Elevated temperature deformation of Zr to large strains
- PDF / 859,759 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 5 Downloads / 215 Views
NANOSTRUCTURED MATERIALS
Elevated temperature deformation of Zr to large strains M. E. Kassner • M. T. Perez Prado • T. A. Hayes • L. Jiang • S. R. Barrabes I. F. Lee
•
Received: 1 November 2012 / Accepted: 30 November 2012 / Published online: 13 December 2012 Ó Springer Science+Business Media New York 2012
Abstract This paper presents new data and a summarization of earlier work, especially by the authors, regarding the large strain deformation (generally severe plastic deformation) of pure zirconium, generally at elevated temperatures (300–800 °C range). It appears clear, now, that Zr deforms by classic five-power-law creep. Large strain deformation revealed recovery controlled mechanisms with grain refinement occurring by geometric necessary boundaries and/or the recovery-based mechanism of geometric dynamic recrystallization depending on the amount of grain elongation that occurs. No discontinuous dynamic recrystallization or grain growth was observed in the authors’ tension and rolling studies. The refined ultrafine grained substructure showed dramatically improved tensile properties over conventionally processed Zr.
This paper discusses the current and previous work, especially by the authors [1–12] relating to the large strain deformation of zirconium at elevated temperatures. Specifically, this paper will discuss large strain deformation in tension, compression, torsion as well as other methods including equal channel angular pressing (ECAP) and high pressure torsion (HPT). Typically, the zirconium was of a purity of about 99.8 %, or higher. This discussion contains several parts: (1) basic mechanisms of plasticity of Zr at elevated temperature from intermediate to high temperatures (2) tensile deformation to large strains, (3) rolling, and (4) other mechanisms of large strain deformation. Discussions in each section will emphasize the examination of the microstructure, plasticity mechanisms, texture and mechanical properties of pure zirconium with large strain deformation at elevated temperature.
Mechanisms of elevated temperature plasticity of Zr M. E. Kassner (&) I. F. Lee Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA 90089-0241, USA e-mail: [email protected] M. T. Perez Prado IMDEA Materials Institute, C/Eric Kandel, 2, 28906 Getafe, Madrid, Spain T. A. Hayes Exponent Failure Analysis Associates, 149 Commonwealth Drive, Menlo Park, CA 94025, USA L. Jiang Implant Direct Sybron International, 27030 Malibu Hills Road, Calabasas Hills, CA 91301, USA S. R. Barrabes Hypertherm, 21 Great Hollow Road, Hanover, NH 03755, USA
123
There has been a great deal of uncertainty regarding the mechanism of elevated temperature deformation. Early work by Ardell and Sherby [13] suggested a dislocation-glidecontrolled mechanism. This was largely due to varying stress exponents for steady-state creep plasticity at homologous temperature and strain-rate combinations where many, if not most, crystalline materials evince classic five-power-law creep. In pure metals
Data Loading...
