Superplastic Forming Characteristics and Microstructural Development of an Aluminium Lithium Alloy (8090)

1990 ◽  
Vol 196 ◽  
Author(s):  
G. J. Mahon ◽  
R. Keyte ◽  
N. C. Parson ◽  
R. A. Ricks
Keyword(s):  
Test Temperature ◽  
Superplastic Forming ◽  
Microstructural Development ◽  
Temperature Range ◽  
Lithium Alloy ◽  
Steady Decrease ◽  
Rapid Fall ◽  
Stress Changes ◽  
Rate Testing ◽  
Forming Characteristics

ABSTRACTSuperplastic testing of the aluminium-lithium alloy 8090 has been performed in the temperature range 485°C to 550°C. Up to 530°C, raising the test temperature has the effect of increasing the m-value and decreasing the flow stress. Changes in superplastic forming characteristics and microstructure have been followed during straining using a variety of techniques. Jump-strain rate testing reveals that in the optimum temperature range (515°C to 525°C).there is a steady decrease in m-value. Cavitation also occurs, but can be suppressed effectively by applying a hydrostatic pressure during testing. Raising the test temperature above this optimum range to 550°C produces a significant decrease in the m-value and a more rapid fall-off with strain. These observations are explained in terms of recrystallisation and grain growth, and the effectiveness of precipitates in pinning grain boundaries at the various temperatures.

The Microstructure and Superplastic Behavior of Clean Mechanically Alloyed Titanium–Titanium Boride Alloys

1999 ◽  
Vol 601 ◽  
Author(s):  
A.P. Brown ◽  
R Brydson ◽  
C. Hammond ◽  
A. Wisbey ◽  
T.M.T. Godfrey
Keyword(s):  
Sheet Material ◽  
Hot Isostatic Pressing ◽  
Superplastic Forming ◽  
Titanium Boride ◽  
Production Cycle ◽  
Microstructural Development ◽  
Mechanically Alloyed ◽  
Boron Powder ◽  
Fine Grained ◽  
The Matrix

AbstractThe superplastic forming (SPF) of titanium alloys is an established technology. A reduction in grain size from that of the typical sheet materials would lead to enhanced SPF properties and hence a reduction in production cycle times. This study describes the microstructural development and superplastic behaviour of fine-grained Ti-6%Al-4%V alloys. Ball-milling Ti-6%Al-4%V powder produces a nanocrystalline material; however on consolidation by hot isostatic pressing rapid grain growth occurs. Addition of boron powder during milling leads to boride precipitates in the matrix of the consolidated alloy. The precipitates are dispersed inhomogeneously, resulting in localized grain refinement. Superplastic testing revealed cavitation formation but in comparison to conventional sheet material, large elongations were achieved at relatively high strain rates.

Superplastic Forming Characteristics of a Fine-Grained Cu-Based Shape Memory Alloy

2012 ◽  
Vol 579 ◽  
pp. 22-31
Author(s):  
Chin Chuan Hsu
Keyword(s):  
Superplastic Forming ◽  
Rate Of Change ◽  
Dome Height ◽  
Base Line ◽  
Fine Grained ◽  
Forming Temperature ◽  
Forming Characteristics ◽  
Temperature And Pressure ◽  
Increasing Temperature ◽  
Free Bulging

The influences of temperature and pressure on the blow forming of CuZnAlZr sheet was investigated under free bulging conditions using argon gas. The effects evaluated were the dome height, measured at the dome apex; the specific thickness, the ratio of the actual thickness to the initial thickness; and the thinning factor, the ratio of the actual thickness to the average thickness. The results show that the dome height and the rate of change of dome height with respect to time, dh/dt, increase with increasing temperature and/or pressure. The specific thickness decreases with increasing fractional height (the ratio of the height of a given point above the base line to the height of the apex), and the specific thickness at the apex decreases with increasing temperature and/or pressure as well. The thinning factor decreases with increasing fractional height. Furthermore, this decrease becomes more significant with an increase in either the forming temperature or pressure. The thinning factor at the apex, as a function of the height to base ratio for all conditions falls into the region between m=0.3 and m=0.75 curves.

Superplastic Forming Response of a Friction Stir Processed Mg Alloy Sheet – A Numerical Approach

2012 ◽  
Vol 735 ◽  
pp. 192-197 ◽  
Author(s):  
Mohammad Albakri ◽  
Bilal Mansoor ◽  
Ahmad Albakri ◽  
Marwan Khraisheh
Keyword(s):  
Thickness Distribution ◽  
Base Material ◽  
Superplastic Forming ◽  
Numerical Approach ◽  
Processing Technique ◽  
Alloy Sheet ◽  
Mg Alloy ◽  
Dome Height ◽  
Friction Stir ◽  
Forming Characteristics

Friction stir process (FSP) is a severe plastic deformation based secondary processing technique that can be utilized to engineer novel microstructures in metallic alloys. It is well known that such techniques are cumbersome and require significant experimental work and material to determine optimum processing conditions. Therefore in this work, we propose a new two step numerical approach, where: (i) CFD simulations coupled with Zener-Holloman relation are used to predict microstructure evolution in stirred, transition and heat affected zones of friction stir processed AZ31 Mg alloy sheets, (ii) Finite element simulations are carried out to evaluate superplastic forming characteristics of different microstructures developed after FSP. Simulation trends including forming pressure profiles, dome height evolution, and thickness distribution of friction stir processed sheets are compared with those of the base material. The proposed combination of numerical approaches to model both processing and forming aspects yields a powerful tool to study and optimize processing and forming technologies with limited experimentation.

Application of Finite Element Method to the Design of Superplastic Forming Processes

1992 ◽  
Vol 114 (4) ◽  
pp. 452-458 ◽  
Author(s):  
N. Chandra ◽  
S. C. Rama
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Metal Forming ◽  
Superplastic Forming ◽  
Design Tool ◽  
Output Pressure ◽  
Pressure Time ◽  
Forming Characteristics ◽  
Element Method

Finite element method is used as a design tool in the prediction of process parameters for superplastic metal forming processes. The method is used in the design of various plane strain and axisymmetric components. The effect of varying die radii and die friction are studied in the forming characteristics of a simple pan. The cone test used for the mechanical characterization of superplastic materials is simulated. A complex component typically used in the aerospace industry is analyzed and the output pressure-time loading and the resulting thickness distributions are determined.

Heat Capacity of Pure Magnesium and Ultralight Congruent Magnesium–Lithium Alloy in the Temperature Range of 300 K to 825 K

2021 ◽  
Vol 30 (2) ◽  
pp. 207-212
Author(s):  
R. N. Abdullaev ◽  
D. A. Samoshkin ◽  
A. Sh. Agazhanov ◽  
S. V. Stankus
Keyword(s):  
Heat Capacity ◽  
Pure Magnesium ◽  
Temperature Range ◽  
Lithium Alloy

Mechanically Alloyed Al-Ti Alloy for Superplastic Forming Characteristics

1992 ◽  
Vol 88-90 ◽  
pp. 647-654 ◽  
Author(s):  
P.W. Sonawane ◽  
W. Krishnawamy ◽  
A. Dutta ◽  
R. Sundaresan
Keyword(s):  
Superplastic Forming ◽  
Ti Alloy ◽  
Mechanically Alloyed ◽  
Forming Characteristics

Comparative Study of Element Formulation on Simulation of Superplastic Forming

2007 ◽  
Vol 551-552 ◽  
pp. 281-286 ◽  
Author(s):  
X.F. Xu ◽  
L.M. Tang ◽  
G.Q. Tong
Keyword(s):  
Finite Element ◽  
Comparative Study ◽  
Strain Rate ◽  
Rate Control ◽  
Superplastic Forming ◽  
Control Algorithms ◽  
Average Strain ◽  
Pressure Time ◽  
Average Strain Rate ◽  
Forming Characteristics

A comparative study of different element formulations in simulating superplastic forming with the MARC finite element code is performed in the paper. Simulations were accomplished with solid, shell, membrane elements to predict forming characteristics and pressure-time curves. Finite element analysis (FEA) predictions of SPF pressure-time curves were found to be greatly affected by the element type and the strain rate control algorithms. Two strain rate control algorithms were applied in the present study: an algorithm based on limiting the rate of deformation with the average strain rate of all the elements, i.e. the build-in method in MARC, and a second algorithm which limits the rate of deformation based on the average strain rate of the elements with the 20 highest strain rates. The resulting pressure-time curves for each of these formulations were compared with respect to each type of element. Under the guide of the analysis, the die was fabricated and the AA5083 bracket was successfully manufactured. Good agreement was obtained between predicted and measured thickness in the part.

EFFECTS OF TEMPERATURE AND COMPOSITION ON DYNAMIC DEFORMATION BEHAVIOR OF ZR-BASED AMORPHOUS ALLOYS

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1153-1158
Author(s):  
DONG-GEUN LEE ◽  
YANG GON KIM ◽  
BYOUNGCHUL HWANG ◽  
YONGTAI LEE ◽  
SUNGHAK LEE
Keyword(s):  
Compressive Stress ◽  
Test Temperature ◽  
Deformation Behavior ◽  
Amorphous Alloys ◽  
Dynamic Deformation ◽  
Shear Bands ◽  
Total Strain ◽  
Maximum Compressive Stress ◽  
Temperature Range ◽  
Dynamic Deformation Behavior

Effects of test temperature and alloy composition on dynamic deformation behavior of Zr -based amorphous alloys were investigated in this study. Dynamic compressive tests were conducted in the temperature range from room temperature to 380°C using a compressive Kolsky bar. Dynamic compressive test results indicated that both maximum compressive stress and total strain of the amorphous alloys decreased with increasing test temperature because shear bands could propagate rapidly as the adiabatic heating effect was added at high temperatures. Maximum compressive stress and total strain of the alloy containing ductile β crystalline phases were higher than those of the monolithic amorphous alloys over the tested temperature range because β phases played a role in forming multiple shear bands. The alloys having lower T g or ductile phases had more excellent dynamic properties than the LM1 alloy.

Superplastic forming characteristics of fine-grained 5083 aluminum

1995 ◽  
Vol 4 (5) ◽  
pp. 543-550 ◽  
Author(s):  
R. Verma ◽  
P. A. Friedman ◽  
A. K. Ghosh ◽  
C. Kim ◽  
S. Kim
Keyword(s):  
Superplastic Forming ◽  
Fine Grained ◽  
Forming Characteristics
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