STUDY ON DIFFUSION WELDING OF ALUMINIUN MATRIX COMPOSITE

Effects of diffusion welding parameters on strength of welded joint based on particle reinforced alumini- um matrix composite Al2O3p/6061Al were studied by comparing with aluminium matrix alloy,Mecha- nism for the loss of joint strength was analyzed.It was pointed out that the key processing parameters affecting the strength of joint was the welding temperature.The high quality joint can be successfully obtained with appropriate diffusion welding parameters.

Predicting effects of diffusion welding parameters on welded joint properties by artificial neural network

The static model for metal matrix composites in diffusion welding was established by means of artificial neural network method. The model presents the relationship between weld joint properties and welding parameters such as welding temperature, welding pressure and welding time. Through simulating the diffusion welding process of SiC w/6061Al composite, the effects of welding parameters on the strength of welded joint was studied and optimal technical parameters was obtained. It is proved that this method has good fault tolerant ability and versatility and can overcome the shortage of the general experiment. The established static model is in good agreement with the actual welding process, so it becomes a new path for studying the weldability of new material.

Diffusion welding of SiCp/2014Al composites using Ni as interlayer

SiCp/2014Al composites were bonded with the vacuum diffusion welding technique using Ni as the interlayer metal. Ni and Al were interdiffused and there were intermetallic compounds formed in the inter transition layer, which was composed of Ni3Al//NiAl//NiAl3. The relation between the diffusion distance and the element concentration was calculated according to Fick＇s second law. The relations of the diffusion concentration and the diffusion welding technique parameters were calculated.

EFFECTS OF DIFFUSION WELDING PARAMETERS ON JOINT STRENGTH OF SiCw/6061AI COMPOSITE

Diffusion welding was used to join SiCw/6061AI composites. The effects of welding pammeters on strength Of welded joint were investigated. JOint Of high quality for SiCw/6061Al composites can be obtained with aPPropriate diffesion welding parameters.

Study on diffusion welding SiCp/ZL101 with Cu interlayer

Through the vacuum diffusion welding SiCp/ZL 101 aluminum with Cu interlayer,the effect of welding parameter and the thickness of Cu on the welded joint property wasinvestigated, and the optimal welding parameters were put forward at the same time. Themicrostructure of joint was analyzed by means of optical-microscope, scanning electron microscope inorder to study the relationship between the macro-properties of joint and the microstructure. Theresults show that diffusion welding with Cu interlayer could be used for welding aluminum matrixcomposites SiCp/ZL 101 successfully.

Study on Diffusion Welding Parameters of Particle reinforced Aluminium Matrix Composite Al_2O_(3p) /6061Al

Effects of diffusion welding process parameters on strength of welded joint based on particle reinforced aluminium matrix composite Al 2O 3p /6061Al have been studied through comparing with aluminium matrix alloy. The mechanism for loss of joint strength has been analyzed. It should be pointed out that key processing parameters affecting the strength of joint was welding temperature. The high quality joint can be successfully obtained with appropriate diffusion welding parameters.

DIFFUSION WELDING FOR 6061 Al REINFORCED WITH SiCw WHISKER

The weldability of SiCw/6061Al -was investigated. From the results of experiments, it is found that the strength of joint is mainly influenced by welding temperature, and high strength of joint is obtained under melding temperature between liquidus and solidus of matrix alloy. Diffusion welding of SiCw/6061Al was successfully realized with appropriate ivelding parameters.

Diffusion welding SiC_p/ZL101 with Ni interlayer

Through the vacuum diffusion welding SiC_p/ZL101 aluminum with Ni interlayer,the effect of welding parameter and the thickness property of Ni on the welded joint wasinvestigated, and the optimal welding parameters were put forward at the same time. Themicrostructure of joint was analyzed by means of optical-microscope, scanning electron microscope(SEM) in order to study the relationship between the macro-properties of joint and themicrostructure. The results show that diffusion welding with Ni interlayer can be used for weldingaluminum matrix composites SiC_p/ZL101 successfully. Under the welding parameters T=560℃, P=5 MPa,t=60 min, H=14μm, the bonding strength of welded joint can up to 121 MPa. Moreover, the thicknessof interlayer should match with the size of reinforced particles. If the thickness of interlayer istoo thin, it would have no effect on the welded joint beneficially. If the thickness of interlayeris too thick, it would cause the 'no-reinforcement zone' to appear.

Effect of welding temperature and duration on properties of 7075 Al to AZ31B Mg diffusion bonded joint

7075 Al alloy and AZ31B Mg alloy were joined by diffusion welding technique at pressure 29 MPa with various welding temperatures and durations. Scanning electron microscopy examination, shear tests and microhardness evaluation were conducted on the samples interface to find out the effect of welding temperatures and durations on the weldability. The results demonstrate that the AZ31B Mg/7075 Al composite plates are bonded well and the intermetallic phases such as Al_（12）Mg_（17） and Al_（3）Mg_（2） within the joint zone form. It is found that due to the grain coarsening and the formation of brittle compounds, high welding temperatures and long welding durations result in a decrease of shear strength and increase of interfacial welding hardness. The minimum shear strength of 15 MPa along with the maximum microhardness of HV 176 are obtained for the diffusion couple processed at 450 °C for 120 min. It is revealed that enhancing the temperature and choosing appropriate holding time makes a remarkable increase of interfacial welding thickness. Increasing the welding temperature from 430 to 450 °C along with long welding duration（120 min） results in the increase of interfacial welding thickness by 26% where this value is 6% at the welding performed for 60 min.

THE INTERFACIAL BEHAVIORS OF ALUMINUM MATRIX COMPOSITE IN DIFFERENT WELDING METHODS

Non-interlayer liquid phase diffusion welding (China Patent) and laser welding methods for aluminum matrix composite are mainly described in this paper. In the non-interlayer liquid phase diffusion welding, the key processing parameters affecting the strength of joint is welding temperature. When temperature rises beyond solidus temperature, the bonded line vanishes. The strength of joint reaches the maximum and becomes constant when welding temperature is close to liquid phase temperature. Oxide film in the interface is no longer detected by SEM in the welded joint. With this kind of technique, particle reinforced aluminum matrix composite Al2 O3p/6061Al is welded successfully, and the joint strength is about 80% of the strength of composite (as-casted). In the laser welding, results indicate that because of the huge specific surface area of the reinforcement, the interfacial reaction between the matrix and the reinforcement is restrained intensively at certain laser power and pulsed laser beam. The laser pulse frequency directly affects the reinforcement segregation and the reinforcement distribution in the weld, so that the weldability of the composite could be improved by increasing the laser pulse frequency. The maximum strength of the weld can reach 70% of the strength of the parent.

AGE STRENGTHENING OF DIFFUSION WELDED JOINT OF Al_2O_(3p)/6061Al COMPOSITE

Tensile strength of diffusion welded joint of aluminum matrix composite is very low due to its poor weld- ability.In this paper, solution and age treatments were conducted on the welded joint of Al2O3p/ 6061Al composite subjected to diffusion welding using Gleeble 1500 machine, and ensile strength and microstructure of welded joint aged at175℃ were measured and analyzed respectively, Results showed that aging precipitation of welded joint is promoted effectively because of redistribution of reinforcement and a few number of dislocations in the matrix of weld zone resulting from welding pressure,and hence tensile strength of welded joint is increased significantly after aging treatment.

Microstructure in the Weld Metal of Austenitic-Pearlitic Dissimilar Steels and Diffusion of Element in the Fusion Zone

Microstructure and alloy element distribution in the welded joint between austenitic stainless steel (1Cr18Ni9Ti) and pearlitic heat-resistant steel (1Cr5Mo) were researched by means of light microscopy, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Microstructure, divisions of the fusion zone and elemental diffusion distributions in the welded joints were investigated. Furthermore, solidification microstructure and S-ferrite distribution in the weld metal of these steels are also discussed.

Scope for improved properties of dissimilar joints of ferrous and non-ferrous metals

Dissimilar joints(DSJs)of ferrous and non-ferrous metals have huge technological importance in the frontiers of newdesigns in new machineries and improved design of conventional systems.This investigation was undertaken to improve mechanicalproperties of joints of two dissimilar metals:one is Ti-based and the other is Fe-based.DSJs were processed using bonding pressurefrom1to9MPa in step of2MPa at750°C for60min.Properties of the DSJs of these two metals using different mechanisms andmethods were compared with the present research for verification.Experimental results from the diffusion bonding mechanism forjoining the dissimilar metals validated the improvement in properties.Superior mechanical properties of dissimilar-metals joints wereachieved mainly due to the third non-ferrous metallic foil,Ni of^200-?m thickness,which avoided the formation of brittleFe-Ti-based intermetallics in the diffusion zone.DSJs processed are able to achieve maximum strength of^560MPa along withsubstantial ductility of^11.9%,which is the best ever reported in the literatures so far.Work hardening effect was detected in theDSJs when the bonding was processed at5MPa and above.Bulging ratio of the non-ferrous metal(Ti-based)was much higher thanthat of the ferrous metal(SS)of the DSJs processed.SEM analysis was carried out to know the details of reaction zone,while XRDwas carried out to support the SEM results.Reasons for change in mechanical,physical,and fracture properties of the DSJs with theprocess parameter variations were clarified.

STUDY ON JOINING PROCESS FOR LAMINATED OBJECT MANUFACTURING USING METALAS MODELING MATERIALS

In order to solve some key problems associated with the rapid manufacturingof metallic functional part, a new technique using vacuum solid-state pressure diffusion weldingprocess to join the metallic slice sheets is put forward. The following results can be drawn fromthe experiments: only 1 percent shrinkage happened in the stack direction and it came from theregular system error. The atoms diffuse between joint interfaces clearly and new grains formedmeanwhile. The average shear strength of welding zone is more than 100 MPa and micro hardness ofwelding zone is almost the same as that of matrix. It is shown from above results that the vacuumsolid-state pressure diffusion welding process is an available technique to join metal slice sheetsfor the rapid manufacturing of metallic functional parts.