本文選題：TB8鈦合金 + 顯微組織��； 參考：《哈爾濱工程大學(xué)》2016年博士論文

【摘要】：TB8鈦合金是一種高強(qiáng)鈦合金,由于具有良好的冷成型性能、耐蝕性能及熱處理工藝性能,可以用作航空航天領(lǐng)域的結(jié)構(gòu)件和復(fù)合材料的基材。本文以TB8合金為研究對(duì)象,系統(tǒng)地研究了軋制變形過(guò)程中的組織轉(zhuǎn)變及熱處理熱處理工藝對(duì)冷軋板材的組織和性能的影響。研究了軋制變形對(duì)TB8合金顯微組織、織構(gòu)演變及力學(xué)性能的影響,結(jié)果表明:隨著變形量的增加,晶粒細(xì)化,同時(shí),冷軋變形量50%時(shí),初始的{110}001織構(gòu)向α纖維織構(gòu)({112}110,{113}110)轉(zhuǎn)變,{113}332向{001}110織構(gòu)轉(zhuǎn)變,變形量增加至67%后,α纖維織構(gòu)增強(qiáng),并出現(xiàn)γ纖維織構(gòu),變形量達(dá)到83%時(shí),γ纖維織構(gòu)進(jìn)一步增強(qiáng)。組織細(xì)化和織構(gòu)演變的協(xié)同作用,特別是α纖維織構(gòu)和γ纖維織構(gòu)增強(qiáng)使得板材的強(qiáng)度和硬度得以提高。對(duì)變形量50%的TB8板材在不同溫度退火過(guò)程中的組織、性能轉(zhuǎn)變進(jìn)行了研究。結(jié)果表明:750℃以下退火lh時(shí),組織沒(méi)有發(fā)生再結(jié)晶轉(zhuǎn)變,主要織構(gòu)組分仍為{001}110、{113}110、{112}110。退火過(guò)程中ω相和α相的析出及位錯(cuò)等亞結(jié)構(gòu)大量消失的協(xié)同作用使板材的抗拉強(qiáng)度隨退火溫度的升高出現(xiàn)降低—升高—降低的變化規(guī)律,塑性的變化與強(qiáng)度呈相反趨勢(shì)。分析了冷軋變形量50%的TB8板材在780℃不同時(shí)間退火時(shí)的再結(jié)晶過(guò)程。變形量50%的冷軋TB8板材再結(jié)晶的形核機(jī)制為亞晶合并機(jī)制。780℃的再結(jié)晶過(guò)程可用JMAK方程描述,Avirami指數(shù)為2.296,再結(jié)晶的激活能為211.08 KJ·mol-1。再結(jié)晶織構(gòu)的形成受“定向形核”和“定向生長(zhǎng)”共同作用,冷軋板材形成的{113}110織構(gòu)有明顯的遺傳特性,再結(jié)晶織構(gòu)有沿{113}晶面擴(kuò)展形成面織構(gòu)的趨勢(shì)。探討了再結(jié)晶溫度以上組織的變化規(guī)律,再結(jié)晶晶粒的長(zhǎng)大過(guò)程可用Sellars模型進(jìn)行描述,溫度區(qū)間為800℃至950℃退火l0min至90min時(shí),n的平均值為3.252,晶粒長(zhǎng)大激活能平均值為186.56KJ/mol。再結(jié)晶晶粒長(zhǎng)大后,織構(gòu)沿{113}晶面進(jìn)一步擴(kuò)展形成了{(lán)113}uvw織構(gòu)。退火溫度超過(guò)900℃時(shí),板材性能顯著降低。分析了不同固溶時(shí)效處理對(duì)TB8冷軋板材組織及力學(xué)性能的影響。結(jié)果表明:TB8合金的性能對(duì)組織非常敏感。冷軋變形存在的結(jié)構(gòu)缺陷促進(jìn)了相變溫度以下固溶條件下晶內(nèi)α相的產(chǎn)生,形成的α相對(duì)時(shí)效過(guò)程中的組織轉(zhuǎn)變有顯著影響。α相的數(shù)量越多,尺寸越細(xì)小,利于獲得更好的強(qiáng)度與塑性。通過(guò)雙重時(shí)效處理,借助ω相的輔助成核作用,可顯著細(xì)化析出次生α相并提高其體積分?jǐn)?shù),從而顯著提高板材的綜合力學(xué)性能,當(dāng)采用845℃固溶,400℃及550℃雙重時(shí)效的熱處理工藝時(shí),TB8板材的抗拉強(qiáng)度可達(dá)1510MPa,延伸率可達(dá)16.5%。
[Abstract]:TB8 titanium alloy is a kind of high strength titanium alloy. Because of its good cold forming property, corrosion resistance and heat treatment process property, it can be used as the base material of structure and composite material in the field of aeronautics and astronautics. In this paper, the microstructure transformation during rolling deformation and the effect of heat treatment on the microstructure and properties of cold-rolled sheet were systematically studied with TB8 alloy as the research object. The effect of rolling deformation on microstructure, texture evolution and mechanical properties of TB8 alloy was studied. The initial {110} 001 texture changed to 偽 -fiber texture ({112} 110, {113} 110), and {113} 332 to {001} 110 texture. When the deformation increased to 67%, the 偽 -fiber texture increased and 緯 -fiber texture appeared. When the deformation reached 83%, the 緯 -fiber texture was further enhanced. The synergistic effect of microstructure refinement and texture evolution, especially the enhancement of 偽 -fiber texture and 緯 -fiber texture, enhances the strength and hardness of the plate. The transformation of microstructure and properties of 50% TB8 sheet during annealing at different temperatures was studied. The results show that there is no recrystallization transition in the microstructure after annealing at below: 750 鈩，

本文編號(hào)：1880974