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

【摘要】：TB8鈦合金是一種高強鈦合金,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合金為研究對象,系統(tǒng)地研究了軋制變形過程中的組織轉(zhuǎn)變及熱處理熱處理工藝對冷軋板材的組織和性能的影響。研究了軋制變形對TB8合金顯微組織、織構(gòu)演變及力學性能的影響,結(jié)果表明:隨著變形量的增加,晶粒細化,同時,冷軋變形量50%時,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,并出現(xiàn)γ纖維織構(gòu),變形量達到83%時,γ纖維織構(gòu)進一步增強。組織細化和織構(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)增強使得板材的強度和硬度得以提高。對變形量50%的TB8板材在不同溫度退火過程中的組織、性能轉(zhuǎn)變進行了研究。結(jié)果表明:750℃以下退火lh時,組織沒有發(fā)生再結(jié)晶轉(zhuǎn)變,主要織構(gòu)組分仍為{001}110、{113}110、{112}110。退火過程中ω相和α相的析出及位錯等亞結(jié)構(gòu)大量消失的協(xié)同作用使板材的抗拉強度隨退火溫度的升高出現(xiàn)降低—升高—降低的變化規(guī)律,塑性的變化與強度呈相反趨勢。分析了冷軋變形量50%的TB8板材在780℃不同時間退火時的再結(jié)晶過程。變形量50%的冷軋TB8板材再結(jié)晶的形核機制為亞晶合并機制。780℃的再結(jié)晶過程可用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”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}晶面擴展形成面織構(gòu)的趨勢。探討了再結(jié)晶溫度以上組織的變化規(guī)律,再結(jié)晶晶粒的長大過程可用Sellars模型進行描述,溫度區(qū)間為800℃至950℃退火l0min至90min時,n的平均值為3.252,晶粒長大激活能平均值為186.56KJ/mol。再結(jié)晶晶粒長大后,織構(gòu)沿{113}晶面進一步擴展形成了{113}uvw織構(gòu)。退火溫度超過900℃時,板材性能顯著降低。分析了不同固溶時效處理對TB8冷軋板材組織及力學性能的影響。結(jié)果表明:TB8合金的性能對組織非常敏感。冷軋變形存在的結(jié)構(gòu)缺陷促進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相對時效過程中的組織轉(zhuǎn)變有顯著影響。α相的數(shù)量越多,尺寸越細小,利于獲得更好的強度與塑性。通過雙重時效處理,借助ω相的輔助成核作用,可顯著細化析出次生α相并提高其體積分數(shù),從而顯著提高板材的綜合力學性能,當采用845℃固溶,400℃及550℃雙重時效的熱處理工藝時,TB8板材的抗拉強度可達1510MPa,延伸率可達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：1880974