ANALYSIS OF HETEROGENEITY IN WIRE ARC ADDITIVELY MANUFACTURED AUSTENITIC STAINLESS STEEL

10.25712/ASTU.1811-1416.2026.02.007

Abstract

Wire arc additive manufacturing (WAAM) is a low-cost method having a high deposition efficiency. Нowever, WAAM fabricated parts fabricated typically exhibit significant heterogeneity in microstructure and mechanical properties. In this study, this characteristic was investigated on samples of austenitic stainless steel AISI 321 produced by WAAM, based on microstructural analysis, hardness measurements, and energy-dispersive X-ray spectroscopic analysis (EDS). Experimental results revealed that the solidification mode in the fusion zone proceeds as follows: δ-ferrite first precipitates from the melt, followed by a eutectic reaction during which δ-ferrite and γ-austenite form simultaneously. In contrast, in the transition zone, γ-austenite is the primary phase to precipitate from the melt, subsequently followed by a eutectic reaction in which δ-ferrite and γ-austenite form simultaneously. This difference is attributed to the distinct cooling rates in these zones. The higher cooling rate in the transition zone also resulted in an increase in its hardness—approximately 20 HV0.1 higher than that of the fusion zone. Furthermore, EDS data indicate that the Cr content in ferrite within the transition zone is 0.21 wt.% higher, while the Ni content is 0.24 wt.% lower, compared to ferrite in the fusion zone.