退火温度对Ti_3Al合金热轧板材微观组织和室温拉伸性能的影响

Effect of Annealing Temperature on Microstructure and Tensile Properties of Ti_3Al Alloy Hot-Rolled Sheets

研究了退火温度对Ti-24Al-15Nb-1.5Mo合金热轧板材的微观组织和拉伸性能的影响,结果表明,热轧板材在600～950℃退火时,微观组织中的基体B2转变组织发生了很大的变化,并直接影响板材的室温拉伸性能。600℃退火获得由初生α2相和基体O相组成的两相组织,这种组织具有最高的强度和最低的塑性;800～900℃退火获得由初生α2相和被保留B2相包围的片状O/B2相集束组成的混合组织,随退火温度的提高,片状O/B2集束粗化,板材强度降低,塑性快速提高;950℃退火处理B2转变组织基体发生了复杂的相变,B2转变组织基体中α2相和B2相增加,O相减少,板材强度、塑性与900℃退火的板材相比略有增加。

The effect of annealing temperature on the microstrueture and tensile properties of hot-rolled sheets of Ti-24Al-15Nb-lMo alloy were studied. The experimental results showed that there were significant changes in the transformed B2 matrix of hot-rolled sheets during annealing at 600- 950 ℃. The phase transformation affected the tensile properties of Ti- 24Al-15Nb-lMo alloy directly. Duplex microstrueture of primary α2 and matrix O phase was obtained during annealing treatment at 600 ℃, which corresponded to the highest tensile strength and the lowest ductility. Mixed microstructure of primary α2, O/B2 plate colonies surrounded by the retained B2 phase was formed during annealing treatment at 800 - 900℃. O/B2 plates became thicker when annealing temperature increased, and resulted in the decrease of tensile strength and ductility. More complex phase transformation appeared when the sheets were annealed at 950℃. Small change of the tensile strength and ductility was found in sheets annealed at 950℃, comparing with that of sheets annealed at 900℃ because of the increase of B2 and α2 phases at the same time during annealing at 950 ℃.