Effects of Cryogenic Forging and Anodization on the Mechanical Properties and Corrosion Resistance of AA6066–T6 Aluminum Alloys

Shih, Teng Shih; Yong, Hwa Sheng; Hsu, Wen Nong

doi:10.3390/met6030051

Cited by 9 publications

(5 citation statements)

References 29 publications

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“…The broken particles is clearly identified in the CF etched sample ( Figure 2f) located inside of a shear band. The same result was reported for cryogenic forged AA6066-T6 aluminum alloys [19]. The finer secondary particles in the CF sample presumably present stronger mechanical strength due to good obstructing and retarding dislocation movement.…”

Section: Initial Microstructure Characterizationsupporting

confidence: 83%

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High Strain Rate Behavior of Ultrafine Grained AA2519 Processed via Multi Axial Cryogenic Forging

Azimi

Owolabi

Fallahdoost

et al. 2019

Metals

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The present work deals with studies on the dynamic behavior of ultrafine grained AA2519 alloy synthesized via cryogenic forging (CF) and room temperature forging (RTF) techniques. A split-Hopkinson pressure bar was used to perform high strain rate tests on the processed samples and the microstructures of the samples were characterized before and after impact tests. Electron backscatter diffraction (EBSD) maps demonstrated a significant grain size refinement from ~740 nm to ~250 nm as a result of cryogenic plastic deformation showing higher dislocation densities and stored strains in the CF sample when compared to the RTF sample. This microstructure modification caused the increase of dynamic flow stress in this alloy. In addition, the aluminum matrix of the CF alloy is more densely populated with fragmented particles than the RTF alloy due to the heavier plastic deformation applied to the cryogenically forged alloy. The results obtained from the stress–strain curve for the RTF sample showed intense thermomechanical instabilities in the RTF sample which led to a severe thermal softening and the subsequent sharp drop in the flow stress. However, no significant decrease was observed in the stress–strain curve of the CF alloys with ultrafine grains which means that thermal softening would probably not be the most effective failure mechanism. Furthermore, higher level of sensitivity of CF alloys to strain rates was observed which is ascribed to transition of rate-controlling plastic deformation mechanisms. In the post-mortem microstructure investigation, deformed and transformed adiabatic shear bands (ASBs) were identified on the RTF alloy when the strain rate is over 4000 s−1 at which it had experienced a significant thermal softening. On the other hand, circular path and aligned split arcs are the various shapes of the deformed ASB seen at no earlier than 4500 s−1 in the CF alloys. This is associated with the crack failure caused by grain boundary sliding.

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Section: Initial Microstructure Characterizationsupporting

confidence: 83%

“…They observed that MAF at cryogenic temperature showed a greater yield strength when compared to that obtained in the cryorolled samples. Shih et al [19] reported a significant increase in the tensile strength of the cryogenically forged AA6066 when compared with the T6 treated samples.…”

Section: Introductionmentioning

confidence: 98%

High Strain Rate Behavior of Ultrafine Grained AA2519 Processed via Multi Axial Cryogenic Forging

Azimi

Owolabi

Fallahdoost

et al. 2019

Metals

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“…Forging Al alloys could offer good tensile strength (≥300 MPa) and high elongation (≥10%) and fatigue strength (≥120 MPa at 1 × 10 7 cycles) [11][12][13]. The forged parts are widely used in the automotive industry.…”

Section: Introductionmentioning

confidence: 99%

“…The concept of the cast/forge process was proposed by Fujikawa et al [14] Chang et al introduced the cast/forge hybrid process to reduce the porosity of 7075 aluminum alloy castings [15]. The tripods produced with this process were shown at ALUMINUM CHINA 2018, Shanghai, New International Expo Centre (2018/07/ [11][12][13]. The block castings were used instead of extruded bars or plates to decrease the processing cost.…”

Section: Introductionmentioning

confidence: 99%

The Optimum Process to Produce High-Strength Cast/Forged Al–8%Zn–2.5%Mg–1%Cu Alloy

Shih

Kwang

Huang

2019

Metals

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Al–8Zn–2.5Mg–1Cu alloy casting blocks were subjected to homogenization and annealing. The treated blocks were then held at different temperatures and forged in different dies to obtain 20 mm-thick plates. After T73 heat treatment, the plates were cut and machined to obtain tensile bar samples that were further subjected to tensile and potentiodynamic polarization tests. Upon analyzing the experimental results, the subzero-treated and forged samples (SO) developed fine grains in their matrix and displayed yield stress (YS) about 400 MPa and an elongation of 11%. The hot-forged samples (HC) displayed a relatively higher YS slightly >440 MPa and a lower elongation of 4%. The intermetallic compound particles confined to the HC decreased its corrosion resistance to be worse than that of the SO. All anodized and sealed samples effectively improved their corrosion resistance. Due to its fine grains, the anodized SO sample produced a higher Icorr than the anodized HC sample.

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“…In [12], both room temperature and cryogenic forging operations were carried out on AA6066-T6 aluminium alloy workpieces. It was shown that the use of liquid nitrogen led to the formation of finer precipitates within the matrix, which improved the corrosion resistance after anodization, since a reduced number of particles, detrimental for the corrosion resistance, remained entrapped within the anodization film.…”

mentioning

confidence: 99%

Mechanical and corrosion resistance properties of AA7075-T6 sub-zero formed sheets

Bertolini

Simonetto

Pezzato

et al. 2021

Int J Adv Manuf Technol

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The poor formability of 7xxx series aluminium alloys represents the major limit to their actual use for automotive and aerospace applications. In the present study, the forming temperature effect on the mechanical, corrosion and anodization behaviours of the AA7075-T6 alloy is investigated. To this purpose, tensile tests at different temperatures, ranging from −100 to 300°C, were carried out at different rolling directions. A 6.6% increase of the ultimate tensile strength and a 28.6% increase of the uniform elongation were registered for the specimens deformed at the lowest temperature compared to highest ones. Further, the corrosion resistance of specimens deformed at ultimate tensile strength before and after anodization was increased of 85% and 95%, respectively, compared to the specimens deformed at 300°C. It was demonstrated that high deformation temperatures led to the coalescence of particles and precipitates as well as the decrease of dislocation density, which, in turn, decreased the mechanical and corrosion performances. On the contrary, the deformation temperature of −100°C was found to be the ideal one able to shorten the manufacturing process chain and improve material formability and durability during its in-service life.

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Effects of Cryogenic Forging and Anodization on the Mechanical Properties and Corrosion Resistance of AA6066–T6 Aluminum Alloys

Cited by 9 publications

References 29 publications

High Strain Rate Behavior of Ultrafine Grained AA2519 Processed via Multi Axial Cryogenic Forging

High Strain Rate Behavior of Ultrafine Grained AA2519 Processed via Multi Axial Cryogenic Forging

The Optimum Process to Produce High-Strength Cast/Forged Al–8%Zn–2.5%Mg–1%Cu Alloy

Mechanical and corrosion resistance properties of AA7075-T6 sub-zero formed sheets

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