Die-cast Aluminum Alloy Research Articles

Aluminum alloy foam core sandwich panels fabricated from die casting aluminum alloy by friction stir welding route

An aluminum foam sandwiches (AFSs) consisting of ADC12 Al–Si–Cu die casting aluminum alloy foam and ADC6 Al–Mg die casting aluminum alloy face plates were fabricated. Using ADC12 die casting plates containing large amounts of gases as the starting material of the foam, ADC12 foam can be fabricated without using a blowing agent. Using FSW, both the uniform dispersion of the segregated gases and pore stabilization powder in the ADC12 die casting plates used to fabricate a foamable ADC12 precursor and the bonding of the ADC12 precursor to the ADC6 plates can be simultaneously achieved. Namely, the AFS precursor is expected to be obtained in fewer processing steps. From the visual observation of the fabricated AFSs, no deformation of the ADC6 plates occurred and the ADC6 plates on both sides of the aluminum foam remained parallel. From the X-ray CT observation of the fabricated AFSs, good pore structures without the infiltration of ADC12 foam into the ADC6 plates can be obtained at a holding temperature of 948K and holding times of t=10 and 11min. In tensile tests on the fabricated AFSs, fracture occurred in the ADC12 foam parts but no fractures were observed at the bonding interface between the ADC12 foam and the ADC6 plates, that is, good bonding was obtained between the ADC12 foam and the ADC6 plates.

GS01 塩水中引張応力下におけるAl合金ダイカストの腐食特性

Effect of tensile stress on the corrosion potential of high pressure die cast aluminum alloy was examined by the tensile test in a corrosive environment with the electrochemical measurement. The aluminum alloy has an oxide film as a corrosion barrier, but the oxide film may partially break by the mechanical stress and the damage leads to a local corrosion such as pitting corrosion by the effect of local cell. To qualitatively evaluate the strength of corrosion fatigue or stress corrosion cracking, the effect of stress on the electrochemical property has to be clarified. The spontaneous potential difference was measured by the three-electrode system during the tensile test, and the relationship between the spontaneous potential and the tensile stress was evaluated. The results showed that the spontaneous potential certainly decreased within the elastic region and saturated after the yielding. The effect of casting skin was also examined, and the spontaneous potential decreased due to the deletion of the casting skin.

Influence of Tool Shape on Friction Stir Welded Joint of Aluminum and Steel with Circular Weld Line

For the weight reduction of drive train in automotive, it is necessary to fabricate circular weld of die casting aluminum alloy and carbon steel with high welding efficiency. In this study, friction stir welding of ADC12 and S45C with circular weld line was evaluated, and the effect of welding tool shape was investigated for improving the weldability. The welding tool with flat shoulder was possible to fabricate the weld of ADC12 and S45C with a thin reaction layer with less than 1 μm. However, the mechanical strength of the weld was lower than that of ADC12. This is attributed to the microstructure of weld interface. Thus, material flow during FSW was enhanced by using a welding tool with a screw probe and a scroll shoulder. The fabricated weld by the welding tool achieved high weld strength equivalent to ADC12. In this weld, uniform and thin reaction layer about 50nm was formed on the weld interface.

Fatigue Limit Prediction of Large Scale Cast Aluminum Alloy A356

Casting defects such as gas pores and shrinkages typically occur during casting process. These casting defects affect fatigue crack initiation and strongly dominate fatigue strength. Particularly, in a large scale component, the molten metal flow is complicated and the cooling rate is dependent on the locations, which affect the formation of casting defects. In the present study, rotating bending fatigue tests of cast aluminum alloy A356 were conducted using the specimens sampled at three locations of a large scale component where the cooling rates were different. The fatigue limit was predicted based on the statistics of casting defect size and compared with the experimental results. Fractographic analyses revealed fatigue crack initiated from casting defect in all specimens. Murakami et al. suggested the method for predicting the fatigue limit of steel using the extreme value statistics of inclusion size (Murakami et al., 1989). Ueno et al. modified Murakami's equation and proposed the equations to predict the fatigue limit of die-cast aluminum alloy based on the defect size (Ueno et al., 2012). The present authors suggest the modified evaluation method of defect size considering the combination of the neighboring defects which exist near to each other. The predictions agree well with the experimental results but they are slightly different, which indicates the other metallurgical factors affect fatigue strength.

Research on the microstructure, fatigue and corrosion behavior of permanent mold and die cast aluminum alloy

Permanent mold (PM) and high pressure die cast (HPDC) AlMg5Si2Mn are employed to investigate the microstructure, fatigue strength and corrosion resistance. Results indicated that the mechanical properties (Rm, R0.2 and δ) of HPDC specimens (314MPa, 189MPa and 7.3%) are significantly better than those of PM specimens (160MPa, 111MPa and 2.5%) due to the finer grain size and less cast defects. Fatigue cracks of PM samples dominantly initiated from shrinkage pores and obscure fatigue striations are observed in crack growth region. Corrosion and pitting potentials of PM and HPDC AlMg5Si2Mn alloy are around −1250mV, −760mV and −1220mV, −690mV respectively. Numerous pits are observed around the grain boundaries because the corrosion potential of Mg2Si is more anodic than that of α-Al matrix. In addition, the superior corrosion resistance of HPDC samples can be attributed to the fine grain size and the high boundary density which improved the formation of oxide layer on the surface and prevented further corrosion.

On the Scatter of the Fatigue Limit of a Die-Cast Magnesium Alloy

In the present study, scatter behavior of fatigue limit for the die-cast magnesium alloy AM60B was investigated. Twelve fatigue limits were determined based on S-N curves obtained according to the standard fatigue test methods (that is based on the 0-2 or 0-1-2 combinations). The scatter of fatigue limit for the die-cast material was large where the values of Weibull modulus and COV were 16 and 6.8, respectively. This value of COV was in agreement with that obtained by simulated staircase method. The scatter of fatigue limit in the die-cast magnesium alloy was comparable to those in the die-cast aluminum alloy. In the die-cast materials, the fatigue limit determined based on S-N curve should be taken into account to have 6-10% of scatter from the mean value.

Numerical Simulation of the Car Oil Pump Support Die Casting

In this paper, the die-casting processing of aluminum alloy was simulated by casting simulation software. The mould filling and solidification process of aluminum alloy die-casting in different cast temperature and shot velocity were investigated. Aiming at achieving the best casting process, this research gave emphasis on analysis the influence of cast temperature and shot velocity to the process of mould filling, temperature field of casting part during filling and solidification, shrinkage and porosity. To improve the process, increase ingate area, carry on the simulation, and analyze the optimal casting parameters.

Development of a 3D Filling Model of Low-Pressure Die-Cast Aluminum Alloy Wheels

A two-phase computational fluid dynamics model of the low-pressure die-cast process for the production of A356 aluminum alloy wheels has been developed to predict the flow conditions during die filling. The filling model represents a 36-deg section of a production wheel, and was developed within the commercial finite-volume package, ANSYS CFX, assuming isothermal conditions. To fully understand the behavior of the free surface, a novel technique was developed to approximate the vent resistances as they impact on the development of a backpressure within the die cavity. The filling model was first validated against experimental data, and then was used to investigate the effects of venting conditions and pressure curves during die filling. It was found that vent resistance and vent location strongly affected die filling time, free surface topography, and air entrainment for a given pressure fill-curve. With regard to the pressure curve, the model revealed a strong relation between the pressure curve and the flow behavior in the hub, which is an area prone to defect formation.

Validation of temperature modified Dirlik method

The paper presents the validation of a temperature modified Dirlik method. This method enables an estimation of high cycle fatigue damage for uniaxial loadings caused by random vibrations directly from a known power spectral analysis with the temperature effect. High cycle fatigue properties of high pressure die-cast aluminium alloy AlSi9Cu3 are investigated at elevated temperatures. Standard fatigue tests are performed to determine the temperature dependent S–N curves. In the next step special fatigue tests are developed and performed to validate the temperature modified Dirlik method. Finally, the numerical simulation results are compared with the experimental results. The temperature modified Dirlik method is tested successfully. Besides, it enables a computationally fast fatigue damage estimation of random stress loadings and temperature histories.

New Expression Method for Tear Toughness of Cast and Die-cast Aluminum Alloys

New Expression Method for Tear Toughness of Cast and Die-cast Aluminum Alloys

Development of a super ductile diecast Al–Mg–Si alloy

The super ductile diecast aluminium alloys have been developed particularly for application in automotive body structure. On the basis of the reviewing aluminium alloys currently available, the requirement of diecast aluminium alloys is summarized and the Al-Mg-Si system is focused in the development. The effect of various alloying elements on the microstructure and the mechanical properties, such as yield strength, ultimate tensile strength and elongation is assessed. The optimized composition of the super ductile Al–Mg–Si alloy has been found to be at 5.0–5.5wt% Mg, 1.5–2.0wt% Si, 0.5–0.7wt% Mn, 0.15–0.2wt% Ti with Fe <0.25wt% for the best combination of strength and ductility, which shows 150MPa of yield strength, 300MPa of ultimate tensile strength, and 15% of elongation under as-cast condition. The paint baking hardenability of the optimized alloy is found to be insignificant. Less than a 10% increase in the yield strength was achieved, with a slight decrease in the elongation after aging at 180°C for 30min, which is a simulated process of paint baking. Cu is found to slightly increase the yield strength under the as-cast condition and after the heat treatment, but with a significant reduction in the ductility. Therefore, Cu should be limited in the super ductile aluminium alloy. The microstructure of diecast aluminium alloys at the optimized composition consists of the primary α-Al phase, the α-AlFeMnSi intermetallics and the Al–Mg2Si eutectics. There are two types of primary α-Al phase: dendritic or fragmented dendritic α-Al phase solidified in the shot sleeve and globular α-Al particles solidified in the die cavity. The α-AlFeMnSi intermetallics is in the form of compact morphology and with a size of less than 3μm. The eutectic cells are at size of 10μm with a typical lamellar morphology of α-Al phase and Mg2Si phase.

Effects of rare earth Er additions on microstructure development and mechanical properties of die-cast ADC12 aluminum alloy

The effects of rare earth erbium (Er) additions (0, 0.3, 0.6 and 0.9wt.%) on the microstructure development and tensile properties of die-cast ADC12 aluminum alloy have been investigated in the present work. The microstructures and fracture surfaces of die-cast samples were examined by optical microscopy and scanning electron microscopy (SEM). It was found that the secondary dendrite arm spacing (SDAS) will decrease with increasing Er content, as the Er content increases to 0.6%, the lowest SDAS was obtained. In addition, the Er modified the eutectic silicon from a coarse plate-like and acicular structure to a fine branched and fibrous one. The microhardness of die-casted alloys were measured, the microhardness corresponding to the die-casted samples with 0, 0.3, 0.6 and 0.9wt.% Er additions are 100.6, 107.1, 113.6 and 108.5Hv, respectively. The tensile properties were improved by the addition of Er, and a good ultimate tensile strength (269MPa) but poor elongation (2%) were obtained when the Er addition was 0.6wt.%. Furthermore, fractographic examinations revealed that refined pore and spheroidized α-Al dendrite were responsible for the high ultimate tensile strength.

Numerical Simulation of Die Casting for Semi-Solid Aluminum Alloy and its Mould Research

Design and manufacture an aluminum alloy semi-solid die-casting. Simulate the process of rheological semi-solid aluminum alloy die-casting, and verification it by casting experiment. The result is that, the heating system of the semi-solid die-casting mold play an important role in the process of forming, and the size of gate has great impact on the quality of casting.

Structure of Water Mist Stream and its Impact on Cooling Efficiency of Casting Die

Structure of Water Mist Stream and its Impact on Cooling Efficiency of Casting Die The work is a continuation of research on the use water mist cooling in order to increase efficiency of die-casting aluminum alloys. The paper presents results of research and analysis process, spraying water and generated a stream of water mist, the effect of the type of nozzle, the nozzle size and shape of the emitting of the water mist on the wall surface of casting die on the microstructure and geometry of water mist stream and cooling efficiency. Tests were used to perform high-speed camera to record video in the visible and infrared camera. Results were used to develop a computerized image analysis and statistical analysis. The study showed that there are statistical relationships between water and air flow and geometry of the nozzle and nozzle emitting a stream of microstructure parameters of water mist and heat the incoming stream. These relationships are described mathematical models that allow you to control the generating of adequate stream of water mist and a further consequence, the cooling efficiency of casting die.

Endurance in Al Alloy Melts and Wear Resistance of Titanium Matrix Composite Shot-Sleeve for Aluminum Alloy Die-casting

Endurance in Al Alloy Melts and Wear Resistance of Titanium Matrix Composite Shot-Sleeve for Aluminum Alloy Die-casting

Scatter analysis of fatigue life and pore size data of die-cast AM60B magnesium alloy

Scatter behavior of fatigue life in a die-cast AM60B magnesium alloy was investigated. For comparison, those in a rolled AM60B alloy and a die-cast A365-T5 aluminum alloy were also studied. Scatter behavior of pore size was also investigated to discuss about dominant factors for fatigue life scatter in the die-cast materials. Three-parameter Weibull function was suitable to explain the scatter behavior of both fatigue life and pore size. The scatter of fatigue life in the die-cast AM60B alloy was almost comparable to that in the die-cast A365-T5 alloy, while it was significantly large compared to that in the rolled AM60B alloy. Scatter behavior of pore size observed on the specimen cross-section was comparable to that of fatigue life. Therefore, the scatter behavior of fatigue life can be estimated, if the scatter behavior of pore size on the cross section of specimen would be evaluated, as proposed in the present study.

Influence of Aging Temperatures and Times on Mechanical Properties of Vacuum High Pressure Die Cast Aluminum Alloy A356

In this study a number of thermal treatment schemes over a wide range of temperatures between 120˚ to 350˚ C and times (30 120 minutes) have been experimented in an effort to understand the effect of thermal treatment on tensile properties of vacuum die cast modified aluminum alloy A356. The results show that, the morphology of eutectic silicon has a sound effect on the tensile properties of the tested alloy. The content of magnesium-based intermetallic phases, their morphology and distribution throughout the matrix affect the mechanical properties of the aged alloy as well. The reduction in the strengths of the alloy treated at 350°C for two hours should be at least attributed partly to the absence of the magnesium-based intermetallic phase. However the presence of sufficient amount of magnesium intermetallic phase had played important role in strengthening the alloy thermally treated at 200°C for 90 minutes.

Effects of Porosity and Pore Structure on Compression Properties of Blowing-Agent-Free Aluminum Foams Fabricated from Aluminum Alloy Die Castings

Aluminum foam was fabricated without the use of a blowing agent by a friction stir processing route using ADC12 aluminum alloy die castings, which contain a large number of gas pores. In this study, ADC12 foams with a porosity of 50­77% were successfully fabricated, and the pore structures and compression properties of the obtained ADC12 foams were investigated. The ADC12 foams had smaller pores than commercially available aluminum foam. Moreover, the pore size of the ADC12 foams was almost the same regardless of the porosity. According to the results of compression tests, the plateau stress and energy absorption tend to decrease with increasing porosity. Commercially available aluminum foam exhibited higher energy absorption at a low compression stress, whereas the ADC12 foams exhibited higher energy absorption at a high compression stress. Also, the ADC12 foams with higher porosity exhibited higher energy absorption per unit mass, regardless of the compression stress. In contrast, the energy absorption per unit volume was greatest for the low-porosity ADC12 foam at a low compression stress but greatest for the high-porosity foam at a high compression stress. [doi:10.2320/matertrans.M2012125]

Influence of Aging Temperatures and Times on Mechanical Properties of Vacuum High Pressure Die Cast Aluminum Alloy A356

In this study a number of thermal treatment schemes over a wide range of temperatures between 120˚ to 350˚ C and times (30 120 minutes) have been experimented in an effort to understand the effect of thermal treatment on tensile properties of vacuum die cast modified aluminum alloy A356. The results show that, the morphology of eutectic silicon has a sound effect on the tensile properties of the tested alloy. The content of magnesium-based intermetallic phases, their morphology and distribution throughout the matrix affect the mechanical properties of the aged alloy as well. The reduction in the strengths of the alloy treated at 350°C for two hours should be at least attributed partly to the absence of the magnesium-based intermetallic phase. However the presence of sufficient amount of magnesium intermetallic phase had played important role in strengthening the alloy thermally treated at 200°C for 90 minutes.

Material properties of long term naturally aged die cast Al–Si–Cu alloys

Die cast aluminium alloys, including automotive parts, are generally understood to suffer some degradation of their mechanical properties over time due to corrosion, specifically when exposed to water and sea breeze (salt air). However, in this study, it is shown that in the absence of a corrosive environment, the mechanical properties of die cast aluminium alloys actually increase over a 10 year period due to natural aging. The increment in the mechanical properties is mainly attributed to precipitation hardening brought about by θ″ phase particles. It also appears that any significant change in microstructure affects the mechanical properties, e.g. the change of the needle-like eutectic Si to a spherical form and the joining of discrete α-Al phases to make larger grains. The driving force for the microstructural changes upon natural aging is related to the residual stress in the die cast sample accumulated by high casting pressure and rapid cooling rate during injection process.