Studies on Titanium Alloys for Aerospace Application

2007

Purpose: The paper reports characteristic of superplasticity phenomenon in titanium alloys and possibility of its applications. Design/methodology/approach: The main objective of the paper is to show features of superplastic forming of titanium alloys and current research trends aiming at widespread application of this technology. Findings: In the paper characteristic of selected superplastic titanium alloys was presented. The effect of microstructural parameters on superplasticity was considered too. Mechanical properties of superplastic deformed titanium alloys, determining criteria of their potential applications, were also addressed. Research limitations/implications: Application of superplastic forming (SPF) in industry is limited due to long time and high temperature of the forming process. In the paper directions of the studies were presented which can lead to increase in effectiveness of the process. Practical implications: SPF enables manufacturing of complex shape details ...

2012

Titanium (Ti-Al-Mn (OT4-1)) alloy is currently being used for aero engine components as well as other aerospace applications by forming through a conventional route which is typically cost, labour and equipment intensive. Titanium alloys such as Ti-6Al-4V is expensive because of the alloying additions like Vanadium are extremely expensive, still this alloy is widely used in aerospace applications by manufacturing the components through superplastic route. The alloy Ti-Al-Mn (made as per the Russian specification, OT4-1) could be a candidate material for replacing the costly Ti-6Al-4V alloys. In the present investigation, tensile tests were carried out on this alloy in the temperature range of 1073 K to 1173 K (800 to 900C) in the strain rate range of 1x10 to 1x10 s in order to characterize the high temperature superplastic deformation behavior. A maximum elongation of 450% was observed at 1123 K at an initial strain rate of 5.52x10 s indicating superplastic behavior of this alloy. ...

Materials AbstrAct Purpose: The paper reports characteristic of superplasticity phenomenon in titanium alloys and possibility of its applications. Design/methodology/approach: The main objective of the paper is to show features of superplastic forming of titanium alloys and current research trends aiming at widespread application of this technology. Findings: In the paper characteristic of selected superplastic titanium alloys was presented. The effect of microstructural parameters on superplasticity was considered too. Mechanical properties of superplastic deformed titanium alloys, determining criteria of their potential applications, were also addressed. Research limitations/implications: Application of superplastic forming (SPF) in industry is limited due to long time and high temperature of the forming process. In the paper directions of the studies were presented which can lead to increase in effectiveness of the process. Practical implications: SPF enables manufacturing of complex shape details in one-step technological operation. Together with diffusion bonding (DB) it offers particular advantages making possible to manufacture complicated multilayer structures. Originality/value: The paper summarizes achievements of the studies on the superplasticity of Ti alloys, emphasizes the role of microstructural parameters and methods of their modification leading to better results and economics of SPF.

Materials Research Express, 2019

This paper introduces an approach for modelling the flow behaviour of different titanium alloys (VT6, OT4-1 and VT14 alloys by Russian specifications) in superplastic deformation temperature and strain rate ranges. The initial microstructure parameters ( d α , β , V α , β ) before starting the deformation test were included in the constructed model for each alloy. The investigated alloys have different initial microstructures and flow behaviour characteristics. The isothermal uniaxial tensile deformation tests were performed at the superplastic deformation temperature and strain rate ranges of each alloy. The VT6, OT4-1 alloys were characterized by strain hardening effect during the deformation test, while VT14 alloy was characterized by strain softening effect. A comparison study between the experimental and modelled data was performed. The general equation of the constructed models was affected by the flow behaviour of the investigated alloys. The comparison results proved the goo...

Metallurgical and Materials Transactions A, 2020

Reducing the deformation temperature is an important research task for superplastic forming of Ti-based alloys. This study demonstrates that the additions of Fe and B significantly improve microstructural homogeneity and superplastic performance, increase the post-forming mechanical strength, and reduce the superplastic deformation temperature of a Ti-Al-Mo-V alloy. The designed alloy exhibits an excellent superplastic deformation behavior with elongation of 590 to 1050 pct at 675°C to 775°C with a constant strain rate in a range of 5 9 10 À4 to 5 9 10 À3 s À1 , and a high room temperature yield strength of 1020 MPa, a UTS of 1080 MPa, and elongation-to-failure of about 6 pct both after annealing and after superplastic deformation with a strain of 0.69 at 775°C. The microstructure and the strain-induced changes in the size and shape of grains are discussed. The modification of the b-phase morphology leads to an increase in the curvature of interphase boundaries in the modified alloy. Advanced superplasticity and improved mechanical properties make the studied alloy a very attractive material for complex parts in numerous advanced applications.

Archives of materials science and engineering, 2007

Purpose: In the present study, the Superplastic Forming and deformation behavior as well as related mechanisms of this titanium alloy were investigated. Design/methodology/approach: The high temperature deformation of a beta titanium alloy (Ti-15V-3Cr3Sn-3Al) was studied in this work. Uniaxial tensile tests were carried out at 650, 750, 850 and 950°C with an initial strain rates from 10-1s-1 to 10-4s-1. The effects of temperatures and initial strain rates on the superplasticity of this alloy were studied. Findings: The studies showed that dynamic recrystallization took place during high temperature deformation and this process not only decrease the average grain size of the alloy but also increase the misorientation angle. Microstructure evolution during high temperature forming as well as related mechanisms were also investigated. Practical implications: The investigation of microstructure of beta titanium alloy as related phenomens during high temperature deformation are important...

2005

The superplasticity of commercially pure titanium alloy at high temperature was studied and the dynamic recrystallization phenomenon of the alloy was investigated by using electron back scattered diffraction. A two-step deformation method was used to increase the ductility of the alloy from 188% to 243%.

Materials Science Forum, 1997

Journal of Manufacturing Processes, 2019

The study presents an integrated approach for superplastic forming of Ti-6%Al-4%V titanium alloy. The flow behavior of the studied alloy was investigated using uniaxial constant strain rate tensile tests in a temperature range of 800-900 °C and a strain rate range of 3×10−4-3×10-3s-1. The obtained flow behavior was modeled using the simple Johnson-Cook (S J-C), modified Johnson-Cook (M J-C) and artificial neural network (ANN) models. An assessment study between the constructed models was performed in order to evaluate the predictability of each model. Standard statistical comparative quantities such as correlation coefficient (R), mean absolute relative error (AARE) and the root mean square error (RMSE) were used to ascertain the model viability. The S J-C model proved ineffectual in predicting the flow behavior of Ti-6%Al-4%V alloy. The M J-C and ANN models are able to successfully describe the flow behavior of the alloy. The validity of the model used for the simulation was ascertained by testing the predicted data with the constructed models at a temperature of 875 °C and a strain rate of 2×10-3s-1 using DEFORM 3D finite element simulation (FES). The obtained results from the FES were verified with the experimental results after superplastic forming process. The FES results show the possibility of using uniaxial tensile test data to simulate superplastic forming process of the Ti-6%Al-4%V titanium sheets.

Acta Materialia, 2019

An alloy design approach for titanium alloys is presented. New alloys are isolated, manufactured and tested with an emphasis on the superplastic response. The superplastic effect is found to be optimal between 650 to 750 • C at strain rates between 8.3×10 −2 and 8.3×10 −3 /s-this is a substantial improvement in terms of temperature and deformation rates over traditional titanium alloys such as Ti-6Al-4V. Elongations approaching ∼2000% are demonstrated. Electron backscatter diffraction studies confirm a randomisation of texture and absence of significant intragranular dislocation density, confirming superplasticity and thus grain-boundary sliding as the overarching deformation mechanism. At strain rates faster than 0.01/s, the alloys exhibit large elongations (∼200-500%) but softening is evident and lower ductility results. Our results reveal that the physical factors controlling the alloy composition/property/manufacturing interrelationship are understood and quantified. Physically-based constitutive equations are presented and used to demonstrate the practical advantages of the designed alloys.