Crystallographic texture and microstructural changes in fusion welds of recrystallized Zry-4 rolled plates

JOURNAL OF NUCLEAR MATERIALS

卷:488

Article

Moya Riffo, A.¹  Vicente Alvarez, M. A.¹  Santisteban, J. R.¹  Vizcaino, P.²  Limandri, S.³  Daymond, M. R.⁴  Kerr, D.⁴  Okasinski, J.⁵  Almer, J.⁵  Vogel, S. C.⁶ 

[1] Consejo Nacl Invest Cient & Tecn, CNEA, Ctr Atom Bariloche, Neutron Phys Dept, Buenos Aires, DF, Argentina

[2] Consejo Nacl Invest Cient & Tecn, CNEA, Ctr Atom Ezeiza, Zirconium Technol Dept, Buenos Aires, DF, Argentina

[3] Univ Nacl Cordoba, Fac Matemat Astron & Fis, Cordoba, Argentina

[4] Queens Univ, Dept Mech & Mat Engn, Kingston, ON, Canada

[5] Argonne Natl Lab, Adv Photon Source, Argonne, IL 60439 USA

[6] Los Alamos Natl Lab, Los Alamos Neutron Sci Ctr, Los Alamos, NM USA

关键词: Zirconium;    Phase transformations;    Variant selection;    Texture;    High energy X-Ray diffraction;    Fusion welding;    Heat affected zone;    GTAW PAW;   

DOI  :  10.1016/j.jnucmat.2017.02.015

来源: Elsevier

【 摘 要 】

This work presents a detailed characterization of the microstructural and crystallographic texture changes observed in the transition region in a weld between two Zircaloy-4 cold rolled and recrystallized plates. The microstructural study was performed by optical microscopy under polarized light and scanning electron microscopy (SEM). Texture changes were characterized at different lengthscales: in the micrometric size, orientation imaging maps (OIM) were constructed by electron backscatter diffraction (EBSD), in the millimetre scale, high energy XRD experiments were done at the Advanced Photon Source (USA) and compared to neutron diffraction texture determinations performed in the HIPPO instrument at Los Alamos National Laboratory. In the heat affected zone (HAZ) we observed the development of Widmanstatten microstructures, typical of the alpha(hcp) to beta(bcc) phase transformation. Associated with these changes a rotation of the c-poles is found in the HAZ and fusion zone. While the base material shows the typical texture of a cold rolled plate, with their c-poles pointing 35 degrees apart from the normal direction of the plate in the normal transversal line, in the HAZ, c-poles align along the transversal direction of the plate and then re-orient along different directions, all of these changes occurring within a lengthscale in the order of mm. The evolution of texture in this narrow region was captured by both OIM and XRD, and is consistent with previous measurements done by Neutron Diffraction in the HIPPO diffractometer at Los Alamos National Laboratory, USA. The microstructural and texture changes along the HAZ were interpreted as arising due to the effect of differences in the cooling rate and beta grain size on the progress of the different alpha variants during transformation. Fast cooling rates and large beta grains are associated to weak variant selection during the beta->alpha transformation, while slow cooling rates and fine beta grains result in strong variant selection. (C) 2017 Published by Elsevier B.V.

【 授权许可】

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