A356 Alloy Research Articles

Effect of Stroke Length on the Abrasive Wear Characteristics of A-356 (0–10 wt%) SiCp Composite in Reciprocating Sliding Conditions

In this study, abrasive wear behavior of A356/(0–10)wt.% SiCp composites are reported using an in house designed and developed pin-on-reciprocating plate abrasive wear and friction test rig confirming to ASTM G133-05 standards. A356 alloy and A356/10 wt.% SiCp composite are prepared through stir casting method adopting standard foundry practices. The hardness of heat treated A356/10 wt.% SiCp composite is found to be 22.56% higher than A356 alloy. This study primarily focused on the effect of variation of stroke length from 65 mm to 100 mm on the abrasive wear characteristics of A356 alloy and it’s composite at different loads (5, 7.5, 10, and 12.5 N) by keeping a constant sliding velocity of 0.2 m/s slid through 25 m. The abrasive wear is found to be higher for the alloy than the composite. It is also revealed from the experimental investigation that as the stroke length is reduced from 100 mm to 65 mm, the abrasive wear loss of A356 alloy and its composites are found to increase. The reason for increase in wear is attributed to high frequency of oscillation and less energy dissipation per cycle at lower stroke length (65 mm) compared to that at higher stroke length (100 mm). Coefficient of friction (CoF) of tribo pairs tested is found to increase with load at the two different stroke lengths studied.

Correlating microstructural features with improved wear and corrosion resistance of laser surface remelted A356 alloy at different scanning speeds

In this work, two scanning speeds (2 mm/s and 8 mm/s) were employed to remelt the surface of an A356 cast Al alloy by a pulsed laser at 300 W, with microstructural features of the laser-remelted surface layers well characterized and correlated with their wear/corrosion resistance. Through high-quality microstructure characterizations, it is found that the as-received A356 alloy is comprised of coarse α-Al dendrites and interdendritic AlSi eutectics. After laser surface remelting (LSR) at both speeds, microstructure homogeneity is greatly improved due to the remarkable refinement of the dendrites and interdendrites. Hardness and wear tests show that surface hardness and wear rate of the 2 mm/s specimen are 71.6 ± 0.6 HV and 1.1 × 10−3 mm3·N−1·m−1, while those of the 8 mm/s specimen are 67.2 ± 1.1 HV and 1.7 × 10−3 mm3·N−1·m−1, respectively, markedly improved compared to the substrate (55.3 ± 0.5 HV and 2.8 × 10−3 mm3·N−1·m−1). Electrochemical test results reveal that self-corrosion potential (Ecorr) and current (Icorr) of the 2 mm/s specimen are −0.82 V and 9.5 × 10−7 μA, while those of the 8 mm/s specimen are −0.89 V and 1.8 × 10−6 μA, respectively. After comparing with the substrate (−0.95 V and 4.3 × 10−6 μA), the corrosion resistance of both the LSRed specimens is confirmed to be significantly enhanced. Comprehensive analyses reveal that after the LSR the simultaneously increased wear/corrosion resistance can be related to the largely homogenized microstructure, the enhanced supersaturation of Si in α-Al, and the refinement and redistribution of AlSi eutectics in the remelted layer.

Mechanical Properties of Refined A356 Alloy in Response to Continuous Rheological Extruded Al-5Ti-0.6C-1.0Ce Alloy Prepared at Different Temperatures

The microstructure is an important factor determining the mechanical properties of A356 alloy. In this experiment, the refiner Al-5Ti-0.6C-1.0Ce master alloys under different preparation temperatures were prepared, and the A356 alloy was refined. The effects of preparation temperature on the number and morphological distribution of each phase in Al-Ti-C-Ce master alloy and the effects of Al-Ti-C-Ce master alloy at different preparation temperatures on the microstructure and mechanical properties of A356 alloy were explored successively. Results showed that, as preparation temperature increased from 850 to 1150 °C, TiAl3 changed from large blocks to long strips and a needle-like phase, and Ti2Al20Ce changed from a bright white block to a broken small block phase. Al-5Ti-0.6C-1.0Ce prepared at 1050 °C can significantly refine the α-Al of A356 alloy and modify eutectic Si. The α-Al grain size was refined from about 1540 to 179.7 μm, and the eutectic Si length was refined from about 22.3 to 17.8 μm with the transition from a coarse needle-like to a short rod-like structure. The ultimate tensile strength and elongation of A356 alloy changed non-monotonically, and the peak values were 282.216 MPa and 3.9% with the Al-Ti-C-Ce preparation temperature of 1050 °C and 950 °C, respectively.

Study of Hot Plastic Deformation in an A356 alloy.

Study of Hot Plastic Deformation in an A356 alloy.

Microstructural Evolutions and Strengthening Mechanism according to the Aging Temperatures of a High Si Cast Aluminum Alloy

A356 cast aluminum alloy contains 7 at.% Si and 0.3 at.% Mg, producing an approximately 50% eutectic microstructure. This high Si content and various casting conditions play a significant role in strengthening A356 alloy, by controlling the eutectic morphology and precipitates of other intermetallic compounds. Understanding how Si-related precipitates and clusters are soluble in the α-matrix is necessary to provide high strength and fatigue resistance to A356 alloys. The aging heat-treatment temperature in the A356 alloy most likely promotes the formation of these precipitates and clusters. The A356 samples were differently aged at temperatures of 110 oC and 130 oC for 2 h, and were labeled 110A, and 130A, respectively. 110A was found to have improved mechanical properties, such as high strength and elongation, compared to 130A, which may be attributed to the formation of secondary phases in the α-phase matrix. Scanning and transmission electron microscopy and atom probe tomography analyses demonstrated Ti2Si precipitation and various-sized cluster formations in 110A. In contrast, 130A had fewer clusters than 110A. Therefore, different aging heat-treatment temperatures relate to a change in the behavior of atoms, affecting the mechanical properties.

Investigation on Microstructure, Hardness, Wear behavior and Fracture Surface Analysis of Strontium (Sr) and Calcium (Ca) Content A357 Modified Alloy by Statistical Technique

The aluminum alloy are extensively used in several industrial applications. Stir casting is one of the most frequently accepted methods. In the present investigation, how the microstructure, mechanical and wear mechanics of A357 alloy were impacted by the presence of Sr/Ca was investigated. The outcomes revealed that addition of elements (Sr/Ca) enhance the microstructural features. Uniform dispersal of particulates (Sr/ Ca) in Al357 alloy and also the modified structure of silicon (Si) were observed. Hardness of modified alloy was evaluated by using hardness tester. A result reveals that hardness of modified alloy was improved by increasing in the Sr/Ca content. The wear rate of modified alloy was evaluated by using Pin and Disc wear test rig. Test trials were conducted according to Taguchi technique. L27 array was implemented for evaluation of data. The effect of varying parameters (factors) on wear loss and COF were analyzed using ANOVA (Analysis of Variance) method. ANOVA outcomes shown that, the Sr/Ca content has a better significant impact on wear behavior and COF of the modified alloy. A wear fractography result shows the internal fracture structure of a wornout surface which was studied by SEM analysis.

Processability of A6061 Aluminum Alloy Using Laser Powder Bed Fusion by In Situ Synthesis of Grain Refiners

Despite the increasing interest in laser powder bed fusion (LPBF), only a few cast aluminum alloys are available for this process. This study focuses on improving the LPBF processability of the A6061 alloy, which is challenging due to its wide solidification range, the dendritic columnar grain growth, and consequent solidification cracking. To address these issues, in situ-synthesized grain refiners can be used to induce equiaxial grain growth and prevent crack formation. A6061 RAM2 powder—a mixture of A6061, Ti, and B4C—was characterized and processed using a low-power LPBF machine to create an in situ particle-reinforced metal matrix composite. Parameter optimization was performed to evaluate the effect of their variation on the printability of the alloy. Microstructural characterization of the samples revealed that the complete reaction and the synthesis of the ceramic reinforcement did not occur. However, TiAl3 was synthesized during the process and promoted a partial grain refinement, leading to the formation of equiaxial grains and preventing the formation of solidification cracks. The tensile tests carried out on the optimized samples exhibit superior mechanical properties compared to those of A6061 processed through LPBF.

Effect of Zr content on microstructure and tensile properties of cast and T6 heat-treated A356-0.3Yb alloy

In this paper,the influence of different Zr addition amounts on the microstructure and tensile properties of A356 alloy modified by 0.3 wt%Yb in cast state and T6 heat-treated state were systematically investigated. The results show that adding Zr on the basis of 0.3 wt%Yb can further refine α-Al and eutectic Si branches. When the content of Zr is 0.25 wt%, α-Al has the smallest grain size of 133 μm, and the aspect ratio of eutectic Si is 1.6. However, the addition of excessive Zr will weaken the modified effect of Yb and make the eutectic Si start coarsening. The addition of Zr forms the (Al,Si)3(Zr,Ti) phase with Ti in the alloy, provides the heterogeneous nucleation base, increases the number of α-Al grains, and refines the α-Al matrix. After T6 heat treatment, the eutectic Si is further spheroidized and the aspect ratio decreases to 1.3. The tensile strength and elongation of A356 alloy with Yb and Zr under cast condition are 187.4 MPa and 5.6% respectively, which are 10.4% and 36.6% higher than those without Zr. The tensile strength and elongation of the alloy after T6 heat treatment are 296.3 MPa and 9.2% respectively, which are 8.2% and 27.7% higher than those of the alloy without Zr after the same heat treatment.

Elastoplastic Deformation of Rotating Disk Made of Aluminum Dispersion-Hardened Alloys

This paper studies the plastic deformation of a rotating disk made of aluminum dispersion-hardened alloys using mechanical tensile tests and a structured study using optical microscopy methods. Alloys such as AA5056 and A356 with dispersed Al3Er and TiB2 particles are used as the initial materials. Tensile strength testing of the obtained alloys shows that the addition of Al3Er particles in the AA5056 alloy composition leads to an increase in its ultimate stress limit (USL) and plasticity from 170 to 204 MPa and from 14.7 to 21%, respectively, although the modifying effect is not observed during crystallization. The addition of TiB2 particles to the A356 alloy composition also leads to a simultaneous increase in the yield strength, USL, and plasticity from 102 to 145 MPa, from 204 to 263 MPa, and from 2.3 to 2.8%, respectively. The study of the stress-strain state of the disk was carried out in the framework of deformed solid mechanics. The equilibrium equations were integrated analytically, taking into account the hardening conditions obtained from the experimental investigations. This made it possible to write the analytical relations for the radial and circumferential stresses and to determine the conditions of plastic deformation and loss of strength. The plastic resistance of a disk depends on the ratio between its outer and inner radii. The plastic resistance decreases with increasing disk width at a constant inner radius, which is associated with a stronger effect from the centrifugal force field. At a higher rotational rate of narrow disks, the tangential stresses are high and can exceed the USL value. A356 and A356–TiB2 alloys are more brittle than the AA5056 and AA5056–Al3Er alloys. In the case of wide rotating disks, AA5056 and AA5056–Al3Er alloys are preferable.

高純度アルミニウムおよびA6061アルミニウム合金におけるポアの成長挙動と水素脱離挙動

An increase in the volume fraction of pores in aluminum alloys causes a decrease in the elongation and the strength of alloys. To improve the mechanical properties of aluminum alloys, it is important to understand the growth and shrinkage behavior of pores. In this study, we analyzed the relationship between hydrogen desorption behavior and the growth/shrinking behavior of pores in A6061 alloys and pure aluminum using thermal desorption analysis and synchrotron radiation X-ray tomography. In pure aluminum, the fine pores began to annihilate at temperatures above 500°C and the relatively large pores coarsened. In contrast, the pores shrank with increasing temperature in A6061 alloy. The influence of second-phase particles has been discussed as a possible explanation for the difference in the nature of pores at elevated temperatures in pure aluminum and A6061 alloys. As in the A6061 alloy, much of the hydrogen desorbed from the pores due to heating is released externally from the second-phase particles on the aluminum surface, resulting in pore shrinkage due to the internal pressure drop of pores.

Effect of Rare Earth Elements Erbium and Europium Addition on Microstructure and Mechanical Properties of A356 (Al–7Si–0.3Mg) Alloy

Effect of Rare Earth Elements Erbium and Europium Addition on Microstructure and Mechanical Properties of A356 (Al–7Si–0.3Mg) Alloy

Fabrication, testing, and microstructural analysis of nitinol-based self-healing metal matrix composite of A356 alloy cast by semi-solid metal processing

ABSTRACT The self-healing of metallic material is a relatively new area in materials engineering. It is inspired by the biological process of healing. This work analyzes the self-healing behaviour of metals-matrix composite. The semi-solid metal processing technology was opted to prepare an aluminium-based self-healing metal-matrix composite. Nitinol is the alloy produced by combining nickel and titanium in a 1:1 ratio, with the wires of the same incorporated within the aluminium matrix during the process. Analysis of the recovery rate of the self-healing material and microstructural investigation of the metal matrix composite is the objective of this research work. The deployment of shape memory wire provides the ability to recover the matrix material even from plastic strain. Nitinol exhibits a shape memory effect by the transformation of the phase. Integration of A356 alloy with nitinol wire enables the material to regain its original shape and dimension by heat as an external stimulus. Semi-solid metal process via rapid slurry formation technique handled delicately so that self-healing effect should not diminish. Microstructural evaluation indicates fair integration of the reinforcement within the matrix material. Analysis of crack closure shows 44.277% positive recovery of the deformed surface.

Enhancing Fe content tolerance in A356 alloys for achieving low carbon footprint aluminum structure castings

Low carbon footprint aluminum structure castings are the mainstream development direction of aluminum alloys in the future. Enhancing the Fe content tolerance upper limit in casting aluminum alloys is considered an effective way to promote the application of recycled aluminum production. In this work, it was found that with the Ce and TiCN NPs (nanoparticles) addition simultaneously to A356 alloys, the acicular Fe-rich phases (β-Al5FeSi) which damages the properties can be changed into beneficial phases (core-shell heterostructures) for the alloy, and hence the mechanical properties of A356 alloys can be improved. The TiCN nanoparticles and rare element Ce play crucial roles in the formation of core-shell heterostructures. The formation mechanism of core-shell heterostructure was also systematically researched from the perspective of thermodynamics and kinetics. This study provides a simple and feasible strategy to eliminate the harmful effects of Fe impurity and contributes to the industrialization of low carbon footprint aluminum structure castings.

Investigation of Phase Transformation and Mechanical Properties of A356 Alloy with Cu and Zr Addition during Heat Treatment

Cast A356(Al-Si-Mg) alloys are widely used in automotive and general applications because of their mechanical properties and castability. Al-Si-Mg-(Cu) alloys typically lose their strength above 170 o C due to coarsening of precipitates, which limits their application to components. To maintain their strength at elevated temperature, Al-Si-Mg-(Cu) alloys are modified by adding transitional metals. Several studies have been carried out to evaluate the effect of Zr addition on the high temperature mechanical properties of cast Al-Si alloys because Zr can form thermally stable phases such as Al3Zr. Despite the relative studies on the influence of Cu and Zr on the mechanical properties of cast Al-Si-Mg-(Cu) alloys, investigations of the effect of Zr on the phase transformations and the mechanical properties during heat treatment remains limited. In this study, the effects of added Cu and Zr on the phase transformations and the mechanical performance during heat treatment of A356 cast alloy were investigated. Needle-like and block-like (Al,Si)3(Ti,Zr) dispersoids formed as some Si and Ti replaced Al and Zr in Al3Zr crystal structures were generally observed. Furthermore, with increasing solution treatment time, the size of Zr dispersoids was reduced, and smaller Zr particles were precipitated at the same time, which caused a decrease in the area fraction of the Zr dispersoids. In addition, the metastable L12 structures of Zr dispersoids in Al-Si-Mg-Cu-Zr alloys were transformed into stable D023 during solution heat treatment as the Cu addition accelerated the transformation. Tensile and low-cycle fatigue (LCF) tests were performed to reveal the effects of (Al,Si)3(Ti,Zr) dispersoids on mechanical properties. As a result, elongation at elevated temperature was highly increased, while maintaining strength, according to the increase in solution heat treatment time, which improved low-cycle fatigue properties.

A comprehensive study of A357 alloy printability via laser metal deposition

Laser metal deposition (LMD) is one of the most important techniques in additive manufacturing (AM) thanks to the high flexibility of the process, which makes the production of free-form shapes possible. However, working with some materials presents some challenges. This is the case with aluminum alloys due to their reflectivity and their very high thermal conductivity. On the other hand, aluminum and its alloys are quite important in several industrial fields, including aerospace, among others, due to their mechanical properties with low density. In this work, LMD is applied on an A357 aluminum alloy. The techniques are investigated moving from a single-track approach up to multi-pass and multi-layer strategies. Densities, microstructures and mechanical performance are investigated as a function of process parameters. Porosities are reduced, resulting in overall densities of over 97% and microhardness values are in the range of 80–100 HV. Differences in mechanical performance are analysed considering different building directions, showing a dependency on loading direction and the distance from the substrate. Tensile tests reveal a promising performance for further investigation with the LMD technique. The obtained evidence is interesting for future trends where large and light components are required while maintaining the mechanical performance of traditional manufacturing methods. Moreover, a comprehensive study is done for the first time on A357 alloy that is deeply used in the aerospace and automotive fields. The investigation and definition of the best process parameters open the possibility of exploiting LMD technology in the production of wide components or for adding features to already existing components overcoming some limits of other AM technologies.

Microstructure and wear characteristics of hybrid reinforced (ex-situ SiC–in-situ Mg2Si) Al matrix composites produced by vacuum infiltration method

Hybrid composite materials combine the advantages of two or more reinforcement materials and may contain unique physical, mechanical and tribological properties that cannot be achieved with any other materials. In this study; A356, A380, and A413 alloys were chosen as matrix materials. Prepared SiC preforms were employed as ex-situ reinforcing material, and AM50 magnesium alloy with 5%, 10% and 15% weight ratios were added to the liquid metal to produce hybrid composites via the vacuum infiltration process. The effects of the amount of added AM50 alloy on the microstructural and mechanical properties were investigated. The formation of primary Mg2Si, eutectic Mg2Si, Si eutectic, SiC particles and α-Al grains were observed in the microstructure. As the weight ratio of the added AM50 alloy increased, the hardness and wear resistance of the composite samples did not significantly improve. However, the wettability of the liquid aluminum to the SiC particles seemed to be improved by the addition of AM50 alloy, especially for A380 and A413 alloys. However, excessive Mg ratio increased the viscosity of the alloy in the liquid state and caused insufficient infiltration in the castings, especially for A413 alloy. The differentiations in the hardness and wear properties depending on the processing parameters are discussed in the paper.

Feasibility Study on the Fabricating of Carbon-Nanotube-Reinforced Al-Si-Cu Alloy Matrix Composites Using Oxygen-Replacing Die Casting Process

A383 Al-Si-Cu alloy matrix composites were reinforced with different amounts (0.5, 1.0, 1.5 and 2.0 wt%) of chopped multiwalled carbon nanotubes (MWCNTs) and fabricated using the oxygen-replacing die casting (ORDC) process to reduce gas porosities via the reaction of molten Al and O2 replaced in the mold cavity. MWCNTs were added to the mold cavity by supplying O2 and using a poly gate in the ORDC mold to improve CNT dispersity in the matrix of the composite. Microstructure studies of the composites showed a uniform CNT distribution within the matrix and grain refinement. X-ray computed tomography images showed that the internal porosities were affected by the CNT addition amount and gate type used in the mold, and Raman spectroscopy analysis indicated that CNTs in the matrix were free of significant defects. The 1.0 wt% CNT-added composite cast using the poly gate showed the highest ultimate tensile strength of 258.5 ± 5.2 MPa and hardness of 157.9 ± 3.0 Hv; these values were, respectively, 21% and 30% higher than those of the monolithic A383 alloy, confirming the feasibility of fabricating the MWCNT-added A383 alloy composite with a poly gate using the ORDC process.

Experimental Investigation of Mechanical Property and Wear Behaviour of T6 Treated A356 Alloy with Minor Addition of Copper and Zinc

The present study examines the effect of trace additions of copper (up to 1 wt.%) and zinc (0.5 wt.%) as the alloying elements on the microstructure, hardness, and wear behaviour of T6 treated A356 (Al-7Si) alloy. Wear tests were conducted using a pin-on-disc tribometer under a constant sliding speed of 200 RPM, varying applied load (20–40 N), and sliding distance (0–3000 m) to determine the wear rate and the coefficient of friction. The results indicated a minimum of 1 wt.% of copper was required to form the Al2Cu intermetallic phase, resulting in a finer grain structure and improved hardness. However, the role of zinc as a trace element was not observed on the microstructure; the observed changes may be the combined effect of copper and zinc as a whole. The highest hardness of 107 VHN (98% increase) was achieved with 1 wt.% copper addition during peak aging at 100 °C. Also, wear tests showed that adding 1 wt.% copper to the A356 alloy and a 100 °C precipitation hardening (T6) treatment improved the wear resistance by 150–182% with a reduced coefficient of friction.

Aging and wear characteristics of A356 alloy with Er and Zr addition

The present work investigates the effect of aging on the microstructure, mechanical properties, and wear behaviour of the cast A356 alloy with Er and Zr addition. The aged A356-0.25Zr and A356-0.25Er alloys revealed some but not all of the eutectic and columnar structures. The microstructure of A356, A356-0.5Er, and A356-0.5Er-0.25Zr alloys exhibited large α-Al grains with discrete eutectic silicon. Various intermetallic types and morphologies were observed after the peak aging. The highest hardness (∼120 HV) and the highest tensile strength (∼215 MPa) were achieved in the A356-0.25Zr alloy under peak-aged conditions. The A356 alloy revealed the lowest weight loss and friction coefficient, though it had the least hardness. Delamination was the dominant wear mechanism in all alloys.

Effect of Al5Ti1B Grain Refiner and Al10Sr Modifier on Mechanical Properties and Corrosion Behavior of A360 Alloy

In this study, the effect of Al5Ti1B grain refiners and Al10Sr modifiers on the mechanical and corrosion properties of the A360 aluminum alloy was investigated. For this purpose, varying amounts of Al5Ti1B grain refiner and Al10Sr modifier were added to the molten A360 alloy and the molten metal was poured into a per-manent mold. Subsequently, microstructural investigations, hardness test, tensile strength and corrosion resistance of the samples were examined. The results showed that, the Al5Ti1B grain refiner promotes finer-grained and coaxial solidifi-cation. The Al10Sr modifier, broke down the eutectic particles in the microstruc-ture and caused a more homogeneous distribution in the structure. While the tensile strength and corrosion resistance of the alloy increased both the grain refiner and the modifier added to the A360 alloy, a slight decrease in hardness was observed in the alloys to which only the modifier was added.