Dynamic and static softening mechanisms of commercial-purity Zr during double-stage hot compressive deformation

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2021-07, Vol.820, p.141578, Article 141578
• Main Authors: Wang, Qingjuan, Gao, Beite, Wang, Kuaishe, Wang, Wei, Tong, Libo, Li, Xiangjun
• Format: Article
• Language: English
• Subjects: Commercial-purity Zr; Compression loads; Deformation; Dynamic and static softening; Electron back-scattering diffraction (EBSD); Flow curve; Grain growth; Hot compression; Morphology; Optical microscopy; Purity; Recovery; Softening; Yield strength; Zirconium
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2021.141578

The dynamic and static softening behavior of R60702 commercial-purity Zr was studied through single-stage and double-stage uniaxial hot deformation tests in the range of 600oC–800 °C. The microstructural evolution to uniaxial compression loading for the different conditions was investigated using a combination of optical microscopy and electron back-scattering diffraction (EBSD). The results show that the static softening fraction increases with an increase in temperature as well as holding time. At 600 °C, the peak stress of the second stage was greater than that of the single-stage, and the sample did not undergo static softening. At 800 °C, the peak stress of the second stage was less than that of the single-stage, and the sample underwent rapid static softening during holding time. As the holding time increased at 700 °C, the peak stress of the second stage of the sample decreased successively. At 700 °C and 1s holding time, the sample did not undergo static softening, and dynamic recovery and recrystallization occurred in the subsequent second stage. At 700 °C and 60s holding time, the sample underwent static recovery and recrystallization; larger grain growth and deformation appeared in the subsequent second stage. This change in the microstructural morphology with the flow stress curve is discussed in the subsequent sections.