Effect of post-quench delay on stress relieving by cold compression for the aluminium alloy 7050

Robinson, J. S.; Tiernan, Peter; Kelleher, Joe

doi:10.1179/1743284714y.0000000571

Cited by 15 publications

(13 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, these observations are similar to those of Robinson et al [10]. In their work [10], 7050 aluminium forging was investigated.…”

Section: Resultssupporting

confidence: 76%

“…3 (e)], possibly because it receives more deformation than B3. Variations and inhomogeneous grain distributions through the samples at various positions along the through-thickness of the forging are evident in these micrographs, in line with the heterogeneous grain distribution observed in aluminium alloy forgings reported in the literature [10]. The microstructures in the thick section die forging have evolved during the thermo-mechanical/metallurgical processing, and the nature of the grain structure is dependent mainly on the amount of working the various regions in the throughthickness face are subject to, and the thermal gradients.…”

Section: Figure 3 Through-thickness Residual Stresses Measured By Thesupporting

confidence: 66%

“…In their work [10], 7050 aluminium forging was investigated. The surface residual stress was compressive and around 40 MPa, after overageing.…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Through Thickness Residual Stress and Microstructural Mapping of AA7085-T7452 Die Forging

Walker

Shekhter

Sharp

et al. 2016

Residual Stresses 2016

View full text Add to dashboard Cite

Abstract. Significant weight savings and reductions in manufacturing costs have motivated the drive towards the use of unitised structures such as large die forgings in modern aircraft. However, detrimental bulk tensile residual stresses, present in these thick forgings can impact the durability and structural integrity of the primary aerospace structure. Residual stresses can lead to distortion during component machining, and part rejection. In addition, failure to account for the residual stress effects in the fatigue crack growth characteristics of the component in design and in performance could impact the structural integrity. Therefore, there is a need to measure and analyse the residual stresses present in the forged components, and examine the residual stress-microstructure, including grain structure/flow relationship for the forging, if such a relationship could be developed. The preliminary results of this experimental program have shown a link between the measured residual stress and hardness, along with changes in the grain structures through the thickness. IntroductionStructural unitisation of components is being actively pursued by the aerospace industry with the primary aim of weight reduction and cost savings. Large aluminium forgings and thick section rolled products make a significant contribution towards unitisation of critical, primary airframe components, such as wing-carry-through bulkheads. Inherent with the thick section wrought product forms, and particularly in die forged components, is the built-in bulk residual stresses on a macro scale [1], arising from the thermal gradients in the thermo-mechanical processing and the postsolution treatment rapid quenching. The presence of process related bulk residual stresses results in: a) part distortion during machining which is a cost driver and b) high degree of scatter and/or variability in fatigue crack growth rate [2], which is a performance driver affecting the durability and damage tolerance of the component. The residual stresses in an aluminium 7050-T7452 forged block that caused distortion during machining was reported to be a major cost driver for a commercial aircraft manufacturer, as a result of excess manufacturing time, schedule overruns, and part rejection and scrapped material [3].The surface and subsurface compressive residual stresses in an as-quenched (before stress relief treatment) aluminium alloy forgings have been reported to be in the range -200 MPa -250 MPa [4]. The mechanical stress relief treatment by cold compression (forgings) or stretching (rolled plate) that follows, aims to relieve (or reduce) the severity of the bulk residual stresses existed in the asquenched state in the component. However, cold compression stress relief in die forged components do not always fully relieve the complex 3 D bulk residual stresses, and the unrelieved residual stresses may be of sufficient magnitude to cause distortion in machined components [4][5][6]. Moreover, the three dimensional residual stress distribution in the stress reli...

show abstract

“…However, these observations are similar to those of Robinson et al [10]. In their work [10], 7050 aluminium forging was investigated.…”

Section: Resultssupporting

confidence: 76%

Section: Figure 3 Through-thickness Residual Stresses Measured By Thesupporting

confidence: 66%

See 1 more Smart Citation

Through Thickness Residual Stress and Microstructural Mapping of AA7085-T7452 Die Forging

Walker

Shekhter

Sharp

et al. 2016

Residual Stresses 2016

View full text Add to dashboard Cite

show abstract

“…16 The obtained results in this study about the pattern of RS in 7075 T6 are in good accordance with the previous researches in this field. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] After performing one pass of CCDF at $25 C and aging at 120 C (sample B), the magnitude and pattern of RS changed significantly. In this condition, the core of the sample is under compression, and surfaces and sub-surfaces are mainly under tensile stresses.…”

Section: Resultsmentioning

confidence: 99%

“…To put it more exactly, the higher the quenching rate and thickness, the higher the RS. [3][4][5][6][7][8][9][10][11] Distortion commonly happens during the machining of precipitation-hardened AA due to RS that was created during the quenching step in the heat treatment process. To control the RS and fabricate the tight tolerance specimens from heat-treatable AA, several methods have been introduced such as thermal stress relieving, 12,13 mechanical stress relieving, 14,15 and quenching in warm water.…”

Section: Introductionmentioning

confidence: 99%

Improving the mechanical properties and reducing the residual stresses of AA7075 by combination of cyclic close die forging and precipitation hardening

Moazam

Honarpisheh

2020

Proceedings of the Institution of Mechanical Engineers, Part L:

View full text Add to dashboard Cite

As one of the major strengthening mechanisms, the precipitation hardening is used to enhance the mechanical properties of aluminum alloys. Based on the results of the residual stress measurement, after fast quenching, the core of the material is under tensile stress while the surfaces are under compressive residual stress. Distortion commonly happens during the machining of precipitation-hardened aluminum alloys due to the residual stresses created during the quenching step in the heat treatment process. In this study, the combination of cyclic close die forging and precipitation hardening was used to improve the mechanical properties and control the residual stresses of AA 7075, simultaneously. According to the results, a considerable level of residual stresses was developed in the sample after the quenching step. Performing the cyclic close die forging process immediately after the quenching step changed the pattern of the residual stresses and reduced them significantly. The reduction of the residual stresses after the first pass of cyclic close die forging was about 50%, while after two passes, the sample was almost fully stress relieved. Besides, the results of the microhardness and uniaxial tensile tests demonstrated the improvement of the mechanical properties of the processed samples when compared to the T6 condition. Also, in comparison to AA 7075-T6, the yield stress, ultimate tensile stress, and microhardness were increased by about 24%, 22%, and 48%, respectively.

show abstract

The Determination of Residual Stress in Quenched and Cold-Compressed 7050 Aluminum Alloy T-Section Forgings by the Contour Method and Neutron Diffraction

Liu

Wimpory

Gong

et al. 2018

J. of Materi Eng and Perform

View full text Add to dashboard Cite

Effect of post-quench delay on stress relieving by cold compression for the aluminium alloy 7050

Cited by 15 publications

References 27 publications

Through Thickness Residual Stress and Microstructural Mapping of AA7085-T7452 Die Forging

Through Thickness Residual Stress and Microstructural Mapping of AA7085-T7452 Die Forging

Improving the mechanical properties and reducing the residual stresses of AA7075 by combination of cyclic close die forging and precipitation hardening

The Determination of Residual Stress in Quenched and Cold-Compressed 7050 Aluminum Alloy T-Section Forgings by the Contour Method and Neutron Diffraction

Contact Info

Product

Resources

About