| Metastable ?titanium alloys has a broad application prospects in the aerospace field for its high strengh,and good match in terms of strength and ductility and toughness after solution and aging treatment.The titanium tube with moderate and high strengh was seldom studied in our country owing to the reason that ?titanium alloys with high strength used in aerospace field is hard to form and which has a long production cycle,inefficiency and high cost.Although some scientific reseach institutions or some companies could provide few sample that meet demand,it is necessary to import to achieve mass application.Which Seriously hampered wide use of China's self-developed titanium alloy tubes with high strength in aerospace field.Based on the research about commercial titanium alloy of Ti5563 tube by institution of biological materials of NIN,whose rolling process and heat treatment performance was fUrther studied.Solution treatment was used between each pass of rolling to improve plasticity,Aging treatment was conducted to regulate the mechanical properties of the finished tube after rolling,making it a good match in strength and toughness.In this paper,Ti5563 tube was taken as the research object,the finite element simulation software Simufact was used to simulate the rolling process of Ti5563 tube,optical microscopy,scanning electron microscopy and X-ray diffraction was used to study on the influence of heat treatment on microstructure and mechanical properties of alloy tube.The main conclusions are as follows:1.It is found from simulation that Q value,the friction conditions and the amoxint of feed has a significant impact on the process of rolling and the surface quality of tube after cold rolling,the maximum rolling force and mill load increases with the increase of Q value,the degree of uneven thickness will reduce yet;The surface quality will be better with the reduction of the friction.While which will make no difference to surface quality of tube when the friction coefficient is 0.3;the larger the amount of feed,the greater the maximum rolling force,the greater the degree of uneven thickness,the smaller the axial extension coefficient.It was found that when the feed is greater than 8mm,tiie increase rate of rolling force reaches a maximum value,wrinkles appears on tiie surface of the pipe after rolling.2.The parameters that was optimized in the simulation was applied in the process of rolling,which obtained finished tube with smooth surface,and uniform thickness.It is illustrated that simulations can guide the actual production.3.when solution treated at 850°C,800°Cand 750°C9 The grain of tube after rolling will transform into coarse equiaxed and Recrystallization occurred meanwhile.The tissue is single ? phase when solution temperature is above the phase transition,while below the phase transition point many chip and isometric primary a phase precipitate from the ? matrix.Compared with cold rolled tubes,solution treatment at 850 °C and 800 °C could reduce the material strength values by lOOMPa approximately,the yield strength could be 730 Mpa.therefore,the solution treatment is in favor of softening titanium alloys.4.The aging heat-treatment at 520 °C, 540°C and 560°C were performed on the tube after solution treatment at 850°C,whose tensile strength and yield strength can reach more tJian lOOOMpa.when aging heat-treatment at 540°C for 4h was done after cold rolling,the tensile strength and yield strength would exceed 1 lOOMpa,and elongation reach 8.5% to achieve a better match for the strength and plasticity,studies have found that the size of secondary a phase magnify with the aging temperature increase,the number drops,while the strength is reduced accordingly. |
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