【摘要】：鈦合金具有密度小、比強(qiáng)度高、耐腐蝕性好、耐高溫、以及良好的焊接性,在航空航天等領(lǐng)域得到廣泛應(yīng)用。然而與鋁、鎂等合金相比,較高的原材料成本和加工成本大大的限制了鈦合金的廣泛應(yīng)用,尤其是民用領(lǐng)域。本課題以廉價(jià)Fe-Cr中間合金替代TC4鈦合金中較貴的金屬V元素,設(shè)計(jì)新型Ti-6A1-xFe-yCr低成本合金,并添加非金屬元素B對(duì)上述合金進(jìn)行微合金化。采用非自耗真空電弧爐熔煉鈦合金錠,利用光學(xué)顯微鏡(OM)、掃描電鏡(SEM)對(duì)合金進(jìn)行顯微組織觀察,采用X射線衍射儀對(duì)物相進(jìn)行分析,利用電子萬(wàn)能試驗(yàn)機(jī)對(duì)合金的拉伸和壓縮性能進(jìn)行測(cè)試,利用維氏硬度計(jì)測(cè)試合金的顯微硬度,利用Gleeble動(dòng)態(tài)熱模擬實(shí)驗(yàn)機(jī)對(duì)合金進(jìn)行不同溫度和壓縮率的高溫壓縮實(shí)驗(yàn)。結(jié)果表明:(1)制備出了一種近β型Ti-Al-Fe-Cr低成本鈦合金,合金的顯微組織主要為等軸狀的β相,在晶界處有針狀和粒狀α相析出。隨Fe和Cr元素含量的增加,組織中β相比例增加,合金的抗拉強(qiáng)度進(jìn)一步增大,顯微硬度也得到進(jìn)一步提升。其中,Fe元素含量增加對(duì)合金的強(qiáng)化效果比Cr元素含量增加的強(qiáng)化效果更為明顯。當(dāng)Fe含量為2%,Cr含量為12%時(shí),合金獲得最佳力學(xué)性能,其抗拉強(qiáng)度為973MPa,伸長(zhǎng)率為3.9%,顯微硬度為338HV。(2)未加B元素時(shí),鈦合金組織主要為β相;加入B元素之后,β相獲得細(xì)化,同時(shí)組織中針狀和等軸狀α相增多。加入0.02%-0.04%B元素之后,鈦合金的維氏硬度得到提高,由不加B元素時(shí)的308.94HV提高到0.04%B時(shí)的476.38HV;加入B元素后鈦合金的壓縮性能得到改變,隨著B(niǎo)元素加入量由0.02%增加到0.04%,鈦合金的屈服強(qiáng)度明顯提高,但壓縮率隨B元素的增加而降低。(3)合金在高溫壓縮時(shí),隨著變形溫度的升高,應(yīng)力應(yīng)變曲線的峰值應(yīng)力和穩(wěn)態(tài)應(yīng)力都有明顯的下降且出現(xiàn)峰值的應(yīng)變量逐漸減小,在850℃~900℃時(shí),曲線的峰值應(yīng)力、穩(wěn)態(tài)應(yīng)力都趨近于固定值;合金在850℃下隨著變形量的增加,鑄態(tài)組織中的α片層被拉斷,當(dāng)形變率達(dá)到50%時(shí)組織出現(xiàn)了球化現(xiàn)象,原來(lái)的片狀α相變成細(xì)小、彌散的α相顆粒,顆粒尺寸與片層寬度的尺寸接近。
[Abstract]:Titanium alloys with low density, high specific strength, good corrosion resistance, high temperature resistance and good weldability are widely used in aerospace and other fields. However, compared with aluminum and magnesium alloys, the high cost of raw materials and processing greatly limits the wide application of titanium alloys, especially in the field of civil use. In this paper, the low-cost Fe-Cr master alloy is used to replace the expensive metal V element in the TC4 titanium alloy, and a new type of low cost Ti-6A1-xFe-yCr alloy is designed, and the non-metallic element B is added to the alloy for microalloying. The microstructure of titanium alloy ingot was observed by (OM), scanning electron microscope (SEM), and the phase was analyzed by X-ray diffractometer. The tensile and compression properties of the alloy were tested by the electronic universal tester, the microhardness of the alloy was measured by Vickers hardness meter, and the high temperature compression test of the alloy was carried out at different temperatures and compressibility by Gleeble dynamic thermal simulation machine. The results show that: (1) A low cost titanium alloy near 尾 type Ti-Al-Fe-Cr has been prepared. The microstructure of the alloy is mainly equiaxed 尾 phase, and there are needle-like and granular 偽 phases precipitated at grain boundaries. With the increase of the content of Fe and Cr, the proportion of 尾 phase in the microstructure increases, the tensile strength and microhardness of the alloy increase further. The strengthening effect of the alloy with the increase of Fe element content is more obvious than that of Cr element content. When Fe content is 2 and Cr content is 12, the alloy obtains the best mechanical properties, its tensile strength is 973 MPA, elongation is 3.9 and microhardness is 338HV. (2) when B element is not added, the microstructure of titanium alloy is mainly 尾 phase; After the addition of B element, the 尾 phase was refined and the acicular and equiaxed 偽 phases in the tissue increased. After adding 0.02-0.04B, the Vickers hardness of titanium alloy was improved from 308.94HV without B to 476.38HVat 0.04B. The compressive properties of titanium alloy changed with the addition of B element, and the yield strength of titanium alloy increased obviously with the addition of B element from 0.02% to 0.04%. But the compression ratio decreases with the increase of B element. (3) with the increase of deformation temperature, the peak stress and steady stress of the stress-strain curve decrease obviously, and the strain with peak value decreases gradually. At 850 鈩，

本文編號(hào)：2352932