Preparation of Ti-based amorphous brazing alloy

A new kind of amorphous active brazing alloy foil with the composition of Ti40Zr25Ni15Cu20 was successfully synthesized using melt spinning in roll forging machine in argon atmosphere. The amorphous structure and composition were examined by X-ray diffraction, differential thermal analysis and energy dispersive X-ray detector. The results show that the Ti40Zr25Ni15Cu20 amorphous alloy foil has excellent wettability on Si3N4 ceramic and demonstrate a strong glass forming ability. The reduced glass transition temperature （Trg） and the temperature interval of supercooled liquid region before crystallization are 0.76 and 78 K, respectively.     

Reduction of metal ions on aluminium in molten flux during aluminium brazing

ＲｅｄｕｃｔｉｏｎｏｆｍｅｔａｌｉｏｎｓｏｎａｌｕｍｉｎｉｕｍｉｎｍｏｌｔｅｎｆｌｕｘｄｕｒｉｎｇａｌｕｍｉｎｉｕｍｂｒａｚｉｎｇＺｈａｎｇＱｉｙｕｎ（ＢｅｉｊｉｎｇＵｎｉｖｅｒｓｉｔｙ）Ａｂｓｔｒａｃｔ：Ｔｈｅｍｅｃｈａｎｉｓｍｏｆａｃｔｉｖｉｔｙ...     

Novel approach of LY12 alloy brazing

The LY12 Al alloy was brazed with the adoption of the improved KF-CsF-AlF3 flux matching Ag-Al-Cu-Zn filler metal. The shear strength of brazed joint could reach 80% of that of the substrate and the tensile strength of butt brazed joint will be 70% of that of the substrate. This was the great progress against the traditional claim that Al alloy reinforced by heat treatment could not be brazed. The experimental results and theoretical analysis had proved that it was the key issue to remove the MgO oxide film below 503℃. The addition of rare earth La was the effective way to obtain better mechanical properties of the filler metal as well as brazed joints.     

Analysis of intermetallic layer in dissimilar TIG welding–brazing butt joint of aluminium alloy to stainless steel

Abstract

Intermetallic layer of dissimilar tungsten inert gas welding–brazing butt joint of aluminium alloy/ stainless steel has been studied. A visible unequal thickness intermetallic layer has formed in welded seam/steel interface, and the thickness of the whole layer is <10 μm. The interface with Al–12Si filler metal consists of τ ₅-Al₈Fe₂Si layer in welded seam side and θ-(Al,Si)₁₃Fe₄ layer in steel side with the hardness values of 1025 and 835 HV respectively, while the interface with Al–6Cu filler metal consists of θ-Al₁₃(Fe,Cu)₄ layer with the hardness of 645 HV. The average tensile strength of the joint with Al–12Si filler metal is 100–120 MPa, and the fracture occurs at θ-(Al,Si)₁₃Fe₄ layer, while the joint with Al–6%Cu filler metal presents high crack resistance with tensile strength of 155–175 MPa, which reaches more than 50% of aluminium base metal strength.     

Behavior and influence of Pband Biin Ag-Cu-Zn brazing alloy

0　ＩｎｔｒｏｄｕｃｔｉｏｎＰｂａｎｄＢｉａｒｅｃｏｍｍｏｎｉｍｐｕｒｉｔｙｅｌｅｍｅｎｔｓｉｎＡｇＣｕＺｎｂｒａｚｉｎｇａｌｌｏｙ[1].ＩｎｔｈｅｎａｔｉｏｎａｌｓｔａｎｄａｒｄｓｏｆＡｍｅｒｉｃａ,Ｊａｐａｎ,ＧｅｒｍａｎｙａｎｄＣｈｉｎａ(ｓｕｃｈａｓＡＮＳＩ/ＡＷＳＡ5.892,ＪＩＳＺ32611985,ＤＩＮ8513386,ＧＢ1004688),ｔｈｅｃｏｎｔｅｎｔｏｆａｌｌｔｈｅｉｍｐｕｒｉｔｙｅｌｅｍｅｎｔｓｉｎｂｒａｚｉｎｇａｌｌｏｙｉｓｒｅｓｔｒｉｃｔｅｄｔｏａｒａｎｇｅｎｏｔｅｘｃｅｅｄｅｄ0.15%[2].Ｂｕｔ,ｉｆｔ…     

Investigation of the weldability of an aluminium–lithium alloy

Investigations were carried out to study the effect of the chemical composition of filler material in welding an alloy of the Al–Mg–Li system on the hot crack formation resistance and the mechanical properties of welded joints. The effect of metallurgical factors on the formation of defects in the fusion zone was investigated using the spot weldability testpiece. The chemical composition of 1420 alloy was optimized and this greatly reduced the number of defects. The investigations were carried out in the framework of the research project 10.8. Technology of fusion welding of new constructional materials (‘Strategic directions of development of materials and technologies of processing these materials for the period up to 2030’) [1 Kablov EN. The strategic directions of development of materials and technologies of processing these materials for the period to 2030. Aviatsionnye materialy i tekhnologii. 2012;5:7–17. [Google Scholar]].     

Uniaxial stress–strain behaviour of aluminium alloy foams

The tensile and compressive stress–strain behaviour of closed cell aluminium alloy foams (trade name “Alulight”) has been measured and interpreted in terms of its microstructure. It is found that the foams are anisotropic, markedly inhomogeneous and have properties close to those expected of an open cell foam. The unloading modulus and the tensile and compressive yield strengths increase non-linearly with relative density. The deformation mechanisms were analysed using image analysis software and a d.c. potential drop technique. The scatter in results is attributed to imperfections within the foam. These include non-uniform density, weak oxide interfaces, and cell faces containing voids and cracks.     

Corrosion behavior of Cu-Ni-Ag-Al alloy anodes in aluminium electrolysis

The behavior of Cu-Ni-Ag-Al alloy used as anode for aluminum electrolysis was directly visualized in a two-compartment see-through cell during electrolysis, and its performances were tested at 850℃ in acidic electrolyte molten salts consisting of 39.3%NaF-43.7%AlF3-8%NaCl-5?F2-4%Al2O3 for 40 h in a laboratory cell. The results show that nascent oxygen oxidizes the anodic surface to form oxide film at the beginning of electrolysis. X-ray diffraction analysis of alloy surface show that the oxide film on the anodic surface consists of CuO, NiO, Al2O3,CuAl2O4 and NiAl2O4. However, SEM image shows the oxide film is porous, loose and easy to fall into electrolyte and to contaminate aluminum. The corrosion mechanism of metal anodes was analyzed.     

Optimisation of the processes of laser,microplasma and hybrid laser–microplasma welding of aluminium alloys

The results of investigation into laser, microplasma and hybrid laser–microplasma methods of welding aluminium alloys are presented. The optimum energy values for welding with the radiation of CO₂ lasers are determined. Shortcomings of microplasma welding are outlined and the main advantages of hybrid laser–microplasma welding are discussed. Detailed study of the macro- and microstructures of the welded joints and the heat affected zone shows that in all cases the structure is sufficiently equiaxed, dense, without visible defects and is dendritic.     

CO2 and Nd–YAG laser beam welding of 5754–O aluminium alloy for automotive applications

Abstract

Federal regulations have recently been enacted to reduce significantly the atmospheric pollution caused by motor vehicles. This has compelled automotive manufacturers to improve the fuel efficiency of cars and light trucks by using lightweight materials such as aluminium. The focus of the present work is to develop welding procedures for autogenous CO₂ (continuous mode) and Nd–YAG (continuous mode) laser beam welding of 5754–O aluminium alloy. The mechanical and microstructural characteristics of the welded joints were evaluated using tensile tests, microhardness tests, optical microscopy, and chemical analysis. Results indicate that this alloy can be autogenously laser welded with full penetration, minimum surface discontinuities, and little if any loss of magnesium through vaporisation from the fusion zone. The total elongation (all weld metal) in the longitudinal direction for 5754–O laser welds produced using 5 kW CO₂ and 3 kW continuous wave (CW) Nd–YAG shows a slight decrease with increasing travel speed. Studies indicate that the decreasing tendency is probably due to the orientation of the grains with respect to the loading direction. The welds produced using the 5 kW CO₂ laser at travel speeds between 127 and 212 mm s^-1 displayed a total longitudinal elongation of 19.13–15.12% and those produced using the 3 kW CW Nd–YAG laser at travel speeds between 85 and 148 mm s^-1 displayed a total longitudinal elongation of 22.6–18.15%, compared with the base metal value of 28.1%. An observation of great interest was that the weld surface condition did not have any effect on the ductility of the 5754–O aluminium alloy studied in the present investigation.     

Homogenisation of chemical composition and microstructure in laser filler wire welding of AA 6009 aluminium alloy by in situ electric current stirring

Owing to the rapid cooling rates, the deposited and base metals could be mixed incompletely during laser welding of Al alloys in most cases. The objective of this research is to explore a possible method to promote the mixing of materials inside the molten pool by making use of the magnetofluid dynamic effect of electric current. Full penetration CO₂ laser welding of 3?mm thick alloy 6009 sheets was performed with an external electric current simultaneously into the weld pool via a filler wire. It is found that the deposited metal is mainly concentrated on the upper part of the weld fusion zone, and the weld zone microstructure is non-uniform without the electric current addition. With the application of an electric current, the weld fusion zone geometry is reshaped, and the chemical composition and microstructure of the weld metal are homogenised. The mechanism is found to be electromagnetic force stirring of the molten pool.     

Visual sensing of weld pool in variable polarity TIG welding of aluminium alloy

1 Introduction Real-time measuring of the size of welding pool is the precondition to weld shape control[1?4]. Among the researched sensing methods, the passive visual image sensing has been proved to be a feasible and promising method due to its abundan…     

Assessment of mechanical properties of aluminium alloy welded joint using small punch test

The small punch test technique （SPT） was used to evaluate the mechanical properties of various materials and the basic method to test material tensile mechanics peqeormance from an inverse finite element （ FE） arithmetic with SPT was put forward. The research shows that specific tensile mechanical behavior and strain-stress distribution of each district of weld seam can be accurately determined by small punch test. Therefore, mechanical behavior of the inhomogeneous joint can be predicted by a numerical model. The simulation comes to good agreement with experimental data.     

Application of laser welding to the aluminium alloy chamber for a huge synchrotron radiation facility (SPring‐8)

This paper reports the results of microstructural characterization studies conducted on copper alloy joints obtained by different brazing processes. In particular, tests have been conducted on Cu–Ni–Zn ternary alloys (nickel silvers), traditionally used in the spectacle industry, in order to highlight the merits and any metallurgical and functional defects in samples obtained using two different heat input methods: induction and LASER beam welding.

Along with the metallographic analysis of joints made using the traditional induction brazing technique, the joints obtained by LASER brazing have been investigated. In particular, it has been evaluated as to how altering the process parameters pertaining to both the LASER beam (power and impact time) and base metal surface conditions (presence or absence of surface oxides) can significantly influence the formation of macroscopic defects in the joints or on deformation of the components themselves.

Hence, the main scope of the paper has been an attempt to identify the optimal process parameters for LASER beam brazing, so that the joints thus obtained have acceptable mechanical properties, while maintaining good aesthetic appearance, a decidedly essential requirement in components for spectacles.     

Modeling of microstructural evolution and flow stress of aluminium alloy during thermomechanical process

The evolution of microstructural variables, including the densities of mobile dislocation, immobile dislo-cation at the cell interiors, immobile dislocation in the cell walls, as well as total dislocation density, of an Al-Mg-Si aluminium alloy during thermomechanical processing were simulated based on a three-internal-variables-model (3IVM) involving dislocation climb and interaction. Optimization was carried out to fit the calculated stress--strain curves to the experimental data of the Al-Mg-Si alloy with minimum mean deviation. Precipitations were taken into consideration of modeling. The stress--strain curves predicted by the kinetic equations of state in the 3IVM have a good agreement with the experimental data.     

Technological special features of welding 1460 high‐strength aluminium alloy

Summary

Aluminium alloys are used extensively, whenever the advantages of high strength-to-density ratio, reduction of dead weight and corrosion resistance, make these alloys competitive with other materials. The major markets for structural application of aluminium alloys are civil engineering and the transport industry, in particular, aircraft construction and more recently, that of electric and low emission cars.

One of the difficulties to be overcome in using aluminium alloys is the reduction of mechanical properties due to HAZ (Heat Affected Zone) deterioration caused by welding.

The mechanical and microstructural characteristics of MIG welded joints in 6082-T6 plate alloy were investigated by means of tensile tests, fatigue bending tests, microhardness analysis, and optical and SEM metallography.

The reduced hardness and tensile strength in the HAZ have been linked to the mechanisms of deterioration of constituents initially present in the alloy, originating from quenching and thermal ageing treatment.     

Interface and microstructure characteristics of SiC_p/2024 aluminium alloy composite

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｉｍｐｏｒｔａｎｃｅｏｆｐａｒｔｉｃｕｌａｔｅｒｅｉｎｆｏｒｃｅｄｍｅｔａｌｍａｔｒｉｘｃｏｍｐｏｓｉｔｅｓ(ＰＭＭＣｓ)ｄｕｅｔｏｈｉｇｈｓｐｅｃｉｆｉｃｓｔｒｅｎｇｔｈ ,ｈｉｇｈｓｐｅｃｉｆｉｃｍｏｄｕｌｕｓ ,ｂｅｔｔｅｒｒｅｓｉｓｔａｎｃｅｔｏｗｅａｒａｎｄｔｈｅｒｍａｌｓｔｅａｄｉｎｅｓｓｈａｓａｔｔｒａｃｔｅｄｍｕｃｈｉｎｔｅｒｅｓｔｉｎｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｔｈｅｍａｎｕｆａｃｔｕｒｉｎｇｐｒｏｃｅｓｓｆｏｒｓｕｃｈｃｏｍｐｏｓｉｔｅｓ .Ｔｈ…     

Mechanical properties of friction stir welded joints of 1050 – H24 aluminium alloy

Abstract

The friction stir welding (FSW) of 1050 - H24 aluminium alloy was performed to investigate the mechanical properties of the joints and determine the optimum FSW parameters. The mechanical properties of the joints were evaluated via tensile tests. The experimental results showed that a distinct softened region located at the weld and heat affected zones occurred in the joints. The degree of softening and tensile properties of the joints are significantly affected by the welding process parameters, such as welding speed and rotation speed. The optimum FSW parameters can be determined from the relations between the tensile properties and the welding parameters, and the maximum tensile strength of the joints is equivalent to 80% of that of the base material. When the welding parameters deviate from the optimum values, a crack like defect or significant softening is produced in the joints, thus the tensile properties of the joints deteriorate and the fracture locations of the joints change. All these results can be explained by the hardness distributions and welding defects in the joints.