A356 Aluminum Alloy Research Articles

Experimental investigation of high velocity impact response of CFRP laminates subjected to flyer plate impact

Carbon fiber reinforced plastic (CFRP) composites are widely used in aircraft and automotive industries due to their extremely high specific strength and stiffness. High velocity impact is inevitable throughout the service life of composite structure and it is important to understand its impact response. In this study, high velocity impact response of CFRP laminates subjected to flyer plate impact were investigated in the velocity range of 32∼100 m/s by a gas gun coupled with 3D Digital Image Correlation (DIC) analysis. For comparison purposes, similar tests were carried out on 2A12 aluminum alloy plates of equivalent thickness. The PVDF pressure sensor was used to measure the impact pressure of the target plate, and the influence of impact velocity and target type on the impact pressure was analyzed. The damage and failure mechanism of CFRP laminates during impact were analyzed by digital microscope, ultrasonic C-scan and sectional image. The results show that the variation trend of the theoretical impact pressure is consistent with that of the experimental impact pressure, and the experimental impact pressure is smaller than the theoretical impact pressure. The damage and failure mechanism of two target plates are different under high velocity impact. For 2A12 plate, a truncated circular cone-shape bulge is generated on the 2A12 plate and this damage patterns appears regardless of the impact velocity. For CFRP laminates, impact indentation with elongated splits extending from the indentation edges is observed on the impacted surface of the target plate. The delamination zone of the adjacent layers is distributed in a fan-shaped area and the delamination direction is consistent with the direction of the fibers in the front ply. The data from the experiments can be used to evaluate and refine composite material models and computational methodologies that are used to predict the impact response of composite.

Influence of Energy Ratio of Hybrid Heat Source on Residual Stress Distribution of 7A52 Aluminum Alloy VPPA-MIG Hybrid Welding

Variable Polarity Plasma Arc-Metal Inert Gas (VPPA-MIG) welding process is a new hybrid welding process with broad application prospects for aluminum alloy structure in the fields of aerospace manufacturing, transportation and others. The heat source of the hybrid welding process is composed of VPPA heat source and MIG heat source. When the total input energy of VPPA-MIG hybrid heat source is constant, the different energy ratio of VPPA arc and MIG arc affects not only the forming effect of hybrid weld, but also the stress distribution of hybrid welding joint. Hole-drilling method was used to analyze the influence of the ratio of VPPA and MIG arc energy on the distribution of welding residual stress in the process of 10 mm 7A52 aluminum alloy VPPA-MIG hybrid welding. The results show that the peak magnitude of hybrid welding residual stress increases with the increase of the ratio of VPPA arc energy. Considering the appearance of weld forming, VPPA-MIG hybrid welding parameters of 7A52 aluminum alloy are optimized on the basis of the distribution characteristic of residual stress. When the ratio of VPPA arc energy is selected between 35% and 40%, the peak magnitude of transverse residual stress is (in the direction vertical to the weld) no more than 92.0 MPa, and the peak magnitude of longitudinal residual stress(in the direction parallel to the weld) is no more than 234.3 MPa. It shows that the VPPA-MIG hybrid welding with optimized parameters can not only produce weld joint with satisfied macroscopic appearance, but also avoid high peak magnitude of residual stress.

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.

Hot deformation behavior and microstructure evolution of hot-extruded 6A02 aluminum alloy

The present work explored the impacts of temperature, strain rate, strain and initial orientation on hot-compression behavior and microstructural evolvement of hot-extruded 6A02 aluminum alloy. Initial samples were cut in two directions: parallel to the original extruding direction (D1) and perpendicular to the extruding direction (D2). Arrhenius and diffusion constitutive models of D1 samples were studied at 400 °C–560 °C under constant strain rate of 0.001 s−1–1 s−1. The predication accuracy of Arrhenius constitutive model was better than diffusion constitutive model considering lattice diffusion. The average activation energy of peak stress was 325.114 kJ/mol. Lattice diffusion was dominant diffusion mechanism and creep exponents n were larger than 5 in all strain ranges. Higher temperature and lower strain rate resulted in lower geometrically necessary dislocation (GND) density, lower stored strain energy E and higher dynamic recrystallization (DRX) degree. Stored strain energy ranged from 0.534 to 0.993 J/mol. The ultimate stress had linear relationship with dislocation density. The continuous dynamic recrystallization (CDRX) was gradually prior to discontinuous dynamic recrystallization (DDRX) with increase of strain rate. Hot deformation experiment of D1 samples with stepped strain rates showed that the large gaps between the two stages had more effective effect on improving DRX degree. Deformation mechanisms were in connection with grain types. For D2 sample, the fraction of DRX grains and texture types were less than D1 sample. Besides, CDRX mechanism was superior to DDRX mechanism at all constant strain rates.

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.

Restirring and Reheating Effects on Microstructural Evolution of Al-Zn-Mg-Cu Alloy during Underwater Friction Stir Additive Manufacturing.

Friction stir additive manufacturing (FSAM) can be potentially used for fabricating high-performance components owing to its advantages of solid-state processing. However, the inhomogeneous microstructures and mechanical properties of the build attributed to the complex process involving restirring and reheating deserve attention. This study is based on the previous research of the underwater FSAMed 7A04 aluminum alloy and adopts a quasi in situ experimental method, i.e., after each pass of the underwater FSAM, samples were taken from the build for microstructural observation to investigate the restirring and reheating effects on microstructural evolution during the underwater FSAM. Fine-grain microstructures were formed in the stir zone during the single-pass underwater FSAM. After restirring, the grain size at the bottom of the overlapping region decreased from 1.97 to 0.87 μm, the recrystallization degree reduced from 74.0% to 29.8%, and the initial random texture transformed into a strong shear texture composed of the C {110}<>. After reheating, static recrystallization occurred in the regions close to the new additive zones, increasing the grain size and recrystallization degree. This study not only revealed the microstructural evolution during the underwater FSAM but also provided a guideline for further optimization of the mechanical properties of the Al–Zn–Mg–Cu alloy build.

Experimental and Finite Element Study on 7A04 Aluminum Alloy Tube Confined High Strength Concrete Long Column

7A04 aluminum alloy has high strength and strong corrosion resistance, and its quality is only 1/3 of steel. Using 7A04 aluminum alloy to replace ordinary steel tube to confined concrete, it can effectively reduce the member section, reduce the weight of the structure, and more in line with the material requirements of large span materials and high-rise buildings. In this paper, nine groups of 7A04 aluminum alloy tube confined high strength concrete long column were tested under axial compression and eccentric compression with aspect ratio and eccentricity as variables. And the corresponding ABAQUS finite element model was established. The results show that the failure phenomena of the nine groups are basically the same, and the specimen deflection curve shape is similar to the sine half-wave curve. The ultimate bearing capacity of the specimen decreases with the increase of aspect ratio and eccentricity. When the axial compression or eccentricity of the specimen is small, the variation of the longitudinal and transverse strain at the midspan is similar in the elastic stage. When the eccentricity is large, the longitudinal and transverse strain at the midspan of the specimen is obviously tensile at one side and compressive at one side at the beginning. Finally, based on the test and simulation results, a formula for calculating the bearing capacity of 7A04 aluminum alloy tube high strength concrete long columns is proposed. This formula can better predict the stable bearing capacity of the specimen, which has certain reference significance for the structural design of 7A04 aluminum alloy tube high strength concrete long columns.

Temperature-dependent creep aging behavior of 2A14 aluminum alloy

The creep deformation behavior, aging hardening response and microstructure evolution of 2A14 aluminum alloy (Al-4.81wt%Cu-0.66wt%Mg-0.97wt%Si) at different temperatures have been systematically investigated by creep test, tensile test, transmission electron microscopy and differential scanning calorimetry. The results show that the total creep strain and steady-state creep rate significantly increase with increasing temperature in the range of 408 K–458 K, while the creep behaviors at the optimum aging temperature of 433 K have shortest primary creep stage and lowest stress sensitivity. Pinning of dislocations by the dense and fine Q′ and θ′ phases precipitated in the alloy creep-aged at 433 K, which contributes to obtaining the best mechanical properties. Also, the primary creep deformation mechanism at different aging temperatures has been discussed. A reference temperature describing the degree of the interaction between aging precipitates and dislocations is introduced into the hyperbolic-sine creep model. The creep strain predicted through the temperature-dependent creep model is in good agreement with the experimental data. The research can provide theoretical support for the temperature-varying creep age forming application in the 2A14 aluminum alloy components.

Combining Heat Treatment and High-Pressure Torsion to Enhance the Hardness and Corrosion Resistance of A356 Alloy

A356 aluminium alloy is subjected to heat treatment and high-pressure torsion (HPT) processing to investigate the impact of the combined treatments on the alloy’s microstructure refinement, corrosion resistance and hardness. The high-pressure torsion process was performed at room temperature for 0.75 and 5 turns. Subjecting the A356 Al alloy to a heat treatment and subsequent HPT processing produced a more refined microstructure, which has the effect of enhancing the alloy hardness and corrosion resistance under fragmentation and the homogenous redistribution of the intermetallic compounds and the Si particles. The results of the treatment show that there is a marked increase in hardness when imposing a strain from 61 HV to 198 HV on the A356 Al alloy, which has been HPTed and heat-treated for five turns. The polarisation curves show that there is a considerable improvement in the corrosion resistance rate of the alloy from 0.043 mm·year−1 for the A356 Al alloy sample to 0.003 mm·year−1 after five turns of HPT. In this work, the microstructure refinement resulted in the improvement of both the mechanical strength and corrosion resistance of the aluminium 356 alloy after heat treatment in comparison to the untreated alloy.

Effect of Mg and TiB on the Mechanical Properties of A356 Aluminium Alloy Base Materials With Die Casting Process

The development of research on aluminum base materials is very rapid at this time. Aluminum base material reinforced with Mg and TiB particles by the die casting method is the simplest way. The purpose of this study was to see the effect of wt.% Mg and the addition of TiB on the mechanical properties of Al356MgTiB alloy. AlSi was used as a matrix reinforced by Mg with a percentage variation of (3, 4, 5 wt%) and TiB 2 wt%. The method used is die casting. In the casting process, the material is melted down to a liquid state at a temperature of 800 oC. After that the temperature was lowered to a stirring temperature of 640 oC. Then heated again to a pouring temperature of 760 oC. The density value obtained increased with the addition of Mg variation, namely the variation of Mg 4%wt 2.69 g/cm3. The porosity value obtained decreased, namely the variation of the 5%wt Mg element, namely 5.19%. The hardness value of Al356MgTiB alloy increases with the addition of Mg. The highest hardness is achieved at the percentage of Mg 5%wt, which is 65.41 HRB or an increase of 33% from the hardness of the base material. The value of tensile strength increases with the addition of Mg. The highest tensile strength is found in the 4%wt Mg variation, which is 198.4 MPa. The %EL value decreased with the addition of Mg and TiB. The decrease in %EL is accompanied by an increase in the strength of the material. The research was conducted by testing density, hardness testing, and tensile testing.

Indentation Size Effect of Composite A356 + 6%FA Subjected to ECAP

In this study, metal matrix-based composite (MMC) was subjected to Equal Chanel Angular Pressing (ECAP) in several passes to determine the influence of deformation on the hardness of the samples. Composite based on A356 aluminum alloy and reinforced with Fly Ash (FA) particles was obtained by the compo casting method. The microstructural analyses and microhardness measurements were performed on the cast and pressed samples. Vickers hardness measurement of composite samples was performed with different indentation load sizes: HV0.02, HV0.05, HV0.1 and HV0.2. Results showed that hardness increases after each ECAP pass. The lowest hardness value of 42 (HV0.02) as well as the lowest arithmetical mean value of 46 (HV0.2) was measured at the cast composite. The greatest composite hardness of 107 (HV0.1) and the highest arithmetical mean value of 94 (HV0.1) was measured at the three-time pressed sample. The mathematical model named Meyer’s law was used for data analysis. In the cast sample, a decrease in hardness was detected with increasing indentation load, termed Indentation Size Effect (ISE), was confirmed with Meyers index n = 1.9112 &lt; 2. Pressed samples showed opposite behavior—an increase in hardness with increasing indentation load—where Meyers index n &gt; 2 indicated Reverse Indentation Size Effect (RISE). For all samples, a high coefficient of determination R2 &gt; 0.99 confirmed that Meyer’s law described this phenomenon well.

Effects of strontium addition and T6 heat treatment on uniaxial fatigue of A356 aluminum alloy: Fatigue life and cyclic behavior

AbstractThe effects of strontium addition and T6 heat treatment on fatigue behavior of A356 aluminum alloy were studied in this paper. Uniaxial fatigue tests were carried out by using constant stress amplitude. In addition, microstructural analysis of porosity and fracture surface were performed on the material. Results showed that the alloy at T6 conditions presented the best fatigue life, mainly in low cycle fatigue. In high cycle fatigue, the fatigue life of as‐cast and heat treatment alloys almost converged to the same alternating stress. The strontium modified alloys presented higher porosity levels than unmodified ones, which reduced the fatigue life. The stress–strain hysteresis loops showed that the A356 + T6 alloy reached the highest total strain ranges and that depending on the stress level applied, the alloy may or not present cyclic hardening. The fracture analysis revealed porosity near the surface was the main fatigue failure nucleation site for strontium modified alloys.

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.

Transient behaviour of electrovortex flow in a cylindrical container

The mechanical behaviour of the oxide film that develops at the metal-air interface of molten A356 aluminum alloy is investigated in relation to the oxidation level. Based on two previous papers - the first one focusing on the chemical aspects of the oxidation process at the liquid surface of molten aluminum, the second one focusing on its mechanical characterization, the present paper aims at reconciling these two approaches usually considered separately in the literature and proposes a stand-alone mechano-chemical model. The oxidation process is first characterized from thermogravimetric analyses together with scanning electron microscopy imaging. Then the mechanical properties of the oxide layer are determined at a given oxidation level, making use of a new annular MHD surface viscometer placed inside a chemical reactor. The kinetic study delivers a better understanding of the oxidation process involved at the surface of the A356 alloy and leads to the development of a revised version of the Deal−Grove model. In addition, the mechanical study reveals the highly viscous and shear-thinning behaviours of the oxide layer. Figs 3, Refs 14.

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.

Microstructure-refinement–driven enhanced tensile properties of high-pressure die-cast A380 alloy through friction stir processing

This work employs friction stir processing (FSP), a well-known severe plastic deformation technique, to selectively modify the microstructure of thin-walled, high-pressure die-cast (HPDC) aluminum alloy A380, a major HPDC alloy fabricated in the die casting sector. FSP effectively breaks down Al dendrites and acicular Si particles, creating a homogenized distribution of equiaxed Si particles in the aluminum matrix. After FSP, the refined Si particles (~1.5 μm) are smaller than the eutectic Si particles (3–8 μm) in HPDC condition. In addition, interparticle distance has decreased almost 50% compared to dendritic arm spacing, and FSP has reduced the aspect ratio of Si particles to ~2. Furthermore, FSP eliminates porosity, and breaks down needle-like second-phase Fe-Mn and Cu-rich particles, yielding a refined, homogeneous distribution. The FSP-induced microstructural refinement and porosity reduction improve bulk yield strength and ductility by 23% and 66%. Tensile properties are enhanced beyond those of the die skin of the HPDC plate, and the alloy possesses lower defect density and a highly refined microstructure. This study establishes the viability of FSP as a tool for microstructure modification and mechanical property improvement for HPDC Al alloys for the light-weighting goal of the automotive industries.

Corrosion Behavior of 7A52 Aluminum Alloy Plasma Arc Welding Joint in Simulated Marine Atmosphere Environment

Corrosion behavior of 7A52 aluminum alloy plasma arc welding (PAW) joint was investigated in simulation of marine atmosphere environment with salt water spray test. The surface morphologies were observed by scanning electron microscopy (SEM), and the effect of corrosion time on corrosion behavior was discussed. The depth of spot corrosion, the corrosion dynamic characteristics, and the distribution of element of 7A52 aluminum alloy welding joint were analyzed by 3D and XRD Microscope. Results show that pitting corrosion is main morphology in heat effect zone at initial stage, pitting corrosion appears in matrix and welding joint with time. The main component compounds existing in the film include Al and O. The depth of pitting corrosion in the heat effect region is the maximum (3.008μm). The law of power function is followed in both phases of the corrosion weight increasing curve, and the corrosion rate decreases with time.

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.

THERMAL-DEFORMATION MODEL OF A Sr-MODIFIED A356 ALUMINUM ALLOY

The hot-deformation behavior of A356 aluminum alloy with a Sr modification was investigated using a Gleeble 1500 thermal simulator. The true stress-strain curves with a deformation temperature of 300–500 °C and a strain rate of 0.01–5 s–1 were clarified. The activation energy of the A356 aluminum alloy with Sr modification was 221.474 kJ/mol. The influences of friction and temperature on the curves were investigated, and then the constitutive equation was established. The results show that the flow stress is obviously affected by temperature and strain rate. The experimental stress is lower than the theoretical stress, and the stress difference between the experimental and theoretical stress increases with the increasing strain. The maximum stress difference reaches 17.8 MPa when the sample deformed at 300 °C/5 s–1 with a reduction of 16 %. For all the deformation conditions the correlation coefficient is 0.99 and the average relative error is 4.8 %, which shows the good predictability of the current model. The developed constitutive equation can provide guidance for the study of the hot-deformation behavior of similar aluminum alloys.