TC4钛合金超塑性的研究

发布时间：2018-03-14 19:54

  本文选题：TC4钛合金　切入点：超塑性　出处：《南昌大学》2016年硕士论文　论文类型：学位论文

【摘要】：TC4钛合金一般具有α+β两相,因具有塑性好、强度高、耐热性和耐腐蚀性好等特点,在航空、舰船、化工等领域广泛应用。钛合金超塑性成形和传统加工相比,其少或无切削加工,变形抗力小,能够成形尺寸精度高、组织致密的复杂零件。因而,探索钛合金新的超塑性工艺具有重要的理论意义和应用价值。本文以2mm厚的TC4钛合金板材为原料对TC4钛合金的超塑性进行了研究。首先,对TC4钛合金板材进行热处理,通过力学性能分析,得到最佳热处理工艺参数;接着对热处理后的试样进行恒应变速率和应变诱发高温拉伸试验,获得试样延伸率。应变诱发试验是以恒应变速率将试样拉伸到预应变量后,卸载保温10min,再以同一应变速率拉伸至断裂。该方法对提高TC4合金超塑性效果显著,工艺较为简单,更适合在工业生产中应用。通过光学显微镜、扫描电子显微镜等设备对试样断口进行观察分析,探索TC4钛合金超塑性变形力学行为、变形过程显微组织演变、变形机制和断裂机制。本文主要结论有:(1).TC4钛合金最佳热处理参数为加热温度820℃、保温时间为1h,此时超塑性最好。(2).原TC4板材晶粒尺寸为1.46μm,经热处理后晶粒尺寸为2.41μm。在加热温度850℃、应变速率1×10-3s-1条件下恒应变速率拉伸,超塑性最好,延伸率可达901%。(3).应变诱发试验在预应变量1.5时,应变速率5×10-4s-1、加热温度850℃条件下,超塑性最好,延伸率可达1270.8%。(4).从试样拉伸前后显微组织和真实应力-应变曲线得出,TC4钛合金超塑性变形机制为晶界滑动、组织动态回复和动态再结晶。(5).断口形貌图呈现出典型的韧性断裂特征,剪切带、韧窝断口、脉状花样,因此表明TC4钛合金具有良好的塑性。
[Abstract]:TC4 titanium alloy is widely used in aviation, ship and chemical industry because of its good plasticity, high strength, heat resistance and corrosion resistance. It has little or no cutting, low deformation resistance, high dimensional precision and compact structure of complex parts. It is of great theoretical significance and practical value to explore the new superplastic process of titanium alloy. In this paper, the superplasticity of TC4 titanium alloy is studied by using 2mm thick TC4 titanium alloy sheet as raw material. Firstly, the heat treatment of TC4 titanium alloy sheet is carried out. Through the analysis of mechanical properties, the optimum heat treatment process parameters were obtained, and the constant strain rate and strain induced high temperature tensile tests were carried out on the samples after heat treatment. The elongation of the specimen was obtained. The strain induced test was carried out after drawing the specimen to a prestrain at a constant strain rate, then unloaded for 10 min and then stretched to fracture at the same strain rate. This method has a remarkable effect on improving the superplasticity of TC4 alloy, and the process is relatively simple. By means of optical microscope, scanning electron microscope and other equipment, the fracture surface of the specimen was observed and analyzed, and the mechanical behavior of superplastic deformation and microstructure evolution of TC4 titanium alloy were explored. Deformation mechanism and fracture mechanism. In this paper, it is concluded that the optimum heat treatment parameters of TC4 titanium alloy are heating temperature 820 鈩，

本文编号：1612669