【作者】 闫世成；

【导师】 刘东；

【作者基本信息】 西北工业大学 ， 材料加工工程， 2005， 硕士

【摘要】 随着航空航天工业的迅速发展,飞机设计的结构效益和结构完整性的综合要求日益提高,这不仅给结构件的设计而且给结构件的选材提出了更高的要求,同时也对减少零件的制造成本提出了更高的要求。钛合金由于是强度,密度,塑性和韧性的良好结合体,因而成为了航空航天工业的重要选材。 Ti-1023合金属于亚稳定近β型钛合金,具有高强、高韧、高淬透性等特点,而且它的相变温度和锻造温度均较低,非常适合采用等温模锻方法制造复杂结构件。 本文在进行大量等温恒应变速率压缩试验的基础上,构造出了以Z-H参数表征的Ti-1023合金本构关系,所建立的本构关系可以很好地反映Ti-1023合金热态变形时的动态行为。 在应用Gegel所提出的稳定性判据的基础上,构造出了Ti-1023合金锻造热力参数稳定区,该图的建立为定量地评估Ti-1023合金锻件质量及其锻造工艺的优劣提供了条件。 有限元数值模拟已经逐渐发展成为研究锻造过程的有效工具。本文使用大型锻造专用软件MSC.Superform对Ti-1023合金复杂结构件等温锻造过程进行了模拟。研究了不同形状的原始坯料对模具型腔的填充能力以及填充规律、锻件内的应变分布均匀性、锻件内温度场的分布规律。在总结三维数值模拟结果的基础上,提出了最优坯料形状。 最后,本文运用QLF(Quality Loss Function)方法对所选择的工艺方案进行了定量评估。研究结果表明:采用不同的工艺方案成形所需的锻件时,以所设计的最优坯料所成形的锻件的组织和性能一致性最好。更多还原

【Abstract】 The comprehensive requirement for both the integrality of structural components and the benefit from them are more rigorous than that ever before as the rapid development in aerospace industry. Therefore, the deliberate design and utilization of materials for the structural components, as well as the cost for producing them, become essential. Titanium alloy, an excellent combination of strength, density, ductility, and toughness, has become a key material and are increasingly attractive in aerospace industry.Compared to other a+p alloys, Ti-1023, a metastable β -Ti alloy, exhibits higher strength/density ratio and good hardenability. Furthermore, the β -transus temperature and the processing temperature of Ti-1023 are relatively lower than the others, and thus make it more suitable for manufacturing complex structural components by isothermal forging processes.In this thesis, a novel constitutive relationship as a function of Zener-Hollomn parameter was formulated for Ti-1023 alloy based on the experimental results of isothermal constant strain-rate compression test. This relationship can represent properly the dynamic behavior of hot deformation of Ti-1023 alloy.The processing maps for Ti-1023 alloy were constructed based on the Mals and Seetharaman’s criteria. These maps lay foundation on evaluation quantitively the quality of the forgings and the fitness of forging process for Ti-1023 alloy.Numerical simulation based on FEM has become a powerful tool on analyzing forging process. In this paper, 3-D numerical simulations for isothermal forging processes of a complex structural component of Ti-1023 alloy were performed by using of MSC.Superform software. The effect of initial configuration of billet on the capability of die filling, the uniformity of strain and temperature distribution within workpiece were analyzing quantitively. Based on the result, an optimal configuration of the billet was proposed.Finally, the quantitively evaluation for different forging processes by using of Quality Loss Function(QLF) was performed. The results show that the best consistency of microstructure and property within the workpiece can be obtained by using the proposed optimal billet.更多还原