Manufacturing Technology Today

Open Access Open Access  Restricted Access Subscription Access
Open Access Open Access Open Access  Restricted Access Restricted Access Subscription Access

Effect of Delta Current on the Microstructure and Tensile Properties of Gas Tungsten Constricted Arc Welded Inconel 718 Alloy Joints


Affiliations
1 Centre for Material Joining and Research (CEMAJOR), Dept. of Mfg. Engg., Annamalai University, Annamalai Nagar, Tamilnadu, India
2 Vikram Sarabhai Space Centre (VSSC), ISRO, Thiruvananthapuram, India
     

   Subscribe/Renew Journal


Inconel 718 is a nickel-based superalloy which is of potential interest in high temperature applications in rocket and gas turbines. This alloy is mostly joined by Gas Tungsten Arc Welding (GTAW) process for clean and precise welds and it is economical and shop friendly. However, due to the high heat input associated with this process, the joints are more prone for metallurgical problems such as coarse dendritic structure and segregation in weld metal region and liquation cracking in heat affected zone (HAZ) which significantly reduces the mechanical properties of the welded joints. To overcome these shortcomings, a recently developed Gas Tungsten Constricted Arc Welding (GTCAW) process is used for joining Inconel 718 alloy. It is the advanced variant of GTAW process with magnetic arc constriction achieved by introducing high frequency pulsing Current (known as Delta Current). Delta Current pulsing at a very high frequency is controlling factor for the rise and fall of magnetic arc constriction during welding. The main objective of this investigation is to make the potential use of Magnetic Arc Constriction to reduce the heat input for minimizing metallurgical problems and enhancing the mechanical properties of the joints. To achieve this, main effect of Delta Current on tensile properties and microstructural characteristics of Inconel 718 alloy is investigated.

Keywords

Gas Tungsten Constricted Arc Welding (GTCAW), Delta Current, Tensile Properties, Microstructural Characteristics.
User
Subscription Login to verify subscription
Notifications
Font Size

  • Lippold, J; DuPont, JC; DuPont, JN; Kiser, SD: Welding metallurgy and weldability of nickel base alloys, 'John Wiley and Sons, Inc.', New Jersey, 2009.

  • Agilan, M; Krishna Chenna, S; Manwatkar, Sushant, K; Vinayan, EG; Sivakumar, Bhanu, D Pant: Effect of welding processes (GTAW & EBW) and solutionizing temperature on microfissuring tendency in Inconel 718 welds, 'Materials Science Forum', vol. 710, 2004, 603-607.

  • Gordine, J: Some problems in welding Inconel 718, 'Welding Journal', 1970, 480-484.

  • Madhusudan Reddy, G; Srinivasa Murthy, CV; Srinivasa Rao, K; Prasad Rao, K: Improvement of mechanical properties of Inconel 718 electron beam welds— influence of welding techniques and post weld heat treatment, 'International Journal of Advanced Manufacturing Technology', vol. 43, 2009, 671 - 680.

  • Janki Ram, G; Reddy, A; Prasad Rao, K; Reddy G; Sarin Sundar, J: Microstructure and tensile properties of Inconel 718 pulsed Nd-Yag laser welds, 'Journal of Materials Processing Technology', vol. 167, 2005, 73 - 82.

  • Sivaprasad, K; Sundra Raman, G: Influence of weld cooling rate, on microstructure and mechanical properties of Alloy 718 weldments, 'Metallurgical and Materials Transactions A', vol. 39A, 2008, 2115 - 2127.

  • Sudarshan Rao, G; Saravanan, K; Harikrishnan, G; Sharma, VMJ; Ramesh Narayan, P; Sreekumar, K; Sinha, P: Local deformation behaviour of Inconel 718 TIG weldments at room temperature and 550°C, 'Materials Science Forum', vol. 710, 2012, 439 - 444.

  • Sivaprasad, K; Ganesh Sundara Raman, S; Mastanaiah, P; Madhusudhan Reddy, G; Influence of magnetic arc oscillation and current pulsing on microstructure and high temperature tensile strength of alloy 718 TIG weldments, 'Materials Science and Engineering A', vol. 428, 2006, 327 - 331.

  • Janaki Ram, GD; Venugopal Reddy, A; Prasad Rao, K; Madhusudhan Reddy, G: Control of Laves phase in Inconel 718 GTA welds with current pulsing, 'Science and Technology of Welding and Joining', vol. 9, no. 5, 2004, 390-398.

  • Radhakrishna, CH; Prasad Rao, K: The formation and control of Laves phase in superalloy 718 welds, 'Journal of Materials Science', vol. 32, 1997, 1977 - 1984.

  • Seidi, FR; Unkel, W: Arc and weld pool behavior for pulsed current GTAW, 'Welding Research Supplement', 1988, 247-255


Abstract Views: 284

PDF Views: 0




  • Effect of Delta Current on the Microstructure and Tensile Properties of Gas Tungsten Constricted Arc Welded Inconel 718 Alloy Joints

Abstract Views: 284  |  PDF Views: 0

Authors

Tushar Sonar
Centre for Material Joining and Research (CEMAJOR), Dept. of Mfg. Engg., Annamalai University, Annamalai Nagar, Tamilnadu, India
V. Balasubramanian
Centre for Material Joining and Research (CEMAJOR), Dept. of Mfg. Engg., Annamalai University, Annamalai Nagar, Tamilnadu, India
S. Malarvizhi
Centre for Material Joining and Research (CEMAJOR), Dept. of Mfg. Engg., Annamalai University, Annamalai Nagar, Tamilnadu, India
T. Venkateswaran
Vikram Sarabhai Space Centre (VSSC), ISRO, Thiruvananthapuram, India
D. Sivakumar
Vikram Sarabhai Space Centre (VSSC), ISRO, Thiruvananthapuram, India

Abstract


Inconel 718 is a nickel-based superalloy which is of potential interest in high temperature applications in rocket and gas turbines. This alloy is mostly joined by Gas Tungsten Arc Welding (GTAW) process for clean and precise welds and it is economical and shop friendly. However, due to the high heat input associated with this process, the joints are more prone for metallurgical problems such as coarse dendritic structure and segregation in weld metal region and liquation cracking in heat affected zone (HAZ) which significantly reduces the mechanical properties of the welded joints. To overcome these shortcomings, a recently developed Gas Tungsten Constricted Arc Welding (GTCAW) process is used for joining Inconel 718 alloy. It is the advanced variant of GTAW process with magnetic arc constriction achieved by introducing high frequency pulsing Current (known as Delta Current). Delta Current pulsing at a very high frequency is controlling factor for the rise and fall of magnetic arc constriction during welding. The main objective of this investigation is to make the potential use of Magnetic Arc Constriction to reduce the heat input for minimizing metallurgical problems and enhancing the mechanical properties of the joints. To achieve this, main effect of Delta Current on tensile properties and microstructural characteristics of Inconel 718 alloy is investigated.

Keywords


Gas Tungsten Constricted Arc Welding (GTCAW), Delta Current, Tensile Properties, Microstructural Characteristics.

References