(西安建筑科技大学 冶金工程学院,西安 710055)
摘 要: 研究连续变断面循环挤压变形道次、变形温度、变形速度对TC4合金组织的影响。结果表明:在临近再结晶温度变形时,随着变形道次的增加,晶粒的细化程度随之增加;而在较高温度变形时,随着变形道次的增加,晶粒的细化程度先增大后减小,且6道次的细化效果较佳。随着变形温度的升高,由于再结晶的作用,晶粒的细化程度先增大再减小,且在800 ℃变形时,细化效果较佳;提高变形速度有利于晶粒的细化,但当变形速度过高时,组织分布的均匀性较差。当TC4合金在800 ℃以2 mm/s经6道次变形后,初生α相尺寸由14 μm细化至2~ 3 μm左右,且组织分布较均匀。
关键字: TC4合金;连续变断面循环挤压;显微组织;晶粒细化
(School of Metallurgical Engineering, Xi’an University of Architecture & Technology, Xi’an 710055, China)
Abstract:The TC4 titanium alloy was deformed by continuous variable cross-section recycling extrusion (CVCE), and the effects of deformation loop, temperature and speed on the microstructure were investigated. The results show that, near the recrystallization temperature, the grain size of the alloy decreases rapidly with increasing deformation loop. However, when deformed at higher temperature, the refinement degree of the grain increases firstly, and then decreases with the increase of deformation loops, and the refinement effect of 6 loops is better. Moreover, with the increase of deformation temperature, the grain size decreases firstly, and then increases due to recrystallization, and the refinement effect is better as the specimen is deformed at 800 ℃. The higher deformation speed is beneficial to refine the grain, but too high deformation speed is unfavourable for the distribution uniformity of microstructure. When the specimen is deformed at 800 ℃ and 2 mm/s for 6 loops, the size of the primary α phase reduces from 14 μm to 2-3 μm, and the microstructure distributes homogeneously.
Key words: TC4 alloy; continuous variable cross-section recycling extrusion; microstructure; grain refinement