低成本合金化对钛合金组织与性能的影响
发布时间：2018-11-24 08:13
【摘要】：钛合金具有密度小、比强度高、耐腐蚀性好、耐高温、以及良好的焊接性,在航空航天等领域得到广泛应用。然而与铝、镁等合金相比,较高的原材料成本和加工成本大大的限制了钛合金的广泛应用,尤其是民用领域。本课题以廉价Fe-Cr中间合金替代TC4钛合金中较贵的金属V元素,设计新型Ti-6A1-xFe-yCr低成本合金,并添加非金属元素B对上述合金进行微合金化。采用非自耗真空电弧炉熔炼钛合金锭,利用光学显微镜(OM)、扫描电镜(SEM)对合金进行显微组织观察,采用X射线衍射仪对物相进行分析,利用电子万能试验机对合金的拉伸和压缩性能进行测试,利用维氏硬度计测试合金的显微硬度,利用Gleeble动态热模拟实验机对合金进行不同温度和压缩率的高温压缩实验。结果表明:(1)制备出了一种近β型Ti-Al-Fe-Cr低成本钛合金,合金的显微组织主要为等轴状的β相,在晶界处有针状和粒状α相析出。随Fe和Cr元素含量的增加,组织中β相比例增加,合金的抗拉强度进一步增大,显微硬度也得到进一步提升。其中,Fe元素含量增加对合金的强化效果比Cr元素含量增加的强化效果更为明显。当Fe含量为2%,Cr含量为12%时,合金获得最佳力学性能,其抗拉强度为973MPa,伸长率为3.9%,显微硬度为338HV。(2)未加B元素时,钛合金组织主要为β相;加入B元素之后,β相获得细化,同时组织中针状和等轴状α相增多。加入0.02%-0.04%B元素之后,钛合金的维氏硬度得到提高,由不加B元素时的308.94HV提高到0.04%B时的476.38HV;加入B元素后钛合金的压缩性能得到改变,随着B元素加入量由0.02%增加到0.04%,钛合金的屈服强度明显提高,但压缩率随B元素的增加而降低。(3)合金在高温压缩时,随着变形温度的升高,应力应变曲线的峰值应力和稳态应力都有明显的下降且出现峰值的应变量逐渐减小,在850℃~900℃时,曲线的峰值应力、稳态应力都趋近于固定值;合金在850℃下随着变形量的增加,铸态组织中的α片层被拉断,当形变率达到50%时组织出现了球化现象,原来的片状α相变成细小、弥散的α相颗粒,颗粒尺寸与片层宽度的尺寸接近。
[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 伪 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 伪 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，
本文编号：2352932
[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 伪 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 伪 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，
本文编号：2352932
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