Effect of Continuous and Pulsed Current GTA Welding on the Performance of Dissimilar Welds Involving Aerospace Grade Alloys
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Dissimilar joints involving Inconel 718 and the martensitic grade stainless steel AISI 416 have been employed in gas turbine applications. In the present study, an attempt has been made to compare the effect of continuous current and pulsed current gas tungsten arc welding of this dissimilar joint. These dissimilar alloys were welded using a low cost, Nb free stainless steel filler, with a view of controlling or eliminating the deleterious Laves phase. Microstructure studies performed at the fusion zones of both CCGTA and PCGTA weldments revealed the formation of martensite at the cap zones. The unmixed zone containing Nb rich phases, observed at the weld interface of Inconel 718 was found to be lower for PCGTA weldments. Tensile failures were experienced at the parent metal of AISI 416 for both the cases. Impact toughness of the weldments were lower than that of parent metals employed in the study. High temperature corrosion studies were performed on the weld coupons by exposing them to an aggressive molten salt environment containing K2SO4 − 60% NaCl at 650 °C. Owing to the recrystallization and grain refinement, the PCGTA weldments experienced better corrosion resistance compared to the CCGTA weldments. Surface analytical techniques were employed to determine the hot corroded species formed and attempts have been made to establish the corrosion kinetics.
KeywordsInconel 718 AISI 416 Welding Microstructure Tensile strength Hot corrosion
The authors sincerely thank the Aeronautical Research & Development Board (AR&DB) [ARDB/01/2031754/M/I] for funding the project. The funding provided by DST-FIST for Instron Universal Testing Machine at our VIT University is gratefully acknowledged. The authors sincerely thank Mr. Arul Maximus Rabel, Scientist, Sathyabama University and Mr. G. Selvakumar, Assistant Professor (Research), PSG Center for Excellence for Industrial and Home Textiles for helping us in the SEM/EDAX analysis. The authors wish to thank Mr. Aditya Chandrasekhar for proof reading the manuscript.
- 3.Mortensen K S, Jensen C G, Conrad L C, and Losee F, Weld Res Suppl 1 (2001) 268.Google Scholar
- 4.Ram G J, Reddy A V, Rao K P, and Reddy G M, Sci Technol Weld Join 9 (2013) 390.Google Scholar
- 11.Ramkumar K D, Dev S, Saxena V, Choudhary A, Arivazhagan N, and Narayanan S, Mater Des 87 (2015) 663.Google Scholar
- 12.Lundin C D, Liu W, Zhou G, and Qiao C Y, Weld Res Counc Bull 428 (1998) 98.Google Scholar
- 14.Davis J R, Stainless Steel-ASM Specialty Handbook, ASM International, New York (1994).Google Scholar
- 16.John L, and Damian J K, Welding Metallurgy and Weldability of Stainless Steels, Wiley, Hoboken (2005) p 61.Google Scholar
- 17.Iamboliev T, Weld Mater Test 4 (2015) 3.Google Scholar