Influence Of T6 Heat Treatment Research Articles

THE EFFECT OF HEAT-TREATMENT ON THE MECHANICAL PROPERTIES OF EXPANDED GLASS PARTICLE/A356 SYNTACTIC FOAM

This research investigates the manufacturing of metal syntactic foams (MSFs) using a packed bed of porous (2-2.8 mm) expanded glass (EG) within an A356 alloy matrix. To this end, the counter-gravity infiltration casting technique is employed to manufacture the specimens. The density of the MSFs ranges from 1.05 to 1.17 g/cm3, making it one of the lowest densities foams, attributed to the filler particles' low bulk density. The study investigates the influence of T6 heat treatment on the mechanical properties and microstructural characteristics of the manufactured MSFs. The mechanical properties of the MSFs are characterized under quasi-static compressive loads at 1 mm/min. After heat treatment, the compression test results indicate a significant enhancement in most mechanical properties. Compression strength and plateau stress are approximately doubled compared to as-cast foams for samples with similar densities. While energy absorption of the MSFs triples in heat-treated conditions. These improvements are attributed to changes in the matrix microstructure due to thermal treatment. Microstructural analysis reveals that Si particles, initially sharp and continuous within inter-dendritic boundaries, become blurry and discontinuous through spheroidization after thermal treatment. This hinders crack growth in the cell wall and mitigates the effects of casting defects and the columnar dendritic structure. The majority of mechanical properties in both heat-treated (HT) and as-cast (AC) foams exhibited an increase in density due to an increase in the matrix fraction. However, plateau end strain and energy absorption efficiency demonstrated an independent effect of heat treatment and density.

Exploring VHCF response in L-PBF AlSi7Mg Alloy: Influence of T6 heat treatment on microstructural characteristics and defect distribution

Laser Powder Bed Fusion (L-PBF) is a popular technique for making intricate parts in various fields. Assessing the load-bearing capacity of components fabricated through L-PBF technique is crucial for broadening their applications across various industrial sectors. While prior research has primarily concentrated on static loads, cyclic loading is critical in real-world engineering applications. The purpose of this study is to investigate the influence of T6 heat treatment on the very high cycle fatigue (VHCF) performance of AlSi7Mg alloy fabricated using L-PBF technique by considering microstructural alteration and defect statistics. This study shows that the investigated heat treatment reduced VHCF response of the alloy. This is attributed to increased hydrogen and oxide porosity in conjunction with their increased diametral sizes along with microstructural alteration. The obtained results bring us closer to better understand and improve the use of the AlSi7Mg alloy in additive manufacturing. This offers a viable option for industries looking to benefit from the advantages of the L-PBF technique for manufacturing components.

Metallurgical and corrosion characteristics of AA7075 alloy reinforced with Nickel foam

ABSTRACT The current work investigates the metallurgical and corrosion characteristics of the interface between Nickel foam and AA7075 alloy. Nickel foam is conjoined with AA7075 alloy (composite) through a melt-infiltration technique. The composite specimen is characterized for microstructure, microhardness, microhardness, exfoliation corrosion susceptibility, and electrochemical corrosion parameters, including corrosion potential, corrosion current density, and polarization resistance. Also, the influence of T6 heat treatment on the corrosion of the composite specimen is analyzed. The texture, morphology, and composition of the interface and corroded surface are comprehensively analyzed using instrumental analytical techniques such as Scanning Electron Microscopy (SEM), Electron Backscatter Diffraction (EBSD), Energy-Dispersive X-ray Spectroscopy (EDS), and X-ray diffraction. The results indicate that T6 heat treatment increases the corrosion resistance of the composite specimen.

Microstructure and mechanical properties of 7075 aluminum alloy parts formed by semi-solid thixoextrusion

Hot-extruded 7075 aluminum alloy was used to form deep cavity cylinders by thixoextrusion. The effects of isothermal temperature and soaking time on the microstructure and mechanical properties of the formed parts were analyzed. The parameters of T6 heat treatment were optimized by orthogonal test, and the influence of T6 heat treatment on the microstructure and mechanical properties of the formed parts was studied. The results indicated that the deep cavity cylinder with a smooth surface could be successfully formed through thixoextrusion. The forming temperature and heating time had remarkable effects on the metallographic structure of the formed components. T6 heat treatment could greatly enhance the mechanical properties of the deep cavity cylinders. The optimum parameters of T6 heat treatment were achieved as: solution at 465 °C for 16 h and aging at 150 °C for 16 h. When semi-solid billets were heated at 600 °C for 10 min, the formed deep cavity cylinder had the best mechanical properties with the ultimate tensile strength of 573.57 MPa, the elongation of 13.44%, and the microhardness of HV 187.12.

Influence of T6 heat treatment on the microstructure and tribological properties of ADC12-GNPs composites

The graphene nanoplatelets (GNPs) were used as reinforcement to fabricate the ADC12-GNPs composites via ultrasonic-assisted casting, then the composites were adopted T6 heat treatment. The microstructures and wear performance were investigated in detail. The GNPs effectively refined the α-Al grains and form a strong Al-GNPs interfacial structure with the matrix, and the T6 heat treatment further rounded the Si phases and precipitated nanoscale θ′-Al2Cu. With the increase of load, the wear rate increases. And with the increase of sliding velocity, the wear rate shows a tendency of decreasing and then increasing. The wear rate and COF of the ADC12-GNPs/T6 composites showed a maximum reduction of 63.3 % and 39.2 %, respectively, compared to the matrix. The self-lubrication and refinement strengthening effect of GNPs improved the wear resistance, and the interaction between nanoscale θ′-Al2Cu precipitates and dislocations enhanced the tribological properties. Wear morphology and three dimensional profile analysis showed that the surface roughness of the ADC12-GNPs/T6 composite was 2.73 μm, which was 150 % lower than that of the matrix (6.82 μm) when the sliding velocity was 0.28 m/s and the load was 40 N, showing typical abrasive wear characteristics.

Fabrication and properties of (W+B)/Al hybrid composites for nuclear radiation shielding

A novel non-lead, lightweight nuclear shielding material was developed by introducing W and B particles as functional components into 6061 Al alloy. The ball-milling and spark plasma sintering (SPS) were employed to fabricate the (W+B)/Al hybrid composites. Some dominant process parameters, such as ball milling time, holding time, etc, were optimized. Subsequently, the effect of W volume fraction on the microstructure and mechanical properties as well as radiation shielding performance of the composites were thoroughly investigated. It is demonstrated that the W particles are homogenously distributed throughout the Al matrix with a W volume fraction less than 20 %. Al12W is identified as an interfacial product at the Al-W interface. The composites containing 20 vol% tungsten particles exhibits the highest mechanical strength. When the volume fraction of W particles increases to 30 vol%, severe agglomeration of W particles occurs, and the mechanical properties are considerably deteriorated. Compared with 6061Al, the influence of T6 heat treatment on the strength of the composites is insignificant, especially for the composites with a high W content. The γ-ray shielding properties of the composites are significantly improved with increasing W content. The linear attenuation coefficient is up to 0.32 cm−1 for the composites with 30 vol% W. The thermal neutron absorption rate of the (W+B)/Al composites all achieve 99 % with a thickness of 2.2 cm. The results suggest that the developed (W+B)/Al hybrid composites exhibit extraordinary application potential as a structure-function integrated nuclear shielding materials.

Characterization of Al Alloys Injected through Vacuum-Assisted HPDC and Influence of T6 Heat Treatment

AlSi12(Fe), AlSi10Mg(Fe), AlSi10MnMg, and AlMg4Fe2 die-casting alloys were produced by high-pressure die casting (HPDC) and vacuum-assisted high-pressure die casting (VADC) under a vacuum level of 200 mbar. The chemical composition, hardness, gas and shrinkage porosity, and mechanical properties were analyzed. The parts under study were subjected to a T6 heat treatment. The VADC led to a decrease in the percentage of defects in the as-cast state for all the alloys, due to a reduction in the amount of gas porosities. After heat treatment, the quantity of gas and shrinkage porosities increased. The efficiency and level of vacuum used were not sufficient to improve the mechanical properties in the as-cast state. The ductility of AlSi10Mg(Fe) and AlSi10MnMg alloys was improved after heat treatment; however, the YS and UTS of AlSi10Mg(Fe) did not increase. The primary aluminum alloys presented higher elongation values than the secondary aluminum alloys due to the reduced amount of the needle-like β-Al5FeSi phase.

Formation and evolution of the interfacial structure in al/steel compound castings during solidification and heat treatment

In this work, Al7SiMg/steel compound castings were produced through a low-pressure die casting process. All steel inserts were galvanized, where half of them were flux-coated to further improve the wettability and remove interfacial oxide layers during casting. The reaction layer formed in the Al7SiMg/steel interface was examined using Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). In addition, Vickers Micro-hardness was measured across the interface. Results show that successful metallurgical bonding can be achieved between aluminum and galvanized steel, both with and without additional flux coating. A large fraction of intermetallic particles formed at the reaction layer, where ternary Al4·5FeSi particles were the dominating phase. The influence of T6 heat treatment (solution treatment at 540 °C, followed by artificial ageing) on the interfacial microstructure was also studied. After heat-treatment, the thickness of the interfacial layer increased significantly, due to the growth of β-Al4.5FeSi and Al–Fe binary particles into the bulk of steel. Consequently, cracks formed and propagated through the inner binary intermetallic layer. Formation mechanisms of various intermetallic phases at the interface during solidification and heat treatment have been discussed.

Fabrication and heat treatment of graphene nanoplatelets reinforced aluminium nanocomposites

The present work reports fabrication of graphene nanoplatelets (0.1, 0.3 and 0.5 wt%) reinforced aluminium matrix naocomposites through non-contact ultrasonic vibrations assisted stir casting process. Microstructure, tensile strength, microhardness and tribological properties of fabricated samples have been examined. The influence of T6 heat treatment on mechanical properties of developed samples was also investigated. Incorporation of graphene in base matrix resulted in grain refinement and an increase of about 37% in ultimate tensile strength and 27% in micro hardness of cast composites. Strength and grain refining action of graphene was attributed as the reason for increment in mechanical properties. Heat treatment causes further improvement of about 83% and 34% in ultimate tensile strength and microhardness of fabricated composites as compared to heat treated base matrix. The enhancement in properties of heat-treated samples was attributed to age hardening. Addition of self-lubricating graphene in aluminium matrix resulted in improved wear behavior of prepared composites. Reduction of about 24% in coefficient of friction of graphene-aluminium composites as compared to base matrix is reported.

Microstructure Evolution and Mechanical Properties of the T6 Heat Treated AA6063 Alloy Produced by Squeeze Casting

The influence of T6 heat treatment on the microstructure, hardness and tensile properties of cast AA6063 aluminum alloy was investigated as a function of squeeze casting pressure. The specimens elaborated were solution treated at 500°C for 8 hours and then were subjected to aging at 140°C. Various test techniques, including optical microscopy, scanning electron microscope, X-ray diffraction, tensile tests, and hardness were used to examine the effect of this alloy produced by the gravity and squeeze casting processes. The experimental results showed that Mg2Si and Al15Si2(FeMn)3 were the primary particles observed in the α-Al matrix. The effect of precipitation on the mechanical properties was investigated. The changes in mechanical properties were correlated with changes in microstructure evolution and Mg–Si precipitation. Furthermore, hardness and tensile properties increased with both heat treatment and squeeze pressure.

Influence of T6 heat treatment on A356 and A380 aluminium alloys manufactured by thixoforging combined with low superheat casting

Abstract The effects of T6 heat treatment on thixoforged A356 and A380 aluminium alloys were studied. Low superheat casting (LSC) technique was carried out to prepare proper specimens for thixoforging process. The samples were poured at 20 °C above their liquidus temperatures which provided the formation of equiaxed grains instead of dendritic growth. Produced billets were reheated for varied time from 20 to 80 min and thixoforged with 50% deformation rate. After thixoforging process, the samples were T6 heat treated for both A356 and A380 alloys. The microstructural evaluation and hardness alteration of thixoforged, solution treated and aged specimens were examined comparatively by using optical microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy and Brinell hardness equipment. T6 heat treatment provided relatively uniform microstructure with newly formed precipitates that are Mg2Si and Al2Cu for A356 and A380 billets, respectively. Accordingly, hardness after artificial aging was increased considerably and reached HB 93 for A356 and HB 120 for A380 alloys.

Influence of T6 heat treatment on mechanical properties and microstructure of aluminum SFC204 used in orbiting scroll

The objective of this research is to study the influence of heat treatment parameters, such as time and temperature, on the microstructure and mechanical properties of the forged aluminum grade SFC204 used for orbiting scrolls. The specimens were at first annealed at the temperature of 530 °C for 2 hours. Each specimen was then heated at the different temperature; 175, 185 and 195°C with and different annealing time at 3, 5 and 7 hours. It was found that the annealing temperature and time of the aging process led to the difference of phase morphology. The increasing time and temperature affected the network of the intermetallic compound of the Aluminum (Al) and Silicon (Si) and/or Al and Copper (Cu). The mechanical testing, such as fatigue, hardness and tensile, was investigated. Comparing to the microstructure observation, the intermetallic network of Cu and Al phase played an important role on the mechanical results. The relationship between microstructure and mechanical properties is further discussed.

Influence of T6-heat treatment on mechanical properties of Al7075 alloy reinforced with Cenosphere

Cenospheres are light weight, inert and hollow spheres filled with air with main constituents of silica and alumina. It is a by-product obtained after combustion of pulverized coal in thermal power plants. Due to its light weight and hollow in nature, Cenospheres are used as reinforcement in metal matrix composites to enhance the mechanical and microstructural properties. The 7xxx series are heat treatable aluminium alloys used in high performance structural, aerospace and transportation applications. The present paper reports the effect of heat treatment on mechanical properties of Cenosphere incorporated Al-7075 composites produced by stir casting technique. The composites were subjected to T6 type heat treatment , subsequently the heat treated specimen of different composition and different heat treatment duration were tested for evaluation of mechanical properties and same has been compared with the results of as cast (un heat-treated) composite specimens. The mechanical properties such as ultimate tensile strength, compression strength and hardness are analyzed as a function of heat treatment duration. The results of heat treated samples are then compared with as cast samples.

Effects of T6 heat treatment on the microstructure, tensile properties, and fracture behavior of the modified A356 alloys

It is known that heat treatment causes the spheroidization of eutectic silicon. This paper presents the influence of T6 heat treatment on the microstructures, tensile properties, and fracture behavior of the A356 alloys modified by mischmetal containing La and Ce elements. Microstructural analysis showed that the size of eutectic silicon particles was greatly reduced and the extent of speroidisation of Si particles was remarkably improved for the modified A356 alloys. Comparison between the unmodified and modified alloys suggested that the values of mean diameter, roundness, and aspect ration of eutectic silicon particles were decreased by 48.10–56.85%, 49.55–54.52%, and 13.36–30.17%, respectively. The tensile properties of the modified A356 alloys can be enhanced, especially the ductility. These could be associated with the decrease of secondary dendrite arm spacing, spheroidization of fine eutectic silicon and precipitation hardening. Scanning electron microscopy (SEM) examination indicated that the ductile fracture mechanism was responsible for the modified alloys due to the existence of a couple of fine and uniformly distributed dimples. And the eutectic silicon particles and RE-containing intermetallic compounds provide the weak locations during the fracture process.

Effect of Rare Earth La Modification on Microstructure and Properties of ZL101 Alloy

In this paper, rare earth La modifying ZL101 alloy was studied by using of optical microscope, scanning electron microscopy, universal materials tester and small-load Brinell hardness. The influence of T6 heat treatment of the alloy’s microstructure and properties was also studied. The results show that microstructure and mechanical properties of the alloy have much obvious modification effect at modification temperature (690°C). The microstructure and mechanical properties are improved remarkably when La content is up to 0.15wt%.

Effect of T6 Heat Treatment on the Microstructures and the Aging Behavior of the Grain-Refined A356 Alloys

The influence of T6 heat treatment on the microstructures and aging precipitation in the grain-refined A356 alloys were investigated. Experimental results showed that, when T6 heat treatment was performed, the average values of mean diameter, aspect ratio, and roundness of silicon particles in the grain-refined specimens were decreased to 2.26~3.14 μm, 2.06~2.2, and 3.1~4.2, respectively. DSC curves revealed that three kinds of precipitates, i.e., β″, β′, and β, were observed in both unrefined and grain-refined A356 alloys. The exothermic peaks in the grain-refined A356 alloy shifted to high temperatures, suggesting the nucleation of β″ precipitates was decelerated. This could be ascribed to the minor solution of Ti or B elements during solid solution treatment.

Heat treatment effect on the microstructure, tensile properties and dry sliding wear behavior of A356–10%B 4C cast composites

In present paper, an attempt was made to examine the influence of T6 heat treatment (solution treatment at 540 °C for 5 h, quenching in hot water and artificial aging at 170 °C for 8 h) on the microstructure, tensile properties and dry sliding wear behavior of A356–10%B 4C cast composites. The composite ingots were made by stir casting process. In this work, the matrix alloy and composite were characterized by optical microscope, scanning electron microscope equipped with energy dispersive X-ray spectroscopy, tensile tests and conventional pin-on-disk experiment. The obtained results showed that in Al–B 4C composite, T6 treatment was a dominant factor on the hardness improvement in comparison with hardness increasing due to the addition of B 4C hard particles. In addition, T6 treatment can contribute to the strong bonding between B 4C and matrix alloy and also it can change eutectic silicon morphology from acicular to near spherical. This case can lead to higher strength and wear properties of heat treated metal matrix composites in comparison with unheat treated state. Observation of worn surfaces indicated detachment of mechanically mixed layer which can primarily due to the delamination wear mechanism under higher applied load.

Influences of Heat Treatment on Microstructure and Creep Properties of Ti<sub>6</sub>Al<sub>4</sub>V Alloy

By means of the measurement of creep curves and microstructure observation, the influence of T6 heat treatment on the microstructure and creep properties of the wrought Ti-6Al-4V the alloy has been investigated. The experimental results showed that the microstructure of the wrought alloy consists of the strip-like +  phases, which results in the alloy displaying a higher strain rate and shorter creep life under the test condition of 575 MPa and 400°C. After T6 treatment, the creep life of the alloy at same conditions enhanced to 548 h from 66 h. Microstructure of T6 treated alloy consisted of the primary  and /phases, and signification amount of the bundle-likephase precipitated along the different orientations in the grains, this is a main reason of enhancing creep life of the alloy. During forging, the denser dislocation rows were activated in the local region of the matrix in the alloy. During creep, the deformed mechanism of the alloy was the double orientations slip of <a> and <a+c> dislocations activated on the pyramidal planes in  phase.

Wear behavior of artificially aged AA2024/40 μm SiC p composites in comparison with conventionally wear resistant ferrous materials

The abrasion wear behavior of T6 AA2024/40 μm SiC p composites was studied using the pin-on-disc technique. Specific wear rate (swr) curves versus load and short sliding distance, were obtained. The processing route of the materials was a combination of the compocasting and squeeze casting techniques. The volume fractions of the composites produced were 0, 8, 14, 19, and 24 vol.%. In order to evaluate the influence of T6 heat treatment in their behavior, the composites were tested in the peak-aged (PA) and over-aged (OA) condition. Then their wear performance was compared with that of conventional wear resistant materials which were the heat resistant X40CrMoV51 (or H13) tool steel and the gray cast iron; the later was extracted from an automotive brake rotor. The composites’ wear behavior was found to be relatively independent of the aging condition. Their wear resistant improved with increasing SiC p content in both the PA and OA condition. All T6 composites of every SiC p volume fraction exhibited considerably lower swr’s than not only those of gray cast iron but of H13 tool steel as well.

Dry sliding wear response of zinc based alloy: influence of heat treatment, sliding speed, and pressure

An attempt was made to study the dry sliding wear behaviour of a Zn-27.5 Al-2.5Cu-0.03Mg alloy over a range of applied pressures and sliding speeds. The influence of T6 heat treatment (solutionising followed by artificial aging) on the wear characteristics of the alloy was also examined under identical test conditions. Wear rate increased with pressure and sliding speed while seizure resistance followed an opposite trend. At the three lower speeds (i.e. 0.42, 1.38, and 2.68 m s-l) two wear regimes, namely mild and severe, were exhibited by the as cast and heat treated specimens wherein low wear rates initially occurred up to a specific pressure. This was followed by the attainment of severe wear at higher pressures. However at the highest speed of 4.60 m s-l, the specimens showed only the severe wear regime. Heat treatment caused improved wear response of the alloy up to the sliding speed of 1.38 m s-1. Further, the heat treated alloy performed better than the as cast alloy before seizure at 2.68 m s-1, while it showed identical wear characteristics in both conditions at 4.60 m s -1. The wear behaviour of the alloy is explained on the basis of the nature of its micro constituents. The results are supplemented with analyses of the wear surfaces, subsurface regions, and the debris particles which have also been able to throw light on the operative wear mechanisms.