Ti-5Al-2V-3Fe-0.2O钛合金热轧板材的热处理工艺研究
发布时间：2018-10-20 08:39
【摘要】：钛合金具有低密度、高比强度、优良的高温低温性能及抗磨损等性能而广泛应用于航空航天、舰船制造、海洋工程、化工、冶金及国防工业领域。TC4(Ti-6Al-4V)是世界上开发最早、应用最广的钛合金。它的产量约占全世界各种钛合金半成品总产量的一半以上,在航空航天工业中超过80%。TC4钛合金的主要特点是优异的综合性能和良好的工艺特性。还具有优良的超塑性,适合于用各种压力加工方法进行成形,并采用各种方式进行焊接。该合金主要在退火状态下使用,也可采用固溶时效强化,然而淬透面不超过25～30mm,固溶时效强化不适合厚大工件。Al、V合金元素成本较高,同时也限制了其更为广泛的应用。目前,针对不同的使用条件和工艺要求,各国都出现了许多TC4钛合金的改型。Ti-Al-V-Fe-O系合金是美国ATI公司研发的一种取代传统TC4的新型双相钛合金,不仅具有较高的强度,同时耐磨耐蚀性能、延展性能等综合性能优异而且成本低廉,因此在航空航天、军工等高科技领域得到了广泛的应用。该合金中添加廉价Fe元素替代部分V作为β稳定元素,添加O替代部分Al作为α稳定元素,降低了合金的成本;Fe和O的加入降低了 ω相的热力学稳定性,从而获得更多的β相,提高了合金的塑性和强度。目前,国外主要将Ti-Al-V-Fe-O系钛合金用于军事和航天工业研发,除对外公布合金的退火组织呈等轴组织外,其它强化热处理工艺、合金元素对力学性能的强化机理及组织演变规律则并未公开。该实验中利用真空感应熔炼技术(ISM)进行熔炼,并轧制得到5mm厚的热轧板,对其进行固溶时效处理。研究了固溶温度和时效温度对其微观结构、组织形貌、力学性能和耐磨性能的影响,并且对其变化机制进行了相应的分析。得出了以下结论:该种钛合金处理前后均由α和β两相组成,在固溶处理过程中,出现了α相向β转变组织的转变,微观形貌由等轴组织向全片层组织转变,经过时效处理,β转变组织分解生成次生α相,片层组织消失,微观形貌由混乱双态组织向等轴组织转变;试样在固溶处理后,910℃的高温退火作用,与热轧态相比,强度降低,断后延伸率有所提高,当温度达到940℃时,强度升高,延伸率下降。当固溶温度超过相变点以后,试样中出现了“β脆”现象,性能急剧下降,强度和延伸率同时下降。时效处理后,强度和塑性均得到了提高。随着时效温度的升高,次生α相逐渐长大,强度逐渐降低,而延伸率逐渐升高。940℃×15min/AC+500℃×6h/AC热处理后的板材强度和延伸率分别达到1260MPa、8.5%,具有较佳的综合性能。与热轧态相比,固溶时效强化以后硬度与耐磨性能都得到了提高。随着时效温度的升高,试样硬度下降,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 伪 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 伪 and 尾 phases before and after treatment. During the process of solution treatment, the transformation of 伪 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，
本文编号：2282629
[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 伪 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 伪 and 尾 phases before and after treatment. During the process of solution treatment, the transformation of 伪 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，
本文编号：2282629
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