Browsing by Author "Pai, K.R."

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    Heat Transfer and Deposition Strategies for Enhanced Mechanical Performance of Wire Arc Additively Manufactured SS316L Alloy
    (Springer, 2025) Pai, K.R.; Vijayan, V.; Samuel, A.; Prabhu, K.N.
    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.
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    Investigation of the effect of process parameters on porosity, microstructure and mechanical properties of Al–5 Mg alloy test samples fabricated by wire arc additive manufacturing
    (Springer Science and Business Media Deutschland GmbH, 2025) Pai, K.R.; Vijayan, V.; Prabhu, K.N.
    Wire arc additive manufacturing (WAAM) of aluminium alloy components has gained a lot of importance due to its ease of production of complex parts. However, its widespread acceptance as replacement for conventional manufacturing processes remains contested. The occurrence of defects, particularly porosity in products manufactured by WAAM remains a dominant reason for its lack of adoption. The gas flow rate, feed rate of wire, work piece and deposition voltage are some of the process parameters that affect the evolution of the porosity. The use of optimal process parameters is essential in obtaining defect-free aluminium products. In the present work, Al–5 Mg alloy was selected to investigate the role of WAAM process parameters on the product quality. The argon gas flow rates and wire feed rates were varied between 8–4 l/min and 3.6–4.7 mm/min, respectively. Melt deposition voltages were varied between 13 and 19.5 V. Microstructural studies using scanning electron microscopy and transmission electron microscopy were carried out to assess the effect of the process parameters on the quality of the product. The specimens were also subjected to mechanical testing. Microstructural analysis and mechanical testing results indicated that the optimal process parameters for producing defect-free products through wire arc additive manufacturing were a gas flow rate of 10 l/min, a wire feed rate of 4 m/min, and a deposition voltage of 14V. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.