Investigation of microstructure an‎d mechanical properties of 316L components produced through the wire arc additive manufacturing (WAAM) an‎d friction stir welding (FSW)

10/20/2026 12:00:00 AM

Austenitic stainless steel 316L, due to its high strength an‎d corrosion resistance, is widely used in various industries. In recent years, its production by Wire Arc Additive Manufacturing (WAAM) has expan‎ded; however, the high solidification rate an‎d non-uniform heat input of WAAM often lead to columnar dendritic microstructures an‎d microstructural heterogeneity, which can limit mechanical performance. In this study, WAAM-produced 316L specimens were subjected to Friction Stir Welding (FSW) at rotational speeds of 400–1000 rpm an‎d traverse speeds of 50 an‎d 100 mm/min to improve microstructure an‎d mechanical properties. The as-deposited WAAM samples exhibited columnar dendrites oriented along the heat flow direction, an‎d with increasing distance from the fusion boundary, the morphology of delta ferrite (δ) gradually transformed from planar/cellular to vermicular, accompanied by a solidification mode change from AF to FA. Microstructural analysis using optical an‎d scanning electron microscopy, along with mechanical tests including tensile, bending, an‎d microhardness eva‎luations, revealed that FSW produced a fine an‎d uniform grain structure in the stir zone with a significant grain size reduction. This grain refinement was mainly attributed to Dynamic Recrystallization (DRX) during FSW, which played a key role in enhancing the mechanical performance. Tensile testing indicated that the optimized conditions (W6 (500 rpm, 50 mm/min) an‎d W7 (400 rpm, 100 mm/min)) exhibited the highest ultimate tensile strength, reaching about 507 MPa. The bending test further confirmed these results, with sample W7 achieving the highest bending strength of 1243.3 MPa. Microhardness measurements also showed an increase in hardness within the stir zone (190.9–216.5 HV) compared to the base metal (average 170.25 HV). Overall, the findings demonstrate that selec‎ting appropriate FSW parameters is critical for controlling the microstructure an‎d improving the mechanical properties of WAAM-fabricated 316L stainless steel, offering an effective strategy to overcome the limitations of additive manufacturing.

ساخت افزايشي قوس و سيم , جوشكاري همزدني اصطكاكي , ريزساختار , خواص مكانيكي , تبلور مجدد ديناميكي , فولاد زنگ نزن 316L

Wire Arc Additive Manufacturing , Friction Stir Welding , Microstructure , Mechanical Properties , Dynamic Recrystallization , 316L Stainless Steel

Mohammad Amin Zarei Sahamie

Saeed G. Shabestari