Double aging and thermomechanical heat treatment of AA7075 aluminum alloy extrusions

Emani, Satyanarayana; Benedyk, Joseph C.; Nash, Philip; Chen, D.

doi:10.1007/s10853-009-3879-8

Cited by 80 publications

(38 citation statements)

References 11 publications

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“…Therefore, the samples with pre-straining at both 480 • C and RT enabled to exhibit the high hardness value that is equivalent to the Al 7075-T6. The reasonably consistent values of Hv ≈180-200 were demonstrated by double aging and thermomechanical double aging processes with aging at 121 and 171 • C on an AA 7075 alloy [24]. Accordingly, although the pre-straining at RT achieved the peak hardening in slightly shorter time of aging than the pre-strained sample at high temperature, as shown in Figure 6, the RT pre-strain is limited for up to 10%, as was shown in Figure 4 for the Al 7075 alloy.…”

Section: Peak Aging Hardness and Aging Timementioning

confidence: 52%

Effects of Pre-Strain on the Aging Behavior of Al 7075 Alloy for Hot-Stamping Capability

Jung

Lee

Kawasaki

2018

Metals

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Abstract:The present study investigates the significance of pre-strain on the T6 aging behavior of an Al 7075 alloy for evaluating the applicability of hot stamping. In practice, the alloy was pre-strained up to 15% during solution heat treatment at 480 • C prior to quenching, and artificial aging was conducted at 120 • C. The peak aging time and precipitation behavior were compared with the alloy with pre-straining at room temperature after quenching but immediately before the artificial aging. The results showed that increasing amounts of pre-strain tend to reduce the aging time up to 50% for achieving peak hardness, which is consistent with the alloy at the T6 condition. There is a limitation for the maximum attainable amount of pre-strain of 10% for the homogeneous distribution of strain when the alloy is strained at room temperature (RT) due to the low formability. The pre-strained alloy as hot stamping exhibited lowering of the peak reaction temperatures for dissolution and formation of Guinier-Preston (GP)-Zones and precipitated with increasing amounts of pre-strain towards 15% through the differential scanning calorimetry analysis, thereby confirming the shortening of the peak aging time. The present study confirms the excellent potential of the hot-stamping process to extend the capability of an Al 7075 alloy.

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Section: Peak Aging Hardness and Aging Timementioning

confidence: 52%

Effects of Pre-Strain on the Aging Behavior of Al 7075 Alloy for Hot-Stamping Capability

Jung

Lee

Kawasaki

2018

Metals

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“…During aging, the size, quantity, and distribution of precipitates such as GP zones, and η and η phases determine the mechanical properties of welded joints. The final mechanical properties of welded joints are determined by the size of the particles, the interfacial relationship of particles with the matrix, and the grain boundary characteristics [36].…”

Section: Discussionmentioning

confidence: 99%

Evolution of Microstructure and Mechanical Properties in a Single-Stage Aged 7075 Aluminum Alloy Pulse Variable Polarity Plasma Arc Welded Joint

Liang

Chen

et al. 2019

Metals

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A 7075 aluminum alloy was successfully welded by pulsed variable polarity plasma arc welding (PVPPAW) and the single-stage aging behavior of the 7075 aluminum alloy PVPPAW joint was systematically investigated. The results demonstrated that the tensile strength of the welded joints initially increased and then decreased with the increase of the single-stage aging temperature and time. After single-stage aging at 490 °C for 80 min and at 130 °C for 24 h, the tensile strength of the welded joint was 551 MPa, which was increased by 38.5% compared to the as-welded joint. Moreover, the conductivity was 25% international annealed copper standard (IACS) at room temperature, and the resistance to stress corrosion was improved. The main strengthening phases of the weld center were η′ and η phase. The average precipitate size slightly increased with the increase of the single-stage aging temperature, but no obvious change was observed with the increase of the single-stage aging time. The area fraction was initially increased and then decreased with the increase of the single-stage aging temperature and time.

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“…For two-step ageing, it has been suggested that, during first-step ageing at 121°C, the radius of the GP zones grow and their volume fraction increases, which enables the GP zones to transform into the metastable η' phase precipitates [11]. The conversion from GP zones to η' precipitates is accelerated in the second-step ageing at 177°C, which enhances the material to its peak strength.…”

Section: Fig 5: Effect Of Thermal History On Hardnessmentioning

confidence: 99%

“…Theoretically, the peak strength increases at first with increasing pre-ageing time and then decreases when the time is too long due to the change in the type of early stage precipitates, which would affect the size and distribution of precipitates in the second-step ageing. It is essential to assign the second-step ageing time appropriately as well; too short a period of time cannot ensure that the η' precipitates are fully transformed, while too long a period of time would convert the η' precipitates to more stable state η precipitates, which would reduce the strength of the material (overageing) [11,25,26].…”

Section: Fig 5: Effect Of Thermal History On Hardnessmentioning

confidence: 99%

Determination of Processing Windows for the Hot Stamping of AA7075

Zhang

Fakir

et al. 2016

KEM

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Abstract. Hot stamping of aluminium alloys is a tailored forming process, with the assigned processing windows determining the quality of each hot stamped component in terms of its post-form strength. In this work, a processing window calculator, 'Tailor', was developed in order to define the optimal processing parameters that should be used in a production line to successfully produce a component with the desired post-form strength using hot stamping. 'Tailor' was developed using the results of forming tests, air-cooling tests and multi-stage artificial ageing tests, which provided guidance on the values for the die closing force, transfer time and artificial ageing time to be used in the hot stamping process. The effectiveness of 'Tailor' was demonstrated in two case studies.

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Double aging and thermomechanical heat treatment of AA7075 aluminum alloy extrusions

Cited by 80 publications

References 11 publications

Effects of Pre-Strain on the Aging Behavior of Al 7075 Alloy for Hot-Stamping Capability

Effects of Pre-Strain on the Aging Behavior of Al 7075 Alloy for Hot-Stamping Capability

Evolution of Microstructure and Mechanical Properties in a Single-Stage Aged 7075 Aluminum Alloy Pulse Variable Polarity Plasma Arc Welded Joint

Determination of Processing Windows for the Hot Stamping of AA7075

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