Microstructure, Texture and Mechanical Properties in Different Deformation Regions of the Compressed Zr-4 Alloy With Lamellar Structure

In the present work, the inhomogeneous plastic deformation of the compressed Zr-4 alloy with lamellar structure has been studied systematically. In the compression test of Zr-4 alloy with reduction of 70% at 650°C, the severe deformed area (SDA) and difficult deformed area (DDA) formed. The differences in DDA and SDA including microstructure, texture, and mechanical properties were investigated, using electron backscattering diffraction (EBSD) and Vickers hardness tester. The results showed that a large number of equiaxed grains appeared in SDA due to the occurrence of dynamic recrystallization (DRX), while coarse lamellar grains were still the main microstructure in DDA, showing that the DDA was the intermediate between the initial alloy and SDA. Furthermore, the discontinuous recrystallization mechanism was proposed. According to electron backscattered diffraction (EBSD) analysis, the predominant texture formed in SDA and DDA made normal direction of its {0001} planes of α phase parallel to the compression direction, and another stronger texture in SDA made the normal direction of part {0001} planes ∼15° away from the compression direction. The observed texture difference in SDA and DDA mainly resulted from the DRXed grains. To evaluate the influence of SDA on the mechanical properties of the Zr-4 alloy, microhardness tests were employed. The alloy in SDA had been proved to be strengthened compared to DDA, which was due to both the grain refinement and the texture diversity.