Heat Transfer and Deposition Strategies for Enhanced Mechanical Performance of Wire Arc Additively Manufactured SS316L Alloy

Abstract

The work investigates the effect of various deposition strategies for wire arc additive manufacturing of SS316L on an SS304 substrate for industrial applications. Droplet deposition of SS316L on an SS304 substrate at varying current values (60–130 A) identifies the operational range for line deposition. The wettability, contact angle and spread area are evaluated along with heat flux transients for each current value. Heat flow calculated during line deposition at 90 A for horizontal and vertical substrates was 34297 kJ/m2 and 24137 kJ/m2 respectively. The corresponding values of porosity and micro-hardness indicate superior deposition at 90 A. Further investigation on deposition strategies such as interlayer current change with and without dwell time, deposition at 90 A with a dwell time of 30 s for five cycles, preheated substrates and Continuous Multi-Pass Deposition with 2 s is explored. Heat flux transients are computed for every deposition cycle using an inverse solver. Heat flow was found to be 63260 kJ/m2 and 58863 kJ/m2 for the 15th layer of interlayer current change of 90 ± 10 A and constant current of 90 A with dwell time respectively. By altering deposition parameters such as interlayer time gap and current the chromium content achieved through high-current density deposition significantly increased from 17.2% to 26% and 25.4% respectively. The ultimate tensile strength for the 80A sample without deposition strategies was found to be lower. Columnar grain morphology with dendritic structure was observed at higher currents. Finer equiaxed grains with lower interlayer fusion were observed at lower currents. Finer grain growth across the layers was achieved by adjusting the current between cycles in response to observed heat flux transients. EBSD analysis reveals the formation of brass texture with {110} in deposition strategies involving time gap and interlayer current change, indicating directional solidification thereby enhancing the overall mechanical performance of the as-deposited SS316L. © ASM International 2025.