TC6钛合金的超塑性研究

【作者】 张志清；

【导师】 李淼泉；

【作者基本信息】 西北工业大学 ， 材料加工工程， 2002， 硕士

【摘要】 建立确定TC6钛合金加工工艺规范的科学方法已经成为科研和生产部门亟待解决的问题。传统的反复实验和依据经验来制定加工工艺的方法难以满足生产发展的要求。本构关系是制定其塑性加工工艺的主要依据之一，也是利用动态材料模拟方法和刚塑性有限元法合理确定这类难变形材料的热力参数范围的前提条件。本文就是在这一背景下，在综合考虑变形温度、初始应变速率的基础上建立了TC6钛合金本构关系的非线性模型，为制定其合理的制造工艺提供理论依据。 在正交法设计的高温拉伸实验结果的基础上，本文建立了TC6钛合金本构关系的非线性模型。这种本构关系能够比较客观的反映TC6钛合金热变形过程中对变形工艺参数的动态响应。 本文对不同初始应变速率和变形温度条件下TC6钛合金的超塑性变形行为进行了系统研究。分析了TC6钛合金在变形过程中不同变形温度、初始应变速率对流变应力的影响规律，并且对变形温度、初始应变速率在TC6钛合金超塑性变形中的显著性进行了探讨。 另外，对TC6钛合金的拉伸断口形貌进行扫描电镜分析。其结果表明，断口形貌呈现大的韧窝，合金显示较高的超塑性潜力。并对不同的初始应变速率和变形温度对断面形貌的影响进行分析，初步探讨了TC6钛合金高温拉伸的断裂机制。更多还原

【Abstract】 At the present time, the formulation of the scientific method for defining process windows of difficult-to-deformation materials such as wrought superalloys has become the frontier in the field of metal forming. The use of traditional ways such as the trial-and-error and empirical method to define the process windows of the difficult-to-deforming materials can not keep pace with the rapid development of modern industry. In order to predict the deformation load and energy, the stress-strain state in the workpiece, we should have the knowledge of the constitutive relationships relating the flow-stress of deformed materials to strain, strain rat and temperature. Appropriate representation of the constitutive relationships for deformed materials is becoming increasingly important with widespread use of dynamic materials modeling and finite-element method to characterize the workpiece behavior under different conditions.Based on the experimental results of isothermal strain rate tension test, a non-linearity model of constitutive relationships for TC6 titanium alloy was established. Therefore, a new approach for establishing the constitutive relationships and determining the thermo mechanical parameters of the TC6 titanium was explored in this thesis.The superplastic behavior of TC6 titanium on the condition of different temperature and different strain rate was explored. The effects of temperature and strain rate were analyzed too.Furthermore, the tensile fracture surface of TC6 titanium was analyzed by SEM. The results have indicated that this titanium has a strong ability in superplastic, the fractographics presented big and deep dimple, so the alloy is of high toughness.更多还原