Study On The Rolling Process Of TC18 Titanium Alloy Plate For Aviation

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 ? and ?phases,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.