Influence of Deep Cryogenic Treatment on Microstructure and Properties of 7A99 Ultra-High Strength Aluminum Alloy

Gao, Wenlin; Wang, Xiangjie; Chen, Junzhou; Ban, Chunyan; Chen, Jianzhong; Lu, Zhonghua

doi:10.3390/met9060631

Cited by 16 publications

(7 citation statements)

References 10 publications

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“…The DCT is equivalent to a special aging treatment, which can accelerate the later aging process and lead to more and finer precipitates. [ 25 ] The effect of DCT on later aging treatment is mainly reflected in the increase in the diffusion rate of Zn and Mg atoms due to the rapid increase of temperature and the formation of the GP region of solute atoms during the DCT. The GP region of solute atoms with sufficient size can act as the center for later nucleation, high energy dislocations can also act as the nucleation center of solute atoms, so the nucleation rate of precipitates is improved.…”

Section: Discussionmentioning

confidence: 99%

Electrochemical study of Al–Zn–Mg–Cu alloy during deep cryogenic process

Zhang

Wang

et al. 2022

Materials & Corrosion

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Al-Zn-Mg-Cu alloy was treated by deep cryogenic treatment combined with T6 treatment to obtain excellent properties. The hardness of the alloy was measured by a Vickers hardness tester. The corrosion behaviors of the alloy were monitored by electrochemical techniques and scanning electron microscopy. Furthermore, the microstructures of the alloy were examined by transmission electron microscope. The results show that after deep cryogenic treatment, the hardness and corrosion resistance of the alloy will be optimized, and the corrosion resistance and hardness will be strongly affected by the precipitate state. When the distance between grain boundary precipitates becomes larger and discontinuous, the corrosion resistance will be significantly improved. When the amount of matrix precipitates is large, the fine dispersion distribution can well increase the hardness. The best combination of the hardness and corrosion resistance is exhibited for the alloy treated at −196°C for 10 h with aging treatment at 120°C for 16 h, the hardness, the intergranular corrosion depth, the current density, and the corrosion rate are 189.6 HV, 31.8 μm, 0.0019 mA/cm 2 , and 0.0022 mm/a, respectively.

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Section: Discussionmentioning

confidence: 99%

Electrochemical study of Al–Zn–Mg–Cu alloy during deep cryogenic process

Zhang

Wang

et al. 2022

Materials & Corrosion

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“…Aluminum alloys 7xxx series are using in many engineering applications, such as aerospace and aircraft structures and recently in the military field [1,2]. Alloy 7001 is an alloy, with zinc as the primary alloying element; it has high mechanical and corrosion resistance and excellent fatigue life due to precipitation hardened.…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

“…Results indicated that the pitting does not significantly influence fatigue performance. Others have examined the influence of (DCT) on the properties of aluminum alloys, [2] have investigated the improvement in hardness, toughness, wear resistance, and fatigue life on an extruded plate of high strength Al 7A99 alloy using (T6) treatment (The T6 thermal cycle consists of a solution heat treatment followed by a water quenching and then an age hardening (or precipitation hardening) then by (T6+DCT) treatment. After the T6 (peak ageing) method.…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

Development mechanical and fatigue properties of AA7001 after combined SP with deep cryogenic treatment and UIP with deep cryogenic treatment

Alhamdany

Khenyab

Mohammed

et al. 2021

EEJET

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Al alloys have long been of interest to the aerospace community, due to their modest specific strength, ease of manufacture, and low cost. In recent years, with the rapid development of weaponry, 7XXX ultra-high strength aluminum alloys used increasingly in military ﬁelds. Chemical analysis of the AA 7001 is supported out at The Company State for Engineering, Rehabilitation and Inspection (SIER) in Iraq. Strengthening the surface (shot penning) is beneficial to delay crack nucleation and extend life. The test samples (tensile and fatigue) are subject to the SP process by using ball steel with the parameters (Pressure=12 bars, Speed=40 mm/min, Distance=150 mm, Shot size=2.25 mm, Coverage=100 %). The ultrasonic impact treatment (UIP) machine is used for enhancing the surface properties. For the Deep Cryogenic Treatment (DCT), the samples have been placed in the cooling chamber. A standard tensile test specimen is prepared in a round section with the dimensions chosen according to ASTM (A370-11). Tensile and fatigue of rotating bending with R=–1 have been conducting, after the effect of deep cryogenic treatment (DCT), combined shot peening (SP+DCT), and ultrasonic impact peening (UIP+DCT) of AA7001 have been examining. The maximum improvement percent in ultimate tensile strength (UTS) due to (DCT), (SP+DCT), and (UIP+DCT) were about 3 %, 8.27 %, and 6.25 %, respectively. The rise in the yield stress due to (DCT), (SP+DCT), and (UIP+DCT) were 9.5 %, 14.6 %, and 13.14 %, respectively. The ductility reduced by constituents of 8.57 %, 12.5 %, and 11.42 % sequentially. The improvement in fatigue strength in a high cycle regime is 16 % for (SP+DCT) due to combined effects, it is an 8 % increase in the endurance limit on fatigue behavior due to inducing compressive residual stress (CRS)

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“…A deep cryogenic treatment with a long soaking time (45 h) had positive effects on the mechanical properties and machinability of a 5083 alloy [14]. Gao et al [15] also found that deep cryogenic treatment improved the strength and plasticity of a 7A99 alloy through refining the precipitates and increasing the uniformity of the precipitate distribution. Park [16] revealed that cryogenic treatment followed by rapid reheating (uphill quenching) released the residual stress and obviously improved the tensile properties.…”

Section: Introductionmentioning

confidence: 98%

The Influence of Cryogenic Treatment on the Microstructure and Mechanical Characteristics of Aluminum Silicon Carbide Matrix Composites

et al. 2023

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Aluminum matrix composites have been widely used in aerospace and automotive fields due to their excellent physical properties. Cryogenic treatment was successfully adopted to improve the performance of aluminum alloy components, while its effect and mechanism on the aluminum matrix composite remained unclear. In this work, the effects of cryogenic treatment on the microstructure evolution and mechanical properties of 15%SiCp/2009 aluminum matrix composites were systematically investigated by means of Thermoelectric Power (TEP), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The results showed that TEP measurement can be an effective method for evaluating the precipitation characteristics of 15%SiCp/2009 aluminum matrix composites during aging. The addition of cryogenic treatment after solution and before aging treatment promoted the precipitation from the beginning stage of aging. Furthermore, the aging time for the maximum precipitation of the θ″ phase was about 4 h advanced, as the conduction of cryogenic treatment accelerates the aging kinetics. This was attributed to the great difference in the linear expansion coefficient between the aluminum alloy matrix and SiC-reinforced particles, which could induce high internal stress in their boundaries for precipitation. Moreover, the lattice contraction of the aluminum alloy matrix during cryogenic treatment led to the increase in dislocation density and micro defects near the boundaries, thus providing more nucleation sites for precipitation during the aging treatment. After undergoing artificial aging treatment for 20 h, the increase in dispersive, distributed precipitates after cryogenic treatment improved the hardness and yield strength by 4% and 16 MPa, respectively.

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Influence of Deep Cryogenic Treatment on Microstructure and Properties of 7A99 Ultra-High Strength Aluminum Alloy

Cited by 16 publications

References 10 publications

Electrochemical study of Al–Zn–Mg–Cu alloy during deep cryogenic process

Electrochemical study of Al–Zn–Mg–Cu alloy during deep cryogenic process

Development mechanical and fatigue properties of AA7001 after combined SP with deep cryogenic treatment and UIP with deep cryogenic treatment

The Influence of Cryogenic Treatment on the Microstructure and Mechanical Characteristics of Aluminum Silicon Carbide Matrix Composites

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