冷变形和时效热处理对TB9钛合金组织和性能影响

Influence of cold deformation and aging heat treatment on microstructure and mechanical property of TB9 titanium alloy

摘要:

利用XRD、OM和SEM等手段研究和分析了冷变形和时效热处理对TB9钛合金组织和性能的影响。结果表明：随变形量的增大，在合金棒材横截面形成旋涡状组织，而沿纵截面形成纤维状组织；合金径向和轴向的显微硬度均随着变形量的增大而增大；合金450oC/8h/AC时效热处理后由α相和β相组成，且随变形量的增大，合金室温拉伸强度增加，塑性降低；同时冷变形过程中引入的位错等缺陷为时效过程中α相的析出提供形核位置，使α相无析出区消失，α相尺寸达到纳米级；合金70% 冷变形样品经时效热处理后最高抗拉强度可达1809MPa，此时还有4% 的延伸率，断裂方式为韧性断裂和脆性断裂混合模式。

Abstract:

The properties of titanium alloys can be improved by cold deformation and aging heat. However, there are limited report on the performance transformation of titanium alloys under the combination of cold deformation and aging heat treatment. In this work, the influence of prior cold deformation and the subsequent aging heat treatment on the phase types, α precipitation behaviors and the tensile properties of TB9 titanium alloy were studied using the X-ray diffraction, optical microstructure, scanning electron microscope and uniaxial tensile. The results showed that longitudinal and cross section of the bars formed different type macro texture through produced different microstructure and affected the microhardness. TB9 titanium alloy consisted of α and β phases after aging heat treatment. With the increase of the cold deformation rate, the tensile strength was increased and the ductile was reduced. Due to the defects produced during the cold deformation process, the precipitation free zones were disappeared in cold deformation samples and the mixmum tensile strength reach 1800MPa with an elongation of 4%.