Sequential modeling of local precipitation, strength and strain hardening in friction stir welds of an aluminum alloy 6005A-T6

Simar, Aude; Bréchet, Y.; Meester, B. de; Denquin, Anne; Pardoen, Thomas

doi:10.1016/j.actamat.2007.07.012

Cited by 227 publications

(149 citation statements)

References 26 publications

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“…This question can however not be tudies of the coherency of the precipitates are needed to do so. The results of Simar et al [80] are used to interpret the changes in storage rate and t investigation.…”

Section: Hollomon and Ludwigson Equationsmentioning

confidence: 99%

“…The study of Simar et al [80] shows better According to Simar et al the storage rate precipitates to a mixture of shearable and non-shearable precipitates and a maximum when a precipitates become non-shearable. These results raise the question whether the storage ra answered by the present study as TEM s recovery rate for the alloys used in the presen…”

Section: Kocks-mecking Strain Hardening Modelmentioning

confidence: 99%

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The heat treatment of Al–Si–Cu–Mg casting alloys

Sjölander

Seifeddine

2010

Journal of Materials Processing Technology

460

223

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Environmental savings can be made by increasing the use of aluminium alloys in the automotive industry as the vehicles can be made lighter. Increasing the knowledge about the heat treatment process is one task in the direction towards this goal. The aim of this work is to investigate and model the heat treatment process for Al-Si casting alloys. Three alloys containing Mg and/or Cu were cast using the gradient solidification technique to achieve three different coarsenesses of the microstructure and a low amount of defects.Solution treatment was studied by measuring the concentration of Mg, Cu and Si in the α-Al matrix using wavelength dispersive spectroscopy (WDS) after various times at a solution treatment temperature. A diffusion based model was developed which estimates the time needed to obtain a high and homogenous concentration of alloying elements for different alloys, temperatures and coarsenesses of the microstructure. It was shown that the yield strength after artificial ageing is weakly dependent on the coarseness of the microstructure when the solution treatment time is adjusted to achieve complete dissolution and homogenisation.The shape and position of ageing curves (yield strength versus ageing time) was investigated empirically in this work and by studying the literature in order to differentiate the mechanisms involved. A diffusion based model for prediction of the yield strength after different ageing times was developed for Al-Si-Mg alloys. The model was validated using data available in the literature. For Al-Si-Cu-Mg alloys further studies regarding the mechanisms involved need to be performed.Changes in the microstructure during a heat treatment process influence the plastic deformation behaviour. The Hollomon equation describes the plastic deformation of alloys containing shearable precipitates well, while the Ludwigson equation is needed when a supersaturated solid solution is present. When non-coherent precipitates are present, none of the equations describe the plastic deformation well. The evolution of the storage rate and recovery rate of dislocations was studied and coupled to the evolution of the microstructure using the Kocks-Mecking strain hardening theory.

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Section: Hollomon and Ludwigson Equationsmentioning

confidence: 99%

Section: Kocks-mecking Strain Hardening Modelmentioning

confidence: 99%

The heat treatment of Al–Si–Cu–Mg casting alloys

Sjölander

Seifeddine

2010

Journal of Materials Processing Technology

460

223

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“…Later, Myhr et al [5] proposed to introduce a mean strength to account for a distribution of precipitates. This approach is now widely used [6,12]. A recent paper by Bahrami et al proposed an elegant coupling between a precipitation class model and a strengthening model [20].…”

Section: Introductionmentioning

confidence: 99%

“…The Kampmann and Wagner numerical model (KWN) [11] was coupled with strain-hardening models to investigate the flow properties in friction stir welded joints [12,13]. However, these types of precipitation models were always based on the assumption of spherical precipitates (e.g.…”

Section: Introductionmentioning

confidence: 99%

Coupled precipitation and yield strength modelling for non-isothermal treatments of a 6061 aluminium alloy

et al. 2014

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In age-hardening alloys, high-temperature processes, such as welding, can strongly modify the precipitation state, and thus degrade the associated mechanical properties. The aim of this paper is to present a coupled approach able to describe precipitation and associated yield stresses for non-isothermal treatments of a 6061 aluminium alloy. The precipitation state (in terms of volume fraction and precipitate size distribution) is modelled thanks to a recent implementation of the classical nucleation and growth theories for needle-shaped precipitates. The precipitation model is validated through small-angle neutron scattering and transmission electron microscopy experiments. The precipitation size distribution is then used as an entry parameter of a micromechanical model for the yield strength of the alloy. Predicted yield stresses are compared to tensile tests performed with various heating conditions, representative of the heat-affected zone of a welded joint.

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“…Aside from the many possibilities offered by alloying, pre-deforming and/or producing composite structures, microstructure refinement is one of the most versatile and powerful way to strengthen a metal. Refining microstructures means for instance reducing the grain size in order to take benefit of the well known Hall-Petch effect (Hall, 1951;Petch, 1953), limiting the precipitate size to an optimal diameter (Simar et al, 2007), decreasing the twin spacing (Dao et al, 2006), or decreasing the thickness of lamellae in lamellar structures (Huang et al, 2001;Modi et al, 2001). Another example, which is the focus of the present research, is related to microstructures involving a second phase which is metastable at operating temperature and which, under mechanical loading, transforms into a harder phase.…”

Section: Introductionmentioning

confidence: 99%

Analysis of size effects associated to the transformation strain in TRIP steels with strain gradient plasticity

Mazzoni-Leduc

Pardoen

Massart

2010

European Journal of Mechanics - A/Solids

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International audienceThe size dependent strenghtening resulting from the transformation strain in Transformation Induced Plasticity (TRIP) steels is investigated using a two dimensional embedded cell model of a simplified microstructure composed of small cylindrical metastable austenitic inclusions within a ferritic matrix. Earlier studies have shown that within the framework of classical plasticity or of the single length parameter Fleck-Hutchinson strain gradient plasticity theory, the transformation strain has no significant impact on the overall strengthening. The strengthening is essentially coming from the composite effect with a marked inclusion size effect resulting from the appearance during deformation of new boundaries constraining the plastic flow. The three parameters version of the Fleck-Hutchinson strain gradient plasticity theory is used here in order to better capture the effect of the plastic strain gradients resulting from the transformation strain. The three parameters theory incorporates separately the rotational and extensional gradients in the formulation, which leads to a significant influence of the shear component of the transformation strain, not captured by the single parameter theory. When the size of the austenitic inclusions decreases, the overall strengthening increases due to a combined size dependent effect of the transformation strain and of the evolving composite structure. A parametric study is proposed and discussed in the light of experimental evidences giving indications on the optimization of the microstructure of TRIP-assisted multiphase steels

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Sequential modeling of local precipitation, strength and strain hardening in friction stir welds of an aluminum alloy 6005A-T6

Cited by 227 publications

References 26 publications

The heat treatment of Al–Si–Cu–Mg casting alloys

The heat treatment of Al–Si–Cu–Mg casting alloys

Coupled precipitation and yield strength modelling for non-isothermal treatments of a 6061 aluminium alloy

Analysis of size effects associated to the transformation strain in TRIP steels with strain gradient plasticity

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