Manufacturing Aluminum Sandwich Structures by Means of Superplastic Forming

1999 ◽  
Vol 601 ◽  
Author(s):  
P. Impiö ◽  
J. Pimenoff ◽  
H. Hänninen ◽  
M. Heinäkari

AbstractThis paper examines the possibilities of manufacturing large-scale aluminium sandwich structures using superplastic forming. The materials tested were Mg-alloyed production quality aluminium (Al 5083-0, Al 5083-H321) and Aluminium 1561. Tensile tests at elevated temperatures were performed in order to establish the suitability of the test materials for superplastic forming. The microstructural changes in the test material specimens were examined. Thereafter numerical simulation of the Al 5083-0 forming process was conducted based on the tensile test results. The numerical simulation results were subsequently used to estimate forming parameters and the feasibility of manufacturing large-scale structures by superplastic forming.The results indicate that higher strain can be reached at higher temperatures for the test materials. Aluminium alloy 1561 exhibited the largest elongation to fracture and Al 5083-H321 the smallest. Strain appeared to be temperature dependent but not much affected by the strain rate. Metallographic examination clarified that Al-5083-0 and AI-5083-H321 showed susceptibility for cavity forming whereas Aluminium 1561 formed relatively few voids. The numerical simulation indicated that Al 5083-0 can be superplastically formed using relatively low forming pressure (0.9 – 1.4 bar).

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 884 ◽  
Author(s):  
Seyed Vahid Sajadifar ◽  
Emad Scharifi ◽  
Ursula Weidig ◽  
Kurt Steinhoff ◽  
Thomas Niendorf

This study focuses on the high temperature characteristics of thermo-mechanically processed AA7075 alloy. An integrated die forming process that combines solution heat treatment and hot forming at different temperatures was employed to process the AA7075 alloy. Low die temperature resulted in the fabrication of parts with higher strength, similar to that of T6 condition, while forming this alloy in the hot die led to the fabrication of more ductile parts. Isothermal uniaxial tensile tests in the temperature range of 200–400 °C and at strain rates ranging from 0.001–0.1 s−1 were performed on the as-received material, and on both the solution heat-treated and the thermo-mechanically processed parts to explore the impacts of deformation parameters on the mechanical behavior at elevated temperatures. Flow stress levels of AA7075 alloy in all processing states were shown to be strongly temperature- and strain-rate dependent. Results imply that thermo-mechanical parameters are very influential on the mechanical properties of the AA7075 alloy formed at elevated temperatures. Microstructural studies were conducted by utilizing optical microscopy and a scanning electron microscope to reveal the dominant softening mechanism and the level of grain growth at elevated temperatures.


2011 ◽  
Vol 189-193 ◽  
pp. 88-91
Author(s):  
Jun Gao ◽  
Zhen Ming Yue ◽  
Shu Xia Lin

Magnesium alloys have been attracting much more attentions due to its low density, high specific strength and its lightweight during the past 30 years. In this paper, the deep drawing performance of AZ31B magnisium alloy sheets at elevated temperature was studied by the experimental approach. The results indicated that the formability of the AZ31B sheets at elevated temperatures could be improved significantly. The best external forming parameters can be obtained such as heating temperature of sheet, die-punch clearance, punch fillet radius, etc. Simulating the forming process by using the numerical simulation software, we investigated the stress-strain distribution, thickness distribution and forming limit, etc. The thickness distribution by the numerical simulation agrees well with the experimental results.


2011 ◽  
Vol 473 ◽  
pp. 707-714 ◽  
Author(s):  
Martin Grüner ◽  
Marion Merklein

The use of high and ultra high strength steels in modern bodies in white raises steadily since the 1980’s. This trend is caused by the consumers’ wish of low fuel consuming cars with an increased passenger’s safety. The processing of these steels brings new challenges e.g. high flow stresses and a low formability at room temperature or high tool loads. These challenges can be resolved by warm forming at temperatures up to 600 °C reducing the flow stresses and increasing formability. For the production of complex parts that can not be produced by deep drawing hydroforming is an appropriate technology which can also help to reduce the number of parts and thus the weight of the body in white. Nowadays typical fluids used for hydroforming are only temperature stable up to about 330 °C so that it is not possible to combine the benefits of warm forming and hydroforming. Media like gases and fluids tend to leakage during the process which can only be avoided by a sealing or high blank holder forces. A new approach is the use of ceramic beads as medium for hydroforming at elevated temperatures. Building up a heatable tool for hydroforming with granular material used as medium makes it necessary to consider thermal conductivity so that there is a need of thick insulation plates. These insulation plates show high elastic deformations affecting the blank holder forces during the forming process. Measurements of the compressibility of these plates and implementation in numerical simulation allow a significant increase of the prediction accuracy of the model. A comparison of real part geometry and numerical results from models with and without consideration of elastic deformation will be given.


2015 ◽  
Vol 1095 ◽  
pp. 698-703
Author(s):  
Ning Ma ◽  
Ke Su Liu ◽  
Quan Kun Liu ◽  
Yu Jie Ma

The hot stamping process and process parameters are investigated for a model of a B-pillar outer plate by numerical simulation. The feasibility of hot stamping forming process and its parameters are analyzed. The effectiveness of numerical simulation and the accuracy of hot stamping forming process and its parameters for B-pillar outer plate are proved by the hot stamping experiment and tensile tests. Three models are designed to analyze the effect of B-pillar in the vehicle side impact. It shows that hot stamping technology has the advantages in the field of lightweight and improving impact resistance. Through the research of the historical process of hot forming part, the residual strain characteristics of hot stamping parts is analyzed, the produce and mechanism of residual strain is explained, and the application method based on the forming history of hot stamping technology is provided.


Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 497
Author(s):  
Zhihao Du ◽  
Guofeng Wang ◽  
Hailun Wang

A front automobile fender with a negative angle was trial produced via rapid superplastic forming (SPF) technology. The tensile test of industrial AA5083 was carried out at elevated temperatures, and the results showed that the maximum elongation was 242% at 480 °C/0.001 s−1. A rigid-plastic constitutive model of the SPF process was established. Initial dies of preforming and final forming were designed. The finite element method (FEM) was used to simulate the forming process and predict the thickness distribution of different areas. Furthermore, the dies were optimized to make the thickness distribution uniform. In the final structure, the maximum thinning ratio decreased from 83.2% to 63% due to the optimized design of the forming dies. The front automobile fender was then successfully fabricated by the preforming process and final forming process at 480 °C. A thickness measurement was carried out, and the minimum thickness of the preforming structure was 2.17 mm at the transverse tank, while that of the final structure was 2.49 mm near the edge of the lamp orifice. The average grain size grew from 20 to 35 μm. The grain growth led to the reduction of mechanical properties. Compared with the mechanical properties of the initial material, the maximum decrease in tensile strength for the material after superplastic forming was 5.78%, and that of elongation was 18.5%.


2007 ◽  
Vol 551-552 ◽  
pp. 545-550
Author(s):  
S. Ding ◽  
Kai Feng Zhang ◽  
Guo Feng Wang

Superplastic deformation behavior of nanocrystalline nickel was investigated under equibiaxial tension at different strain rates and forming temperatures. The nickel sheets with a thickness of 0.1 mm were prepared by pulse electrodeposition process. The average grain size of the as-deposited nickel was 70 nm and equiaxed. To determine the optimum processing parameters relevant to micro deep drawing, uniaxial tensile tests were carried out at temperatures ranging from 370°C to 500°C and strain rates ranging from 10-4 to 10-3s-1. In the selected temperature and strain rate ranges, the elongation value is larger than 200%, which indicates good superplastic formability of the electrodeposited nickel. Equibiaxial forming was subsequently performed at 370°C and 450°C, using a punch with a diameter of 1mm. The effects of forming temperature, punch rates on deep drawing process were experimentally investigated. The results indicated that the nickel specimens can be readily drawn at 450°C and punch rates ranging from 0.1mm• min-1 to 5mm• min-1. TEM and SEM were also used to examine microstructures of the as-deposited nickel sheet and deformed nickel specimens. The observations showed that significant grain growth occurs even at low superplastic forming temperatures. Microstructure was found to depend on the stress state and level of deformation.


2007 ◽  
Vol 551-552 ◽  
pp. 263-268
Author(s):  
Quan Lin Jin ◽  
Zhi Peng Zeng ◽  
Yan Shu Zhang

A numerical simulation of superplastic backward extrusion of a magnesium alloy part is presented in this paper. In fact, the simulated superplastic forming is not a pure superplastic forming because of the billet with coarse cylindrical grains. The forming may become a pure superplastic forming only after dynamic recrystallization and grain refinement appear and the grain boundary sliding has been the main deformation mechanism. In order to simulate the special forming process, a constitutive relation considering dynamic recrystallization and the multiform deform mechanism and the parameter identification of the constitutive relattion are studied. The program for simulation is able to predict the grain refinement and the transform between different deformation mechanisms. Finally the calculated results on the grain size and dynamic rerystallization are presented. A comparison between the calculated and the experimental results shows there is a good agreement between calculated results and experimental results.


Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 646
Author(s):  
Chuandong Chen ◽  
Jicai Liang ◽  
Yi Li ◽  
Ce Liang ◽  
Wenming Jin

Springback is a common defect caused by elastic recovery in the plastic forming process, which can cause the formed workpiece to deviate from the target shape. The purpose of this paper is to grasp the influence law of process parameters on springback deviation so as to optimize process parameters to reduce springback. Taking the Y-profile as the research object, the influence of process parameters such as horizontal bending radius, vertical bending radius, transition zone length, radius of roller dies, and wall thickness of the profile on springback deviation is discussed by numerical simulation. Additionally, the validity of the numerical simulation is verified through experiments. The springback law obtained by numerical simulation is applied to practical production, and the large-scale production of the Y-profile is realized.


2005 ◽  
Vol 488-489 ◽  
pp. 499-508 ◽  
Author(s):  
Klaus Siegert ◽  
Stephan Jäger ◽  
Mihai Vulcan ◽  
C. Wizemann

This paper deals with pneumatic bulging of Magnesium AZ31 sheet metal and AZ31 tubes at elevated temperatures. Flow-stress curves determined by tensile tests and pneumatic bulging at different forming temperatures and strain rates are presented for magnesium AZ31 sheet metal. It is shown that based on basic investigations an automotive sheet-metal component can be formed at elevated temperatures. To determine the material properties of magnesium tubes, tensile tests have been conducted at different forming temperatures and constant strain rate. It is shown how a forming process followed by a heat treatment process influences the microstructure and the formability of magnesium AZ31 tubes.


2021 ◽  
Author(s):  
Hui Wang ◽  
Lizi Liu ◽  
Haibao Wang ◽  
Jie Zhou

Abstract With the development of lightweight vehicles, tailor welded blanks (TWBs) are increasingly used in the automotive industry. Splitting and wrinkling are the main defects during the deep drawing of TWBs. A new method to control the forming defects was introduced in the forming process of TWBs in this study. The microstructure and mechanical properties of TWBs were characterized through metallography and tensile tests. Finite element modelling of an automobile rear door inner panel made of TWBs was built to analyse deep drawing. Edge cutting and notch cut were introduced in the drawing to deal with forming defects and reduce the number of stamping tools. The minimum distance between the material draw-in and trimming lines, thinning index and thickening index were defined as the measurable index to analyse the numerical results. Orthogonal experiment, numerical simulation and multiobjective experiment were utilised to optimize the forming parameters. The proposed method and optimised parameters were verified through experiments. The experimental results are basically consistent with the numerical simulation. Results demonstrate that the proposed method can provide some guidance for controlling the defects in deep drawing of TWBs for complex shape automotive panel.


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