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Giant Hardening Response in AlMgZn(Cu) Alloys

59 Pages Posted: 3 Sep 2020 Publication Status: Accepted

See all articles by Lukas Stemper

Lukas Stemper

Montanuniversität Leoben - Christian Doppler Laboratory for Advanced Aluminum Alloys

Matheus A. Tunes

Chair of Nonferrous Metallurgy, Montanuniversitaet Leoben

Phillip Dumitraschkewitz

Chair of Nonferrous Metallurgy, Montanuniversitaet Leoben

Francisca Mendez-Martin

Department of Materials Science, Montanuniversitaet Leoben

Ramona Tosone

AMAG rolling GmbH

Daniel Marchand

Institute of Mechanical Engineering, EPFL Lausanne

William A. Curtin

Institute of Mechanical Engineering, EPFL Lausanne

Peter J. Uggowitzer

Montanuniversität Leoben - Chair of Nonferrous Metallurgy

Stefan Pogatscher

Montanuniversität Leoben - Chair of Nonferrous Metallurgy

Abstract

This study presents a thermomechanical processing concept which is capable of exploiting the full industrial application potential of recently introduced AlMgZn(Cu) alloys. The beneficial linkage of alloy design and processing allows not only to satisfy the long-standing trade-off between high mechanical strength in use and good formability during processing but also addresses the need for economically feasible processing times. After an only 3-hour short pre-aging treatment at 100°C, the two investigated alloys, based on commercial EN AW-5182 modified with additions of Zn and Zn+Cu respectively, show high formability due to increased work-hardening. Then, these alloys exhibit a giant hardening response of up to 184 MPa to reach a yield strength of 410 MPa after a 20-minute short final heat treatment at 185°C, i.e. paint-baking. This rapid hardening response strongly depends on the number density of precursors acting as preferential nucleation sites for T-phase precursor precipitation during the final high-temperature aging treatment, and is significantly increased by the addition of Cu. Minor deformation (2%) after pre-aging and before final heat treatment further enhances the development of hardening precipitates additionally by activating dislocation-supported nucleation and growth. Tensile testing, quantitative and analytical electron-microscopy methods, atom probe analysis and DFT calculations were used to characterize the alloys investigated in this work over the thermomechanical processing route. The influence of pre-strain on the hardening response and the role of Cu additions in early-stage cluster nucleation are discussed in detail with the latter supported by first-principles calculations.

Keywords: Aluminum Alloys, Precipitation hardening, thermomechanical treatment, mechanical testing, Microstructure evolution

Suggested Citation

Stemper, Lukas and Tunes, Matheus A. and Dumitraschkewitz, Phillip and Mendez-Martin, Francisca and Tosone, Ramona and Marchand, Daniel and Curtin, William A. and Uggowitzer, Peter J. and Pogatscher, Stefan, Giant Hardening Response in AlMgZn(Cu) Alloys. Available at SSRN: https://ssrn.com/abstract=3683513 or http://dx.doi.org/10.2139/ssrn.3683513

Lukas Stemper (Contact Author)

Montanuniversität Leoben - Christian Doppler Laboratory for Advanced Aluminum Alloys ( email )

Leoben, 8700
Austria

Matheus A. Tunes

Chair of Nonferrous Metallurgy, Montanuniversitaet Leoben

Phillip Dumitraschkewitz

Chair of Nonferrous Metallurgy, Montanuniversitaet Leoben

Francisca Mendez-Martin

Department of Materials Science, Montanuniversitaet Leoben

Ramona Tosone

AMAG rolling GmbH

Daniel Marchand

Institute of Mechanical Engineering, EPFL Lausanne

William A. Curtin

Institute of Mechanical Engineering, EPFL Lausanne

Peter J. Uggowitzer

Montanuniversität Leoben - Chair of Nonferrous Metallurgy

Leoben
Austria

Stefan Pogatscher

Montanuniversität Leoben - Chair of Nonferrous Metallurgy

Leoben
Austria

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