Pulsed directed energy deposition-arc technology for depositing stainless steel 309L: Microstructural, elements distribution, and mechanical characteristics

Abstract

In recent years, additive manufacturing has increased in prominence as a primary method of manufacturing around the globe. Modern metal additive manufacturing presents an innovative approach to manufacturing complex structures for the aerospace, energy, and construction sectors, due to technological advancements. In the present study, the austenitic stainless steel 309L (SS-309L) thick wall component was manufactured employing pulsed current gas tungsten arc welding (PC-GTAW) WAAM technology. The metallurgical characteristics of the as-deposited SS-309L thick wall part were evaluated. The investigation of material characteristics in the manufactured areas encompasses a study of cross-sectional (CS) and transverse-sectional (TS) regional portions, specifically the upper, middle, and lower regions. The microstructures of the CS and TS planes showed austenite, columnar, and delta ferrite dendrites in the upper, middle, and lower regions, respectively. The CS sample reveals the greatest grain size at 159.4 μm, following the EBSD investigation. The average size of the grains across the TS is 127.09 μm. The thermal cycles in multi-layer production result in changes in grain size. The microhardness in the transverse sectional regions is higher than in the CS regions, measuring average values of 257 HV, 253 HV, and 251 HV for the upper, middle, and lower sections, respectively. The ultimate tensile strengths (UTS) in the cross-sectional parts are 656 MPa, whereas in the transverse regions it was 661 MPa for the topmost regions. This study investigates the correlation among the mechanical and metallurgical properties of wire arc additively fabricated SS-309L austenite steel material.

Keywords

• Additive manufacturing
• WAAM
• Welding
• Microstructure
• Mechanical properties