Rolling and recrystallization behavior of pure zirconium and zircaloy-4

ABSTRACT Rolling and recrystallization of pure zirconium and zircaloy-4 have been studied comparatively in this paper. For the as-received condition, zirconium presented a recrystallized microstructure and the alloy a typical basketweave microstructure. Comparative rolling tests were performed, and reduction limit curves as a function of the rolling temperature were determined. At room temperature, pure Zr shows substantial plasticity and the alloy presents low ductility and many cracks. The ductility of both materials increases significantly with an increase in rolling temperature at the range between 300 and 500ºC. In static recrystallization studies, samples of the two materials with similar recrystallized grain size were cold-rolled with a thickness reduction of 55%. During annealing, pure Zr and the alloy soften by recovery and recrystallization, however the relative contribution of recovery is lesser pronounced in the alloy, for which the recrystallization temperature increases by about 60°C.

摘要 本研究对纯锆与锆合金Zircaloy-4的轧制及再结晶行为开展了对比性研究。原始态试样中，纯锆呈现再结晶组织，而该合金则呈现典型的篮状织构组织。研究开展了对比轧制试验，并绘制了轧制极限压下率随轧制温度变化的曲线。室温条件下，纯锆展现出优异的塑性，而该合金则塑性较低且易产生大量裂纹。在300~500℃的轧制温度区间内，两种材料的塑性均随轧制温度升高而显著提升。静态再结晶研究中，选取两种材料中再结晶晶粒尺寸相近的试样，进行55%厚度压下率的冷轧处理。退火过程中，纯锆与该合金均通过回复与再结晶实现软化，但合金中回复的相对贡献程度更低，且其再结晶温度较纯锆提升约60℃。