Microstructure Evolution of Ti-Al-Mo-V Titanium Alloy During the Superplastic Forming with FES Estimated Strain Rates Across the Formed Parts at Constant Gas Pressure

2020 ◽  
Vol 306 ◽  
pp. 43-52 ◽  
Author(s):  
Ahmed O. Mosleh ◽  
Anton D. Kotov ◽  
Svetlana V. Medvedeva ◽  
Anastasia V. Mikhaylovskaya
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Microstructure Evolution ◽  
Lamellar Microstructure ◽  
Superplastic Forming ◽  
Gas Pressure ◽  
Grain Structure ◽  
Forming Process ◽  
Initial State ◽  
Forming Temperature

This paper studies the influence of the strain rate during the superplastic forming on the microstructure evolution of Ti-4Al-3Mo-1V titanium alloy. The finite elements simulation (FES) of the superplastic forming process at a temperature of 875 °C, which considered to be the optimum forming temperature of this alloy, and at a constant uniform gas pressure of 0.4, 0.7, and 1 MPa were performed. The strain rate response across the formed part via FES at each applied gas pressure was analyzed. The superplastic forming using the same forming condition of the FES, applied gas pressure and forming time, was performed via lab forming machine. In initial state before forming, the studied alloy exhibits a mixture of lamellar and equiaxed grain structure. The microstructure evolution after the superplastic forming process for each applied gas pressure was investigated. It was observed that the lamellar microstructure significantly affects the superplastic forming process and the uniformity of the thickness profile after forming.

A Study on Gas Pressure for Superplastic Forming of Titanium Alloy Bellows

2005 ◽  
Vol 475-479 ◽  
pp. 3051-3054 ◽  
Author(s):  
Gang Wang ◽  
Jun Chen ◽  
X.Y. Ruan
Keyword(s):  
Titanium Alloy ◽  
Thin Shell ◽  
Deformation Theory ◽  
Shell Theory ◽  
Superplastic Forming ◽  
Gas Pressure ◽  
Forming Process ◽  
Compressive Axial Load ◽  
Thin Shell Theory ◽  
Gas Pressures

The complex superplastic forming (SPF) technology applying gas pressure and compressive axial load is an advanced forming method for bellows made of titanium alloy, which forming process consists of the three main forming phases namely bulging, clamping and calibrating phase. The influence of forming gas pressure in various phases on the forming process are analyzed and models of forming gas pressure for bellows made of titanium alloy are derived according to the thin shell theory and plasticity deformation theory. Using model values, taking a two-convolution DN250 bellows made of Ti-6Al-4V titanium alloy as an example, a series of superplastic forming tests are performed to evaluate the influence of the variation of forming gas pressure on the forming process. According to the experimental results models are corrected to make the forming gas pressures prediction more accurate.

Influence of Superplastic Forming on Reduction of Yield Strength Property for Ti-6Al-4V Fine Grain Sheet and Ti-6Al-4V Standard

2016 ◽  
Vol 838-839 ◽  
pp. 171-176 ◽  
Author(s):  
P. Sartkulvanich ◽  
Don Li ◽  
Ernest Crist ◽  
K.O. Yu
Keyword(s):  
Yield Strength ◽  
Strain Rate ◽  
Strength Property ◽  
Grain Growth ◽  
Superplastic Forming ◽  
Influential Factor ◽  
Fine Grain ◽  
Sheet Materials ◽  
Forming Temperature

The SPF experiments were conducted on two sheet materials: Ti-6Al-4V Fine Grain Sheet (Ti-64 FGS) and Ti-6Al-4V Standard (Ti-64 STD) to investigate the influence of SPF conditions on the reduction of yield strength (YS) and change in microstructure for those two products. Results show that a) Ti-64 FGS has better formability at high testing strain rate than Ti-64 STD, b) initial YS values of Ti-64 FGS is 10% higher than Ti-64 STD, c) reduction of YS in Ti-64 FGS is 15-27%, which is much higher than 4-9% YS reduction for Ti-64 STD, d) the most influential factor on YS reduction is the forming temperature for Ti-64 FGS, but is the strain rate for Ti-64 STD, and e) microstructure pictures of initial Ti-64 FGS before forming is finer and more isotropic than Ti-64 STD, but Ti64 FGS shows more grain growth after SPF, which results in greater drop of yield strength.

New Strategy for the Prediction of the Gas Pressure Profile of Superplastic Forming of Al-5083 Aluminium Alloy

2012 ◽  
Vol 735 ◽  
pp. 204-209 ◽  
Author(s):  
Nagore Otegi ◽  
Lander Galdos ◽  
Iñaki Hurtado ◽  
Sean B. Leen
Keyword(s):  
Strain Rate ◽  
Constant Strain Rate ◽  
Superplastic Forming ◽  
Pressure Profile ◽  
Bulge Test ◽  
Forming Process ◽  
Optimum Pressure ◽  
New Approach ◽  
Superplastic Alloy ◽  
New Strategy

This paper describes a new approach for identification of the optimum pressure history for SPF processes, based on mechanisms-based hyperbolic constitutive equations. This equation set has been modified to incorporate the effect of the damage behaviour the material suffers due to the cavitational evolution of Al-5083 superplastic alloy. A large deformation, multiaxial formulation of the constitutive equation set is implemented and applied to finite element modelling of a bulge test forming process to characterise the cavitation evolution behaviour in the bulge test, using conventional (constant strain rate) and the newly proposed (variable strain rate) strategy.

scholarly journals Defect Prediction at The Superplastic Forming Process of The Bipolar Plate by Simulation

2018 ◽  
Vol 3 (1) ◽  
pp. 49
Author(s):  
Ismi Choirotin ◽  
Moch. Agus Choiron
Keyword(s):  
Effective Stress ◽  
Superplastic Forming ◽  
Bipolar Plate ◽  
Thickness Reduction ◽  
Trial And Error ◽  
Forming Process ◽  
Maximum Thickness ◽  
Forming Temperature ◽  
Trial And Error Method ◽  
Error Method

 Improper parameter setting at the bipolar plate forming by superplastic process will outcome damage to the final workpiece. By employing computer simulation, the defect at the bipolar plate could be predicted close to the maximum thickness reduction and the effective stress data. Simulate the fabrication of bipolar plate by a number of forming temperature (350 – 450 °C) and air pressure (0.25 – 1 MPa) utilize Ansys, resulting maximum thickness reduction and effective stress occurred at 450 °C and 1 MPa. Make reference to the result, the bipolar plate didn’t expose any deficiency with 36.75% maximum thickness reduction. Have recourse to simulation will abbreviate the trial and error method as of the production process will more effective and efficient in terms of time and cost

The Effects of Laser and Mechanical Forming on the Hardness and Microstructural Layout of Commercially Pure Grade 2 Titanium Alloy Plates

2017 ◽  
Author(s):  
Kadephi V. Mjali ◽  
Annelize Els-Botes ◽  
Peter M. Mashinini
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Scanning Speed ◽  
Grain Structure ◽  
Laser Forming ◽  
Major Influence ◽  
Forming Process ◽  
Commercially Pure ◽  
Profound Influence ◽  
Pure Grade

This paper illustrates the effects of the laser and mechanical forming on the hardness and microstructural distribution in commercially pure grade 2 Titanium alloy plates. The two processes were used to bend commercially pure grade 2 Titanium alloy plates to a similar radius also investigate if the laser forming process could replace the mechanical forming process in the future. The results from both processes are discussed in relation to the mechanical properties of the material. Observations from hardness testing indicate that the laser forming process results in increased hardness in all the samples evaluated, and on the other hand, the mechanical forming process did not influence hardness on the samples evaluated. There was no change in microstructure as a result of the mechanical forming process while the laser forming process had a major influence on the overall microstructure in samples evaluated. The size of the grains became larger with increases in thermal gradient and heat flux, causing changes to the overall mechanical properties of the material. The thermal heat generated has a profound influence on the grain structure and the hardness of Titanium. It is evident that the higher the thermal energy the higher is the hardness, but this only applies up to a power of 2.5kW. Afterwards, there is a reduction in hardness and an increase in grain size. The cooling rate of the plates has been proved to play a significant role in the resulting microstructure of Titanium alloys. The scanning speed plays a role in maintaining the surface temperatures of laser formed Titanium plates resulting in changes to both hardness and the microstructure. An increase in heat results in grain growth affecting the hardness of Titanium.

Development of Hot Press Machine for Superplastic Forming Technology

2011 ◽  
Vol 228-229 ◽  
pp. 563-567 ◽  
Author(s):  
Ho Sung Lee ◽  
Jong Hoon Yoon ◽  
Joon Tae Yoo ◽  
Yeng Moo Yi
Keyword(s):  
Control Process ◽  
Superplastic Forming ◽  
Gas Pressure ◽  
Process Variables ◽  
Hot Press ◽  
Forming Force ◽  
Forming Process ◽  
Forming Technology ◽  
Bonding Technology ◽  
And Diffusion

In most superplastic forming process, one or more sheets of superplastic grade materials are heated and forced onto or into single surface tools by gas pressure. Since the assembly includes only clamping dies, temperature chamber and regulated gas pressure to provide forming force, the assembly is easy to use for aircraft components. However, it is not easy to control process variables at high temperature. This paper presents an economic machinery method to develop hot press machine for manufacturing complex contoured components using superplastic forming and diffusion bonding technology.

scholarly journals Comparative Study of Hot Deformation Behavior and Microstructure Evolution of As-Cast and Extruded WE43 Magnesium Alloy

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 429
Author(s):  
Yuehua Kang ◽  
Zhenghua Huang ◽  
Hu Zhao ◽  
Chunlei Gan ◽  
Nan Zhou ◽  
...  
Keyword(s):  
Strain Rate ◽  
Microstructure Evolution ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
True Strain ◽  
Fiber Texture ◽  
Grain Structure ◽  
Hot Deformation Behavior ◽  
Fine Grain ◽  
We43 Alloy

Under compressive testing at 400 °C and a strain rate range of 0.05–5 s−1, the hot deformation behavior and microstructure evolution of an as-cast (AC), as-extruded (with a bimodal grain structure (named as Ex-1) or a relatively uniform fine grain structure (Ex-2)) WE43 alloy have been investigated and compared. The results indicate that the AC sample exhibits the highest peak stress, while the Ex-2 sample has the lowest value. Within the AC material, fine grains were firstly formed along the pancake-like deformed grains (as a necklace structure). The necklace structure was also formed within the Ex-1 and Ex-2 materials at high strain rates of 0.5 and 5 s−1. However, a lamellar structure that the coarse elongated grains divided by parallel boundaries was formed within the Ex-1 material. A relatively more homogeneous fine grain structure is achieved after a true strain of 1.0 within the Ex-2 material at a low strain rate of 0.05 s−1. In addition, a discontinuous dynamic recrystallization mechanism by grain boundary bulging is found to occur. After a true strain of 1.2, a (0001) fiber texture, a typical rare earth (RE) texture, and a relatively random texture are formed within the AC, Ex-1, and Ex-2 WE43 alloy material, respectively.

Hot Draw Mechanical Preforming of an Automotive Door Inner Panel

2008 ◽  
Author(s):  
S. George Luckey ◽  
Peter A. Friedman
Keyword(s):  
Elevated Temperature ◽  
Automotive Industry ◽  
Superplastic Forming ◽  
Gas Pressure ◽  
Die Design ◽  
Second Step ◽  
Forming Process ◽  
Forming Technology ◽  
The Press ◽  
Critical Aspects

A novel sheet metal forming technology based on aspects of both warm forming and superplastic forming has recently been developed. The new forming process, referred to as hot draw mechanical preforming (HDMP), uses two sequential steps to form a panel within a single tool at elevated temperature. In the first step, the cushion system acts on a binder and upper die to draw the blank over a punch which serves to draw in metal from the perimeter of the blank. In the second step gas pressure is applied to finish the panel details. This two step process of drawing in metal followed by gas forming can result in a significant expansion of the forming envelope for conventional AA5xxx series aluminum sheet alloys commonly used within the automotive industry. Similar to SPF, the HDMP process is performed within a single forming press equipped with heated platens and using gas pressure to shape the component during elevated temperature forming. However, the HDMP process utilizes a blankholder to control the flow of material into the forming cavity during the drawing stage and therefore requires the addition of an integrated cushion system in the bed of the press. HDMP dies are of interest in automotive applications because they maintain the low-investment attributes of SPF tooling while also significantly reducing the forming time as compared to conventional SPF. This work details the CAE based design of an HDMP die to form a one-piece aluminum door inner that can not be formed with conventionally forming processes. Critical aspects addressed in the development of the die include manufacturing targets, part design for manufacturing, and die design for operation at elevated temperature.

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