Migration of cations in glass plays an essential role in anodic bonding and formation of defects in anodically-bonded joints by the reverse voltage. Alkali ions in glass were replaced with Ag or Cu ions, and migration of those ions with application of voltage was investigated.

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The interfacial reaction behavior and resultant microstructure between silicon carbide (SiC) single crystal substrates and multilayered deposition films of titanium and aluminum were investigated to obtain basic knowledge required for manufacturing good Ohmic contacts on p-type SiC wide band-gap semiconductors. SiC single crystal with (0001) surface orientation was used as the substrate. Pure titanium and aluminum were deposited on SiC substrates sequentially and then annealed in vacuum. The interfacial microstructure was analyzed by transmission electron microscopy.

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Diffusion liquefaction bonding process forms liquefaction of bonding surface by reaction diffusion below melting point of material. This bonding method accomplishes Al/Cu dissimilar bonding in air. Change of phase formation in bond affects displacement history in bonding process significantly. In this study, effect of bonding conditions on displacement history was investigated systematically.

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The purpose of the present study is to investigate the influence of the oxide layer on the growth of the interfacial reaction layers during the Cu/Sn/Cu solid state bonding, where the bonding temperature are below melting point of Sn. Interfaces bonded in vacuum were compared with those bonding in ambient pressure.Difference of thickness of oxide layer on the surface of sample originated from exposure time to the atmosphere after chemical polishing was also taken into account.

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In the present reserch, we examined dissimilar bonding of aluminum alloy to steel for light-weight auto body using diffusion bonding. We fundamentally analyzed the observational study of interface reaction and interfacial microstructure and the effects of alloy elements onthe interface reaction. Also, we measured joint strength and then evaluated the correlation between interfacial microstructure and joint strength. On the basis of these data, we proposed the idea of interfacial microstructure and alloying of the dissimilar joints.

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The method for evaluating the intrinsic fracture toughness transition temperature of the laser beam weld was proposed. Using this method, the fracture transition temperature of beam weld and that obtained with standard Charpy test were correlated analytically with each other.

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The analytical method for correlation between Charpy and CTOD fracture toughness transition temperature based on Weibull stress criterion and local plastic strain criterion was proposed. Furthermore, the effect of mechanical properties on transition temperature shift was formulated.

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The ductile cracking behavior for two-phase structural steel was simulated by means of developed meso-scale 3D micro-structural FE-model together with damage evolution model. The effect of applied triaxial stress state on critical macro-strain for ductile cracking, in which critical strain could be decreased with increasing stress triaxiality, was numerically predicted.

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This study proposed damage model based on the micro-mechanism and mechanical properties controlling ductile crack growth resistance. It enabled to simulate the effect of plastic constrain and mechanical properties on ductile crack growth resistance.

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Comparing with the effect of toe grinding, effect of ultrasonic impact treatment (UIT) on fatigue properties at the boxing of welded structure model was discussed. These test results demonstrated that the UIT treatment extended the fatigue life and the fatigue crack initiation life of welded structures than toe grinding.

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For the welding of bridge components, high current pulsed MAG welding has been introduced to reduce the fabrication cost. However, it is pointed out that the pear shaped bead crack may happen if the welding conditions are not appropriately chosen. To clarify the influence of the heat input and the penetration shape on the formation of hot cracking, FE analyses using temperature dependent interface element are conducted.

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We evaluated the mechanical properties and toughness of the welded joint with three kinds of Ceq ofweld metal. We can find the relationship between the microstructure of weld metal and toughness of welded joint

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White spots occurred in the autogeneous GTAW welds of Fe-36% Ni alloy plates. This paper covers the analysis results of the white spots formation with welding conditions.

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The Monte Carlo simulation method was used to model the precipitation of ferrite as well as that of austenite in repeated laser heating and cooling, and investigated the influences of grain size of matrix, temperature, and repetition times on refinement of ferrite grain

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In the newly developed ultra fine weathering steels, a large amount of Al and Si elements was added to increase the atmospheric corrosion resistance. And it has been reported that weld bond toughness of the steel increases with carbon content. To clarify this specific phenomenon, we made 0.1C and 0.17C CCT diagrams for welding and showed microstructure and transformation behavior.

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To clarify the microstructural evolution in low carbon low alloy steel weld metal, the inclusions related to acicular ferrite formation were investigated from the crystallographic points of view. The inclusions related to acicular ferrite formation were multi-phase. It was observed that these inclusions were enclosed by Ti concentrated aria.

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From the analyses of the microstructure of weld metal with tensile strength of 650MPa, it was found that FATT would depend on the size of intragranular bainite, while USE depend on the number density of inclusions. The compositions of inclusions were considered to be dominant to the bainite nucleation and the distribution of inclusions.

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Al powder was sintered and simultaneously bonded to bulk materials such as magunesium and copper. Intermetallic layer formed at the interface between the sintered aluminum powder and the bulk materials was also investigated.

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Heating rate will affect formation of Al oxide film on bonding surface and deformation of bonding surface significantly. Effect of heating rate on Al liquid phase diffusion welding by Al-4.7Mg commercial alloy was investigated in this study. Heating rate was varied from 1K/s to 10K/s. Initial bonding time was shortened by 5K/s.

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We have proposed a novel bonding process using Ag nanoparticles, which can be alternative to lead-rich high melting point solder. The bonding mechanism of Ag metallo-organic nanoparticles to bulk materials is discussed based on the observations of the bonded interface using TEM.

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We brazed Cu rods with Pd40Cu30Ni10P20 metallic glass filler. The brazing was carried out at 873K, then the specimens were quenched. According to X-ray diffraction analysis, metallic glass filler was amorphous. Tensile fracture strength ranged from 20 MPa to 250 MPa.

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For cast Ni-based superalloy, activate diffusion brazing is widely applied as joining and repair method with various braze gap from micrometer to several millimeter. The deformation and rapture behavior of braze joint is severely affected by the gap. In this research, the effect of braze gap for the creep property is examined.

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We have proposed a novel bonding process using composite Ag nanoparticles. In this research, the sintering mechanisms of the composite Ag nanoparticles and the effects of the Ag2CO3 contents on bondability are discussed based on the results of observation of sintering behaviors, thermal analyses and tensile strengths test.

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Creep deformation characteristic of BAg8 was examined by means of stress relaxation test at high temperatures for the bonding of cemented carbide-metal. Residual stress in a cemented carbide/SKS3 joint made by the standard cooling processes with a brazed metal was analyzed by using an elasto-plastic-creep FEM model. The joint was brazed at 1113K and cooled under standard cooling condition to room temperature. Residual stress value measured by X-ray stress measuring method in a cemented carbide/SKS3 joint with a brazed metal was compared for the value of the simulation. It was found residual stress profile in a cemented carbide/SKS3 joint obtained by the simulation conformed to measured residual stress value.

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In TIG arcs, since the current in the arc plasma is originated mainly from thermionic emission on the high temperature cathode surface, it is significantly important to know the temperature of the cathode surface to realize required properties of the arc plasma. In this presentation, the experimental results on the measurement of the cathode surface temperature of helium TIG arcs are discussed.

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We have developed non-equilibrium simulation model of GTA. In this presentation, simulation results of plasma property of argon GTA at atmospheric pressure are reported and, furthermore, the reliability of the simulation model is evaluated.

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It aims to construct the nonstationary numerical analysis model of GTA welding process which considers the behavior of the metal vapor from the molten pool and to clarify a dynamic change in the distribution of the metal vapor concentration and the temperature of the arc plasma quantitatively.

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In this presentation, we will report results of numerical analysis of nucleation, condensation and aggregation mechanism of welding fume that is produced of metal vapor evaporated from high temperature droplet and weld pool.

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Coaxial solid hybrid wires, in which the center part is Inconel and the outer part is steel, have been developed. The wire melting behavior and the droplet transfer behavior change by the area ratio of the Inconel (center part) and steel (outer part).So, we made several hybrid wires which have different area ratio. We examined the influence of the area ratio on the droplet transfer and the wire melting behavior. In this experiment, the high current welding condition and pure Ar shielding gases were used. In addition, we examined the distribution of the composition element about the weld metal to evaluate the properties of weld metal.

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By making the solid wire of various diameters included in Flux Cored Wire, it was clarified that the form of the flux column which is individual arc phenomenon of Flux Cored Wire changes, and the successful possibility of the improvement of the arc phenomenon of the Ni alloy Flux Cored Wire was obtained.

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As for the welding consumables for 9%Ni steel, Ni alloy Flux Cored Wire which has good crack resistance, low-temperature toughness, and weldability was developed by the optimization of the alloy elements, and the application of fluoride and high basic slag. Furthermore, the arc phenomenon has improved by including solid wire.

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The authors will report the results of MIG arc brazing of austenitic and ferritic stainless steels with Cu-Si and Cu-Al wires. Especially, the phenomena of copper penetrating into grain boundary and causing intergranular cracking were examined.

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We have developed a microwelding technique using glow discharge by a microneedle. Gold particles of 40-80 microns were welded onto a fine thermocouple by the technique. Output of the thermocouple was read out about 0.05 seconds after the end of discharge.

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Shielding is very important to keep good welding condition. Much oxygen reacts on weld pool during welding process in bad shielding condition. Surface behavior and temperature were measured in various shielding conditions to consider oxidation reaction.

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The effect of aluminum content in ferritic stainless steel plates and the amount of oxygen in shielding gas on the amount of oxygen in TIG weld metal was investigated. Furthermore, it was observed the molten pool action with the high speed camera, and the efffct of oxygen content on the penetration depth is clarified in TIG welding.

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The purpose of this study was to develop the ultra-high-speed TIG welding process with the hot-wire system using pulsed current to heat filler wire. The bead formation observed in detail using a high seed camera and the wire temperature distribution was measured precisely using a radiation thermometer.

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There is few date about experimental data of CO2 welding droplet temperature up to now. Most measuring methods are indirect methods. In this study We used a High-speed digital video camera, and We took pictures of the infrared region with a high -speed digital video camera. We report that two color temperature of droplet in CO2 welding.

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In groove welding, each welding condition in multi pass process governs the soundness of welds and/or occurrence of weld defects depending on the product specification, materials, groove geometry and so on. The objective is to make clear the weld pool phenomena together with welding arc behavior.

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Arc shape is an important factor in determining the quality and the efficiency of gas shielded arc welding. The arc shape can be changed by electromagnetic force of external magnetic field. Our results expect an increase of power density of the welding arc.

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The numerical analysis of the temperature field and the magnetic field and the electromagnetic force distribution was done. That analysis aimed to clarify the influence of various control parameters of Electromagnetic Controlled Molten Pool Welding Process that authors had developed.

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We have discussed effect of plasma forming gas on hollow cathode arc (HCA) as the basic study of HCA under the condition of low pressure. Concretely speaking, we have experimented and researched discharging and plasma characteristics of HCA under a few plasma forming gases.

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We produced butt weld joints by space GHTA (Gas Hollow Tungsten Arc) welding process under simulated space environment. And, mechanical properties of those weld joints were investigated. As a result, we identified that mechanical properties were improved by supplying filler metal compared with meltrun weld joints.

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The GHTA(Gas Hollow Tungsten Arc) cutting experiments using the DC-pulsed GHTA were performed in the vacuum in order to investigate the effect of cutting parameters on aluminum arc cutting situation. The optimal cutting parameters were decided based on the evaluation of cutting kerf.

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Distribution of heat input by preheating gas flame was able to be predicted by Gaussian distribution. Heat input by gas cutting was able to be predicted by modified Wells equation. And, distribution of heat input by gas cutting along thickness is effected by preheating gas flame and molten metal.

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Laser brazing process to join zinc-coated steel and aluminum is discussed. Silver alloy brazing metal is used. Microstructures of interfaces of braze metal at steel and Al alloy sides are evaluated . From tensile test, fracture position of joint occurred along HAZ of aluminum.

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Tamdem beam brazing with the aluminum filler metal was conducted in order to develop the fluxless laser brazing technique of aluminum steel to galvanized steel. Sound braze bead could be formed by optimizing the preheating and main beam powers. The fracture strength of lap joint attained approx. 60-75% of the base metal strength of aluminum alloy.

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Laser brazing was performed to the butt joint of dissimilar materials between titanium alloys and stainless steels. The tensile strength of joints exceeded the half of strength of base materials was obtained by using flux corresponding to each materials.

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An interfacial evaluation by the transmission electron microscopy has been carried out about dissimilar Laser brazing of Boron Nitride and Tungsten Carbide using Ag-Cu-Ti alloy braze. It was suggested that Ti reacted with N in h-BN to generate TiN as an interfacial precipitation.

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This report shows welding condition for obtaining cladding layer of thin and low melting rate of 10% or less by using YAG laser.

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