Microstructure And Properties Of Pure Zirconium At Room Temperature By ECAP

In the actual production,the high strength and strong plasticity of metal materials is its essential quality.At the same time,it’s also important for its service and application on structural stability of the material.With the application of pure zirconium in industrial production,it is necessary to have more excellent microstructure and mechanical properties.Therefore,it is very important to further study the organizational evolution and thermal stability of zirconium.This paper mainly studies the microstructure evolution and properties of pure zirconium at room temperature by ECAP.The microstructure evolution and the thermal stability after two passes by ECAP,were analyzed by optical microscopy(OM),microscopy of transmission electron(TEM),tensile testing machine,microscopy of scanning electron(SEM)and X-ray diffraction(XRD).The contents conclusions as followsAfter two passes of ECAP,the coarse slabs with width of 0.5μm-1μm through further shearing will be refined,and the grain size is about 200 nm,there are also a large number of equiaxed subuniform cellular tissue exist.The texture strong diffraction intensity and type are changed after two passes.The former is gradually decreased with the increase of the deformation times,and the latter is changed from the original bimodal texture to the B texture and the C1 texture after one pass,after two passes,all become B texture.The results of mechanical properties in ECAP deformation show that the hardness,tensile strength and yield strength of ECAP after two passes are improved obviously.After one pass and two passes,the increase values respectively in hardness was 119% and 138%,in tensile strength was ~ 45% and ~ 84%,and the yield intensities were ~ 47% and ~ 93%.With the deformation times increasing,the change of stress and strain is obviously increased,there will be significant linear hardening,and softening occurs at the highest point of stress at the same time.The microstructure evolution of the ECAP after two passes annealing shows that,a certain annealing texture will be produced,and the annealing texture will be different with the changing of temperature.At 300 ℃,the texture were almost not changed;At 400 ℃,the grain begins to recover and recrystallize,and the texture will be strengthened with the deformation and growth of the subgrains.At 500 ℃,the grains were completely recrystallized and the microstructure was fine uniform equiaxed but the texture was weakened.