TC21合金的超塑行为及形变热处理后的组织特征

发布时间：2018-06-15 13:42

  本文选题：TC21 + 超塑性　； 参考：《南昌航空大学》2013年硕士论文

【摘要】：TC21是我国研制的、具有自主知识产权的一种高强韧损伤容限型α+β钛合金，在航空航天以及化学等众多领域有着广泛的应用。在超塑成形过程中，高温低应变速率下合金显微组织的聚集长大粗化会影响其使用性能。所以对TC21钛合金的超塑成形及热处理的微观组织演变进行研究对等温锻造有着非常重要的意义。本课题采用超塑性恒应变速率拉伸试验，分析了变形条件对流变应力的影响，，借助金相显微镜研究了该合金的微组织演变；并对变形组织进行双重退火热处理期望获得综合性能较好的网篮组织。主要的研究内容如下： 采用SANS-CMT4104电子万能实验拉伸机对TC21钛合金进行超塑性恒应变速率拉伸实验，TC21合金以恒应变速率进行超塑性拉伸变形，观测其在不同变形条件下的延伸率。变形后的合金进行了双道次热处理，分析材料微观组织的演变规律。实验表明：轧制态的TC21合金在870℃~930℃温度区间，3×10-4s-1~3×10-2s-1应变速率条件下都具有超塑性。较好的超塑性变形条件为：变形温度910℃，应变速率3×10-4s-1，获得的延伸率为373.3%。变形区域发生动态再结晶，初生α晶粒发生聚集、合并形成不规则的晶界，呈片状，条状初生α相破碎，并有细小晶粒生成；变形后的试样经双重退火处理后，显微组织为双态组织，由初生α相和不同形态的β转变组织构成。与未变形区域相比，塑性变形区域的组织形态有显著差异。并分析了其流变应力的变化规律以及显微组织的演变，并通过真应力-真应变曲线计算出了该合金的热激活能为766.7kJ/mol，建立了峰值流变应力的本构方程。
[Abstract]:TC21 is a kind of 伪 尾 titanium alloy with high strength and toughness damage tolerance, which has been developed in China and has its own intellectual property rights. TC21 has been widely used in many fields such as aerospace and chemistry. During superplastic forming, the agglomeration and growth coarsening of alloy microstructure at high temperature and low strain rate will affect its performance. Therefore, the study of superplastic forming and microstructure evolution of TC21 titanium alloy is very important for isothermal forging. In this paper, the superplastic constant strain rate tensile test was used to analyze the effect of deformation conditions on the rheological stress, and the microstructure evolution of the alloy was studied by means of metallographic microscope. Furthermore, double annealing heat treatment of deformed microstructure was carried out in order to obtain a basket structure with better comprehensive properties. The main research contents are as follows: the superplastic constant strain rate tensile test of TC21 titanium alloy is carried out by using SANS-CMT4104 electronic universal tensile machine and TC21 alloy is superplastic tensile deformation at constant strain rate. The elongation under different deformation conditions was observed. The microstructure of the alloy was analyzed by double pass heat treatment. The experimental results show that the rolled TC21 alloy has superplasticity at the strain rate of 3 脳 10-4s-1~3 脳 10-2s-1 at 870 鈩

本文编号：2022191