Weldability of a zirconium alloy comparing resistance and pulsed laser methods

Author(s)

Sakamiti, Guilherme Pennachin ^{[1, 2]} ; Mota de Siqueira, Rafael Humberto ^{[1, 3]} ; de Carvalho, Sheila Medeiros ^{[3, 4]} ; Meireles, Joao Batista ^{[2, 5]} ; Fernandes de Lima, Milton Sergio ^{[1, 3]}

Affiliation

^[1] ITA, Technol Inst Aeronaut, Grad Program Space Sci & Technol, Sao Jose Dos Campos, SP - Brazil

^[2] Ind Nucl Brasil SA, INB, Rezende - Brazil

^[3] IEAv, Inst Adv Studies, Photon Div, Sao Jose Dos Campos, SP - Brazil

^[4] FIESC SENAI SC, SENAI Inst Laser Proc Innovat, Joinville - Brazil

^[5] Fed Fluminense Univ UFF Volta Redonda, Met Engn Postgrad Program, Volta Redonda - Brazil

• Document type: Journal article
• Source: NUCLEAR MATERIALS AND ENERGY; v. 20, AUG 2019.
• Web of Science Citations: 0

Abstract

The current study intends to characterize the microstructure resulting from the autogenous welding of zircaloy-4 and its influence on the mechanical behavior. For comparison purposes, laser beam welding (LBW) and electric resistance welding (ERW) were used for joint tubes to sleeves suitable for fuel elements of the Brazilian power reactor Angra 1. The tubes measured 14.15 mm external diameter with a wall thickness of 1.76 mm and the sleeves measured 15.61 internal diameter with a wall thickness of 0.64 mm. Under conventional ERW, the process parameters were chosen to produce an approximately 2 mm wide weld bead appropriate for the thermo-mechanical loading of the component. However, laser methods could be an alternative for automation and reproductiity. The microstructure in the fusion zone (FZ) for the welding processes was characterized by a martensite for LBW and a Widmanstatten for ERW. It was verified tin segregation in specific regions of the ERW coupons, however, without affecting the tensile strength or the hardness of the coupons. The maximum load for ERW coupons were about 8 kN, higher than LBW case (3 kN), although both above the standard requirements. The relative low value of LBW tensile strength was due to the gap between the tube and the sleeve, as conceived for ERW, and not optimized for the laser process. Loss of coolant accident (LOCA) shown a white ZrO2 coating on the LBW surface as a result of massive oxidation of the resolidified material. (AU)

• FAPESP's process: 16/11309-0 - The study, development and application of a hybrid process: Additive Manufacturing (AM) plus High Speed Machining/Grinding (HSM/G)
• Grantee: Reginaldo Teixeira Coelho
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 16/16683-8 - Experimental development of high temperature laser welding for ultra-high strength steels for aerospace applications
• Grantee: Milton Sergio Fernandes de Lima
• Support Opportunities: Regular Research Grants