【作者】 李斌；

【导师】 王快社； 陈战乾；

【作者基本信息】 西安建筑科技大学 ， 材料工程（专业学位）， 2019， 硕士

【摘要】 TC18(Ti-5Al-5Mo-5V-1Fe-1Cr)钛合金是一种合金化程度较高、且具有较高的力学性能的近β型钛合金。该型钛合金在热处理后的金属显微组织中含的α和β相比例各占一半,其热处理后的室温力学性能是目前研发的钛合金中室温力学强度最高的。TC18钛合金所包含的优良特点有:极高的强度、较高的韧性、优良的塑性以及较好的焊接能力等,该合金目前主要通过模锻的形式用于生产大规格锻件,另外其最大淬透深度可达200 mm以上。目前受制于TC18钛合金加工难度大,该合金多年来主要以棒丝材方式应用,未在航空钛合金的其它领域有更多拓展。近年来我国航空工业及钛合金加工工业技术水平都有了突飞猛进的发展,对TC18这一类的高温高强钛合金在应用上的需求日益显著,提升该类合金加工技术水平迫在眉睫。本文为丰富拓展高温高强TC18钛合金的应用,特对TC18钛合金板材加工过程进行了研究。通过对开坯加热温度、成品轧制加热温度、轧制方式、轧制变形量以及后续处理等方面的设计,成功的打通了8.0 mm TC18钛合金板材生产工艺流程。8.0 mm TC18钛合金板材采用一火开坯后切宽换向、二火轧制成品的工艺,其中开坯温度为900℃,成品轧制温度为850℃,成品轧制变形量为70.4%,此时获得的板材纵、横向性能比在0.97-1.03范围内。成品板材板型采用热矫直的方式进行控制。另外,经过复杂双重退火热处理和普通退火实验,得出了TC18钛合金板材热处理制度与其显微组织和力学性能等的对应关系。结果表明:在复杂双重退火热处理过程中,TC18钛合金板材力学性能主要受高温和低温两个阶段的影响,而中温阶段影响不显著。在实验温度范围内,高温阶段随着热处理温度的升高,强度先降低后升高;低温阶段强度随着温度的升高先升高后降低。采用普通退火工艺热处理时,从强度和延伸率两方面综合考虑,热处理制度选取760℃/1h,AC。更多还原

【Abstract】 The TC18(Ti-5Al-5Mo-5V-1Fe-1Cr)alloy is a high-alloying,high-strength near-beta titanium alloy.The tissues in the annealing state of the alloy contain about 50 % of the α and βphases,and the strength in the annealing state is the highest among the existing alloys.The alloy has the characteristics of high strength,high toughness,good plasticity and excellent welding performance.It is mainly used in the production of die forgings with a quenching depth of 200 mm.Due to the difficulty of its material processing,the alloy has been mainly used as a bar wire for many years and has not expanded in other areas of aerospace titanium alloys.In recent years,aviation industry and titanium alloy processing industry has developed rapidly in China.The application demand of TC18 high temperature,high strength titanium alloy is increasingly significant,and it is urgent to upgrade the processing technology of this alloy.In order to expand the application of high temperature and high strength TC18 titanium alloy,the processing of TC18 titanium alloy plate was investigated.Based on the analysis of the cogging rolling temperature,finished product rolling temperature,rolling mode,finished rolling deformation and subsequent treatment,the production process of 8.0 mm TC18 titanium alloy plate was successfully designed.The rolling method of 8.0 mm TC18 titanium alloy plate is alternative rolling process with the cogging temperature 900℃,the finished product rolling temperature 850℃,and the finished rolling deformation 70.4%,thus the ratio of the transverse and longitudinal performances of the TC18 titanium alloy plate is within the range of 0.97-1.03.During the production of the TC18 plate,the straightness of finished plate is controlled by hot straightening.In addition,the corresponding relationship between the heat treatment system of TC18 titanium alloy plate and its microstructure and mechanicalproperties was obtained through heating treatment experiments.The results show that during the complex double annealing heat treatment,the mechanical properties of TC18 titanium alloy plates are mainly affected by stages of high temperature and low temperature,and the influence of medium temperature is not significant.Within the experimental temperature range,the strength decreases first and then increases with the increase of the heat treatment temperature in the high temperature stage;while the strength increases first and then decreases with the increase of temperature in the low temperature stage.Considered from strength and elongation,760℃/1h,AC is chosen as the heat treatment system of normal annealing.更多还原