135°ECAP+旋锻变形工业纯钛的热稳定性研究

摘要

Commercially pure(CP) Ti fabricated by 135° ECAP and swaging was annealed at 100, 150, 200, 250, 300, 350, 400, 450℃ and 500℃ for 1h, respectively.The microstructure and properties of annealed commercially pure Ti were investigated by transmission electron microscopy, scanning electron microscopy, uniaxial tensile test and microhardness test.The results show that when annealing temperature is below 400℃, dislocation density reduces gradually and grain boundary becomes clear, no obvious change occurs in the microstructure,ultimate tensile strength and microhardness decrease slightly and no obvious increase occurs in the elongation;when annealing temperature is above 400℃, recrystallization occurs with the increase of annealing temperature, and the grain size increases obviously, the average size is about 5μm, the ultimate tensile strength and microhardness decrease significantly and elongation increases at the same time.The tensile fracture shows the tensile fracture of annealed commercial pure Ti by ECAP and swaging is ductile fracture.With the increase of annealing temperature, the size and depth of dimples increase.%对经过135°ECAP+旋锻变形后的工业纯钛100,150,200,250,300,350,400,450℃和500℃下保温1h退火.采用透射电子显微镜(TEM)、扫描电子显微镜(SEM)、拉伸试验机及显微硬度仪等技术研究ECAP+旋锻变形工业纯钛退火后的组织与性能变化.结果表明:在400℃以下退火时,显微组织中位错密度降低,晶界逐渐清晰,变形组织未发生明显变化,材料的抗拉强度和显微硬度略有降低,伸长率增加不明显;在400℃以上退火时,随着退火温度的升高,发生再结晶,晶粒尺寸明显增大,平均晶粒尺寸约为5μm,材料的抗拉强度和显微硬度均出现明显降低,伸长率增加.拉伸断口表明,ECAP+旋锻变形退火后工业纯钛的拉伸断裂均为韧性断裂.随着退火温度的升高,韧窝尺寸变大,韧窝深度变深.