TA15钛合金多向锻造组织和拉伸性能研究

Microstructure and Tensile properties of Multi-directional forging of TA15 Titanium Alloy

摘要:

通过多向锻造工艺制备不同变形道次和变形温度的TA15钛合金试样,利用金相观察、EBSD、晶粒尺寸统计和准静态拉伸试验,分析变形过程中组织形貌、晶粒尺寸、相含量、晶界取向差和力学性能的变化。结果表明：TA15钛合金经700 ℃中温多向锻造后获得显著细化的等轴组织,且随着变形道次的增加,促使大角度晶界含量增加,同时晶粒尺寸逐渐减小,3道次后初生α平均晶粒尺寸细化至约为6.0 μm,变形后组织为α+β相,相比初始组织α相含量减少,β相含量增加；在800 ℃和900 ℃变形条件下晶粒尺寸增加,但小于初始试样；坯料的强度经多向锻造后有较大提升,700 ℃、3道次后材料抗拉强度为1443 MPa,延伸率为13.6%,比初始试样略有降低,900 ℃材料抗拉强度为1178 MPa,延伸率提高到15.8%,综合性能得到明显提升。

Abstract:

TA15 alloy samples with different forging passes and deformation temperature were prepared by multidirectional forging process. Using metallographic observation, EBSD, grain size statistics and qusai-static tensile test, the microstructure morphology, grain size, phase content, misorientation angles and mechanical properties during deformation process were analyzed. The experimental results show that a significant equiaxed structure of TA15 alloy is obatained after multidirectional forging at mediun temperature of 700 ℃, and the ratio of high angle boundary increased. Moreover, after 3 pass deformation the average grain size of primary α phase can be refined to 6.0 μm. Besides the deformation microstructure is (α+β) phase, the content of β phase increases compared with initial microstructure. With the increasing of deformation temperature, the grain size increases at 800 ℃ and 900 ℃, but is still smaller than the intial sample. The tensile strength has been improved significantly after multidirectional forging, correspondingly after 3 pass MDF at 700 ℃, the tensile strength of the samples is increased to 1443 MPa and the elongation is 13.6%, which have been slightly lower than the as-received sample. Deformation sample at 900℃,tensile strength is 1178 MPa, the elongation is increased to 15.8%. Finally, comprehensive properties of materials are significantly improved