Bimetal Composite Research Articles

Analysis of heat transport and thickness of bimetal composition layer between low-alloy steel and high-chromium white cast iron

Two-liquid bimetal casting technique was worthy of being widely used in wear-resistant materials. Research on the fusion mechanism at the bimetal composite layer can lay the theoretic foundation for the extension of the dissimilar ferroalloy composition material. Two-liquid bimetal between the low-alloy steel and high-chromium white cast was prepared by controlling the pouring temperature, and the composite layer microstructure and composition distribution were studied. In accordance with the detected results, two-liquid bimetal casting technique can be assured, and the various casting technique parameters have an obvious effect on the composite layer microstructure. To maintain the casting technique stability, the freezing time and element diffusion of the low-alloy steel were evaluated and analysed.

Investigation of Al/Steel Bimetal Composite Fabrication by Vacuum Assisted Solid Mould Investment Casting

Bimetal composites are a group of promising engineering materials with high developing and service potential.Especially in many elds they can be a powerful low cost alternative to metalceramic composites. The mostcommonly encountered type of these composites is steel reinforced aluminium matrix composites which stand outwith high wear and abrasion resistance. Signi cant fabrication processes of metal/metal composites are based onliquid metal techniques. In this study, Al/steel composite specimens were produced by using acuumv assisted solidmould investment casting technique. A7075 wrought aluminium alloy were in ltrated into steel preforms, whichwere produced with 304 stainless steel and H13 hot-work tool steel turnings, in the plaster based solid investmentcasting moulds. Microstructure observations, HV microhardness measurements, scanning electron microscopy andenergy dispersive X-ray spectroscopy analysis were carried out for characterization.DOI:10.12693/APhysPolA.126.1327ACS:P 81.30.Fb, 81.30.t, 81.20.n

Analyse eines durch das Co-Spray-Verfahren hergestellten Werkzeuges zur Warmumformung

Abstract In the industrial manufacturing chain of roller bearings the hot bars are subsequently sheared into billets and these are automatically transported to the first forming stage of the press. Normally the cobalt-based hard-facing alloys for the blades are deposited by manual metal arc or plasma transfer arc welding. In the research work presented here, the hard-facing alloys are produced by spray forming to increase the life time of the tool. Long life time is expected because of the advantages of spray forming: homogeneity of the microstructure, a low segregation and absence of a heat affected welding zone. For this purpose a bi-metal composite is deposited in a co-spray process to combine the hard-facing alloy layer with a hot working steel to insert the blade into a carrier. The interface between the two different materials was analyzed in terms of porosity, hardness, adhesive strength and machinability to describe the new composite material.

Functional properties of ‘Ti50Ni50–Ti49.3Ni50.7’ shape memory composite produced by explosion welding

A bimetal composite, Ti50Ni50–Ti49.3Ni50.7, was produced by explosion welding, causing a Martensitic transformation. The functional properties of these objects were studied. It was found that explosion welding partially depressed the Martensitic transformation; however, a subsequent annealing resulted in the recovery of the kinetics of Martensitic transformations. Moreover, a variation in the annealing temperature allowed the control of a sequence of Martensitic transformations in the Ni-rich layer. The influence of the ratio of the equiatomic TiNi layer thickness to the total thickness of the bimetal composite on the recoverable strain was studied, and it was found that the maximum recoverable strain was observed when the thickness of the equiatomic TiNi layer was approximately equal to 55% of the total thickness of the sample. Functional properties were studied in the bimetal composite using the optimal ratio of the layer’s thickness. It was found that the value of the recoverable strain depended on the value of the residual strain as well as the sequence of the Martensitic transformations that occurred in the Ni-rich TiNi layer.

The Influence of Grain Interactions on the Plastic Stability of Heterophase Interfaces.

Two-phase bimetal composites contain both grain boundaries and bi-phase interfaces between dissimilar crystals. In this work, we use a crystal plasticity finite element framework to explore the effects of grain boundary interactions on the plastic stability of bi-phase interfaces. We show that neighboring grain interactions do not significantly alter interface plastic stability during plane strain compression. The important implications are that stable orientations at bimetal interfaces can be different than those within the bulk layers. This finding provides insight into bi-phase microstructural development and suggests a pathway for tuning interface properties via severe plastic deformation.

Fabrication and performance of a Mn–La metal composite for remarkable decontamination of fluoride

Fluoride contamination has become a great issue of concern in recent years as it could cause a high risk to human health through water consumption. In this study, a new manganese–lanthanum bimetal composite was developed by a co-precipitation method. The adsorption was highly pH dependent, and the optimal adsorption was obtained at pH 5.0. The Langmuir equation better fitted the experimental data of the adsorption isotherm. The maximum adsorption capacity of 292.9 mg g−1 was achieved at the optimal pH, much higher than most currently reported sorbents. The adsorption occurred rapidly in the first 1 h; the adsorption equilibrium was reached within 8 h. The presence of chloride, sulfate, carbonate and humic acid had an insignificant influence on the fluoride uptake; however, phosphate greatly hindered the removal. The adsorption reactions due to the presence of weak acid functional groups and the ion exchange reaction between sulfate and fluoride could be responsible for the removal of fluoride. The adsorption history was described by the intraparticle diffusion model.

An investigation of metallurgical bonding in Al–7Si/gray iron bimetal composites

Abstract

Mathematical modelling of producing hollow ingot by electroslag casting with liquid metal

Electroslag casting with liquid metal (ESC LM) is a new technology in electroslag metallurgy. Solid ingot, hollow ingot and bimetal composite can be produced by the ESC LM process. Using both internal and external current carrying moulds for ESC LM is a new method for manufacturing hollow ingots. Liquid metal is employed directly during the ESC LM process rather than the conventional consumable electrode. The process was simulated using infinite element software ANSYS. The results indicate that the conductive path of the ESC LM process is entirely different from the conventional electroslag remelting process. There are two conductive current paths: one conductive path is transformer→external current conductive mould→liquid slag→internal current conductive mould→transformer, and another conductive path is transformer→external current conductive mould→liquid slag→molten steel pool→liquid slag→internal current conductive mould→transformer. Current density, magnetic inductive intensity, electromagnetic force, Joule heat distributions and fluid flow are concentrated on the upper area of the slag pool. In addition, the higher temperature region of the slag pool is at the upper area of the slag pool. The superheat of the molten steel pool is lower than the conventional electroslag remelting process, which favours improving the quality of the hollow ingot. Simulation of the ESC LM process will help understanding the process and choose better operating parameters.

Mechanical Properties of Hypo/Hyper-Eutectic Al-Si Bi-Metal Composite Parts Prepared by Thixo-Forging

Hypo/hyper-eutectic Al-Si bi-metal composite parts were prepared by the strain-induced melt activated (SIMA) thixo-forging. The interfaces of the bi-metal composites were observed using OM, and SEM. The tensile strength and hardness of the matrix alloys and the bonding strength at the interface were assessed by tensile test and micro-indent test. Results show that the eutectic structure joined together on the interface under the pressure. However, there are some defects such as holes and impurities were found near the interface. The tensile test samples were broken in Al-20 wt. % Si matrix. The bonding strengths at the interfaces were higher than 80 MPa. Results show that the hardness gradually increasing from 55 HV in Al-7 wt. % Si alloy to 180 HV in Al-20 wt. % Si alloy, which demonstrate the composite interface transited smoothly. The composite interface has an average hardness of 80 HV.

Structure–Property–Functionality Relationships in Bimetal Composites

Structure–Property–Functionality Relationships in Bimetal Composites

On the interface and mechanical property of Ti/Al–6%Cu–0.5%Mg–0.4%Ag bimetal composite produced by cold-roll bonding and subsequent annealing treatment

Ti/Al–6%Cu–0.5%Mg–0.4%Ag bimetallic composite has been successfully produced by cold-roll bonding and subsequent annealing treatment. The threshold deformation is about 44% total rolling reduction in a single rolling pass. The highest interlaminer shear strength up to about 40MPa in the composite is obtained by 515°C/12h annealing treatment. The calculation indicates that the tensile strength of Ti/Al–6%Cu–0.5%Mg–0.4%Ag bimetal composite is consistent with the mixture rule obeyed by composites. TiAl3 is the first and the only phase formed during the annealing process, and it experiences a lateral growth in the direction parallel to the interface then a thickening in the direction perpendicular to the interface.

Study on Lining Board with Bimetal Liquid Composite Casting

The effect of chemical constitution, casting technique and heat treatment parameters on microstructure, properties and wearing resistance of the bimetal composite were primarily researched by SEM, EDAX, TEM etc.. The results showed that the higher impact toughness at bimetal combination region than corresponding part of the high carbon steel was obtained. The impact toughness was 23J/cm2 and the hardness of resistant surface was HRC59. The high carbon steel region initiated the impact fracture, however its abrasion resistance was substantially improved over double than Mn13.

Effect of the composition of the shielding gas and design of the non-consumable cathode on the penetrating capacity of the arc and formation of welded joints

Processing features of a d.c. arc in helium and its mixtures with argon are considered, using non-consumable electrodes of three types, i.e. with conic grinding of the working area, butt end cavity, and bi-metal composite. Influence of the electrode working area construction and shielding gas composition on the depth, width, and penetration shape ratio, as well as on the weld seam formation quality, is investigated.

Tribological performance of graphite containing tin lead bronze–steel bimetal under reciprocal sliding test

As a solid self-lubricating material to serve under heavy load and low velocity, graphite containing tin lead bronze–steel bimetal composites were prepared using the powder metallurgy (P/M) technique. Effects of graphite content on tribological performance under reciprocal sliding were studied using the UMT-2MT tribo-meter. The optimal performance of average friction coefficient, maximum friction coefficient, friction coefficient amplitude and wear resistance can be achieved at the graphite content of ∼3 wt%. Appropriate graphite content and hardness are the two most crucial factors to achieve a good quality lubricating film on the worn surface and hence the desired solid lubrication performance.

Observation of interface of two kinds of bi-metal composite parts prepared by thixo-forging

Two kinds of bi-metal composite parts (Sn-15%Pb and Pb-22%Sn bi-metal system, and Al-7%Si and SiC p/6061 MMC bi-metal system) were prepared by the strain-induced melt activated thixo-forging. The interfaces of the bi-metal composites were observed by OM and SEM. The observations show that the semisolid metals keep independence during thixo-forging. The solid phases in the semisolid slurries maintain their original morphologies after thixo-forging. The liquid phases near the interface mix together and form a thin layer. The interfaces are bonded firmly with the metallurgical bonding. No oxide layers are found at the interfaces. Strengths of the interfaces were investigated by the micro-hardness test. The experimental results show that the composite interfaces have high strength. However, the agglomerated enhancing particles cause fine defect on the interface of the Al-7%Si and SiC p/6061 MMC bi-metal composite.

Functional properties of bimetal composite of “stainless steel–TiNi alloy” produced by explosion welding

The functional properties of “TiNi–stainless steel” bimetal composite produced by explosion welding were studied. The influence of the ratio of the TiNi layer thickness to the total thickness of the sample as well as the influence of preliminary deformation on the recoverable strain and a temperature of shape memory effect were studied. It was found that the best combination of strain variation observed in repeated thermal cycles was demonstrated by the bimetal sample in which the thickness of the TiNi layer was 64% of the thickness of the sample. The preliminary deformation resulted in an increase in stress stored in the sample and led to an increase in recoverable strain.

Porous Anisotropic Metal Nanostructures Through Controlled Transmetallation Across a Dialysis Membrane

Nanostructured metals with hollow interiors are of technological importance due to their unique optoelectronic properties and enhanced surface area. We describe herein, a novel method for the synthesis of anisotropic gold and palladium nanoparticles through a simple galvanic replacement reaction across a semi-permeable dialysis membrane. The control over the reaction kinetics achieved by the presence of membrane enables one to tune the bimetal composition, particle porosity and morphology. Rapid outward diffusion of silver ions generated from the sacrificial silver nanoparticles even at room temperatures prevents the precipitation of high quantities of silver chloride, thereby circumventing the need for product purification. The porous anisotropic nanostructures have potential applications in catalysis, cell imaging and therapeutics.

Effect of neutron irradiation on the mechanical properties of 316L(N) steel for International Thermonuclear Experimental Reactor applications

One of the features peculiar to the application of 316L(N) steel for International Thermonuclear Experimental Reactor components is that it will be used in such components as the divertor and the first wall, mainly as part of the Cu–stainless steel bimetal composition. The main purpose of this investigation was to estimate the effect of heat treatment on the radiation hardening and embrittlement of 316L(N) steel. The report presents the results from an experimental investigation into the effect of low-temperature neutron irradiation on the radiation hardening and embrittlement in 316L(N) steel after different heat treatments. Specimens of 316L(N) steel were irradiated at T irr=150 and 80 °C in the dose range 0.001–2 dpa in the RBT-6 and SM-2 reactors. It is shown that heat treatment does not cause a significant effect on the radiation hardening and embrittlement of 316L(N) steel.

Growth rate of intermetallic compounds in Al/Cu bimetal produced by cold roll welding process

The aim of this article is to study the growth rate of intermetallic compounds at the interface of cold roll bonded Al/Cu bimetal at 250°C and compare the results with a similar study performed on friction welding of Al to Cu. Samples of tri-layered Cu–Al–Cu composite were produced by the cold roll welding process and heat treated at constant temperature of 250°C for 1 to 1000 h. The thickness, morphology and composition of the intermetallic compound at the interface of Cu and Al were studied by optical and scanning electron microscope and EDX analyzer. The presence of various intermetallic compounds (Cu 3Al, Cu 4Al 3, CuAl and CuAl 2) was detected and the priority of formation of each compound was studied. The bond strength and electrical resistivity of different samples were measured by peeling test and a high precision micro-ohmmeter, respectively. The variations of resistivity and bond strength versus thickness of intermetallic compound were plotted. It was observed that the strength and electrical conductivity are greatly reduced by increasing the thickness of intermetallic compounds. Moreover, the growth rate of intermetallic compounds in roll welded bimetal composite is lower compared with that reported for similar friction welded specimens.

Thermocyclic treatment of the bimetal steel-wear-resistant iron blanks

1. TCP of blanks made from the bimetal steel-wear-resistant iron does allow one to eliminate the defects of the overheated steel base, i.e., the Widmanstaten structure, and large grain practically without changing the structure of the coating layer whose microhardnes is slightly higher than it was in the initial condition. 2. Use of TCP for the treatment of the bimetal steel-wear-resistant iron permits one to increase the serviceability and life of parts for which these bimetal composites are used.