteristics. Microstructural analysis revealed a uniform and well-distributed phase structure, contributing to the superior performance of the resulting alloys. 3.1 Microstructure In the first case, where the WFR of SS-304 is zero, it produces only ferrite and is proven by Fig. 4(a) and 5(a), where there is no formation of austenite. Increasing the feed rate of SS-304 introduces more nickel, chromium, and other elements that stabilize the austenite phase. This increases the percentage of austenite in the final structure. At low SS-304 feed rates, ferrite is dominant. As the WFR of SS-304 increases, the austenite content grows, resulting in a heterogeneous phase structure with improved properties, as depicted in Fig. 4 and 5.

Fig. 4. Inverse Pole Figures (a) Case 1, (b) Case 2, (c) Case 3, (d) Case 4, and (e) Case 5

Fig. 5. Phase Distribution (a) Case 1: 0% Austenite, (b) Case 2: 2.5 % Austenite, (c) Case 3: 5.6% Austenite, (d) Case 4:9.6 % Austenite, (e) Case 5: 13.1% Austenite,