铍材轧制过程温度对其塑性及显微组织的影响

Effect of Rolling Temperature on the Plasticity and Microstructure of Beryllium

纯铍在室温条件下轧制的低塑性和冷脆性限制了其板材厚度超薄化、面积大尺寸化。采用金相显微镜、单向拉伸和轧制试验,研究了变形温度对纯铍板材断后伸长率、最大道次加工率和显微组织的影响。结果表明:随着变形温度的增加,纯铍板材塑性呈先增强后降低的波动变化趋势,并在325~350℃和600~700℃区间出现两个最佳塑性区。纯铍板材在第二个最佳塑性区轧制变形时,晶粒沿轧制方向被拉长并发生一定程度的动态再结晶,晶粒得到细化,显微组织得到一定程度的改善,且轧制温度越高显微组织改善的程度越高。纯铍板材在第二个最佳塑性区退火过程的再结晶程度随温度的升高逐渐趋向完全。为了显著改善纯铍板材的显微组织并使其再结晶程度趋于完全,热轧温度和退火温度宜选择在600~700℃区间。

The low plasticity and cold brittleness of pure beryllium rolled at room temperature limit the ultra-thin thickness and large-size area of its sheet.Using metallographic microscope, uniaxial tension and rolling tests, the effects of deformation temperature on fracture elongation, maximum pass processing rate and microstructure of pure beryllium sheets were investigated.The results show that with the increase of deformation temperature, the plasticity increases at first and then decreases with a fluctuating trend, and two optimal plastic zones appear at 325~350 ℃ and 600~700 ℃.When the pure beryllium sheet is rolled and deformed in the second optimal plastic zone, the grains are elongated along the rolling direction and undergo a certain degree of dynamic recrystallization, so that the grains are refined and the microstructure is improved to a certain extent.And the higher the rolling temperature, the greater the degree of microstructure improvement.The recrystallization degree of pure beryllium sheets during annealing in the second optimal plastic zone gradually tends to be complete with the increase of temperature.In order to significantly improve the microstructure of pure beryllium sheets and make the recrystallization degree tend to be complete, the hot rolling temperature and annealing temperature should be selected in the range of 600~700 ℃.