Faculty Publications
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Publications by NITK Faculty
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Item Failure Analysis of Cooling Tower Fan-Arm(Springer, 2020) Padasale, B.; Kumar, J.K.R.; Sondar, P.R.; Cadambi, S.; Hegde, S.R.This work presents failure investigation of cooling tower fan-arms commissioned in a chemical processing plant. The analysis aims at understanding the mechanism and root-cause of the failure. The investigation involves site visits, microstructural analysis, fracture surface analysis, hardness measurements, numerical stress analysis and experimental simulation. Work concludes that the fan-arms failed due to the lack of post-weld heat treatment, which caused localized stress-corrosion and pitting at critical locations that served as crack initiation sites. Fatigue loading condition and presence of residual stresses at the weld enabled easy propagation of cracks that led to recurring premature failure. Based on the root-cause and the mechanism identified in this analysis, proper pre-heating and post-weld heat treatment is recommended to relieve the residual stresses at the critical locations and thus to avoid/minimize such recurring failures in future. © 2020, ASM International.Item High Velocity Air Fuel Spraying for Surface Restoration of Worn-out IN718(Springer, 2025) Sreerag, M.P.; Abhijith Vijay, V.; Babu, N.N.; Ali, S.S.; Cadambi, S.; Rajasekaran, B.This study explores the efficacy of high velocity air fuel (HVAF) spraying for repairing worn-out IN718 thrust collars used in the chemical industry. We investigated the characteristics and application potential of thick IN718 depositions for surface restoration, focusing on their adhesion. To evaluate microstructure and adhesion, approximately 2-mm-thick IN718 layers were deposited onto IN718 wrought coupons. The HVAF-sprayed layers were notably dense (99.5%) and exhibited excellent hardness, reaching 450 HV0.3, which suggests superior mechanical properties compared to the bulk material. A three-point bending test was conducted to assess the adhesion strength of these thick deposits. The results demonstrated excellent adhesion in both compressive (1281 MPa with > 2% strain) and tensile bending. Trusting in these promising substrate-layer interfacial adhesion characteristics, the investigation was extended to demonstrate the refurbishment of an actual worn-out industrial IN718 thrust collar. A 2-mm-thick IN718 deposition was applied to the entire worn area, and excess material was subsequently machined to achieve the desired surface finish for reuse. Overall, HVAF spray technology shows significant promise for developing thick metallic layers with excellent interfacial adhesion, providing a robust and viable solution for effectively refurbishing heavily worn metallic components and extending their service life. © ASM International 2025.