Papers by Keyword: Titanium Alloy Sheet

Abstract: Superplastic forming/diffusion bonding (SPF/DB) process is widely used in aviation titanium alloy parts forming. PAM-STAMP was utilized to simulate the SPF/DB process of a Ti-6Al-4V double layer structure part in rear fuselage at 920°C and reach the thickness distribution of the part. Then the part was formed based on simulation. The thickness distribution of the practical part was measured and compared with the simulation result. The results show that the thickness distributions of practical and simulated part fit well with each other.

Abstract: The new method of laser prestressed bending of Titanium alloy sheet is put forward in this paper. Titanium alloy sheet is produced pre-deformation by a clamp, the laser beam with some certain intensity scans its surface along the given path, and it is formed due to the thermal effect of the laser to reduce the yield strength of the scanning area and enhance its plastic deformation ability. A feasibility experiment for Ti-6Al-4V sheet is done and the bending effect is remarkable. Laser prestressed bending mechanism is described and the main influence factors are analyzed.

Abstract: The diffusion bonding of Ti to Ti, Ti-Cu alloy at different temperatures ranging from 673 K to 923 K under an applied stress of 100 MPa for 1 h was studied. The observation of the microstructure reveals that sound joints between the Ti-Ti and dissimilar titanium/Copper metals sheet were successfully joined by diffusion bonding process. Ti-Cu alloy without any pores or cracks can be achieved through diffusion bonding at temperatures over 873 K under the applied stress of 100 MPa for 1 h. The bond is composed of the zones, and its width increases with the increase of bonding temperature. The Micro hardness at the interface of joints bonded under different conditions was evaluated through Micro hardness testing and the fracture mode was analyzed by SEM observation.

Abstract: The thermo-stress sizing is a technology that enables sheet metal part using high elastic material such as titanium alloy to eliminate spring-back and distortion. The paper expounds and proves the principle of fixing shape of thermal stress sizing, that is, they are synthetic effects of materia1 softening and stress relaxation in short time．Then the theoretical rule of hot sizing for bending spring-back is established by this principle．On the basis of principle of the thermo-stress sizing, relevant replication experiment is implemented. The results show quantitatively effects of main factors, such as material property, part geometry, temperature and time for the rule of hot sizing． The theoretical values of spring-back in the process of hot sizing are in good agreement with that of experiments. They may be used to estimate technological parameters of thermal stress sizing．In addition thermo-mechanical characteristics under standard temperatures of forming or sizing and the experimental curves of thermo-stress sizing for Ti-6Al-4V and Ti-2A1-1.5M n are given．

Abstract: Raising processes of titanium alloy sheets TC1Mδ1.45 were simulated based on ADINA FEA software. The shape distortions induced by plastic anisotropy during forming and springback processes were described. A series of forming tests were conducted for the comparison of simulation prediction and test measurements. Reasonable agreement was obtained between the predicted and measured profiles of formed parts，It shows that the ADINA software is suitable for the analysis of the forming and springback processes of anisotropic titanium alloy sheets. Two sorts of shape distortion phenomena exhibit in the raised workpieces fabricated in room temperature after springback or elastic recovery process: Firstly, the bottom of the flange in the specimen distorts to be a wavy surface and not a plane. There two high points and two low points, and the high points locate in the flange periphery along the transverse direction (TD), and the low points locate in the periphery along the rolling direction (RD); Secondly, the top surface of the raising specimen distorts to be a wavy surface too, and the distortion shape is similar to that in the flange. During thermoforming at 600°C, the elastic recovery can be suppressed effectively and the shape distortion resulted from springback processes can be eliminated, but the anisotropy characteristics of the titanium alloy sheets can not be changed, so forming at high temperature can not solve all the shape distortion problems except the distortion occurred for the reason of springback, unhomogeneous deformation in thickness still exists. Keywords: Titanium Alloy Sheet; Raising; Springback; Shape Distortion; Adina

Abstract: Raising processes of titanium alloy sheets TC2M were simulated by using ADINA FEM software. The shape distortions induced by plastic anisotropy during forming and springback processes were described. A series of forming tests were conducted for the comparison of simulation predictions and test measurements. Reasonable agreement was obtained between the predicted and measured profiles of formed parts. Two sorts of shape distortion phenomena exhibited in the raised workpieces fabricated in room temperature after springback or elastic recovery process: Firstly, the bottom of the flange in the specimen was distorted to be a wavy surface and not a plane. There are two highest points and two lowest points, and the highest points located in the flange periphery along the transverse direction (TD), and the lowest points located in the periphery along the rolling direction (RD); Secondly, the top surface of the raising specimen was distorted to be a wavy surface too, and the distortion shape is similar to that in the flange.

Abstract: Titanium and its alloys are difficult-to-form materials due to limited slip system and plastic anisotropy. Titanium is also prone to change in color due to oxidation at high temperatures. It is thus advisable to conduct deep drawing of titanium and its alloys at temperatures below 600°C. In this study, the drawability of Ti-6Al-4V sheet is evaluated in respect to the process parameters such as forming temperature, forming speed, and blank holding force at elevated temperatures. It is shown that the limit drawing ratio (LDR) increases with increasing temperature, but varies insignificantly with forming speed. The development of residual stresses in the wall of drawn cups during deformation was evaluated.

Abstract: Titanium alloy sheets have excellent specific strength and corrosion resistance as well as good performance at high temperature. Recently, titanium alloys are widely employed not only aerospace parts but also prosthetics and motorcycle. However, titanium and its alloys are difficult-to-form materials due to limited slip system and plastic anisotropy. Titanium alloy sheets were usually formed by slow forming or hot forming with heating die and specimen. In the sheet metal forming area, FE simulation technique to optimize forming process is widely used. To achieve high accuracy FE simulation results, identification of material properties and deformation characteristics such ad yield behaviors are very important. In this study, the yield locus of Ti-6Al-4V sheet was obtained at warm temperature. The experimental results are compared with the theoretical predictions. Also, the Forming Limit Curves (FLC) was achieved at warm temperature.