STP939

    Laser Beam Beta Heat Treatment of Zircaloy

    Published: Jan 1987


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    Abstract

    A commercially viable process of beta-phase heat treatment of Zircaloy tubing has been developed that circumvents the problems of dimensional stability at the treatment temperature, protection from oxidation, and control of beta grain size. The method utilizes a high-power, geometrically shaped laser beam that impinges on the surface of the tubing as the tubing is rotated and translated through the focused beam. Beam energy, surface temperature, and translation speed are chosen such that the zone of beta-phase formation penetrates approximately 30% of the wall thickness, and the self-quenching provided by the underlying material produces a uniformly rapid cooling rate. The laser treatment is performed in an argon-filled chamber on next-to-final-sized tubing, and tube properties are recovered by cold working to final size and final annealing. Tubing of Zircaloy-2 and Zircaloy-4 produced by the laser beam beta-phase treatment is immune to nodules on both the inside and outside surfaces in the 24 h, 773 K steam test, and post-transition corrosion rates of Zircaloy-4 are lower than those of conventionally processed tubing by factors of two to three in the 633 to 673 K temperature range. The laser beta heat treatment process and the resultant tubing properties are described.

    Keywords:

    zirconium, alloys, Zircaloy, laser, heat, corrosion, nodules, properties, tubing, phase, transformation, strength, creep, beta treatment


    Author Information:

    Sabol, GP
    Westinghouse R&D Center, Pittsburgh, PA

    McDonald, SG
    Westinghouse Nuclear Fuel Division, Monroeville, PA

    Nurminen, JI
    Westinghouse R&D Center, Pittsburgh, PA

    Jacobsen, WA
    Westinghouse Specialty Metals Plant, Blairsville, PA


    Paper ID: STP28116S

    Committee/Subcommittee: B10.02

    DOI: 10.1520/STP28116S


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