Study of Variation in Fracture Location of Electron Beam-Welded Hastelloy C-276 Sheets under Uniaxial Tension
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Study of Variation in Fracture Location of Electron Beam-Welded Hastelloy C-276 Sheets under Uniaxial Tension Kalinga Simant Bal, Jyotsna Dutta Majumdar, and Asimava Roy Choudhury Submitted: 3 June 2020 / Revised: 20 October 2020 / Accepted: 20 October 2020 In the present study on the analysis of fractured tensile specimens of welded Hastelloy C-276 sheets, it was inferred that the failure of the weldment depends on the type of intermetallic phases formed in the weld zone (WZ). This failure phenomenon is also influenced by the inclination between the adjacent grains formed in the WZ. For instance, the welded specimens having a lower inter-granular inclination angle (= 39.68°) and containing 47Cr-26Ni-rich precipitate in the WZ were observed to fail from the base metal (BM). The presence of 47Cr-26Ni-rich precipitate provided restriction to the dislocation motion through pinning. On the other hand, the specimen containing 40Ni-27Mo-rich precipitate was observed to fail at the WZ due to decohesion and fragmentation of the precipitates under tension. The relative ease of dislocation motion due to a higher inter-granular inclination angle (= 103.76°) in the WZ also led to the early failure of the weldment. The percent elongation (PE) of the WZ-fractured specimen was lowered by 15% as compared to that of the BM-fractured specimen. The introduction of apparent percent elongation (APE) helped in identifying the zone (BM or WZ) that underwent maximum plastic deformation during the tensile test.
Kalinga Simant Bal, Department of Mechanical Engineering, C. V. Raman Global University, Bhubaneswar, Odisha 752054, India; and Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur, West Bengal 721302, India; Jyotsna Dutta Majumdar, Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur, West Bengal 721302, India; and Asimava Roy Choudhury, Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur, West Bengal 721302, India. Contact e-mail: [email protected].
Journal of Materials Engineering and Performance
Graphic Abstract
Keywords
characterization, welding
dislocations,
fracture,
plasticity,
1. Introduction The major issues related to the welding of Hastelloy C-276 include: (a) failure of the tensile specimen at the WZ, (b) correlation of the failure with Mo-rich precipitate formation, and (c) limited analysis on fracture morphology of electron beam-welded (EBW) Hastelloy C-276 sheets. Hastelloy C-276 has found applications in many industries due to its ease of weldability (Ref 1) . However, after welding, improvement in one tensile property could occur at the expense of another. For
example, Manikandan et al. (Ref 2, 3) have reported that the UTS(Welded Hastelloy C-276) > UTS(Hastelloy C-276 BM) but the PE(Welded Hastelloy C-276) < PE(Hastelloy C-276 BM); here UTS corresponds to ultimate tensile stress. Tensile strength has been correlated with dislocation motion in Hastelloy C-276 by Qi
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