The development of a forming limit surface for 5083 aluminum alloy sheet
TL;DR: In this paper, a Nakazima-based stretching setup was designed and built for testing sheet metals at elevated temperatures, and the deformed specimens were combined to construct a unique three-dimensional forming limit surface for describing material formability limits at wide-ranging temperatures.
Abstract: A custom mechanical stretching setup based on the Nakazima method was designed and built for testing sheet metals at elevated temperatures. Specimens from a fine-grained 5083 aluminum alloy sheet were deformed at various temperatures, spanning between those associated with warm forming (250°C) and hot forming (550°C). Circle grid analysis of the deformed specimens produced the forming limit curves at each of the covered temperatures, hence revealing the great influences of forming temperature on the material’s formability limits. Finally, all the curves were combined to construct a unique three-dimensional forming limit surface, which we present here as a more comprehensive map for describing material formability limits at wide-ranging temperatures.
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TL;DR: In this article, a digital image correlation (DIC) system was used to perform in situ strain measurement on AA3003 brazing sheet and formability experiments were conducted.
Abstract: Warm forming has some important advantages, the most significant being that forming limit strains increase at elevated temperatures. To quantify this advantage for an AA3003 brazing sheet, forming limit diagrams were determined using warm tooling developed to perform limiting dome height (LDH) experiments together with a digital image correlation (DIC) system used to perform in situ strain measurement. Forming limit curves (FLCs) were developed at several temperature levels and strain-rates. The formability experiments demonstrated that while temperature has a significant effect on formability, forming speed has a mild effect within the studied range. Elevating the temperature to 250 °C improved the formability more than 200 % compared to room temperature forming while forming at lower speeds increased the limiting strains by 10 % and 17 % at room temperature and 250 °C, respectively. A comparison between FLDs developed using DIC methods versus circle grid (CG) analysis showed good agreement between the two methods; however, the degree of scatter in the CG method increased significantly for the higher temperature tests.
26 citations
26 Aug 2012
TL;DR: In this article, the GOM ARGUS system was employed for measuring surface strain based on pre-applied grids (pattern), and limit strains were determined according to the ISO 12004-2:2008 standard.
Abstract: An experimental procedure has been developed for the determination of FLCs at elevated temperatures. The GOM ARGUS system was employed for measuring surface strain based on pre-applied grids (pattern), and limit strains were determined according to the ISO 12004-2:2008 standard. Forming limit curves (FLCs) have been determined for AA5754 under warm forming conditions in an isothermal environment. The tests were carried out at various temperatures up to 300C and forming speeds ranging from 5 – 300 mm s. Results reveal the significant effect of both temperature and forming speed on FLCs of AA5754. Formability increases with increasing temperature above 200C. Formability also increases with decreasing speed. The presented FLC results show that the best formability exists at low forming speed and the high temperature end of the warm forming range.
15 citations
TL;DR: In this paper, a test machine called a biaxial test was devised that would provide the capability to test the specimen in multiaxially stress states by varying the independent load or displacement on two independent axis.
Abstract: For centuries, metals and materials have been characterized using a traditional method called a uniaxial tension test. The data acquired from this test found to be adequate for operations of simple forming where one axis stretching is dominant. Currently, due to the demand of lightweight component production, multiple individual parts eliminated by stamping a single complex shape, which also further reduces many secondary operations. This change is driving by the new fuel-efficiency requirement by corporate average fuel economy of 55.8 miles per gallon by 2025.1 Due to complex part geometry, this forming method induces multiaxial stress states, which are difficult to predict using conventional tools. Thus, to analyze these multiaxial stress states limiting dome height tests and bulge tests were recommended in many research publications. However, these tests limit the possibilities of applying multiaxial loading and rather a sample geometry changes are required to imply multiaxial stresses. Even this capability is not an option in bulge test due to leakage issue. Thus, a test machine called a biaxial test was devised that would provide the capability to test the specimen in multiaxial stress states by varying the independent load or displacement on two independent axis. In this paper, two processes, limiting dome tests and biaxial tests were experimented, modeled, and compared. For the biaxial tests, a cruciform test specimen was utilized, and conventional forming limit specimens were used for the dome tests. Variation of sample geometry in limiting dome test and variation of loading in biaxial test were utilized to imply multiaxial stress states in order to capture the limit strain from uniaxial to equibiaxial strain mode. In addition, the strain path, forming, and formability investigated and the differences between the tests provided. From the results, it was noted that higher limit strains were acquired in dome tests than in biaxial tests due to contact pressure from the rigid punch. The literature shows that the contact pressure (which occurs when the rigid tool contacts the deformed body), increases the deformation and thus increases the limit strains to failure. This contact pressure parameter is unavailable in biaxial test, and thus, a pure material behavior can be obtained. However, limit strains from biaxial test cannot be considered for a process where rigid tool is processing the metal, and thus, calibration is necessary.
5 citations
01 Jan 2016
4 citations
Cites background from "The development of a forming limit ..."
...Flow behavior, formability and deformation mechanisms have been investigated for several AA5xxx sheets at a wide range of SPF/QPS conditions [5-8]....
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TL;DR: In this paper, a theoretical analysis of the process of the generation of the groove based on anisotropic plasticity theory is presented, and the system of equations derived was solved numerically with the aid of a computer, which enabled the limiting strain of the sheet metal to be determined as a function of the material.
1,814 citations
TL;DR: In this paper, the results of deep drawing tests with magnesium alloys AZ31B, AZ61B, and M1 showed very good formability in a temperature range between 200 and 250°C, and the influence of forming speed on limit drawing ratio has been investigated.
341 citations
TL;DR: In this paper, the formability and surface quality of the final product of these alloys are not good if processing is performed at room temperature, however, they have been shown to increase at temperature range from 200 to 300°C and better surface quality has been achieved.
295 citations
TL;DR: In this article, biaxial warm forming behavior in the temperature range 200-350°C is investigated for three automotive aluminum sheet alloys: Al 5754, Al 5182 containing 1% Mn (Al 5182+Mn) and Al 6111-T4.
187 citations
TL;DR: In this article, the effects of forming speed and temperature on the forming limit diagram (FLD) were investigated experimentally for a fine-grain Al-Mg alloy (5083-O) sheet by performing stretch-forming tests at various forming speeds (0.2-200mm-min−1) at several temperatures from 293 to 573
167 citations