Ultrasonic vibration assisted laser welding of nickel-based alloy and Austenite stainless steel

Superalloy C-276 is known to be prone to hot cracking during fusion welding by Gas Tungsten Arc method. Microsegregation occurring during cooling of fusion zone with consequent appearance of topologically close-packed phases P and µ has been held responsible for the observed hot cracking. The present work investigated the possibility of suppressing the microsegregation in weldments by resorting to current pulse. Weldments were made by continuous current gas tungsten arc welding and pulsed current gas tungsten arc welding using ERNiCrMo-4 filler wire. The weld joints were studied with respect to microstructure, microsegregation, and mechanical properties. Optical microscopy and scanning electron microscopy were employed to study the microstructure. Energy-Dispersive X-ray Spectroscopy was carried out to evaluate the extent of microsegregation. Tensile testing was carried out to determine the strength and ductility. The results show that the joints fabricated with pulsed current gave rise to narrower welds with practically no heat affected zone, a refined microstructure in the fusion zone, reduced microsegregation, and superior combination of mechanical properties.

Improvement of Microstructure and Mechanical Behavior of Gas Tungsten Arc Weldments of Alloy C-276 by Current Pulsing

Effects of filler metals on the segregation, mechanical properties and hot corrosion behaviour of pulsed current gas tungsten arc welded super-austenitic stainless steel

Recently, the pulsed current tungsten arc welding process (PC-TAW) has cemented their potential in various sorts of industrial application such as automobile, aerospace, and structural joining. However, the involvement of multiple process parameters in PC-GTAW process usually makes the process cumbersome to understand; and thereby, it is difficult to develop the mathematical model. Here, in this scientific work, the major efforts have been made to optimize multiple parameters for selected output responses through the use of evolutionary computational approaches. For this purpose, the particle swarm optimization (PSO), simulated annealing (SA) algorithm, and hybrid PSO-SA (HPSOSA) techniques have been employed and compared in terms of the quality responses for input parameters. From the soft computing modeling results, it has been observed that the HPSOSA improved the process performance and has revealed the global optimal solution within minimum interval of time. The developed models were statistically significant at 95% confidence interval. The experimental and mathematical outcomes for the welded specimens are duly supported with microscopic analyses.

Multi-objective parametric appraisal of pulsed current gas tungsten arc welding process by using hybrid optimization algorithms

https://ro.uow.edu.au/cgi/viewcontent.cgi?article=5384&context=eispapers1

Microstructure and mechanical properties of wire arc additively manufactured Hastelloy C276 alloy

Microstructure and mechanical properties of alloy C-276 weldments fabricated by continuous and pulsed current gas tungsten arc welding techniques

Investigation of Microstructure and Mechanical Properties of Super Alloy C-276 by Continuous Nd: YAG Laser Welding☆

Optimization of the Pulsed Current Gas Tungsten Arc Welding Process Parameters for alloy C-276 using the Taguchi Method☆

The present study aims to compare the hot corrosion resistance of bare and Ni-20%Cr coated Ni-Fe based superalloy 825 in Na2SO4-60%V2O5 molten salt environment at 900°C. Superalloy 825 was thermal spray coated with Ni-20%Cr by high-velocity oxy-fuel (HVOF) coating process. During hot corrosion study, weight measurement was done at the end of each cycle to obtain the corrosion kinetics by thermogravimetric technique. Surface morphology study, surface chemical analysis and phase identification of the corrosion products were carried out using scanning electron microscope, energy dispersive spectroscopy and X-ray diffraction. Cross-sectional analysis was performed on the hot corroded specimens to determine oxide layer thickness and depth of corrosion attack. Elemental distributions on the cross-sectioned hot corroded specimens were studied using X-ray mapping analysis. The Ni-20%Cr coated specimen showed better corrosion resistance than the bare specimen. Spallation and cracking of scale was observed on the uncoated specimen with progress of corrosion reaction.

M. Nageswara Rao

Papers

Microstructure and mechanical properties of alloy C-276 weldments fabricated by continuous and pulsed current gas tungsten arc welding techniques

Improvement of Microstructure and Mechanical Behavior of Gas Tungsten Arc Weldments of Alloy C-276 by Current Pulsing

Investigation of Microstructure and Mechanical Properties of Super Alloy C-276 by Continuous Nd: YAG Laser Welding☆

Optimization of the Pulsed Current Gas Tungsten Arc Welding Process Parameters for alloy C-276 using the Taguchi Method☆

Investigation of hot corrosion resistance of bare and Ni-20%Cr coated superalloy 825 to Na2SO4-60%V2O5 environment at 900°C