Properties Of A356 Alloy Research Articles

Effect of Ultrasonic-Assisted Modification Treatment on the Microstructure and Properties of A356 Alloy.

Ultrasonic treatment was applied to an A356 aluminum melt with different modifiers, and the effects of ultrasonic treatment on the structure and properties of the A356 alloy were studied. The results showed that α-Al was effectively refined with different ultrasonic modification treatments. In particular, ultrasonic treatment showed the most obvious refinement with macroscopic grains of unmodified alloy and optimized the refinement of secondary dendrite arm spacings in the Sr/Ce synergistic alloys. The eutectic Si of the unmodified A356 alloy had no obvious change after the ultrasonic treatment, but the branch diameter of the eutectic Si reduced in the Sr and Sr/Ce modification alloys after the ultrasonic treatment. The ultrasonic treatment significantly improved the ultimate tensile strength and elongation of the as-cast A356 alloy with the unmodified material, which was due to refinement of the α-Al grains by the ultrasonic treatment. After the T6 heat treatment, the ultimate tensile strength values of the alloys showed no obvious change due to the ultrasonic treatment, but the plasticity of the alloy was significantly improved. Mg2Si precipitation was the dominant strengthening mechanism during the T6 heat treatment, while the plasticity was determined by the size and distribution of the eutectic Si. Acoustic cavitation caused by the ultrasound-activated impurities and the induced heterogeneous nucleation and supercooled nucleation in the groove melt was the main cause of the α-Al refinement, the eutectic Si modification and the improvement in the mechanical properties.

Effect of Al–Nb–B2O3–CuO system reaction products on microstructure and wear resistance of A356 alloy

The aim of present work is study the effcet of Al-Nb-B2O3-CuO system reaction products on microstructure and properties of A356 alloy. B2O3 powder, Al powder, CuO powder and Nb powder were used as raw materials to form Al–Nb–B2O3–CuO reaction system, and A356 alloy was refined by in situ reaction and near-liquidus casting. The size, phase, morphology and distribution of in situ reaction products were observed and analysed by optical microscope, x-ray diffractometer, scanning electron microscope and transmission electron microscope. The products of the Al–Nb–B2O3–CuO reaction system are mainly Al3Nb, NbB2 and Al2O3. The ratio of the prefabricated block is 8:1:1:2 . When the prefabricated block was added at 2.5 wt%, the particle size of NbB2, Al3Nb and Al2O3 is 0.5–1 μm. The microstructure of A356 alloy is fine and uniform. The average grain size is refined to less than 20 μm. Compared with untreated A356 alloy, the wear rate is reduced from 2.091% to 0.882%, and the average hardness of the alloy is increased from 41.3HRC to 58.2HRC.

The Effect of Holding Time After Sr Addition on Microstructural and Mechanical Properties of A356 Alloy

The spheroidization of the silicon eutectic phase in aluminum is an important parameter for casting and significantly influences the material properties. Sr has been used for a long time for eutectic modification in aluminum and many researches have been made on this subject. In this study, the effect of holding time after Sr addition on the mechanical properties and eutectic phase modification of the aluminum were investigated. 200 ppm Sr was chosen as the amount of Sr and the holding times were chosen as 20, 40 and 80 minutes. Tensile test was performed for the determination of mechanical properties and ultimate tensile strength and percentage of elongation values were measured. In order to quantify eutectic modification, the length / width (aspect ratio) ratios of eutectic silicon particles were measured. In addition, Bifilm Index of the molten metal was determined with the reduced pressure test (RPT). With the increase in the holding time, an increase in the aspect ratio and in the Bifilm Index was measured. It has been observed that the tensile strength and elongation values have decreased as the holding time has increased.

Grain Refining Effect of Al-5Ti-1B Master Alloy on Microstructures and Mechanical Properties of A356 Alloy

In this study, the structures of Al-5Ti-1B master alloy and its influence on microstructures and mechanical properties of A356 alloy were investigated. The results show that Al-5Ti-1B master alloy consisted of the uniform distribution of lump-like TiB2 and network of TiAl3 on α-Al matrix. The addition of the Al-5Ti-1B master alloy can significantly reduce the grain size of A356 alloy. The mechanical properties of A356 alloy, i.e. ultimate tensile strength, yield strength and elongation were also improved. The use of Al-5Ti-1B master alloy as a grain refiner in the casting process of A356 alloy can effectively enhance the grain refinement and thus improve the mechanical performance of A356 alloy.

Effects of Al-Ti-B-Sr Master Alloy on the Microstructure and Mechanical Properties of A356 Alloy

A356 alloy was refined with a new master alloy of Al-5Ti-B-10Sr. The microstructure and mechanical properties of the refined A356 alloy with different content of master alloy (0, 0.1, 0.3, 0.5 and 0.7 wt.%) were investigated. The results show that the refining effect becomes stronger as the master alloy content increasing from 0.1 to 0.3 wt.%, and then shows slight decrement until 0.7 wt.%. An optimal combination of the tensile strength (193 MPa) and the elongation (17.8%) of as-cast A356 alloy was achieved with 0.3 wt.% of refining master alloy. Compared to the non-modified A356 alloy, the tensile strength and the elongation were improved by 10% and 242%, respectively.

Effect of heat treatment on microstructures and mechanical properties of A356 alloy cast through rapid slurry formation (RSF) process

The effect of T5 heat treatment on microstructure and mechanical properties of A356 alloy was observed. The as-cast A356 alloy exhibited coarse dendrites and long Si needles. RSF process changed the dendritic α-Al phase to globular morphology which helps in improving the mechanical properties of the alloy. The addition of 0.6wt-% Al–5Ti–1B grain refiner refined the average grain size of primary α-Al phase. T5 heat treatment at 170 °C for 20 h in different processing conditions was given to A356 alloy. T5 heat treatment led to further refinement of α-Al phase and Si needles, precipitation hardening due to Mg2Si phase and reduction in the porosity level (%). The Quality Index for A356 alloy in different processing conditions was also measured. Results showed that RSF process with the use of baffles, addition of grain refiner and T5 heat treatment had improved the mechanical properties over other processing conditions.

Effect of TiN-Coated Al Powders on the Microstructure and Mechanical Properties of A356 Alloy

The core/shell nano-TiN-coated Al powders (TiN/Al) were prepared and added into A356 alloy by ultrasonic-assisted casting method in this work. The results show that TiN/Al has a better dispersion in A356 matrix and a stronger strengthening effect than TiN without the core/shell structure. With the addition of TiN/Al, most of the coarse primary α-Al dendrites of A356 turn into equiaxial. After T6 heat treatment, it is found that eutectic silicon in A356 with TiN/Al becomes columnar or globular in shape and smaller in size, which causes a greatly enhanced elongation of 11.7%. The results also suggest that the addition of nanoparticles can affect the precipitation behaviors and change the shapes and sizes of the precipitation.

The Effect of Scandium on the Mechanical Properties of A356 Aluminium Alloy

In this project, the addition of scandium (Sc) into A356 aluminium alloy was studied for its effect on the mechanical properties after gravity die casting process. Scandium addition was administered at the weight percentages of 0.1, 0.2 and 0.3. The results obtained in this work revealed that scandium can significantly enhance the mechanical properties of A356 alloy in terms of tensile strength, hardness and charpy impact strength. In general, the addition of 0.2 wt% Sc in A356 alloy was found to be able to achieve the maximum tensile strength of 172.94MPa as compared to 136.03MPa for sample without Sc. No significant improvement in tensile strength was found when more than 0.3wt% added to the alloy. As for hardness, the sample with 0.3 wt% Sc attained the maximum Vicker’s hardness of 86.60 HV as compared to 76.48 HV for unmodified A356. Similarly, the addition of 0.3wt% Sc in A356 can achieve highest impact energy of 2.71J as compare to 1.09J for unmodified A356.

Effects of Warm Laser Peening on Thermal Stability and High Temperature Mechanical Properties of A356 Alloy

To study the effects of warm laser peening (WLP) on the thermal stability and mechanical properties of A356 alloy, the samples were treated by WLP using a Nd:YAG solid-state laser and temperature control device. The residual stress, micro-hardness and microstructures of samples treated by WLP were observed. The result shows that the temperature significantly affects the strengthening effect of laser peening (LP). The residual stress induced by WLP decreases with the increasing temperature. The micro-hardness and dislocation density increase first, and then decrease with the increases of temperature. The grain refinement degree of the samples treated by WLP is much higher than that of LP. In addition, after aging for 100 min at 220 °C, the samples treated by LP and WLP were comparatively investigated in thermal stability. Obviously, the residual compressive stress, micro-hardness and microstructure induced by WLP present a better thermal stability property than that of LP. The residual stress and micro-hardness of WLP samples are obviously improved, and the increasing degrees are 23.31% and 19.70%, respectively. The dislocation density remains at a high level, while the grains are still in fine crystalline state.

Effect of the Spinning Deformation Processing on Microstructure and Mechanical Properties of A356 Wheels

The influences of spinning deformation and heat treatment on microstructure and tensile properties of A356 alloy at different cooling rates were investigated in this study by optical and scanning electron microscopes. The results indicated that spinning deformation enhanced the tensile properties of the alloy due to the reduction of Si size and porosity percentage, especially in the samples with coarse microstructure. Heat treatment increased the strength while decreased the ductility of the alloy because of the precipitation of brittle Mg2Si in Al matrix. It is suggested that the spinning deformation processing is an effective technique to produce A356 alloy wheels with high mechanical properties.

The effects of scandium on A356 aluminium alloy in gravity die casting

In this project, the addition of scandium into A356 aluminium alloy was studied for its effect on the mechanical properties as well as the changes in microstructure and eutectic morphology after casting process. Scandium addition was administered at the weight percentages of 0·2, 0·4 and 0·6. The results obtained in this work revealed that scandium can significantly enhance the mechanical properties of A356 alloy in terms of hardness and tensile strength. In general, the addition of 0·4 wt-% scandium in A356 alloy was found to be able to achieve the maximum tensile strength of 119·48 MPa as compared to 91·36 MPa for sample without scandium. Similarly, the sample with 0·4 wt-% scandium attained the maximum hardness of 20·36 HRA as compared to 17·32 HRA for unmodified A356. The mechanism that renders the enhancement in mechanical properties can be attributed to grain refinement. In SEM micrographs of samples with scandium, grain refinement can be observed in the microstructure and the morphology of eutectic structure. The eutectic morphology was also converted into a finer and fibrous structure.

Influence of Stirring Time and Holding Time on Microstructure and Properties of the A356 Alloy Modified by Sc

Effects of the holding time and the stirring time on the microstructure and mechanical properties of A356 alloy modified by Sc are researched. According to the test results, most of the eutectic silicon phases have changed to the shape of creeping point, dispersed in the grain boundary of α (Al) phase while stirring 1 minute, in which case both the tensile strength and elongation reach the highest, resulting in the best modification effect. The results also indicate that microstructure and mechanical properties of the alloy reach are the best modification effect when the melt is held 15 minute. It can be known that the optimal stirring time is 1 minute and the optimal holding time is 15 minute in the experiment condition of the work.

Effects of sample thickness on microstructures and mechanical properties of A357 alloy

The effects of sample thickness on the density, microstructures and mechanical properties of as cast Al alloy were investigated. Microstructures were observed with a scanning electron microscope. Mechanical properties were studied at room temperature. The results show that the sample thickness has minor influence on the relative density of Al alloy. The obtained relative density up to ∼99·24% was confirmed that the vacuum counter–pressure casting has the excellent solidification mechanism. The microstructures were refined and the secondary dendrite arm spacing was decreased with the decrease in sample thickness, and the ultimate tensile strength, yield strength and elongation were improved. The ultimate tensile strength and elongation could be related to their secondary dendrite arm spacing using linear equations. With the increase in sample thickness, the quasi-cleavage fractures were increased and the number of dimples got an evident reduction in fracture surfaces.

Correlation of Mechanical Properties of Cast Al 3xx Alloys to Processing Variables and Alloy Chemistry Using Regression Analysis and Artificial Neural Network Techniques

The mechanical properties of aluminium alloy castings, such as EL%, YS and UTS, are controlled by the casting and heat treatment variables, alloy’s composition, and melt treatment. Despite the abundance of literature data, the large number of the controlling parameters has made it difficult to predict and model the mechanical properties by the conventional techniques. Another obstacle encountered when making such a prediction is the complex kinetics and interactions that exist among the many variables. The goal of this study was to develop Artificial Neural Network (ANN) and Multiple Regression models to predict the mechanical properties of A356 alloy from the processing variables. Several standard nonlinear regression and multi-layer ANN models were developed and trained using data from the literature and experimental results. Due to the complexity of A356’s solidification behaviour, the nonlinear regression produced results that were not as accurate as those produced by the ANN model. The results indicate that ANN is a suitable technique for predicting mechanical properties from alloy chemistry and processing variables.

Influence of Solution Temperature and Time on Microstructure and Properties of A357 Alloy

Metallographic analysis, hardness testing and diffusion kinetics analysis were used to investigate the influences of temperature and time on morphology of eutectic Si and properties of A357 alloy under the solution heat treatment, and optimal solution parameters were determined. The results indicate that solution heat temperature strongly influences the morphology of eutectic Si and mechanical properties of the A357 casting alloys. Spheroidization degree of eutectic Si decreases and the mechanical properties of A357 alloy with the increasing of solution temperature. According to the experiment results, optimal solution parameters of A357 alloy were determined as 550°C×6h.

Study on the Reinforcement of Aluminum Alloy A356 Using SiC Particles by Mechanical Stirring

This paper is to research the manufacturing process of A356 alloy matrix composites reinforced by SiC particles by mechanical stirring and how the size of particles ,volume fraction affect mechanical property has been studied , too. The text results revealed that larger particles especially particle size larger than 30um were suitable using this technique, meanwhile, it will hard to adding particles into the alloy when particle lower than 20um size. The effects of SiC particle addition on the hardness properties of A356 alloy and with higher volume fraction particles lead to greater hardness.

Effect of trace Ce addition on the microstructures and mechanical properties of A356 (AL–7SI–0.35 Mg) aluminum alloys

A356 hypoeutectic alloy is a heat-treatable Al–Si–Mg system with a normal composition of Al–7 wt.% Si and about 0.35 wt.% Mg which has seen widespread applications in the aerospace and automotive industries. The purpose of this study is to determine the influence of different amounts of Ce on the microstructures and mechanical properties of A356 alloys. The findings indicate that modification efficiency in microstructures and mechanical properties of A356 alloy are greatly enhanced by adding 1.0 wt.% Ce. Two kinds of intermetallic compounds are found in the study, including Ce–23Al–22Si and Al–17Ce–12Ti–2Si–2 Mg (in wt.%) phases. Moreover, though the ductility of the Ce modified alloys are both greatly improved, there is no positive effect on the ultimate tensile strength that can be attributed to the formation of an Al–17Ce–12Ti–2Si–2 Mg phase. Furthermore, the results of thermal analysis reveal that there is no direct relationship between eutectic growth temperature and silicon morphology/modification rating.

Influence of Ti, B and Sr on tribological properties of A356 alloy

The wear behaviour of an A356 alloy has been investigated in this paper. To understand the wear behaviour of the materials, the experiments were carried out using a pin on disc testing machine at various combinations of normal pressure, sliding speed and sliding distances. Tribological results reveal that weight loss of A356 alloy increases with increasing normal pressure and decreases with increasing sliding speed. Also, the results at microlevel revealed a structural change from coarse columnar dendrites to fine equiaxed ones on the addition of grain refiner (Al and B) and furthermore, plate-like eutectic silicon to fine particles on addition of modifier (Sr). It is further noted in the present study that addition of modifier does not disturb the influence of grain refiner and vice versa. Abrasive wear mechanism was interrupted by the formation of microwelds and later by oxidation of the Al matrix.

Effects of Spinning on Microstructure and Mechanical Properties of A356 Alloy

The tube-shaped parts of A356 alloy were deformed from 0% to 83% by spinning process. The microstructure and mechanical properties of A356 alloy were discussed. The results showed that as the wall thickness reduction increases, the dendrite cells of cast alloy are lengthened gradually and the average Secondary Dendrite Arm Spacing (SDAS) is reduced from 37.2μm to 23μm and eutectic silicon particles are distributed orderly along the spinning direction. The coarse acicular β-Al5FeSi is broken into many sections, and its length is reduced from 37.5μm to 12.5μm in the cross-section. The tensile strength and elongation exhibit a strong dependence upon the variation in wall thickness, with a parabolic relationship. The tensile fractured surface of parts with deformation ratio above 35% exhibits many equiaxial dimples, with intergranular ductile fracture mode.

The Effect of Ultrasonic Injection on the Microstructure and Mechanical Properties of A356 Alloy

A356 alloy is one of the wide used casting aluminum alloys and intense research activities of worldwide on casting process or refinement agent and procedure. In this study, we attempted refinement on Al primary phase and eutectic phase of A356 alloy by ultrasonic injection into the melts. The effect of ultrasonic injection into the melts could be summarized as follows: the morphology of the Al primary phase was refined and changed shape from dendritic to nondendritic and the eutectic phase of A356 was also refined and changed morphology from dendritic to plate shape.