基于Murty判据的Ti-6.5Al-3.5Mo-1.5Zr-0.3Si钛合金α+β相区热变形机制及工艺优化(英文)

Hot Deformation Mechanism and Process Optimization for Ti-Alloy Ti-6.5Al-3.5Mo-1.5Zr-0.3Si during α+β Forging Based on Murty Criterion

根据Murty失稳判据，利用原始等轴组织的TC11钛合金在780～990℃和0．001～70s^-1范围内的等温恒应变速率压缩实验数据，建立了该合金的加工图。依据加工图研究了TC11钛合金的变形机制和变形缺陷与变形热力参数之间的关系。结果表明，在780～990℃和0．001～0．01s^-1范围是超塑性变形区；在780～990℃和高于0．0ls^-1范围，易出现口相裂纹和空洞、局部流动以及绝热剪切等流变失稳现象。根据加工图分析，结合微观组织观察结果，并考虑变形抗力的大小，确定出了较佳的变形热力参数范围为850～940℃和0．001～0．01s^-1，最佳的变形热力参数在900℃和0．001s^-1附近。

To investigate the hot deformation and optimize the process configuration for Ti-alloy Ti-6.5A1-3.5Mo-1.5Zr-0.3Si in α＋β forging process, the processing maps （P-maps） are developed for the alloy with α＋β microstructure based on Murty instability criterion. The P-maps are constructed by the experimental results obtained through the isothermal and constant strain rate compression test at the temperatures of 780-990℃ and the strain rates of 0.001-70 s^-1. The relationship between the deformation mechanism, deformation defect and deformation thermomechanical parameter is studied by using the generated P-maps. The results show that the superplasticity deformation would occur at the temperature range of 780-990℃ and the strain rate range 0.001-0.01 s^-1. In addition, flow instability including cracks and cavities in fl phase, flow localization and adiabatic shear bands would occur at the above mentioned temperature range under the strain rates greater than 0.01 s^-1. According to the P-maps, microstructure and flow stress status, the preferred deformation thermomechanical parameters are identified, e.g. the temperature range of 850-940℃ and the strain rate range of 0.001-0.01 s^-1. The optimum deformation thermomechanical parameter is around the temperature of 900 ℃ and the strain rate of 0.001 s^-1.