Detailed Investigation of Forming Limit Determination Standards for Aluminum Alloys

Dilmeç, Murat; Halkacı, Hüseyin Selçuk; Öztürk, Fahrettin; Türköz, Mevlüt

doi:10.1520/jte104356

Cited by 16 publications

(8 citation statements)

References 12 publications

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“…Besides, the evaluation shows that a cross-shaped pattern with insufficiently heated zones with a minimum temperature of 322 °C is recognizable at the heat treated specimens. Studies have already shown in the past that multiple irradiations of the same component area cause an increase in distortion angle [15], so no overlapping of the irradiation points was used to achieve a more homogeneous temperature distribution of the samples. For linearly treated components, the maximum temperature of up to 456 °C indicates a significant temperature rise.…”

Section: Temperature Distribution Of Different Radiation Strategiesmentioning

confidence: 99%

Numerical and experimental investigations for distortion-reduced laser heat treatment of aluminum

Rigas

Merklein

2021

Prod. Eng. Res. Devel.

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In the field of mobility, increased safety and emission requirements lead to steadily rising demands on materials used and their performance. Over the last decades, 5000 and 6000 series aluminum alloys have become more and more attractive as lightweight material due to their beneficial weight to strength ratio. The 7000 series offers extended lightweight potential due to its high strength. Until now, this class of alloys has not been widely used in mass production due to its limited corrosion resistance and poor forming behavior. By using so-called Tailor Heat Treated Blanks, it is possible to set increased forming limits of previously locally heat treated components. The reason for the enhanced formability is the local softening, with the resulting improved material flow and the reduced critical forming stresses of the sheet metal before the forming operation. Despite these advantages, the use of previously heat treated materials has been very limited so far. For example, the distortion that occurs during local heat treatment reduces geometrical accuracy and thus automated handling. Therefore, the focus of this thesis is the investigation of tailored heat treatment strategies, permitting a distortion-reduced local short-term heat treatment. For this purpose, the distortion behavior is represented and quantified both numerically and experimentally. The generated knowledge is then transferred to a large volume component and characterized.

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Section: Temperature Distribution Of Different Radiation Strategiesmentioning

confidence: 99%

Numerical and experimental investigations for distortion-reduced laser heat treatment of aluminum

Rigas

Merklein

2021

Prod. Eng. Res. Devel.

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“…For both aluminum alloy conditions, forming limit diagrams were determined. The FLDs were constructed using the Nakajima method [16]. The test samples were formed by a 600 kN Zwick model BUP 600 test machine.…”

Section: Determination Of Forming Limit Diagrammentioning

confidence: 99%

Investigation of Effects of Material Dimensions on Wrinkling in Flexforming Process

Yılgın

Yilmaz

Öztürk

et al. 2021

Preprint

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Sheet metal forming processes are very common manufacturing and leading processes in automotive and aerospace industries. Flexforming is one of the sheet metal forming processes which is preferable due to its flexible manufacturing capabilities and its ability to produce multiple parts simultaneously. Convex contoured shaped parts are very much used in aerospace structures which are mostly produced by flexforming. Wrinkling is a characteristic defect for those kinds of parts. Prediction of wrinkling before manufacturing is highly crucial in order to reduce scrap rates, labor time, and other unexpected costs. In this research work, extensive amounts of experiments are conducted on flexforming press, and the process parameters such as material condition, contour radius, flange length, and material thickness which induce wrinkling are investigated in detail. Results have shown that sheet thickness is the most effective parameter, and as the sheet thickness is increased, wrinkling tendency is reduced extensively. Besides, increasing convex contour radius decreases wrinkling occurrence. Experimental findings are then used to generate wrinkling limit diagrams in which safety and failure zones are specified for different material conditions and sheet thicknesses. The developed diagrams might help to designer who can design defect free parts, reduce scrap rates, and reduce production costs significantly.

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“…Although necking due to load instability is not possible in biaxial tension, local imperfections in the thickness can lead to localized strains and necking [3]. Usually, a single local neck forms perpendicular to the direction of larger principal strain (ε1) [3,62,63]. In this case, surfaces were machined precisely and there was no significant thickness variation along the surface that would cause imperfections (Figure 4.7).…”

Section: Obtaining Large Strains and Fracture At The Centermentioning

confidence: 99%

“…Within Microstructure scale strain map. the neck, the major strain quickly reaches to the fracture limit, preventing material to deform under equibiaxial tension until fracture[3,62,63].When experimentally determining the FLC, the standard procedure (ISO 12004-2:2008)[53,61] is to smooth out the major strain inside the neck, resulting in approximately equal strains as the limits under biaxial tension[61]. Analytical methods such as Marciniak -Kuczynski analysis (known as the M-K analysis) or numerical methods can also model and simulate the FLC[64,65].…”

mentioning

confidence: 99%

“…15 documents the limiting effective strains under equibiaxial condition as a function of n for various multi-axial tests and materials[5,9,13,46,62,64,[66][67][68][69][70][71][72], including the cruciform test results for Al 6061-T6. Standard procedure was followed for determining the FLC (ISO 12004-2:2008) in results in order to make a fair comparison.Since there are no sharp necks in the tests, it was averaged (smoothened) the principal strains over an area instead of a line that is perpendicular to the neck[63,65].…”

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confidence: 99%

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Large Strain and Small-Scale Biaxial Testing of Sheet Metals

2016

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Detailed Investigation of Forming Limit Determination Standards for Aluminum Alloys

Cited by 16 publications

References 12 publications

Numerical and experimental investigations for distortion-reduced laser heat treatment of aluminum

Numerical and experimental investigations for distortion-reduced laser heat treatment of aluminum

Investigation of Effects of Material Dimensions on Wrinkling in Flexforming Process

Large Strain and Small-Scale Biaxial Testing of Sheet Metals

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