高强TA18钛管微观织构对拉伸力学性能与弯曲成形性能影响研究

Effect of Texture on Tensile Mechanical Properties and Bending Formability of High-strength TA18 Titanium Alloy Tube

目的揭示高强钛管微观织构强度与宏观各向异性指标CSR值的定量关系,阐明微观织构对钛管拉伸力学性能与弯曲成形性能的影响,为高强钛管冷轧微观织构及性能精确调控奠定重要基础。方法选取不同轧制工艺条件下获得的高强钛管进行单向拉伸测试及EBSD表征,分析微观织构对管材拉伸力学性能的影响;选取具有典型微观织构分布状态和CSR值的高强钛管进行数控绕弯试验及成形质量测试。结果单向拉伸力学性能测试结果表明,当CSR值为0.65~2.43时,随着CSR值的增大,颈缩阶段管材的应变与整体伸长率不断增大;数控绕弯试验结果表明,当高强钛管CSR值从1.27提高到1.48时,其断裂前最大弯曲角度从20°提高到110°,当CSR值增大到1.71时,可以成功实现120°的弯曲,并且随着CSR值进一步增大到2.14,弯管件的截面畸变率和壁厚减薄率不断减小。结论建立了可以准确描述宏观CSR与微观织构强度指标之间定量关系的双曲函数表达式,高强钛管径向织构强度的增强会提升高强钛管变形过程中抗壁厚减薄的能力,并有利于管材弯曲成形质量的提升。

The work aims to reveal the quantitative relationship between texture intensity and macroscopic anisotropy index CSR value of high-strength TA18 titanium tubes,and investigate the effects of texture on the tensile mechanical properties and bending formability of the tubes.The high-strength TA18 tubes prepared under different rolling process conditions were taken for uniaxial tensile testing and EBSD characterization and the effects of texture on the tensile mechanical properties of tubes were analyzed.Moreover,the tubes with typical texture distribution and CSR values were selected for rotary draw bending experiment and forming quality testing.The uniaxial tensile tests results indicated that when the CSR value was in the range of 0.65-2.43,the strain of necked stage and overall elongation of the tube increased with the increase of CSR value.The rotary draw bending experiments results indicated that when the CSR value was in the range of 1.27-1.48,the maximum bending angle before fracture increased from 20°to 110°.When the CSR value increased to 1.71,120°bending could be successfully realized.With the CSR value further increasing to 2.14,the cross-section distortion rate and wall thickness reduction rate of the bent tube were continuously reduced.A hyperbolic function expression that can accurately describe the quantitative relationship between macro CSR and micro texture strength index is established.The increase of radial texture intensity of high-strength titanium tubes will enhance the ability to resist wall thickness thinning during plastic deformation,which is also beneficial for improving the forming quality of tube in bending process.