本文選題：TC21 + 超塑性��； 參考：《南昌航空大學(xué)》2013年碩士論文

【摘要】：TC21是我國研制的、具有自主知識(shí)產(chǎn)權(quán)的一種高強(qiáng)韌損傷容限型α+β鈦合金，在航空航天以及化學(xué)等眾多領(lǐng)域有著廣泛的應(yīng)用。在超塑成形過程中，高溫低應(yīng)變速率下合金顯微組織的聚集長大粗化會(huì)影響其使用性能。所以對(duì)TC21鈦合金的超塑成形及熱處理的微觀組織演變進(jìn)行研究對(duì)等溫鍛造有著非常重要的意義。本課題采用超塑性恒應(yīng)變速率拉伸試驗(yàn)，分析了變形條件對(duì)流變應(yīng)力的影響，，借助金相顯微鏡研究了該合金的微組織演變；并對(duì)變形組織進(jìn)行雙重退火熱處理期望獲得綜合性能較好的網(wǎng)籃組織。主要的研究內(nèi)容如下： 采用SANS-CMT4104電子萬能實(shí)驗(yàn)拉伸機(jī)對(duì)TC21鈦合金進(jìn)行超塑性恒應(yīng)變速率拉伸實(shí)驗(yàn)，TC21合金以恒應(yīng)變速率進(jìn)行超塑性拉伸變形，觀測(cè)其在不同變形條件下的延伸率。變形后的合金進(jìn)行了雙道次熱處理，分析材料微觀組織的演變規(guī)律。實(shí)驗(yàn)表明：軋制態(tài)的TC21合金在870℃~930℃溫度區(qū)間，3×10-4s-1~3×10-2s-1應(yīng)變速率條件下都具有超塑性。較好的超塑性變形條件為：變形溫度910℃，應(yīng)變速率3×10-4s-1，獲得的延伸率為373.3%。變形區(qū)域發(fā)生動(dòng)態(tài)再結(jié)晶，初生α晶粒發(fā)生聚集、合并形成不規(guī)則的晶界，呈片狀，條狀初生α相破碎，并有細(xì)小晶粒生成；變形后的試樣經(jīng)雙重退火處理后，顯微組織為雙態(tài)組織，由初生α相和不同形態(tài)的β轉(zhuǎn)變組織構(gòu)成。與未變形區(qū)域相比，塑性變形區(qū)域的組織形態(tài)有顯著差異。并分析了其流變應(yīng)力的變化規(guī)律以及顯微組織的演變，并通過真應(yīng)力-真應(yīng)變曲線計(jì)算出了該合金的熱激活能為766.7kJ/mol，建立了峰值流變應(yīng)力的本構(gòu)方程。
[Abstract]:TC21 is a kind of 偽 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

本文編號(hào)：2022191