Indian Welding Journal

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Effect of Delta Current Frequency (DCF) on Microstructure and Tensile properties of Gas Tungsten Constricted Arc (GTCA) welded Inconel 718 Alloy Joints


Affiliations
1 Centre for Materials Joining and Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University , Annamalai Nagar 608002, Tamilnadu, India
2 Vikram Sarabhai Space Centre (VSSC), ISRO, Thiruvananthapuram 695022, Kerala, India
     

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Inconel 718 is a nickel-based superalloy mostly used in high temperature applications in aerospace sector due to its extensive mechanical properties and weldability . Gas T ungsten Arc Welding (GT AW) process is widely used for joining of Inconel 718 alloy for cleaner , precise and high-quality welds. However , due to the high heat input and wider arc associated with this process, it is having certain metallurgical problems in welding, such as coarse dendritic structure and segregation of alloying elements in weld metal region which significantly reduces the mechanical properties of the joints. T o overcome these limitations, a newly developed Gas T ungsten Constricted Arc Welding (GTCAW) process is employed to join Inconel 718 alloy . It is the advanced configuration of GTAW process, based on magnetic arc constriction induced by high frequency pulsing of the current known as Delta Current. The main objective of this investigation is to study the effect of Delta Current Frequency (DCF) on the weldability of Inconel 718 alloy for its viability in aerospace applications. The joints welded at 4 kHz showed superior tensile properties due to the refinement of grains in fusion zone. Increase in DCF results in decrease in tensile properties of the joints due to the coarsening of dendritic fusion zone microstructure. It is attributed to the stacking of heat input during welding.

Keywords

Gas Tungsten Constricted Arc Welding, GTCAW, Delta Current Frequency, Inconel 718, T Ensile Properties, Microstructure.
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Abstract Views: 250

PDF Views: 7




  • Effect of Delta Current Frequency (DCF) on Microstructure and Tensile properties of Gas Tungsten Constricted Arc (GTCA) welded Inconel 718 Alloy Joints

Abstract Views: 250  |  PDF Views: 7

Authors

Tushar Sonar
Centre for Materials Joining and Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University , Annamalai Nagar 608002, Tamilnadu, India
V. Balasubramanian
Centre for Materials Joining and Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University , Annamalai Nagar 608002, Tamilnadu, India
S. Malarvizhi
Centre for Materials Joining and Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University , Annamalai Nagar 608002, Tamilnadu, India
T. Venkateswaran
Vikram Sarabhai Space Centre (VSSC), ISRO, Thiruvananthapuram 695022, Kerala, India
D. Sivakumar
Vikram Sarabhai Space Centre (VSSC), ISRO, Thiruvananthapuram 695022, Kerala, India

Abstract


Inconel 718 is a nickel-based superalloy mostly used in high temperature applications in aerospace sector due to its extensive mechanical properties and weldability . Gas T ungsten Arc Welding (GT AW) process is widely used for joining of Inconel 718 alloy for cleaner , precise and high-quality welds. However , due to the high heat input and wider arc associated with this process, it is having certain metallurgical problems in welding, such as coarse dendritic structure and segregation of alloying elements in weld metal region which significantly reduces the mechanical properties of the joints. T o overcome these limitations, a newly developed Gas T ungsten Constricted Arc Welding (GTCAW) process is employed to join Inconel 718 alloy . It is the advanced configuration of GTAW process, based on magnetic arc constriction induced by high frequency pulsing of the current known as Delta Current. The main objective of this investigation is to study the effect of Delta Current Frequency (DCF) on the weldability of Inconel 718 alloy for its viability in aerospace applications. The joints welded at 4 kHz showed superior tensile properties due to the refinement of grains in fusion zone. Increase in DCF results in decrease in tensile properties of the joints due to the coarsening of dendritic fusion zone microstructure. It is attributed to the stacking of heat input during welding.

Keywords


Gas Tungsten Constricted Arc Welding, GTCAW, Delta Current Frequency, Inconel 718, T Ensile Properties, Microstructure.

References





DOI: https://doi.org/10.22486/iwj.v53i2.195584