Die-cast Aluminum Alloy Research Articles

High strength and ductility aluminium alloy processed by high pressure die casting

A high strength (Yield strength ≥ 320 MPa) and high ductility (Tensile elongation ≥ 10%) die–cast aluminium alloy was first developed. The AlSiCuMgMn alloy processed by high pressure die casting can provide the high yield strength of 321 MPa, the high ultimate tensile strength of 425 MPa and the high ductility of 11.3%, after solution treated at 510 °C for 30 min and aged at 170 °C for 12 h. The alloy demonstrated 150% increase in ductility over the reported most advanced die–cast aluminium alloy, also comparable tensile properties to the 6000 series wrought aluminium alloys but with much lower manufacturing cost. The as–cast microstructure of the alloy mainly contained the primary α1–Al phase solidified in the shot sleeve, the secondary α2–Al phase solidified in the die, the Al–Si eutectic phase and the intermetallic phases Q–Al5Cu2Mg8Si6 and θ–Al2Cu. The intermetallic phases Q and θ were dissolved into the α–Al matrix during solution. Nanoscale precipitates Q′ and θ′ were precipitated from the α–Al matrix for the strengthening of the alloy through ageing treatment. Multiple effects resulted in the high ductility of the alloy.

Study of the solubility of die-cast steels in silumin AK12 (AL2)

The results of the research of solubility of die-cast steels in silumin AK12 (AL2), depending on the chemical composition, method of refining, thermal and chemical-thermal treatment. Perspective marks of steels for the manufacturing molds pressure die-casting aluminum alloys are established. The expediency of application for the press-tools of cast alloys, ni-triding and methods of arc-plasmous and electroslag remelting on the example of steel DI – 22 is shown.

Experimental and boundary element method study on the effect of stress on the polarization curve of cast aluminum alloy in sodium chloride solution

The effect of stress on the polarization curve of high pressure die cast aluminum alloy in sodium chloride solution was evaluated by mechano-electrochemical experiments and boundary element electrostatics simulations. The polarization curve was measured under a constant stress condition, and a decrease in natural potential due to stress was observed. A periodic arrangement of intact and damage surfaces was assumed in the mechanically damaged oxide film, and the polarization curve of the damage surface was identified. The simulation results showed that the decrease in natural potential is explained by the nucleation of the damage surface by plastic strain.

Dissimilar friction stir lap welding of magnesium to aluminum using plasma electrolytic oxidation interlayer

Joining the die-cast non-combustible magnesium alloy AMX602 to the die-cast aluminum alloy ADC12 via friction stir lap welding (FSLW) was investigated. The aluminum alloy on the top can more easily form a sound dissimilar joint than that on the bottom. Strong dissimilar joints were achieved after the magnesium alloy was subjected to a plasma electrolytic oxidation treatment. After the welding process, the plasma electrolytic oxidation interlayer was stirred and flowed into the aluminum alloy side. The growth of the intermetallic compound was restrained by the plasma electrolytic oxidation interlayer by reducing the reaction time of the magnesium alloy and aluminum alloy.

Improved degassing in laser beam welding of aluminum die casting by an electromagnetic field

An electromagnetic system was used to reduce the porosity in laser beam welding of aluminum die casting. The difference of electrical conductivities between gases and molten aluminum is used by an electromagnetic system to displace the included gases to the top during a laser beam welding process. It bases on generating Lorentz forces within the weld pool via an oscillating magnetic field. A partial penetration laser beam welding of standard die-cast aluminum alloy AC-AlSi9MnMg in flat position is used. An optimized laser beam process was taken to investigate the porosity content and the surface smoothing by applying an electromagnetic field. The produced weld seams were analyzed in cross section views, by x-ray imaging and by computer tomography (CT). Depending on the magnetic flux density, a significantly reduction of the porosity down to 75% can be achieved. Especially big pores can be removed successfully. A surface smoothing of up to 75% can also be reached by using this system.

Application of a Force Model Adapted for the Precise Turning of Various Metallic Materials

The knowledge of cutting forces is critical. They might affect the load of the machine and, in the case of fine turning, the deformation of thin and slim workpieces. The generated forces depend not only on material properties (hardness, tensile strength) and on cutting parameters, but also on the tool edge geometry, that strongly determines the geometry of the chip (thickness and width). This article deals with the application of a force model adapted for precise turning technology. Three different types of materials widely used in mass production were taken into consideration (C45 and KO36 steel types and AS12 die-cast aluminium alloy). The components of cutting force were measured in three directions (Fc , Ff , Fp ) and the specific cutting forces were calculated. The main values of specific cutting forces were introduced for precision turning (k1, 0.1); using this, a new force model was constructed based on the theoretical parameters of the non-deformed chip cross-section (heq is equivalent chip thickness and leff effective length of the edge of the tool) in case of all three examined materials. Investigations revealed that the influence of leff on specific cutting force components is not negligible; however, it has the least effect on kc and is the most influential in case of kp. The errors of the constructed new force models follow Gaussian distribution with low values of standard deviation. Thereby, the models can be applied to estimate cutting force components during the technological process planning procedure with adequate accuracy.

Effect of Artificial Ageing on the Defect Susceptibility of Tensile Properties to Porosity Variation in A356 Aluminium Alloys

The present study aims to estimate the dependence of the tensile properties on microporosity variation in low-pressure die-cast A356 aluminium alloys with respect to various T6 treatment conditions and to investigate the relative contribution of the strain-hardening exponent and damage evolution of eutectic Si particles in terms of the defect susceptibility of the tensile properties to effective void area fraction. The solution treatment was performed for 3, 6 and 12 h at 540 °C, and the artificial ageing was conducted for 4, 16 and 48 h at 140–180 °C. The defect susceptibility of the tensile properties to microporosity variation depends practically upon the ageing time, whereas the solutionising time has a minor effect on the variability in the defect susceptibility. Additionally, the maximum value of the ultimate tensile strength (UTS) achievable in a defect-free condition remarkably increases with the ageing treatment, and it also slightly increases with the solutionising time. The maximum value of the tensile elongation for a defect-free condition depends practically upon the solutionising time, even though it generally decreases with ageing treatment. The main reason that the UTS and elongation exhibit different responses with regard to the solutionising and ageing treatments is the variation in the strain-hardening exponents associated with the T6 treatment. The frequency of the damage evolution of eutectic Si particles by the cracking mode is considerably decreased with the ageing treatment, and this transition under ageing treatment has additional contributions to the variation in the defect susceptibility of tensile properties to effective void area fraction.

Effect of Si, Cu and processing parameters on Al-Si-Cu HPDC castings

Chemical composition of secondary Al-Si-Cu alloys and working variables of high-pressure die casting process (HPDC) may change for the same casting parts from one country to another in the world. They can even sometimes vary from one manufacturing site to another within the same country. An experimental study on the influence of alloying elements contents (Si and Cu), casting temperature and injection pressure on mechanical properties of die cast aluminum alloys was carried out to support the automotive industry suppliers in designing their cast parts. The microstructural features and the porosity level were also investigated and assessed. The primary objective is to highlight the modification mechanisms of the achieved properties using tensile tests, hardness measurements and microstructural observations performed on a HPDC casting parts. Low pressure and low temperature increase the rate of porosity, promote the formation of coarse Fe-rich intermetallic compounds and change the morphology of α-Al phases. These in turn deteriorate mechanical tensile properties. However, variation of alloying elements contents modifies the optimum properties achieved when part is made at constant casting processing parameters. Finally, the interactions between the studied parameters of HPDC and the chemical alloying elements show also a significant influence on the tensile properties.

Ductile fracture of an Al-Si-Mg die-casting aluminum alloy

Abstract The anisotropic plastic flow and ductile fracture of Al-Si-Mg die-cast aluminum alloy (trade name, Aural2) is investigated using a combination of experiments and analysis. The material is in the form of a 2 mm thick sheet and was received in the –T7 temper. The plasticity of the material is probed using uniaxial tension and plane-strain tension experiments at 3 angles to the material direction, and disc-compression experiments. Good repeatability is obtained in every case. These experiments are used to calibrate the Yld2004-18p anisotropic yield function. This function is flexible enough so that very good fitting of the experiments is obtained. The ductile fracture of the alloy is then probed using notched-tension (with 6 mm and 20 mm notch radii) and central-hole experiments. Each of these specimens is designed so that it provides a different stress triaxiality in the region of rupture, while still requiring only a universal testing machine. Digital Image Correlation is used throughout the experimental work to assess the surface strain fields. However, since the sheet is relatively thick, rupture did not necessarily initiate at the surface. For this reason, fully-3D finite element simulations, using the Yld2004-18p yield function and 3 post-necking hardening models (Swift, Voce and combined) are performed. The surface strains predicted by the simulations depend strongly on the material model adopted. Hence the predicted fracture strains reported here underscore the fact that the plasticity of the material needs to be carefully established before any fracture study is undertaken.

Effect of heat treatment on gravity die-cast Sc-A356 aluminium alloy

The effects of scandium addition (0.00 wt.%, 0.2 wt.%, 0.4 wt.% and 0.6 wt.%) and T6 heat treatment on the microstructure and mechanical properties of A356 aluminium alloy have been investigated in the research reported in this paper. The Sc inoculated specimens were prepared by gravity die-casting, according to ASTM B557-06 standard. The cast samples were then subjected to heat treatment at solutionizing temperature of 540 °C for 8 h followed by water quenching and artificial aging at 160 °C for 6 h. The microstructure, microhardness and tensile strength of the heat-treated samples were examined with use of scanning electron microscope (SEM), optical microscope, Vicker’s hardness tester, and Instron static machine respectively. Heat treatment was found to be able to effectively reduce grain size down to 16 μm (0.6 wt.% Sc), from 40 μm (original A356). The tensile strength was significantly improved, up to 338 MPa for heat treated 0.6 wt.% Sc-A356 having been achieved. The microhardness of 118 HV has been obtained for heat treated 0.6 wt.%Sc-A356.

Effects of microstructure and casting defects on the fatigue behavior of the high-pressure die-cast AlSi9Cu3(Fe) alloy

High-pressure die-cast (HPDC) components are being increasingly used due to good flexibility and high productivity. These aspects make HPDC suitable to produce several mass components, especially for the automotive sector. Due to the rapid filling of the die and high cooling rate, the process generally leads to the formation of a wide variety of defects, such as porosity and oxide films. Such defects might act as starting points for fatigue cracks and thus deteriorating the fatigue behavior of the casting. To this respect, the fatigue behavior of die cast aluminum alloys is an important aspect to consider when assessing the performance of complex castings for automotive applications. In the light of these aspects, the goal of this work is to describe how the microstructure affects the fatigue crack initiation and propagation. Die cast AlSi9Cu3(Fe) specimens were produced by means of a specifically designed die and the microstructure was preliminary characterized. Uniaxial fatigue tests were performed at load control with a stress ratio of R = 0.1 and at a single level of stress amplitude. After the fatigue tests, the samples were investigated to assess the propagation of the fatigue cracks; the starting points of cracks were specifically identified and the obtained data suggested how defects strongly influence the damage mechanism of the material.

Simultaneous Effect of Plunger Motion Profile, Pressure, and Temperature on the Quality of High-Pressure Die-Cast Aluminum Alloys

High-pressure die casting has been used widely to manufacture a large variety of products with high dimensional accuracy and productivity. Although this process has a considerably lower cycle time than the other metal forming processes, it is not yet optimized, due to the complexity of the process and the number of parameters to be controlled. Hence, the identification of the parameters affecting quality of castings is the current challenge toward efficient and effective production. In their previous work, the authors proposed and validated some novel kinematic parameters of the plunger, which explain and forecast both the static mechanical properties and the internal quality of castings. The present work extends such an approach by including two other meaningful parameters, which describe the effect of upset pressure and temperature on the final outcome. These parameters are here formulated and have been validated by means of a statistically significant sample manufactured with different plunger motion profiles, upset pressures, and temperatures of the melt and die. The quality of the castings was assessed through static mechanical properties and density measurements. As further proof, internal defects were analyzed on the fracture surfaces of some meaningful castings.

Effects of casting and heat treatment processes on the thermal conductivity of an Al-Si-Cu-Fe-Zn alloy

In this study, the effects of casting processes and heat treatments on the thermal conductivity of an Al-10wt% Si-0.6wt% Cu-0.9wt% Fe-0.7wt% Zn aluminum alloy were studied. Both gravity- and die-casting processes were used. The porosity in die castings was controlled by varying the injection pressure and plunger velocity. The porosity, microstructures, and thermal and electrical conductivities of the die castings were characterized. The thermal conductivity of gravity-cast material achieved 143.4Wm−1K−1, whereas those of die-cast materials ranged from 110.8 to 126.8 Wm−1K−1. The die-cast aluminum alloys demonstrated considerably finer interconnecting precipitates than did the gravity castings. The closely spaced precipitates acted as barriers for thermal conduction, leading to reduced thermal conductivity. Die-casting pressures and velocities were controlled to form die castings with up to 3.73% porosity, which led to a 12.6% decrease in thermal conductivity. The die-cast Al alloys were then subject to solutionization (T4) and aging treatments (T6). The silicon precipitates were spheroidized, thus widening the paths for heat conduction. The thermal conductivity was greatly enhanced, increasing from 126.8Wm−1K−1 in the die-cast condition to 151.6Wm−1K−1 after 550°C solutionizing and 4h of aging at 200°C. The thermal conductivity of the gravity-cast materials remained unchanged after the same heat treatments. Improving the thermal conductivity of die castings through proper heat treatments is crucial for aluminum alloys in rigorous heat-dissipating applications.

Study on the Composition and Properties of Salt Cores for Zinc Alloy Die Casting

Soluble salt cores have been successfully used for the die casting of aluminum and magnesium alloys. However, it has not been reported that the soluble salt cores were used for zinc alloy die casting. In this paper, a soluble salt core system of low melting salt A–potassium chloride-reinforcing particles was put forward for zinc alloy die casting in the sanitary industry. Reinforcing particles included layered material B, acicular material C and alpha-Al2O3 (α-Al2O3). The salt core system and the mixtures of salts and reinforcing particles were analyzed by scanning electron microscopy, differential thermal analysis, thermogravimetric analysis and X-ray diffraction. In addition, the “triplet” salt cores prepared by high pressure core-making were used for zinc alloy high pressure die casting (HPDC). “Triplet” articles were washed, dried, pretreated, electroplated and detected according to the die casting industry standards. The salt core system could be recycled and had no corrosion to casting articles. It was observed that the zinc alloy articles basically met the technical requirements of zinc alloy castings. In conclusion, the salt core system was suitable for a certain shape of zinc alloy castings by HPDC.

Recovery of Aluminum Alloy A380 from Machining Chips

Die casting aluminum alloy A380 were recoveredfrom high pressure die cast machining chipsunder a series of designed experiments using Taguchi Method, where flux types (FT), chips/flux ratio (CFR), holding times (Ht) and temperatures (HT) were selected as four factors. For each factor, three levels were chosen to create Taguchi orthogonal array. The recovery rate (Rr) was selected as a response to evaluate the effectiveness of the recovery process. An analysis of the mean of noise-to-signal (S/N) ratios indicates that the recovery rate is affected considerably by the levels in the Taguchi orthogonal array. The optimum combination leads to the highest recovery rate of 92.03% by using Al-clean 101 as the refining flux, 10:5 as the chips/flux ratio, 60 minutes and 760°Cas the holding time and holding temperature.

Plunger Kinematic Parameters Affecting Quality of High-Pressure Die-Cast Aluminum Alloys

The selection of the optimal process parameters in high-pressure die casting has been long recognized as a complex problem due to the involvement of a large number of interconnected variables. Among these variables, the effect of the plunger motion has been proved to play a prominent role, even if a thorough and exhaustive study is still missing in the literature. To overcome this gap, this work aims at identifying the most relevant plunger kinematic parameters and estimates their correlation with the casting quality, by means of a statistically significant sample manufactured with different plunger motion profiles. In particular, slow and fast shot velocities and switching position between two stages have been varied randomly in accordance with design of experiment methodology. The quality has been assessed through the static mechanical properties and porosity percentage. As a further proof, the percentage of oxides has been estimated on the fracture surfaces. These measurements have been correlated to novel parameters, representing the mechanical energy and the inertial force related to the plunger motion, that have been extracted from the time-history of the displacement curves. The application of statistical methods demonstrates that these novel parameters accurately explain and predict the overall quality of castings.

자동차 경량화를 위한 다이캐스팅용 알루미늄합금 브레이크 페달의 강도해석

Article history: In this study, a strength analysis was performed to assess die-cast aluminum alloy brake pedals as an improved alternative to wrought alloys. Aluminum brake pedal shapes are considered to be suitable for the die-casting process. The strength criterion of Volvo trucks was used as the criterion for the pedal strength. The results of this analysis showed that the frame thickness of the aluminum brake pedal must be increased from 12 mm to 18 mm to have a strength superior to that of a steel brake pedal. Additionally, the stress and weight of the aluminum brake pedal were found to be approximately 24% and 26% lower than those of the steel brake pedal, respectively. Mounting tests and strength assessments verified that the proposed die-cast aluminum alloy brake pedal demonstrated sufficient

Effect of chemical compositions on tensile behaviors of high pressure die-casting alloys Al-10Si-yCu-xMn-zFe

Effects of chemical compositions on the tensile properties, deformation behavior and fracture mechanism have been studied in a die-casting aluminum alloys Al-10Si-yCu-xMn-zFe. The test specimens were taken from the engine support brackets and tested at 20°C, 150°C and 300°C. Addition of Mn and Cu elements in the Al-10Si alloys can significantly increase the YS and UTS of the alloys. The as-cast Al-10Si-1.5Cu-0.8Mn-0.15Fe alloy exhibits the highest tensile properties (RT: YS of 190MPa and UTS of 308MPa, 150°C: YS of 176MPa and UTS of 249MPa, 300°C: YS of 94MPa and UTS of 111MPa). Increasing test temperature reduces the YS and UTS and improves the ductility of the alloys. Chemical compositions (such as Mn, Cu and Fe) do not significantly affect the work-hardening behavior of the alloys. Increasing test temperature significantly decreases the n and k values. Phase particles (both Si and (Fe/Mn)-rich) cracking and debonding determine the fracture mechanism of the alloys. Final failure of the alloys mainly depends on the global instability (HT, necking) and local instability (RT, shearing).

Identification of material properties using nanoindentation and surrogate modeling

In theory, identification of material properties of microscopic materials, such as thin film or single crystal, could be carried out with physical experimentation followed by simulation and optimization to fit the simulation result to the experimental data. However, the optimization with a number of finite element simulations tends to be computationally expensive. This paper proposes an identification methodology based on nanoindentation that aims at achieving a small number of finite element simulations. The methodology is based on the construction of a surrogate model using artificial neural-networks. A sampling scheme is proposed to improve the quality of the surrogate model. In addition, the differential evolution algorithm is applied to identify the material parameters that match the surrogate model with the experimental data. The proposed methodology is demonstrated with the nanoindentation of an aluminum matrix in a die cast aluminum alloy. The result indicates that the methodology has good computational efficiency and accuracy.

Thermal Fatigue of Die-Casting Dies: An Overview

Coupled studies by experimental and numerical simulations are necessary for an increased understanding of the material behaviour as related to the interaction between the thermal and mechanical conditions. This paper focus on the mechanisms of thermal fatigue in the failure of dies and cores used in the die casting of aluminum alloys. The thermal fatigue resistance is expressed by two crack parameters which are the average maximum crack and the average cracked area. Samples of various types of H13 steel were compared with a standard H13 steel by testing under identical thermal fatigue cycles. To determine the thermal constraint developed in the sample during the test, a finite difference technique was used to obtain the temperature distribution, based on temperature measurements at the boundaries. The resulting stresses and strains were computed, and the strain calculated at the edge or weakest point of the sample was used to correlate the number of cycles to crack initiation. As the strain at the edge increased, the number of cycles to failure decreased. The influence of various factors on thermal fatigue behavior was studied including austenitizing temperature, surface condition, stress relieving, casting, vacuum melting, and resulfurization. The thermal fatigue resistance improved as the austenitizing temperature increased from 1750 to 2050oF.