Uphill Quenching of Aluminum Alloys

Mattos, Wellington da Silva; Totten, George E.; Canale, Lauralice de Campos Franceschini

doi:10.1520/mpc20160125

Cited by 9 publications

(5 citation statements)

References 8 publications

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“…Therefore, it is of great importance to remove such residual stress. So far, a number of methods such as natural aging, annealing [11], vibratory stress relief [12][13][14], and uphill quenching [15,16] have been employed to eliminate residual stress in steel and aluminum alloys. Among them, annealing has also been used to eliminate the residual stress in magnesium alloys [17,18].…”

Section: Introductionmentioning

confidence: 99%

Effect of Pulsed Magnetic Field on the Residual Stress of Rolled Magnium Alloy AZ31 Sheet

Meng

Luo

et al. 2020

Acta Metall. Sin. (Engl. Lett.)

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A novel method of pulsed magnetic field (PMF) treatment was developed to eliminate the residual stress of rolled magnesium alloy AZ31 sheet in this study. The effect of PMF on residual stress of rolled AZ31 sheet was investigated and its mechanism was analyzed. The experimental results revealed that the pulse frequency had a significant impact on residual stress. After 10.0 Hz PMF treatment, the average and maximum reduction rates of residual stress along the rolled direction were 26.6% and 30.3%, respectively. It was found that the dislocation density and parallel dislocation in grains of the rolled sheet increased after it was treated by the pulsed magnetic field. The simulation results showed that the Lorentz force generated by the pulsed magnetic field can lead to basal slip, thereby resulting in local plastic deformation. Besides, the Joule heat produced during the PMF treatment was conducive to the elimination of residual stress.

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Section: Introductionmentioning

confidence: 99%

Effect of Pulsed Magnetic Field on the Residual Stress of Rolled Magnium Alloy AZ31 Sheet

Meng

Luo

et al. 2020

Acta Metall. Sin. (Engl. Lett.)

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“…Therefore, the hot sheet should be transferred to the cold tools and immediately stamped. Teams of Mackenzie (Mackenzie and Nwekirk 2001) and Mattos (Mattos et al 2016) described that using high pressure allows transferring the heat from the blank to the tools so quickly that the material becomes saturated at ambient temperature [23,24]. Xiao et al and Hu et al have proved that the supersaturated state is necessary for further heat treatment such as artificial aging.…”

Section: Introductionmentioning

confidence: 99%

Warm sheet metal forming of energy-absorbing elements made 7075 aluminum alloy in the hardened state T6

Jaśkiewicz

Skwarski

Kaczyński

et al. 2022

Int J Adv Manuf Technol

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The article covers experimental research on the forming of products made of 7075 aluminum alloy. This aluminum alloy grade is characterized by high strength, but due to its low formability in T6 temper, its use in the stamping processes of complex structural elements is limited. The authors have manufactured a U-shaped element at an elevated temperature and determined the optimal parameters of the process. Conventional heating of the sheet and shaping it at the temperature of 100 and 150 °C allowed to obtain a product of high strength similar to the T6 state, above 540 MPa. Due to the excessive springback of the sheet during forming, these products were characterized by a large deviation of the shape geometry, exceeding the allowable values of + / − 1 mm. Only the use of an alternative method of heating the sheet to temperatures of 200 and 240 °C (between plates at 350 °C, heating time 2 min, heating rate 1.8 °C/s) allowed to obtain a product that meets both the strength and geometric requirements. The determined optimal process’ parameters were later transferred to the stamping process of elements of a more complex shape (lower part of the B-pillar). The sheet was heated up and formed in the previously pre-heated tools. In the subsequent series of tests, the heating method and the blank’s temperature were being analyzed. In the case of the foot of the B-pillar, it was necessary to lower the initial blank temperature to 200 °C (heating in a furnace with a temperature of 340 °C, heating speed 0.5 °C/s). The appropriate combination of the process parameters resulted in the satisfactory shape deviation and reaching the product’s strength comparable to the strength of the material in as-delivered T6 temper. Using electron microscopy, it was verified that the structure of the finished product contained particles MgZn2 that strongly strengthen the alloy. The obtained results complement the data on the possibility of using 7075 aluminum alloy to produce energy-absorbing elements of motor vehicles.

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“…Complex critical parts can be quenched less aggressively and the example of polyalkylene glycol (PAG) quenching is investigated here. An alternative technology is uphill quenching (UHQ) which reverses the thermal gradients encountered during quenching [13][14][15][16]. Uphill quenching can be applied to complex geometries that cannot be stress relieved economically by mechanical methods.…”

Section: Introductionmentioning

confidence: 99%

Uphill Quenching to Reduce Residual Stress in Aluminium Alloy 7449 Hollow Structures

Robinson

O’Donovan²,

Wimpory

2022

Exp Mech

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Background Uphill quenching (UHQ) of heat treatable aluminium alloy components is a long established but rarely practiced or investigated method of reducing residual stresses. The efficacy of the technique has not been quantified on thin walled structures before and this investigation will address that deficiency. Objective To quantify the impact of uphill quenching on thin walled structure with regards to residual stress and warpage, and compare and contrast to both quenching into cold water and a 30% polyalkylene glycol (PAG) solution. Methods Rectilinear hollow boxes were made from the very high strength aerospace aluminium alloy 7449. These were heat treated and aged using a variety of processing methods including uphill quenching from -196 °C to 100 °C using steam. Residual stresses have been characterised using neutron and x-ray diffraction. Results Compared to conventional quenching into cold water, both PAG and UHQ are shown to significantly lower the residual stresses. However, while PAG quenching results in a large uniform reduction in both residual stress and warpage, UHQ is much more localised and limited to regions adjacent to direct steam impingement. These regions are also warped. The depth of penetration of the stress relief during UHQ is shown to be 5 mm. Conclusions While uphill quenching is shown to be capable of locally stress relieving an aluminium alloy, it is far less effective compared to PAG quenching.

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Uphill Quenching of Aluminum Alloys

Cited by 9 publications

References 8 publications

Effect of Pulsed Magnetic Field on the Residual Stress of Rolled Magnium Alloy AZ31 Sheet

Effect of Pulsed Magnetic Field on the Residual Stress of Rolled Magnium Alloy AZ31 Sheet

Warm sheet metal forming of energy-absorbing elements made 7075 aluminum alloy in the hardened state T6

Uphill Quenching to Reduce Residual Stress in Aluminium Alloy 7449 Hollow Structures

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