张力退火对Zr–4合金织构和再结晶行为的影响

Effect of stress annealing on texture and recrystallization behavior of Zr–4 alloy

  • 摘要: 以易控的工艺条件为基础,通过设计简易实验装置来模拟锆合金在实际生产中的张力退火过程。采用X射线衍射(XRD)和电子背散射(EBSD)技术,对不同温度和不同张力下退火处理后的Zr–4合金织构和再结晶行为进行研究。结果表明,施加外加应力和提高退火温度可显著改变再结晶织构演化过程。随着外加应力值的增加以及退火温度的升高,锆合金的主要织构(\overline 1 2\overline 1 5) 10 \overline 1 0总量减少,极密度减弱,从而导致材料各向异性减小;外加应力和退火温度对材料再结晶过程中小角度晶界数量以及再结晶比例产生了显著影响,随着外加应力的增加以及退火温度的升高,材料内部发生动态回复和再结晶,位错和亚结构逐渐消失,材料再结晶过程中的小角度晶界数量明显减少,材料的再结晶过程加快,材料的再结晶比例显著提高。外加应力的施加以及退火温度的升高均有利于材料内部再结晶过程的加速进行。研究结果对Zr–4合金退火处理优化有指导作用,为解决锆合金在工程应用中所遇到的问题提供了科学基础。

     

    Abstract: The texture of Zr–4 alloy not only affects its irradiation growth performance, but also affects mechanical properties, stress corrosion cracking, and water-side corrosion. Therefore, it is important to control the texture of Zr–4 alloy during processing. The effect of the applied external stress, annealing temperature, and annealing time on texture evolution and recrystallization of Zr–4 alloy is still unclear. Based on controllable process conditions, the stress annealing process of zirconium alloy in practical production was simulated by designing a simple experimental device. The texture and recrystallization behavior of Zr–4 alloy after annealing at different temperatures and stresses were studied by X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) techniques. The results show that applying external stress and increasing annealing temperature significantly change the evolution of recrystallized texture. With an increase in stress and annealing temperature, the texture of the zirconium alloy (\overline 1 2\overline 1 5)10 \overline 1 0, and the polar density decreases, thereby resulting in a decrease in material anisotropy. The annealing temperature has a significant effect on the amount of small-angle grain boundary and recrystallization ratio during material recrystallization. With an increase in applied stress and annealing temperature, dynamic recovery and recrystallization occur inside the material. The sub-structures in dynamic recovery and the dislocation sub-structures in the grains that undergo dynamic recrystallization gradually disappear. The small-angle grain boundary in the material recrystallization process is reduced significantly. The process is accelerated and the recrystallization ratio of the material is significantly increased. The application of applied external stress and the increase of annealing temperature are beneficial to the acceleration of the internal recrystallization process of the material. The main results from this paper can guide the optimization of annealing treatment of Zr–4 alloy, and provide a scientific basis for solving the problems encountered in the engineering application of Zr–4 alloy.

     

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