【摘要】：鈦合金具有低密度、高比強(qiáng)度、優(yōu)良的高溫低溫性能及抗磨損等性能而廣泛應(yīng)用于航空航天、艦船制造、海洋工程、化工、冶金及國(guó)防工業(yè)領(lǐng)域。TC4(Ti-6Al-4V)是世界上開發(fā)最早、應(yīng)用最廣的鈦合金。它的產(chǎn)量約占全世界各種鈦合金半成品總產(chǎn)量的一半以上,在航空航天工業(yè)中超過80%。TC4鈦合金的主要特點(diǎn)是優(yōu)異的綜合性能和良好的工藝特性。還具有優(yōu)良的超塑性,適合于用各種壓力加工方法進(jìn)行成形,并采用各種方式進(jìn)行焊接。該合金主要在退火狀態(tài)下使用,也可采用固溶時(shí)效強(qiáng)化,然而淬透面不超過25～30mm,固溶時(shí)效強(qiáng)化不適合厚大工件。Al、V合金元素成本較高,同時(shí)也限制了其更為廣泛的應(yīng)用。目前,針對(duì)不同的使用條件和工藝要求,各國(guó)都出現(xiàn)了許多TC4鈦合金的改型。Ti-Al-V-Fe-O系合金是美國(guó)ATI公司研發(fā)的一種取代傳統(tǒng)TC4的新型雙相鈦合金,不僅具有較高的強(qiáng)度,同時(shí)耐磨耐蝕性能、延展性能等綜合性能優(yōu)異而且成本低廉,因此在航空航天、軍工等高科技領(lǐng)域得到了廣泛的應(yīng)用。該合金中添加廉價(jià)Fe元素替代部分V作為β穩(wěn)定元素,添加O替代部分Al作為α穩(wěn)定元素,降低了合金的成本;Fe和O的加入降低了 ω相的熱力學(xué)穩(wěn)定性,從而獲得更多的β相,提高了合金的塑性和強(qiáng)度。目前,國(guó)外主要將Ti-Al-V-Fe-O系鈦合金用于軍事和航天工業(yè)研發(fā),除對(duì)外公布合金的退火組織呈等軸組織外,其它強(qiáng)化熱處理工藝、合金元素對(duì)力學(xué)性能的強(qiáng)化機(jī)理及組織演變規(guī)律則并未公開。該實(shí)驗(yàn)中利用真空感應(yīng)熔煉技術(shù)(ISM)進(jìn)行熔煉,并軋制得到5mm厚的熱軋板,對(duì)其進(jìn)行固溶時(shí)效處理。研究了固溶溫度和時(shí)效溫度對(duì)其微觀結(jié)構(gòu)、組織形貌、力學(xué)性能和耐磨性能的影響,并且對(duì)其變化機(jī)制進(jìn)行了相應(yīng)的分析。得出了以下結(jié)論:該種鈦合金處理前后均由α和β兩相組成,在固溶處理過程中,出現(xiàn)了α相向β轉(zhuǎn)變組織的轉(zhuǎn)變,微觀形貌由等軸組織向全片層組織轉(zhuǎn)變,經(jīng)過時(shí)效處理,β轉(zhuǎn)變組織分解生成次生α相,片層組織消失,微觀形貌由混亂雙態(tài)組織向等軸組織轉(zhuǎn)變;試樣在固溶處理后,910℃的高溫退火作用,與熱軋態(tài)相比,強(qiáng)度降低,斷后延伸率有所提高,當(dāng)溫度達(dá)到940℃時(shí),強(qiáng)度升高,延伸率下降。當(dāng)固溶溫度超過相變點(diǎn)以后,試樣中出現(xiàn)了“β脆”現(xiàn)象,性能急劇下降,強(qiáng)度和延伸率同時(shí)下降。時(shí)效處理后,強(qiáng)度和塑性均得到了提高。隨著時(shí)效溫度的升高,次生α相逐漸長(zhǎng)大,強(qiáng)度逐漸降低,而延伸率逐漸升高。940℃×15min/AC+500℃×6h/AC熱處理后的板材強(qiáng)度和延伸率分別達(dá)到1260MPa、8.5%,具有較佳的綜合性能。與熱軋態(tài)相比,固溶時(shí)效強(qiáng)化以后硬度與耐磨性能都得到了提高。隨著時(shí)效溫度的升高,試樣硬度下降,耐磨性降低。
[Abstract]:Titanium alloys are widely used in aerospace, shipbuilding, marine engineering, chemical, metallurgical and national defense industries due to their low density, high specific strength, excellent high temperature and low temperature properties and wear resistance. TC4 (Ti-6Al-4V) is the first developed in the world. The most widely used titanium alloy. Its output accounts for more than half of the total output of all kinds of titanium alloy semi-finished products in the world. The main characteristic of 80%.TC4 titanium alloy in aerospace industry is its excellent comprehensive properties and good technological characteristics. It also has excellent superplasticity, which is suitable for forming by various pressure processing methods and welding by various methods. The alloy is mainly used in annealing and can also be strengthened by solid solution aging. However, the quenching surface is not more than 250mm and the solution aging strengthening is not suitable for the thick workpiece. The cost of Al,V alloy elements is higher, and its wider application is limited. At present, according to different application conditions and process requirements, many modification of TC4 titanium alloys have appeared in many countries. Ti-Al-V-Fe-O series alloys are a new type of dual-phase titanium alloys developed by ATI Company of USA, which not only have high strength, but also replace traditional TC4. At the same time, wear and corrosion resistance, extensibility and other comprehensive properties are excellent and low cost, so it has been widely used in aerospace, military industry and other high-tech fields. The cost of the alloy is reduced by adding cheap Fe element to replace part V as 尾 stable element and adding O to replace part of Al as 偽 stable element, and the addition of Fe and O reduces the thermodynamic stability of 蠅 phase. As a result, more 尾-phases were obtained, and the plasticity and strength of the alloy were improved. At present, Ti-Al-V-Fe-O series titanium alloys are mainly used in military and aerospace industry research and development abroad. In addition to announcing the annealing structure of the alloy as equiaxed structure, other strengthening heat treatment processes are also used. The mechanism of strengthening mechanical properties and the law of microstructure evolution of alloy elements have not been disclosed. In this experiment, the vacuum induction melting technology (ISM) was used to melt the hot rolled plate with 5mm thickness and the solution aging treatment was carried out. The effects of solution temperature and aging temperature on microstructure, mechanical properties and wear resistance were studied. The conclusions are as follows: the titanium alloy is composed of 偽 and 尾 phases before and after treatment. During the process of solution treatment, the transformation of 偽 phase to 尾 phase occurs, and the microstructure of the alloy changes from equiaxed structure to whole lamellar structure. After aging treatment, the 尾 -transition microstructure decomposes to form a secondary phase, the lamellar structure disappears, the microstructure changes from disordered two-state structure to equiaxed structure, and the strength of the sample annealed at 910 鈩，

本文編號(hào)：2282629