Papers by Keyword: Aluminium Alloy

Abstract: Based on measurement data and the specific morphology of corrosion pit, three-dimensional finite element model of the corrosion damage specimen is established. Then the local stress condition of corrosion pits is given making use of finite element method, the results of stress concentration due to corrosion pits are also obtained, we can compare the stress concentration arised from the corrosion pit on aluminum alloy specimens in different corrosion time. Results show that the corrosion pits produce stress concentration and become the source of fatigue crack initiation and propagation. With the increasing of corrosion time, the pits get deeper and deeper, and the stress concentration gets more serious near the pits.

Abstract: To improve the corrosion resistance of Al alloy, triethylamine (TEN) was added into the sealing solutions. Tafel polarization and electrochemical impedance spectroscopy(EIS) techniques were used to investigate the electrochemical behavior of sealing coatings formed in different concentrations of triethylamine(TEN). Compared with the coatings with D. I. water and the bare aluminum alloy, the polarization curves show that the sealing coatings formed in 5.0 – 7 .0 g.L-1 triethylamine (TEN) solutions have more positive corrosion potential (Ecorr) and pitting corrosion potential (Epit), and lower corrosion current density (icorr). Electrochemical parameters of EIS indicate that the sealing coatings have higher corrosion resistance. The electrochemical test results show the prepared sealing coatings have better corrosion resistance.

Abstract: In order to improve the wear resistance and extend service life of aluminum alloy parts, the Ni-base alloy anti-wear coatings were prepared on the surfaces of 7A05 aluminum alloy by plasma spraying technology. The microstructure and interface of the coatings were analyzed, and the friction and wear properties of Ni-base alloy coatings and aluminum alloy substrates were investigated under dry friction condition at room temperature. The research results show that the main phases of Ni-base alloy coating are γ-Ni, CrB and Cr23C6. The thicknesses of diffusion layers existing between intermediate layer and coating, intermediate layer and substrate are respectively 15μm and 20μm. The bonding types of the coating and the substrate are mechanical combination accompanied with partially metallurgical combination. When wore against GCr15 steel balls, the average friction coefficient of the Ni-base alloy coatings is 11.6% lower than that of the aluminum alloy substrates, and the average wear loss of the former is 9.3mg, which is only 1/3 of that of the latter. With the increase of loads, the wear mechanisms of the Ni-base alloy coatings change from slightly micro-cutting wear and fatigue wear to abrasive wear and micro-fracture wear, while those of the aluminum alloy substrates are mainly adhesive wear and abrasive wear as well as slight oxidation wear.

Abstract: To establish the efficacy of electromagnetically assisted sheet metal stamping (EMAS), the corner-fill ability of AA5052 sheets specified in conventional deep drawing was experimentally demonstrated and evaluated within a two-step EMAS process. First, conventional axisymmetric deep drawing was conducted to make a cylindrical cup with a rough-shaped bottom corner. The second step utilized a shaped coil to force the pre-formed cup into the die cavity, and the related electromagnetically assisted corner-fill performance was investigated. Experimental results show that the ideal of hybrid stamping-EMF sequence can successfully solve the formability problem involved in conventional stamping. During electromagnetically assisted corner-fill process, the deformation dispersion effect of dynamic phenomenon works remarkably on the fully deformed sheets, which will inhibit local instability of deformation and thus enhance materials formability.

Abstract: Creep age forming (CAF) is an effective process to manufacture aircraft panels with better performance including improved strength and toughness, lower weight and increased resistance to fatigue and corrosion. Due to restrictions of aging cycle to create the desired property, springback in CAF is larger than other forming processes. That makes its prediction one of the key technologies in CAF. A solution is developed to predict springback in CAF of aluminium components. The studies are mainly concentrated on the pure bending of aluminium strips. Comparisons of predictions with experimental data yield agreement. Effects of T-beam’s structural factors, like width, skin thickness, rib width and transitional radius on springback are investigated. And a relationship between geometrical data and springback is given by the proposed algorithm.

Abstract: Rotating bending fatigue tests had been performed using A5052 aluminum (Al) alloy with the hybrid coatings which consisted of tungsten carbide including 12% cobalt (WC-12Co) interlayer and diamond-like carbon (DLC) film, in order to investigate the effect of hybrid coating on the fatigue behavior. The WC-12Co layer was thermally sprayed by a high velocity oxygen fuel (HVOF) method on A5052 with the thickness of 70, 120 or 170μm. Subsequently, the DLC film was deposited with the thickness of 15μm. The fatigue strengths of the specimens with WC-12Co single layer were higher than those of the substrate and increased with increasing the thickness of WC-12Co layer. The fatigue strengths of the specimens with the hybrid coating of 70μm WC-12Co interlayer and 15μm DLC film were better than those of the specimen with 70μm WC-12Co single layer. Thus the hybrid coating structure was effective to improve fatigue strengths. However the beneficial effect of hybrid coating was not apparent in the specimens with thicker WC-12Co interlayer of 120 and 170μm.

Abstract: Split Hopkinson pressure bar setup was used as experimental method for dynamic impacted testing at 573K at the strain rate of 7030s-1. The microstructure of Al-5.8Cu aluminum alloy impacted plate was characterized by transmission electron microscopy (TEM). The findings indicated that dislocation network of Al matrix was observed, which was attributed to isothermal and adiabatic process during impaction. The researched results indicated the dislocation network of Al matrix was inhabited by coarsened precipitate in Al-5.8Cu alloy impacted plate.

Abstract: The low-cycle fatigue behaviors of permanent-mold cast and die-cast Al-Si-Cu-Mg-Sc alloys at room temperature were investigated. The results show that at the higher total strain amplitudes, both permanent-mould cast and die-cast Al-Si-Cu-Mg-Sc alloys exhibit the cyclic strain hardening. However, at the lowest total strain amplitude, the cyclic strain hardening occurs in the initial and middle stages of fatigue deformation and the stable cyclic stress response is noted in the later stage of fatigue deformation for the permanent-mould cast alloy, while the cyclic strain hardening phenomenon is observed during whole fatigue deformation for the die-cast alloy. At the same total strain amplitude, the die-cast alloy shows the higher cyclic deformation resistance than the permanent-mold cast alloy. Compared with the permanent-mold cast alloy, the die-cast alloy possesses the longer fatigue life at the lower total strain amplitudes. The relationship between both elastic and plastic strain amplitudes with reversals to failure shows a monotonic linear behavior for both permanent-mold cast and die-cast Al-Si-Cu-Mg-Sc alloys

Abstract: The high pressure die casting (HPDC) process of an ADC12 aluminum alloy auto part is researched by the software ProCAST and FLOW-3D, respectively. The possible HPDC defects of the auto part are analyzed. The difference of the filling process with the same technological parameter is studied. Compared with the simulation result of ProCAST, FLOW-3D software simulation result is closer to the die casting of the actual production.

Abstract: Ther BP neural net model which is a branch of artificial neural net theory was adopted to analyse the problem of aircraft LY12CZ structure corrosion fatigue life considering the effect of stress level and corrosion environment,and Newton interpolation algorithm was used to increase the quantity and enhance the quality of BP net model training data. The application result show that the BP net model can simulate the value and development trend of corrosion fatigue life with higher precision contrast to the traditional method of exponential function fitting.