Forming limit prediction for AA7075 alloys under hot stamping conditions

Gao, Haoxiang; Politis, Denis J.; Luan, Xi; Ji, Kang; Zhang, Q; Zheng, Yuan; Gharbi, Mohammad M.; Wang, Liliang

doi:10.1088/1742-6596/896/1/012089

Cited by 5 publications

(4 citation statements)

References 9 publications

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“…'The material viscoplastic models for AA6082 [48] and AA7075 [49] were implemented in the FE model, while the material properties defined in the FE model were shown in Table 3.' 'The same quadrangle thermal shell elements with sizes of 1 x 1 mm 2 and 2 x 2 mm 2 were used for the blank and forming tools respectively.…”

Section: Commentmentioning

confidence: 99%

“…5 (b). The material viscoplastic models for AA6082 [48] and AA7075 [49] were implemented in the FE model, while the material properties defined in the FE model were shown in Table 3. The developed FE model enables symmetrical heat transfer from the hot blank to cold tools as well as the homogeneous distribution of the load/pressure on the contact area of the aluminium blank.…”

Section: Fe Simulation Setup To Identify the Critical Contact Pressurementioning

confidence: 99%

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A general IHTC model for hot/warm aluminium stamping

Liu

Cai

Zheng

et al. 2020

Applied Thermal Engineering

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Different hot and warm stamping technologies with particular processing parameters were applied to deform aluminium alloy sheets to satisfy desired requirements, of which the post-form strength of formed components is one of the most important criteria. In order to save experimental efforts, the present research described an efficient method to determine the critical processing parameters, i.e. the integration of the finite element (FE) simulated temperature evolutions with the continuous cooling precipitation (CCP) diagrams of the aluminium alloys. Through the optimisation of the processing parameters, the temperature evolutions and CCP diagrams do not intersect, indicating that the post-form strength of the aluminium alloys could be fully retained after proper artificial ageing processes. Therefore, a precise FE simulation of the temperature evolution is of great importance to this method, which requires the implementation of an accurate interfacial heat transfer coefficient (IHTC) as a decisive boundary condition. A general aluminium alloy-independent model with one set of fixed model constants was therefore developed to predict the IHTC evolutions as a function of contact pressure, surface roughness, initial blank temperature, initial blank thickness, tool material, coating material and lubricant material. Subsequently, the predicted IHTCs for 6082 and 7075 aluminium alloys were used to simulate their temperature evolutions, which were then integrated with their CCP diagrams to identify the critical processing parameters in hot/warm stamping processes and thus meet the desired post-form strength of the 6082 and 7075 aluminium alloys. The developed IHTC model and determined critical processing parameters were then experimentally verified by the fast alloy stamping (FAST) of the dissimilar aluminium alloys.

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Section: Commentmentioning

confidence: 99%

Section: Fe Simulation Setup To Identify the Critical Contact Pressurementioning

confidence: 99%

A general IHTC model for hot/warm aluminium stamping

Liu

Cai

Zheng

et al. 2020

Applied Thermal Engineering

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“…As pointed out by Krauer and Hora [ 17 ] as well as by Gao et al [ 19 ], the differential form of theoretical FLC models with thermal extensions can be implemented directly in FE routines, such that non-linearity in strain and temperature paths can be directly considered. The validity of that modeling approach has been demonstrated lately in the literature (e.g., [ 19 , 20 ]).…”

Section: Introductionmentioning

confidence: 99%

A Generalized Stress State and Temperature Dependent Damage Indicator Framework for Ductile Failure Prediction in Heat-Assisted Forming Operations

Camberg

Erhart²,

Tröster

2021

Materials

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Heat-assisted forming processes are becoming increasingly important in the manufacturing of sheet metal parts for body-in-white applications. However, the non-isothermal nature of these processes leads to challenges in evaluating the forming limits, since established methods such as Forming Limit Curves (FLCs) only allow the assessment of critical forming strains for steady temperatures. For this reason, a temperature-dependent extension of the well-established GISSMO (Generalized Incremental Stress State Dependent Damage Model) fracture indicator framework is developed by the authors to predict forming failures under non-isothermal conditions. In this paper, a general approach to combine several isothermal FLCs within the temperature-extended GISSMO model into a temperature-dependent forming limit surface is investigated. The general capabilities of the model are tested in a coupled thermo-mechanical FEA using the example of warm forming of an AA5182-O sheet metal cross-die cup. The obtained results are then compared with state of the art of evaluation methods. By taking the strain and temperature path into account, GISSMO predicts greater drawing depths by up to 20% than established methods. In this way the forming and so the lightweight potential of sheet metal parts can by fully exploited. Moreover, the risk and locus of failure can be evaluated directly on the part geometry by a contour plot. An additional advantage of the GISSMO model is the applicability for low triaxialities as well as the possibility to predict the materials behavior beyond necking up to ductile fracture.

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“…It is called precipitation hardening as it makes use of solid impurities or precipitates for the strengthening process. Metals were aged through heating it or by keeping it stored at low temperatures to form precipitates to the materials [4]. Table 1 shows the parameters influencing results of heat treatment within input, function and output stages.…”

Section: Introductionmentioning

confidence: 99%

Reviews on the Forming Process of Heat Treatable Aluminium Alloys

Yahaya

Lai

et al. 2018

IJIE

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Available forming process applied for heat treatable aluminium alloy were reviewed and presented in this paper. The reviews emphasized on the heat treatment, application and contribution of the forming methods. Forming methods discussed includes traditional, warm forming, hydroforming, superplastic forming, hot forming with in-die quench (HFQ) and hot press forming (HPF). The effects of forming processes towards heat treatable aluminium alloy were presented through the understanding on each process strengthening phenomena and the heat treating phenomena. These were to ensure better understanding on heat treatable aluminium alloy composition changes throughout forming process. Finally, concluding remarks the underline challenges of forming heattreatable aluminium alloy and subsequently highlights the potential work that can be applied in order to ensure a more efficient and sustainable manufacturing agenda for heat treatable aluminium alloy.

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Forming limit prediction for AA7075 alloys under hot stamping conditions

Cited by 5 publications

References 9 publications

A general IHTC model for hot/warm aluminium stamping

A general IHTC model for hot/warm aluminium stamping

A Generalized Stress State and Temperature Dependent Damage Indicator Framework for Ductile Failure Prediction in Heat-Assisted Forming Operations

Reviews on the Forming Process of Heat Treatable Aluminium Alloys

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