Forming Limit Diagrams for AA5083 under SPF and QPF Conditions

Kulas, Mary Anne; Krajewski, Paul E.; Bradley, John R.; Taleff, E.M.

doi:10.4028/0-87849-435-9.129

Cited by 6 publications

(10 citation statements)

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“…[5,6] The intermetallic particle-size population density of material CC-B is shown in Figure 8 along with data previously reported for materials CC-A and DC-C. The CC-B data lay on the same line as the CC-A data, and both CC materials contain a larger population density of fine particles than does the DC-C material.…”

Section: Failure Mechanismssupporting

confidence: 71%

“…When GBS creep controls deformation, the failure of AA5083 materials typically occurs by cavitation. [5][6][7][8] However, as strain rate is increased and temperature is reduced, superplastic AA5083 materials transition to deformation controlled by solutedrag (SD) creep. [4] The SD creep provides a lower value of strain-rate sensitivity than does GBS creep, but has an effect sufficient to significantly retard flow localization, providing tensile ductilities of about 200 pct.…”

Section: Introductionmentioning

confidence: 99%

“…[4] The SD creep provides a lower value of strain-rate sensitivity than does GBS creep, but has an effect sufficient to significantly retard flow localization, providing tensile ductilities of about 200 pct. [5,6,9] The good forming characteristics from SD creep in AA5083 are used in the quick-plastic forming (QPF) process, [10] which is a proprietary variation on SPF developed by General Motors Corp (Detroit, MI). The QPF process produces parts for the automotive industry at significantly lower temperatures and shorter cycle times than traditional SPF processes can achieve.…”

Section: Introductionmentioning

confidence: 99%

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Deformation and failure of a superplastic AA5083 aluminum material with a cu addition

Green

Kulas

Niazi

et al. 2006

Metall Mater Trans A

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A modified AA5083 aluminum sheet material containing a Cu addition of 0.61 wt pct has been investigated under conditions relevant to commercial hot-forming technologies. This material was produced by continuous casting followed by industrial hot and cold rolling into sheet. Deformation and failure mechanisms at elevated temperatures were investigated through mechanical testing, thermal analysis, and microscopy. The effects of Cu addition are evaluated by comparisons with data from AA5083 sheet materials without Cu addition, produced both by continuous and direct-chill (DC) casting techniques. At low temperatures and fast strain rates, for which solute-drag (SD) creep governs deformation, the Cu addition slightly increases tensile ductility at 450°C but does not otherwise alter deformation behaviors. At high temperatures and slow strain rates, for which grainboundary-sliding (GBS) creep governs deformation, the Cu addition decreases flow stress and, at 450°C, improves tensile ductility. A strong temperature dependence for tensile ductility results from the Cu addition; tensile ductility at 500°C is notably reduced from that at 450°C. The Cu addition creates platelike particles at grain boundaries, which produce incipient melting and the observed mechanical behavior.

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Section: Failure Mechanismssupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Deformation and failure of a superplastic AA5083 aluminum material with a cu addition

Green

Kulas

Niazi

et al. 2006

Metall Mater Trans A

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“…Evidence has been cited for the association of cavitation in superplastic AA5083 materials with the presence of intermetallic particles, [15,18,[22][23][24] particularly with (Mn,Fe)Al 6 and (Fe,Mn)Si 2 Al 15 intermetallic products, [39] which are necessary for the development of fine, stable grain sizes. Typical examples of intermetallic particles are shown in the optical micrographs of Figure 8 for (a) a DC cast material, DC-C, and (b) [ 39] The particles in the CC material are visibly finer than those of the DC material.…”

Section: Data Points Shown Inmentioning

confidence: 99%

“…[4][5][6][7][8][9][10][11][12][13][14][15][16] For the QPF process, however, temperatures are lower and strain rates are faster than in traditional SPF operations. It has been shown that the dominant deformation mechanism shifts toward solute-drag (SD) creep under these conditions, [12,[17][18][19] as is observed in other commercial 5000-series alloys at elevated temperatures and slow strain rates. [20,21] The purpose of the present investigation is to examine the effects of this transition in deformation mechanisms on the tensile failure of commercial AA5083 materials.…”

Section: Introductionmentioning

confidence: 99%

Failure mechanisms in superplastic AA5083 materials

Kulas

Green

Taleff

et al. 2006

Metall Mater Trans A

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Forming-Limit Diagrams for Hot-Forming of AA5083 Aluminum Sheet: Continuously Cast Material

Kulas¹,

Krajewski

Bradley

et al. 2007

J. of Materi Eng and Perform

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Fine-grained AA5083 aluminum sheet is used for hot-forming automotive body panels with gas pressure in the superplastic forming (SPF) and quick plastic forming (QPF) processes. Deformation under QPF conditions is controlled by two fundamental creep mechanisms, grain-boundary-sliding (GBS) and solute-drag (SD) creep. The failure mechanisms of AA5083 materials under QPF conditions depend strongly on these deformation mechanisms and on the applied stress state. Failure can be controlled by flow localization, cavitation development or a combination of both. There is interest in using continuously cast (CC) AA5083 materials instead of direct-chill cast (DC) materials in QPF operations as a means of reducing material cost. However, CC and DC AA5083 materials can produce significantly different ductilities under hot forming. Rupture-based forming-limit diagrams (FLDs) have been constructed for a CC AA5083 sheet material under hot-forming conditions. Forming limits are shown to be related to the controlling deformation mechanisms. Differences between FLDs from DC and CC AA5083 materials are investigated. The differences in FLDs between these materials are related to differences in cavitation development.

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Forming Limit Diagrams for AA5083 under SPF and QPF Conditions

Cited by 6 publications

References 0 publications

Deformation and failure of a superplastic AA5083 aluminum material with a cu addition

Deformation and failure of a superplastic AA5083 aluminum material with a cu addition

Failure mechanisms in superplastic AA5083 materials

Forming-Limit Diagrams for Hot-Forming of AA5083 Aluminum Sheet: Continuously Cast Material

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