Influence of heat treatment on the cyclic deformation properties of aluminium alloy AA7030

Hörnqvist, Magnus; Karlsson, Birger

doi:10.1016/j.msea.2007.06.078

Cited by 27 publications

(15 citation statements)

References 28 publications

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“…They demonstrated that the increase in the fatigue resistance property with ageing time was linked with the vacancies assisted diffusion mechanism and also by the hindering of dislocation movement by impure atoms. AA7030 aluminum alloy was tested under low cycle fatigue loadings by Hoernqvist and Karlsson [10]. Their objectives were to determine the cyclic deformation properties and to investigate the influence of heat treatment.…”

Section: Introductionmentioning

confidence: 99%

Heat treatment effect on thermo-mechanical fatigue and low cycle fatigue behaviors of A356.0 aluminum alloy

Azadi

Shirazabad

2013

Materials & Design

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a b s t r a c tIn the present paper, the heat treatment effect on A356.0, a cast aluminum alloy which has been widely used in diesel engine cylinder heads, is investigated under out-of-phase thermo-mechanical fatigue and low cycle fatigue (at different temperatures) loadings. A typical heat treatment is applied to the material including 8 h solution at 535°C, water quench and 3 h ageing at 180°C. The experimental fatigue results show that the heat treatment process has considerable influence on mechanical and low cycle fatigue behaviors, especially at room temperature, but its effect on thermo-mechanical fatigue lifetime is not significant. The improvement in the strength can be explained by the dislocation theory. Under thermomechanical fatigue loadings, the difference between the fatigue lifetime of A356.0 alloy and A356.0-T6 alloy decreases when the temperature range increases. In this condition, plastic strain increases severely during the fatigue cycles in A356.0-T6 alloy due to over-ageing phenomenon and therefore, the amount of cyclic softening in heat treated alloy is more.

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Section: Introductionmentioning

confidence: 99%

Heat treatment effect on thermo-mechanical fatigue and low cycle fatigue behaviors of A356.0 aluminum alloy

Azadi

Shirazabad

2013

Materials & Design

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“…[7,[18][19][20][21][22][23][24][25][26] The 7xxx-series aluminum alloys exhibit very high strength but also poor ductility and high notch sensitivity. [27] The fatigue of the commercial 7075Al-T6 alloy has received considerable attention. [28] The FSW offers high joint quality and good fatigue performance.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Cyclic Deformation Behavior of a Friction-Stir-Welded 7075 Al Alloy

Feng

Chen

2010

Metall Mater Trans A

119

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Microstructural changes and cyclic deformation characteristics of friction-stir-welded 7075 Al alloy were evaluated. Friction stir welding (FSW) resulted in significant grain refinement and dissolution of g¢ (Mg(Zn,Al,Cu) 2 ) precipitates in the nugget zone (NZ), but Mg 3 Cr 2 Al 18 dispersoids remained nearly unchanged. In the thermomechanically affected zone (TMAZ), a high density of dislocations was observed and some dislocations were pinned, exhibiting a characteristic Orowan mechanism of dislocation bowing. Two low-hardness zones (LHZs) between the TMAZ and the heat-affected zone (HAZ) were observed, with the width decreasing with increasing welding speed. Cyclic hardening and fatigue life increased with increasing welding speed from 100 to 400 mm/min, but were only weakly dependent on the rotational rate between 800 and 1200 rpm. The cyclic hardening of the friction-stir-welded joints exhibiting a two-stage character was significantly stronger than that of the base metal (BM) and the energy dissipated per cycle decreased with decreasing strain amplitude and increasing number of cycles. Fatigue failure occurred in the LHZs at a lower welding speed and in the NZ at a higher welding speed. Fatigue cracks initiated from the specimen surface or near-surface defects in the friction-stirwelded joints, and the initiation site exhibited characteristic intergranular cracking. Crack propagation was characterized by typical fatigue striations along with secondary cracks.

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“…In previous investigations it was shown that naturally aged AA7030 cyclically hardens until the on-set of crack growth, in spite of strong strain localization [20]. Normally, the repeated localization of strain into slip bands as a result of precipitate shearing leads to a softening during cycling [21][22][23], as was observed in the peak-aged version of the same alloy [20].…”

Section: Introductionmentioning

confidence: 89%

“…Normally, the repeated localization of strain into slip bands as a result of precipitate shearing leads to a softening during cycling [21][22][23], as was observed in the peak-aged version of the same alloy [20]. One explanation for this anomalous behavior could be that DP occurs during cycling, which continuously increases the flow stress level.…”

Section: Introductionmentioning

confidence: 90%

Dynamic strain ageing and dynamic precipitation in AA7030 during cyclic deformation

Hörnqvist

Karlsson

2010

Procedia Engineering

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The effects of dynamic strain ageing (DSA) and dynamic precipitation (DP) on the stress strain response during low-cycle fatigue of naturally aged (NA) and peak-aged (PA) AA7030 alloy at different temperatures was investigated. The results show that the PA temper is largely unaffected by DSA/DP, and the cyclic deformation behavior is controlled by the accumulation of dislocations and strain localization due to repeated shearing of precipitates. In the NA temper, on the other hand, the effect of temperature on DSA and DP is the main mechanism controlling the stress strain response. At temperature above room temperature, DP in the intense slip bands inhibits cyclic softening and the samples harden until the on-set of crack growth. At lower temperatures, the rate of DP is too slow to compensate for the softening in the slip bands and the stress amplitude saturates or decreases. The stress amplitude development is shown to primarily be a result of the evolution of the effective stress associated with dislocation precipitate interactions.

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Influence of heat treatment on the cyclic deformation properties of aluminium alloy AA7030

Cited by 27 publications

References 28 publications

Heat treatment effect on thermo-mechanical fatigue and low cycle fatigue behaviors of A356.0 aluminum alloy

Heat treatment effect on thermo-mechanical fatigue and low cycle fatigue behaviors of A356.0 aluminum alloy

Microstructure and Cyclic Deformation Behavior of a Friction-Stir-Welded 7075 Al Alloy

Dynamic strain ageing and dynamic precipitation in AA7030 during cyclic deformation

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