A356 Aluminum Research Articles

Studies of A356 Aluminum Alloy for Sand Mould Casting Gating System

The present study focus on tackling the casting defect of aluminium A356 alloy, this alloys have very good casting and machining characteristics, which dominantly affects the part produced by identifying the major defects caused by existing gating system. The major objective of this study is to minimize casting defect of spare part manufactured in textile Share Company by using Pro CAST software. This study is conducted in Bahirdar textile foundry workshop, the casting parameters which highly contributes to the soundness casting are identified with basic metallurgical and foundry properties of aluminium A356 alloy. The development of gating system for aluminium alloy is done by following American foundry society standard for getting reliable results. The optimization of Ingate and riser of gating system is carried out by Taguchi Method. The analysis result reports the shrinkage (macro) porosities and hot spot defects under existing gating system practised in the factory. After identifying the porosity defect; results of analysis process are iterated to get the optimum results, porosity found to be minimized for various gating system parameters. From simulation result; it is found that the best suited gating system parameter for aluminium A356 alloy sand casting is tapered sprue in decreasing initiation of defect from scratch. Finally, it is recommended that the company should implement the optimized processes parameters in addition to taking remedial action on the influential factors of the casting process.

Penambahan sr pada aluminium paduan a356 dengan metode lost foam casting (lfc)

The casting process and cooling rate determine the morphology of the authentic silicon particles produced in aluminum alloys. The slow cooling rate of aluminum alloy through the Lost Foam Casting (LFC) method a result of low mechanical properties. The purpose of this study was the effect of added Strontium (Sr) modifier to aluminum A356 on the microstructure and mechanical properties of the LFC method. The Aluminum A356 alloys are melted using a crucible and poured at a temperature of 730 oC on the surface of the polystyrene pattern which has been coated with refractory materials. The addition of the Strontium modifier was studied for its effect on changes in microstructure and mechanical properties (hardness, impact strength, and tensile strength). The results of this study indicate a change in the authentic silicon particles from an acicular to a filamentous form. The value of hardness, maximum tensile strength, and impact strength on the castings increased after the addition of Sr modifier to aluminum alloy A356.

Effects of cryogenic deformation on the microstructure and mechanical properties of high-strength aluminum alloys

7A85 aluminum alloy forgings were compressed at 10% to 30% deformation at room and cryogenic temperatures, followed by solid-solution treatment, water quenching, 3% cold deformation, and two-stage aging. The results indicated that cryogenic deformation increased coarse second-phase particle fragmentation and led to massive dislocation proliferation, which facilitated particle dissolution due to the formation of more interfaces and dislocation-promoted dissolution. These increased the driving force for aging precipitation and produced denser matrix precipitates and narrower grain boundary precipitate-free zones. Meanwhile, numerous dislocations provided more nucleation sites for recrystallization and thus refined grains during solution treatment. The grains were refined from 500 μm in the undeformed state to an average size of 35 μm under 20% cryogenic deformation. The excessive dislocation energy and stored deformation energy at 30% deformation caused recrystallized grain growth. The optimal mechanical properties were obtained at 20% cryogenic deformation with an ultimate tensile strength, yield strength, and elongation of 499 MPa, 435 MPa, and 13.1%, which were respectively 1.6%, 2.1%, and 37.9% higher than those of the undeformed sample. • Uniformly fine equiaxed grains and the best elongation were obtained at 20% cryogenic deformation. • Excessive dislocation energy and stored deformation energy at 30% deformation led to recrystallized grain growth. • Increasing the deformation and decreasing the temperature resulted in denser matrix precipitates. • Increasing the deformation and decreasing the temperature resulted in narrower grain boundary PFZs.

Microstructure and mechanical properties of 2A12 aluminum alloy welded joint through CMT double side welding

In this work, the cold metal transfer (CMT) double side welding was carried out to weld 2A12 aluminum alloy plate. The influence of the heat input on the weld appearance was studied, which indicated that when the heat input was exceeded to 651.75 J/mm the better weld appearance was obtained. Through the scanning electron microscope (SEM), electron back-scatter diffraction (EBSD) and tensile testing, the microstructure and mechanical properties of welded joints were investigated. The results showed that the size of microstructure in the front weld seam was less than that of the back weld seam due to the secondary thermal cycle. With the increases of heat input, the average grain size and elongation of welded joints were increased, the tensile strength of welded joints was reduced. The strength coefficient of welded joint was about 70%. The fracture model of welded joint belonged to ductile fracture.

Impact strength and structural refinement of A380 aluminum alloy produced through gas-induced semi-solid process and Sr addition

Semi-solid processing of A380 aluminum alloy was performed by gas induced semi-solid (GISS) process. The effects of argon inert gas flow rate, starting temperature and duration of gas purging as key GISS parameters and also modification with Sr on the structural refinements, hardness and impact strength of GISS alloys were investigated. Microstructural evolution shows that there is an important effect of the pouring temperature and Sr addition on the morphology and size of primary α(A1) in the alloy to change from coarse dendritic to fine globular structure. The best sample which has fine grains of 51.18 μm in average size and a high level of globularity of 0.89 is achieved from a GISS processing of Sr modified alloy in which the gas purging started at 610 °C. The impact strength of the GISS optimized samples ((4.67±0.18) J/cm2) shows an increase of about 40% with respect to the as-cast sample due to the globular structure and fibrous Si morphology. Moreover, the hardness of the optimized GISS sample ((89.34±2.85) HB) increases to (93.84±3.14) HB by modification with the Sr and GISS process. The fracture surface of Sr modified alloy is also dominated by complex topography showing typical ductile fracture features.

Investigation of the effect of the addition of grain refiner and modifier addition on wear properties in sand and permanent mould casting of A357 and A380 aluminium alloys

ABSTRACT The aim of this study is to improve the tribological behaviour of aluminium alloys by using grain refiner and modifier. The effects of Al5Ti1B grain refiner and Al10Sr modifier additives on friction and wear properties on A380, A357 alloys produced by pouring sand andpermanent mould casting were investigated. Abrasion tests were carried out under dry conditions against St1040 steel disc using a pin-disk system with 20 N load and 1.0 m/s sliding speed. It was determined that grain refiner and modifier additives decrease the friction coefficient and increase the wear resistance. It was determined that the samples produced by permanent mould casting method decreased the friction resistance by 9% and the abrasion resistance increased by 40% compared to the samples produced in sand mould. The lowest wear rate was obtained in A380 alloy with TiB and Sr added with a value of 4.87 × 10–11 m2/N.

Effect of hot isostatic pressing on fatigue behavior and fracture mechanism of A319 aluminum alloy under uniaxial and nonproportional multiaxial loading conditions

AbstractThe effect of hot isostatic pressing (HIPing)‐induced porosity difference on the fatigue behavior and fracture mechanism of A319 aluminum alloy under uniaxial and nonproportional multiaxial loading is investigated. Non‐HIPed alloy exhibits weaker nonproportional additional hardening capacity than HIPed alloy, which is ascribed to the nonproportional multiaxial loads that enhance the cyclic softening induced by casting pores. Additional plastic damage caused by nonproportional multiaxial loads is highly susceptible to HIPing. Torsional loads trigger the tension‐compression asymmetry of the axial stress response during nonproportional multiaxial fatigue. Multiaxial fatigue life is more sensitive to HIPing at minor total strain amplitudes. The rapid bridging among adjacent pores serves as the preferred channel for fatigue crack propagation. Nonproportional multiaxial loads improve the probability of encountering pores during fatigue crack initiation and propagation.

Multi-step hydroforming process and wall thickness optimization of 5A02 aluminum alloy five-way tube with different branch diameters

The different branch diameters of five-way tube affect the design of loading internal pressure in the hydroforming process, where the large-diameter branch is broken more easily than the small-diameter one due to the same ultimate stress of tube material in one-step forming method. Therefore, the first four-way and then five-way of multi-step forming (FFTF) method and the first three-way and then five-way of multi-step forming (FTTF) method were proposed to fabricate the 5A02 aluminum alloy five-way tube with two kinds of branch diameters to avoid the burst of large-diameter branch tube. The finite element simulation of five-way tube hydroforming process shows that the height of small-diameter branch tube is lower and serious wrinkles appear at the large-diameter branch tube in the one-step forming and FFTF method. By optimizing the length of punch, a five-way tube with a big branch height and uniform wall thickness was obtained with the FTTF method. The approach of lengthening the punch in the experiment increased the height of formed branch and reduced the wall thickness reduction rate of five-way tube in FTTF method. Overall, the findings mentioned above cannot only offer guide in creating five-way tube with excellent quality, but also be taken as reference to the hydroforming studies on multi-way tube in the future.

Obtaining Uniform High-Strength and Ductility of 2A12 Aluminum Alloy Cabin Components via Predeformation and Annular Channel Angular Extrusion

A 2A12 aluminum alloy component with uniform high-strength and ductility was developed via predeformation (one-pass repetitive upsetting extrusion) and annular channel angular extrusion (ACAE). Moreover, the microstructure evolution and age-hardening behavior were investigated. The results show that the upsetting-extrusion predeformation improved the cumulative strain of the component and refined the grain size, and that the second Al–Cu–Mg phases were obviously broken and refined, and that, especially, the distribution of the second phases along the extrusion direction was weakened. Thus, compared with directly ACAE-formed components, after the T6 heat treatment, the axial ultimate tensile strength (UTS) of the cabin increased from 476 to 484 MPa, and the elongation (EL) increased from 12.9% to 17.5%. The circumferential UTS increased from 426 to 482 MPa, and the EL increased from 9.24% to 16.8%. A large number of dislocations were introduced into the upsetting extrusion (UE) + ACAE method, which resulted in strain hardening and higher precipitation strengthening in the late artificial aging process. The finer and denser grains and s precipitates significantly enhanced the strength and ensured the good ductility of the alloy. It is suggested that the combination of predeformation and annular channel angular extrusion is an effective method for forming aluminum alloy cabin components with higher and more uniform mechanical properties.

Characterization of Refining the Morphology of Al–Fe–Si in A380 Aluminum Alloy due to Ca Addition

Aluminum–silicon (Al–Si) alloys are the most commonly cast aluminum alloys. Fe is the most deleterious element for Al–Si die casting alloys, as its existence causes the precipitation of substantial intermetallics that result in the unsatisfactory mechanical performance of the alloy, such as its ductility. Hence, controlling the morphology and formation of the AlFeSi phase, particularly the β-AlFeSi phase, is vital for improving the ductility of Al–Si die casting alloys. Herein, Ca was added to the A380 alloy, and the morphological changes resulting from the influence of Ca on the AlFeSi phase were characterized. The outcomes revealed that according to different cooling rates, specific amounts of Ca addition (0.01–0.1 wt.%) were capable of refining α-AlFeSi and β-AlFeSi morphology and transforming the β-AlFeSi phase into α-AlFeSi. Moreover, Ca addition could also modify eutectic silicon. The transformation mechanism and refining role of Ca in AlFeSi and the different morphologies of Al2CaSi2 were analyzed.

Tribological Study on Effect of Chill Casting on Aluminium A356 Reinforced with Hematite Paticulated Composites

Tribological Study on Effect of Chill Casting on Aluminium A356 Reinforced with Hematite Paticulated Composites

New HPDC Mg-RE based alloy with exceptional strength and creep resistance at elevated temperature

We have successfully prepared a new high pressure die-casting (HPDC) Mg-RE based alloy possessing excellent heat resistance. The alloy exhibits a tensile strength of 229 MPa at 200 °C, the highest tensile strength among HPDC Mg alloys reported so far, even competing with A380 aluminum alloy. Moreover, it has a minimum creep rate of 1.76 × 10−10 s−1 which is one order of magnitude smaller than the well-known HPDC AE44 alloy at 200 °C/70 MPa. Such superior elevated temperature strength and creep resistance are associated with fine-grained structure, co-segregation of Y and Zn atoms as well as coherent long period stacking ordered (LPSO) phase with networking distribution. This newly developed alloy gives a promising outlook for HPDC Mg alloys in automotive powertrain components.

Corrosion behavior of A6061 aluminum alloy in cation containing aqueous medium

Corrosion behavior of A6061 aluminum alloy in cation containing simulated aqueous medium was investigated by surface analysis techniques and electrochemical tests. The mass of specimens was increased after the immersion tests, and a smaller mass change was observed in the Zn2+ containing solution. Electron microscopic images showed the deposited products on the specimen that were Al-hydroxide confirmed by X-ray photoelectron spectroscopy. Zn-layer was formed on the specimen immersed in Zn2+ containing solution, and corrosion inhibition of Al resulted in a smaller number of Al products deposited on the alloy surface. Electrochemical results showed higher impedance in the Zn2+ containing solution due to the formation of the Zn related layer on the surface with oxide film.

Static recovery of A5083 aluminum alloy after a small deformation through various measuring approaches

Static recovery was confirmed to be the dominant softening mechanism during annealing for the studied A5083 aluminum alloy. The kinetics of static recovery, described based on the activation parameters (activation energy and volume of static recovery) and the static softening fraction, were mainly studied through two thermomechanical tests, namely, double-pass compression and stress relaxation tests. A new approach was proposed to measure the static softening fraction in the stress relaxation test. In general, a higher temperature or strain rate accelerates static recovery, while interestingly, the effect of pre-strain on static recovery is opposite in cases with and without external stress, owing to the enhanced static recovery by external stress during annealing. In addition, microhardness tests and electron backscatter diffraction (EBSD) characterization were also conducted to verify the accuracy of the results. The grain average misorientation approach based on EBSD characterization was confirmed to be effective in distinguishing and quantifying static recovery. It is noteworthy that the special stress hardening phenomenon occurring at 400 °C and 0.1/s is caused by strain aging, showing the complexity of the material behaviors after deformation of the studied aluminum alloy.

Environmental Damage Behavior of 2A12 Aluminum Alloy under Coupling Action of Marine Atmospheric Environment and Tensile-Compressive Load

The coupling test of marine atmospheric environment and tensile-compressive fatigue load for 2A12 aluminum alloy was carried out in outdoor environment of Hainan station by coupling test equipment of mechanical load. The coupling effect of marine atmospheric environment corrosion and tensile-compressive fatigue load on the environmental damage behavior of 2A12 aluminum alloy was discussed from the aspects of corrosion morphology, tensile properties and fracture morphology. The results show that the corrosion characteristics of 2A12 aluminum alloy in coupling test and static exposure test are consistent. The corrosion depths of the static exposure test for 6 months and the coupling test for 35 days are 71 μm and 121 μm, respectively. The results of tensile properties show that the decrease rate of tensile properties of 2A12 aluminum alloy are accelerated by the coupling effect. And the accelerated ratio of the coupling test was more than 10 times that of the static exposure test. The fracture morphology shows that the coupling fracture crack of 2A12 aluminum alloy starts from the corrosion surface, and the crack source and propagation zone are quasi-cleavage fatigue crack propagation characteristics. The coupling test results are closer to the actual situation of equipment, which has important reference value for the design and material selection of bearing structure.

Artificial neural network approach for mechanical properties prediction of as-cast A380 aluminum alloy

In this study, the dataset of as-cast A380 aluminum alloy involving chemical composition, processing parameter and mechanical properties was experimentally established. On this basis, the relationship between four input variables of Fe/Mn ratio, Sr content, cooling rate and porosity content, and two outputs of ultimate tensile strength (UTS) and elongation (El) was linked by two artificial neural network (ANN) models for comparison: (1) back propagation - artificial neural network (BP-ANN) model, and (2) back propagation optimized by particle swarm optimization - artificial neural network (PSO-BP-ANN) model. The results showed that the established PSO-BP-ANN model has better reliability and prediction accuracy than BP-ANN model, for lower root mean square errors (RMSE), 6.19 MPa for UTS and 0.08% for El, and higher determination coefficient (R2), 0.9775 for UTS and 0.9798 for El, respectively. Sensitivity level analysis result by the preferable PSO-BP-ANN prediction model showed that the order of relative importance for UTS is Sr content, cooling rate, Fe/Mn ratio, and porosity content while the importance ranking for El is Sr content, Fe/Mn ratio, cooling rate, and porosity content. The research results and dataset in this work lay a foundation for the control of casting performance in industrial practice and for secondary development of mechanical properties prediction module in commercial casting software.

Microstructure and Wear Characteristics of Multilayer Laser-Cladded Hypereutectic Al-Si Alloys

In this study, a multilayer laser-cladding method was used to increase the Si content in a hypereutectic Al-Si alloy laser cladding. One-, two-, and three-layer claddings were produced by printing Si powder paste on A1050 aluminum surfaces using 180-, 210-, and 250-㎛-thick plastic tape, respectively, and then irradiating laser pulses over them. The two- and three-layer claddings were produced by printing on the one- and two-layer cladding surfaces, respectively. The one-layer cladding had a thickness of approximately 190 ㎛ and was uniform and defectless. The cladding had a chemical composition of Al-20.2 wt.% Si and had a fine eutectic Al-Si microstructure in most regions. By contrast, the two-layer cladding had a thickness of approximately 250 ㎛ and exhibited many pores and some cracks. The cladding had a chemical composition of Al-60.5 wt.% Si and a hypereutectic Al-Si microstructure with many coarse primary Si particles. Finally, the three-layer cladding had a thickness of approximately 280 ㎛ and exhibited many large pores and a few large cracks. The cladding had a chemical composition of Al-72.6 wt.% Si and a hypereutectic Al-Si microstructure with very coarse primary Si particles. Block-on-roll wear tests were then performed on the claddings. The weight losses in the one-, two-, and three-layer claddings following the wear test were 5.5, 7.7, and 8.3 mg, respectively.

Metadynamic recrystallization in A5083 aluminum alloy with homogenized and as-extruded initial microstructures

The static softening behavior of A5083 aluminum alloy with different initial microstructures was studied using various characterization techniques. To calculate the recrystallized fraction, in the compression test, a new method based on the offset yield stress method and the Hall–Petch relationship was proposed, which is more accurate than the conventional methods and applicable even when the initial microstructure is complex. And in the stress relaxation test, a method proposed in our previous study was applied, indicating that this method could be employed in materials with incomplete recrystallization or a complex initial microstructure. Although the as-extruded initial microstructure led to a more developed metadynamic recrystallization, the recrystallization became heterogeneous, compared with the homogenized initial microstructure. When the anvil was not unloaded during the interpass time, the resulting external stress accelerated static recovery but impeded metadynamic recrystallization. New insights were discussed that challenge the conventional view in metadynamic recrystallization. First, metadynamic recrystallization always required an incubation time, unless the experimental conditions were sufficiently favorable for recrystallization. Second, when recovery was active, not only the dynamic recrystallized grains but also the recovery-enhanced subgrains were the potential nuclei for the subsequent metadynamic recrystallization.

Significant reinforcement of mechanical properties in laser welding aluminum alloy with carbon nanotubes added

Laser welding 2A12 (Chinese grade) aluminum alloy with carbon nanotubes (CNTs) added was carried out, and the mechanism of CNTs strengthening joints was explored in detail. Firstly, to achieve the same penetration depth, single laser welding and laser welding with CNTs require speeds of 40 mm/s and 60 mm/s respectively. The addition of CNTs increases the welding efficiency by 50%. Furthermore, the maximum tensile strength of the joint with CNTs increased by 45.5% to 326 MPa. Fracture analysis showed that the significant improvement in the mechanical properties of the joint was partly due to the CNTs reducing the pore size by an order of magnitude. Then, phase analysis reveals that a large number of precipitated phases increase the dislocation density and provide a basis for dislocation strengthening. The failure mode of CNTs is pulled out and the HRTEM test found that the CNTs are dispersed in the aluminum matrix. Indicating that the CNTs in the weld are tightly bonded to the surrounding Al matrix and load transfer from the matrix to CNTs is improved. This work provided an idea of laser welding aluminum with high efficiency and significantly enhanced mechanical properties. Finally, the process window for laser welding 2A12 aluminum alloy has also been established.

Local electrically assisted necking and thickening technology for 5A02 aluminum alloy tube

Local electrically assisted necking and thickening technology for 5A02 aluminum alloy tube