Modeling of GP(I) zone formation during quench in an industrial AA7449 75 mm thick plate

Schloth, P.; Deschamps, A.; Gandin, Charles‐André; Drezet, Jean‐Marie

doi:10.1016/j.matdes.2016.09.052

Cited by 26 publications

(14 citation statements)

References 39 publications

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“…In addition, the electrical conductivity is decreased upon heating too, as shown in Figure 4b. These findings indicate that the accumulated as-quenched hardeners (clusters) may dissolve upon heating because the structural stability of clusters are far less than those of large precipitates, as mentioned by the in situ SAXS results [11]. The mechanism of residual stress production has been well recognized in previous research, which is considered to be the result of inhomogeneous elastoplastic deformation due to the thermal stress during quenching [15][16][17].…”

Section: Resultsmentioning

confidence: 64%

“…In a more recent study, the in situ small-angle X-ray scattering (SAXS) measurements demonstrated that the nanosized precipitates formed during quenching in an AA7449 alloy harden the material significantly, and these authors suggested that the hardeners formed during quenching are mainly solute clusters, and that other larger precipitates can be neglected [10]. It should be noted that a special phenomenon was exhibited during the experiment, wherein the volume fraction of accumulated clusters after quenching decreased significantly after reheating to temperatures between 80 to 150 • C [11]. This phenomenon can be explained as follows: The solute clusters formed in such short times during quenching that they were supercritical nucleated and were not as stable as the larger precipitates were.…”

Section: Introductionmentioning

confidence: 99%

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A New Path of Quench-Induced Residual Stress Control in Thick 7050 Aluminum Alloy Plates

Chen

Zhu

et al. 2019

Metals

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The high magnitude of quench-induced residual stress in thick aluminum plates is attributed not only to high thermal stress but also to high yield strength due to quench-induced precipitation hardening. To date, lowering the thermal stress is the only path to reduce the residual stress in the design of quenching technology. In this paper, a new path is proposed that reduces the residual stress through decreasing the yield strength at ambient temperatures by eliminating the precipitation hardening effect during quenching. As certified in several experiments, the high yield strength of thick as-quenched plates decreases rapidly from a short period of extra heat preservation at relatively higher temperatures. Therefore, an interrupted quenching method is proposed, wherein quenching is interrupted after an initial cooling period and the sample is placed in air to make the temperature field uniform; afterward, the sample is cooled to room temperature. Interrupted quenching tests were conducted on 115 mm thick 7050 aluminum plates and significant residual stress reductions were observed in the specimens compared with the residual stresses in the specimens subjected to regular quenching.

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Section: Resultsmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 99%

A New Path of Quench-Induced Residual Stress Control in Thick 7050 Aluminum Alloy Plates

Chen

Zhu

et al. 2019

Metals

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“…The transformed volume during quenching is calculated by visualizing the quench cooling process as the superposition of a series of consecutive isothermal precipitation steps. In the analysis of hardenability and/or as-aged performance prediction, the precipitation discussed is coarse precipitation (approximately 100 nm), which occurs in an intermediate temperature range from 200-400 • C [8,9]. These coarse precipitates are ineffective hardeners, and their formation may reduce the available solute, thereby reducing the age hardening effect.…”

Section: Discussion Of Qfa Assumptionsmentioning

confidence: 99%

“…In classical QFA, the transformed volume of this coarse precipitation is linked with as-aged performance loss, and a performance loss of approximately 10-15% is generally of interest. However, in the analysis of the quench-induced hardening effect and/or the as-quenched performance prediction, the precipitation discussed is the nanosized precipitation, i.e., solute clusters, that occurs at temperatures below 200 • C [9,15,16]. Cluster hardening may result in a rapid increase in yield strength, and a performance increase beyond 10-15% is generally of interest.…”

Section: Discussion Of Qfa Assumptionsmentioning

confidence: 99%

“…However, this model was designed for a long-term age hardening curve and is questionable for the quench-induced hardening effect in short quenching times. Recently, P. Schloth et al proposed a prediction of the quench-induced hardening effect by using statistical microstructure information obtained from in situ small-angle X-ray scattering (SAXS) [9]. An important fact suggested in this study was that the quench-induced hardening effect was mainly linked with nanosized precipitates, i.e., solute clusters formed at low temperatures, and other subsequent precipitates can be ignored.…”

Section: Introductionmentioning

confidence: 87%

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Prediction and Experimental of Yield Strengths of As-Quenched 7050 Aluminum Alloy Thick Plates after Continuous Quench Cooling

Chen

Liu

et al. 2019

Metals

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The aim of this study was to predict the yield strength of as-quenched aluminum alloys according to their continuous quench cooling path. Our model was established within the framework of quench factor analysis (QFA) by representing a quenching curve as a series of consecutive isothermal transformation events and adding the yield strength increments after each isothermal step to predict the yield strength after continuous quench cooling. For simplification; it was considered that the effective hardeners during quenching were the nanosized solute clusters formed at low temperatures, whereas the other coarse precipitates were neglected. In addition, quenching tests were conducted on aluminum plates with different thicknesses. The predictions were compared with the experimental measurements, and the results showed that the predictions fit the measurements well for the 40-and 80-mm-thick plates but overestimated the as-quenched yield strength at the mid-thickness of the 115-mm-thick plates.

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Dynamic Precipitation in Supersaturated Al–Zn–Mg–Cu Alloy During Warm Stretching

Robson

Jessner

Taylor

et al. 2023

Metall Mater Trans A

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High-strength Al–Zn–Mg–Cu alloys such as AA7075 rely on precipitation to obtain their properties, and the evolution of these precipitates can be strongly influenced by deformation. In this study, the effect of warm stretching on precipitation in supersaturated AA7075 was investigated. A dilatometer was used to enable rapid quenching directly from the solution treatment temperature to the warm stretching temperature. The evolution of precipitates was monitored using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). SAXS revealed the presence of clusters only 5 seconds after quenching, and the subsequent evolution of the microstructure involved the growth and coarsening of these clusters. Deformation strongly enhanced the cluster/precipitate growth rate, which increased linearly with increasing strain. A strain rate effect was also noted, with the growth rate being faster at the higher strain rate for the same strain level. However, the acceleration of growth with increasing strain rate was not sufficient to compensate for the reduced time, so that deformation at higher strain rate led to small precipitates (at iso-strain). TEM revealed the precipitates to be homogeneously dispersed in the matrix both with and without deformation. There was no evidence for enhanced nucleation due to deformation, indeed the opposite was the case, with fewer but larger precipitates observed in the deformed microstructure. The linear increase in growth rate with strain is consistent with a dominant effect of excess vacancies in enhancing diffusion rates.

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Modeling of GP(I) zone formation during quench in an industrial AA7449 75 mm thick plate

Cited by 26 publications

References 39 publications

A New Path of Quench-Induced Residual Stress Control in Thick 7050 Aluminum Alloy Plates

A New Path of Quench-Induced Residual Stress Control in Thick 7050 Aluminum Alloy Plates

Prediction and Experimental of Yield Strengths of As-Quenched 7050 Aluminum Alloy Thick Plates after Continuous Quench Cooling

Dynamic Precipitation in Supersaturated Al–Zn–Mg–Cu Alloy During Warm Stretching

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