Showing papers on "Spray forming published in 2020"

Microstructure and mechanical properties of 2195 alloys prepared by traditional casting and spray forming

Abstract: The 2195 alloys prepared by traditional casting and spray forming technology were investigated by using X-ray diffraction, X-ray microscopy, electron probe microanalyser, scanning electron microscopy, transmission electron microscopy and tensile testing. The results show that the as-cast alloy consisted of large-scale grains with small amount of pores, while the as-sprayed alloy is composed of mainly fine equiaxed grains with abundant pores. In the grain boundary, continuous secondary phases (Al–Cu–Mg phase, Al–Cu phase, and Al–Cu–Fe phase) exist in the as-cast alloy, while semi-continuous/discontinuous secondary phases (Al–Cu phase and Al–Cu–Fe phase) present in the as-sprayed alloy. The main phases in the grain interior of the as-cast alloy are T1 (Al2CuLi), TB (Al7·.5Cu4Li) and σ (Al5Cu6Mg2) phases while T1 and TB phases for the as-sprayed alloy. The same homogenization treatment shows more solute contents dissolved in the spray formed 2195 alloy. The as-sprayed alloy has advantage of 35% in ultimate strength, 26% in yield strength and 54% in elongation compared to the as-cast alloy, respectively. This detailed studies manifest that subsequent processes of deformation and heat treatment for spray formed alloy need to be tailored based on its featured microstructure, compared with that of traditional cast alloy.

Influence of heat treatment on the microstructural evolution and mechanical properties of W6Mo5Cr4V2Co5Nb (825 K) high speed steel

Abstract: Spray forming (SF) is a newly developed rapid solidification and near-net-shape technique for preparing high-speed steels (HSSs) in recent years. However, a large amount of overspray powders will be produced in the SF process, which brings about a serious material pollution and waste. To solve this problem, a new method of the two-step sintering and subsequent heat treatment was used to fabricate high-performance W6Mo5Cr4V2Co5Nb (825 K) HSSs using the overspray powders. The microstructural evolution and mechanical properties by the heat treatment were systematically studied. Results show that near full dense 825 K alloys with many uniformly distributed carbides are obtained by the two-step sintering. After quenching and triple tempering, the alloys consist of the martensite, M6C and MC carbides, and a small amount of retained austenite. The carbides have smaller particle size of less than 3 μm and greater sphericity than the as-sintered alloy. The diffusion of alloying elements determines the dissolution and re-precipitation of carbides. The fabricated 825 K alloy quenched at 1180 °C and triple tempered at 540 °C possesses the best mechanical properties, with a hardness of 64.2 HRC and bending strength of 2858 MPa, which is much higher than that of casting alloy with similar composition. This work provides a feasible way to recycle the overspray powders.

Influencing mechanisms of heat treatments on microstructure and comprehensive properties of Al–Zn–Mg–Cu alloy formed by spray forming

Abstract: In this research, the effects of solid solution, peak aging (PA), over aging (OA) and retrogression re-aging (RRA) on microstructure, mechanical properties, and corrosion resistance of the spray-formed Al–Zn–Mg–Cu alloy were systematically and comparatively studied. It was found that after solid solution, most of the secondary phases dissolved into the α(Al) matrix and created a favorable condition for aging treatment. When the material was subjected to the RRA, the microstructure of the alloy consisted of fine precipitates within the grains similar to the PA condition and discontinuous coarse precipitates along the grain boundaries resembling the OA condition, allowing the RRA specimens to possess optimal strength (747 MPa) and high intergranular corrosion (IGC) resistance. The mechanism of IGC on mechanical properties on different aged samples was elaborated.

Microstructure Evolution and Recrystallization Resistance of a 7055 Alloy Fabricated by Spray Forming Technology and by Conventional Ingot Metallurgy

Abstract: The effect of different fabricating processes (spray forming and conventional casting) and homogenization treatment on the microstructure of an 7055 alloy was investigated by optical microscopy (OM), scanning electron microscopy (SEM), electron probe X-ray micro-analyzer (EPMA), and transmission electron microscopy (TEM). It was found that the grain size of the as-deposited (spray formed) 7055 alloy had half the size as that of the as-cast 7055 alloy and there was no Al2CuMg phase that embedded in the coarse Mg(Zn, Cu, Al)2 phase distributed along the grain boundaries in the as-deposited 7055 alloy. No segregation of zirconium was observed in the as-deposited 7055 alloy. After homogenization heating at 350 °C/5 hours + 470 °C/24 hours, Al3Zr dispersoids were inhomogeneously distributed within grains in the traditionally cast 7055 alloy, while more homogeneously distributed within grains in the spray-formed 7055 alloy. Compared with the traditional cast 7055 alloy, the uniform distribution of Al3Zr dispersoids in the spray-formed 7055 alloy retards recrystallization more effectively. This investigation highlights the advantage of spray forming technology on improving microstructure of a 7055 alloy.

Mechanical and Tribological Behavior of Warm Rolled Al-6Si-3Graphite Self Lubricating Composite Synthesized by Spray Forming Process

Abstract: In this investigation, the mechanical and tribological behavior of warm rolled Al-6Si-3Gr (graphite) self-lubricating composite have been studied. A spray forming process was used to synthesize the composite. The graphite particles were reinforced externally into the jet of the spray of molten Al-Si alloy. The porosity was generated under the spray forming process that was eliminated by the secondary process (warm rolling). Warm rolling was carried out with 20, 40, 60 and 80% thickness reduction in multi-passes on high non-reversing mills. Refinement and distribution of silicon and graphite particles in the composite were increased. The mechanical properties namely hardness and strengths were also improved by warm rolling. Wear properties of the composite after each thickness reduction were also investigated under dry sliding condition. Composite after warm rolling showed the better results in the coefficient of friction and wear rate. Wear properties improvement, nature of the debris particles and mechanical properties of the composite after warm rolling were discussed in details with its microstructural features. Different characterization techniques were also used to support the prediction of change in properties. The load bearing capacity of the composite was increased by warm rolling. These composites could be used for those applications where load bearing capacity and less wear is required.

Outstanding Tensile Ductility in High Iron-Containing Al-Si-Cu Alloys

Abstract: Cast Al(5.5 to 6.3 wt pct)Si-(3.1 to 3.7 wt pct)Cu alloys containing 0.6 and 1.2 wt pct Fe were processed by spray forming, rotary swaging, and homogenization/solution heat treatment, which led to a tensile ductility of 16 pct. Such outstanding ductility is ascribed to the microstructure formed: globular silicon particles, refined iron-rich intermetallics, and a supersaturated solid solution of Cu in the α-Al matrix that promoted dynamic strain aging and homogenization of the deformation process.

Study of the influence of δ-ferrite on the TRIP effect of a low-density high aluminum steel by using full-field crystal plasticity modeling

Abstract: Low-density high aluminum transformation induced plasticity (TRIP) steel is a new developed light-weight structural material. In the conventional casting (CC) TRIP steel, however, the presence of high Al content results in the formation of coarse dendritic δ-ferrite, which seriously deteriorates the performance of the material. The spray forming process show good potential to refine and homogenize the microstructure. It was found that the δ-ferrite in the spray formed (SF) TRIP steel is refined remarkably and its distribution is more homogeneous. Uniaxial tension tests demonstrate that the ductility of the SF TRIP steel is increased by 5% compared with the CC TRIP steel. The difference of their properties is mainly due to the different morphologies of the δ-ferrite. We further employed a full-field crystal plasticity (CP) modeling to probe the micromechanical mechanisms in details, and a new simplified model was proposed to describe the TRIP effect and phase transformation. The material parameters of three individual phases δ-ferrite (δ), austenite (γ), and martensite (α′) for the CP model were identified from the loading curves of nanoindentation tests. Through the simulation, it was found that compared with SF TRIP steel, there are large deformation bands formed in the CC TRIP steel during the deformation. These areas are the regions in which austenite has the priority to transform into martensite. It is the initial heterogeneity of deformation in the CC TRIP steel that results in the heterogeneous phase transformation, and thus intensifies the heterogeneous deformation at the phase boundaries, which ultimately accelerates the generation of cracks.

Study of microstructure and tribological behaviour of spray cast high silicon hypereutectic Al-Si alloy

Abstract: This paper presents the study of the microstructure, wear properties of spray-deposited and hot compressed Al-35Si and Al-45Si alloys. The microstructure analysis and wear mechanisms of spray forme...

Effects of Cu and Mg alloying on the microstructure and properties of Al–12Si alloy prepared by spray forming

Abstract: Al–12Si alloys for electronic packaging shell were prepared by spray forming followed by hot pressing and the effects of 0.5%Cu and 0.6%Mg alloying on the microstructure, thermo-physical, and mechanical properties were examined. The microstructural observations show that Al2Cu, Mg2Si, and β″ phases were formed in the matrix by adding Cu and Mg. With the addition of Cu and Mg, the strength and hardness of the Al–12Si alloy increase from 154 to 234 MPa, and 55 to 75 HV, respectively, with an increment of approximately 51.9% and 36.3%. The strengthening effect is attributed to the combination of solution strengthening and precipitation strengthening. Compared with the unmodified alloy, the coefficient of thermal expansion of the modified alloy is increased slightly while the thermal conductivity is decreased slightly. Consequently, the alloying route of Al–12Si alloy is feasible for electronic packaging application.

Microstructure evolution and strengthening by cold rolling of CrMnFeCoNi high-entropy alloy processed by spray forming

Abstract: High-entropy alloys (HEAs) are defined as alloys that contain five or more major elements in atomic fractions ranging from 5 to 35%at Despite the presence of a large number of components, CrMnFeCoNi HEAs show simple FCC crystal structureThis work reports for the first time the effects of cold rolling on the final microstructure and the mechanical properties of a CrMnFeCoNi HEA processed by spray-formed and deformed to 30, 50, 90 and 146% of true strain The results presented an alloy with excellent workability and exhibited a large work hardening capacity in cold rolling It is concluded that the main deformation and hardening mechanisms during cold work are associated with the nanotwinning deformation of this alloy

Test parameters optimization for constrained spray forming of aluminum alloy based on artificial neural network

Abstract: Spray deposition with following continuous extrusion (SD-CE) forming technique is a novel technology that combines spray forming and continuous extrusion. Optimization of test parameters for spray deposition is an important part of SD-CE. In this study, Al-20Si alloy was produced by spray forming at different melt temperature and gas pressure, and obtained grain diameter of 8 group primary silicon phase. Based on the experimental results, an Artificial Neural Network (ANN) with single hidden layers composing of 10 neurons was employed to simulate optimizing of test parameters for spray deposition. The inputs of the model are melt temperature and gas pressure. The output of the model is grain diameter. Finally, the minimum relative error of grain diameter is 0.09%, the maximum relative error is 8.38%, and error majority concentrate within 3.80%, the average absolute relative error(AARE) is 1.04%, R is 0.097, the error is small. The optimal test parameters for spray deposition are melt temperature(829 °C) and gas pressure(0.2 MPa). The results indicate that the ANN model is an easy and practical method to optimize the test parameters for spray deposition of Al-20Si alloy. Thereby this model is a useful reference for optimizing the test parameters of SD-CE

Influences of a Hot-Working Process on the Microstructural Evolution and Creep Performance of a Spray-Formed Nickel-Based Superalloy

Abstract: A new third generation nickel-based powder metallurgy (PM) superalloy, designated as FGH100L, was prepared by spray forming. The effects of hot isostatic pressing (HIP) and isothermal forging (IF) processes on the creep performance, microstructure, fracture, and creep deformation mechanism of the alloy were studied. The microstructure and fracture were characterized by optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The coupled HIP and IF process improved the creep performance of the alloy under the creep condition of 705 °C/897 MPa. As for both the HIPed and IFed alloys, the creep process was dominated by the accumulation of dislocations and stacking faults, cutting through γ′ precipitates. The microstructural evolution was the main factor affecting the creep performance, which mainly manifested as coarsening, splitting, and morphology change of γ′ precipitates. Both the creep fractures of the HIPed and IFed alloys indicated intergranular fracture characteristics. In the former, wedge-shaped cracks usually initiated at the trigeminal intersection of the grain boundaries, while in the latter, cavity cracks generate more easily around the serrated curved grain boundary and carbides.

Stable Eutectic Formation in Spray-Formed Cast Iron

Abstract: Spray forming is an advanced casting process that produces refined and homogenous microstructure directly from the liquid metal regardless of the alloy system. However, the microstructure evolution during spray forming is complex because the process comprises two sequential steps with very different cooling rates, i.e., atomization and deposition. It is well known that the microstructure of cast irons is highly dependent on the chemical composition and the cooling rate imposed to the liquid. In order to better understand the microstructural evolution during solidification by spray forming, this study investigated the solidification of two cast irons with different stable–metastable eutectic temperature interval (ΔTES−M), 30 K and 17 K. The microstructures of both overspray powders presented a dendritic array of austenite with cementite in the inter-dendritic spacing. Despite the high cooling rates imposed to the alloys during the atomization step, the final microstructure was defined by the cooling conditions prevailing during the final step of deposit solidification and stable eutectic was formed. This was ascribed to the dynamic process involving heating and remelting of the low melting temperature phases present in the droplets that arrives completely or partially solid in the deposition zone.

Preparation method of high-strength and high-toughness aluminum-based composite material

Abstract: The invention relates to a preparation method of a high-strength and high-toughness aluminum-based composite material. The preparation method comprises the following steps of uniformly mixing Ti powder, carbon nanotube powder, carbon black and Al powder, carrying out ball milling, putting the mixture into a mold, and carrying out cold pressing to obtain a preform; carrying out combustion synthesisreaction to obtain a micro-nano mixed Al-C-Ti particle intermediate alloy sintered blank; mixing the micro-nano mixed Al-C-Ti particle intermediate alloy sintered blank with an an aluminum alloy meltin spray forming equipment, after atomizing, carrying out spray deposition to obtain a micro-nano mixed Al-C-Ti particle reinforced aluminum-based composite material blank; and carrying out extrusiondeformation and solution aging treatment to finally obtain the tubular or rod-shaped high-strength high-toughness aluminum-based composite material. According to the method, the strength and the elongation of aluminum alloy can be improved at the same time, when the mass percentage of micro-nano mixed Al-C-Ti particles in the aluminum-based composite material is 0.5%, the tensile strength is improved by 23.9%, and the elongation is improved by 33.3%; and the preparation method of the composite material is simple, low in cost, high in controllability and suitable for mass production.

High-strength and high-toughness aluminum-lithium alloy plate for aerospace and manufacturing method

Abstract: The invention provides a high-strength and high-toughness aluminum-lithium alloy plate for aerospace and a manufacturing method. The aluminum-lithium alloy plate comprises, by mass, 3.7%-4.3% of Cu, 1.1%-1.45% of Li, 0.12%-0.25% of Zn, 0.25%-0.8% of Mg, 0.08%-0.16% of Zr, 0.25%-0.6% of Ag, 0.08%-0.12% of Ti, and the balance Al. By adopting the spray forming technology to prepare the aluminum-lithium alloy plate, the novel aluminum-lithium alloy with high quality and high yield is realized, and the high-strength aluminum-lithium alloy plate for the aerospace is produced by adopting a special process so as to meet the requirements of aerospace technology. The structure of the aluminum-lithium alloy plate is a typical fibrous structure, the size is uniform, the tensile strength after solutionaging is 660 MPa, the specified non-proportional extension strength is 630 MPa, and the elongation rate after breaking is up to 15%. The problems of high casting forming difficulty and low strength of an existing aluminum-lithium alloy produced by an existing process are solved.

A method of spray forming an object.

Abstract: The invention relates to a method of forming a 3-dimensional solid object, comprising the steps: a) cold spraying one or more metallic powder to form a solid three dimensional item; b) thermally sintering the item such that a portion of the sprayed powder liquefies and reduces spaces between, and/or non-adhesion of, one or more solid portions of the item; and c) causing or allowing the portion of the sprayed powder that liquefied on heating, to become solid.

The Dispersion of Lead in Hypoeutectic Aluminium-Silicon Alloys by Spray Forming Process and their Characterization

Abstract: The present paper describes the Lead dispersion in hypoeutectic Aluminium-Silicon alloys and their microstructural characteristics. The homogeneous dispersion of Lead (Pb) in Aluminium-Silicon alloys (Al-6Si+Pb (=0, 10, 15, 20, 25)) were fabricated by using of spray forming technique (also known as spray casting or spray deposition) in the form of near-net shape disc. The microstructural characterization has been done for different location of spray formed disc by using optical microscopy (OM), Scanning electron microscopy (SEM) and X-Ray Diffraction (XRD) respectively. The results of the optical image were exhibited the equiaxed and globular grain morphology of primary Aluminium with the homogeneous dispersion of extremely fine and malleable particles of Lead and spherical particles of silicon in α–Aluminium matrix. The dispersed Lead has seen clearly in the SEM images of spray formed Aluminium-Silicon alloys and result of XRD pattern confirmed the phases of Aluminium-Silicon and Lead. The grain size of Aluminium has been analyzed by intercept line method. The lattice parameter and lattice strain have been calculated with the help of the XRD pattern to determine the effect of Lead dispersion on Al-Si alloy.

Novel heat treatment process for spray-formed 7055 ultrahigh-strength aluminum alloy extrusion sheet homogenizing annealing and solid solution aging

Abstract: The invention discloses a novel heat treatment process for spray-formed 7055 ultrahigh-strength aluminum alloy extrusion sheet homogenizing annealing and solid solution aging. The novel heat treatmentprocess comprises the following steps that (1) 7.6%-8.4% of Zn, 1.8%-2.3% of Mg, 2.0%-2.6% of Cu, 0.08%-0.25% of Zr, and the balance Al are taken in percentage by weight, and a 7055 aluminum alloy blank is obtained through a spray forming process; (2) hot working extruding is carried out to further improve the density of the 7055 aluminum alloy blank to obtain an extrusion material; and (3) the F-state extrusion material is subjected to homogenizing annealing heat treatment and solid solution aging heat treatment in sequence. According to the novel heat treatment process for spray-formed 7055ultrahigh-strength aluminum alloy extrusion sheet homogenizing annealing and solid solution aging, a spray forming technology is used for preparing a large-specification spray-formed 7055 aluminum alloy circular ingot with homogeneous structure components; extruding hot working is used for obtaining the densified extrusion strip material with a homogeneous structure; and the anisotropy of a spray-formed 7055 ultrahigh-strength aluminum alloy extrusion sheet is greatly improved through the homogenizing annealing and solid solution aging heat treatment process, and the spray-formed 7055 ultrahigh-strength aluminum alloy extrusion sheet with three-dimensional tensile strength not lower than 600 MPa, three-dimensional elongation not lower than 4% and excellent whole performance is obtained.

Aluminum lithium alloy for large-depth pressure bearing shell and preparation method of aluminum lithium alloy

Abstract: The invention discloses an aluminum lithium alloy for a large-depth pressure bearing shell and a preparation method of the aluminum lithium alloy. The alloy comprises the metal materials in percentageby mass: 1.0-1.5% of Li, 3.2-5.0% of Cu, 0.2-1.0% of Mg, 0.4-0.9% of Ag, 0.08-0.18% of Zr, 0.1-0.5% of Mn, 0.2-1.0% of Zn, less than or equal to 0.05% of Si, less than or equal to 0.8% of Fe, less than or equal to 0.1% of Ti, and the balance of Al. The preparation method includes the following steps of (1) batching; (2) preparation of an alloy ingot blank through spray forming; (3) extruding; (4)forging and upsetting; (5) reverse extruding; (6) thermal treatment; and (7) distressing aging. High-quality melt with high cleanliness and less hydrogen content is prepared through argon-shield smelting and furnace refining, the aluminum lithium alloy cast ingot with high metallurgical quality is prepared through spray deposition and electromagnetic stirring technologies, and the spray deposition technology solves the problems of non-uniform structure and macroscopic segregation of the aluminum lithium alloy cast ingot. According to the specification of the prepared aluminum lithium alloy ingot blank, the diameter is greater than phi 550 mm, the shape is regular, the density is high, and the chemical compositions are uniform and free of macroscopic segregation.

Spray forming process of thermoplastic composite material

Abstract: The invention discloses a spray forming process of a thermoplastic composite material. The spray forming process of the thermoplastic composite material comprises the following steps of (1), continuously spraying heated and pressurized resin powder to a fiber reinforcement body which moves at a uniform speed, impacting the surface of the fiber reinforcement body by the resin powder and enabling the resin powder to enter the inner part of a fiber bundle, instantly converting part of kinetic energy of the resin powder into heat energy, instantly melting and plasticizing the resin powder, impregnating the fiber reinforcement body, and obtaining a prepreg primary sample after impregnation; and (2) sequentially carrying out preheating treatment and shaping treatment on the prepreg primary sample to obtain the thermoplastic composite material after completion. According to the spray forming process of the thermoplastic composite material, the impregnating effect of the thermoplastic composite material is effectively improved.

Spray forming method of ZSM-5 molecular sieve catalyst

Abstract: The invention discloses a spray forming method of a ZSM-5 molecular sieve catalyst. By adopting two-step spray forming, the method comprises the following steps of: firstly adding a small amount of alkaline silica sol, carrying out spray forming on a ZSM-5 molecular sieve, then adding aluminum sol into the obtained product, and carrying out secondary spray forming. According to the invention, spray molding of the molecular sieve catalyst is realized by a two-step spray molding method under the condition of adding a small amount of binder. The forming rate of the formed ZSM-5 molecular sieve catalyst is greatly improved, and the formed ZSM-5 molecular sieve catalyst has excellent fluidity and wear resistance, shows good catalytic activity, meets industrial application, and has great practical application value and broad prospects.