Micro-parallel seam joining equipment provided with multiple functions was newly developed based on experimental results as previously reported to facilitate establishment of seam joining conditions over a wider range for hermetic sealing of ceramic packages of a highly reliable integrated circuit which are becoming larger in size and diversified. It has also enabled the reinforcement of product quality assurance system as regards to hermeticity, seam joining strength and package temperature rise. Listed below are the summary of major functions. (1) In order to prevent damaging the lid due to misalignment or improper positioning of package and lid, inprocess displacement monitor was developed and the performance as calculated was obtained. (2) The equipment was systemized with use of CPU whereby complex seam joining conditions can be easily entered and also they can be verified as well as stored. (3) Introducing travelling mechanism which is able to travel to any location on the work table, range of seam joining head travel (X Axis) and the work table travel (Y, Theta Axis) were expanded by a factor of 1.5 to 3 times as compared with the experimental equipment and yet positioning accuracy was improved by a factor of tenth. (4) A desired distance can be designated on any axis of X, Y and Theta and allow travelling as same joining condition changed for that designated distance (Pitch Feed Function). As a result, prevention of splash generation around the corner section of specially shaped package was achieved as well as suppression of package temperature rise. At the same time, formation of reactive layer due to Au and Ni plated layer melting together was positively achieved at the joining boundary of lid and seal frame and specified hermeticity and joining strength were secured.
It is well known that fusion welding between titanium and foreign materials is almost impossible because of occurring brittle intermetallic compound in its weld metal. From this reason, there are few research reported for the welding titanium to other steels up to date. And also, there are a few investigations reported for it by using other welding process except fusion welding. In this study, to establish the welding process between titanium and SUS 304L austenitic stainless steel by using friction welding process with argon shielding, the effect of welding conditions on the tensile strength and metallurgical characteristics of the weld joint was evaluated. The results obtained are as follows: (1) There was little or no deformation observed in SUS 304L after weld. (2) The welding conditions, which increase the tensile strength, are, a. low rotational speed, b. high upsetting pressure and c. polishing of the faying surface of SUS 304L before welding. (3) Upsetting pressure was the most effective to tnesile strength than the other factors. (4) The tensile strengths of the joints, which were welded by using conditions described in (2), were from 348MPa to 378MPa. (5) The characteristics of the faying surface of SUS 304L before joining affected the tensile strength of the joint. That is, the roughness and foreign materials on the faying surface decrease the degree of metal bonding.
The deformation behavior of the weld during the friction welding of copper-tungsten sintered alloy (Cu-W) to oxygen free copper (OFC) has been investigated for W contents from 70 mass% to 100 mass% (pure tungsten). At the friction pressure of 50MPa, the degree of the deformation of the Cu-W was negligibly small compared with that of the OFC. As the W content was increased, the friction time at which the OFC started deforming was increased, and the deformation rate of the OFC was decreased. The friction torque and the temperature at friction interface were decreased with the increase in the W content. In order to interpret these results, the temperature at friction interface is calculated, assuming that the friction interface is a plane heat source generating the heat proportional to the friction torque and that deformation of the OFC and Cu-W is negligible. The calculated temperature is in good agreement with the experimental in the early stage of the friction process. From this calculation, the temperature at which the OFC starts deforming is estimated to be 810-830 K irrespective of the W content from 80 to 100 mass%. Therefore, it can be accounted for by the decrease in the heating rate of the friction interface that the friction time at which the OFC started deforming was increased with the W content. The decrease in the deformation rate of the OFC can also be accounted for by the decrease in the friction torque and resulting decrease in the heating rate.
Copper-tungsten sintered alloys (Cu-W) containing 70, 80, 90 and 100 (pure tungsten) mass%W have been friction-welded to oxygen free copper (OFC), in order to investigate the effect of the W content on bond strength. The tensile strength of joints obtained decreased with the increase in W content. In the joints of Cu-90%W to OFC, a layer which consisted of W grains elongated in a direction parallel to the weld interface was observed in the Cu-W adjacent to the weld interface. A similar layer, including many microcracks, was also observed in the joint of pure W to OFC. Since the layer consisting of elongated grains was also observed on the faying surface, the formation of this layer was attributed to plastic deformation introduced by machining (turning, grinding) of the faying surface. The joint with this layer was fractured in the Cu-W or pure W adjacent to the weld interface as well as the weld interface. However, when this layer was removed by polishing on metallographic paper, joint was not fractured in the Cu-W or pure W. These results suggest that the layer was embrittled. In contrast to this, for W content less than 80%W, the layer with elongated grains was not observed at weld, and the joint was fractured at weld interface and/or in the OFC. In this case, since a lot of W particles were found to be picked up in the OFC adjacent to the weld interface, the surface layer with elongated grains was presumably removed during friction welding.
It is not easy to obtain the sound diffusion-welded joints of aluminum, because the oxide film on diffusion-welded interface does not disappear during welding. To improve the mechanical properties of the diffusion-welded joints of aluminum, the relations between alloynig elements and the behavior of oxide film at diffusion-welded interface of aluminum alloys were investigated with a tensile test, Auger electron spectroscopy, X-ray photospectroscopy and electron probe microanalyzer. Materials used were pure Al, A1070, A2014, A3003, A4032, A5083, A6N01, A7003 and Al-2.5Li alloy. The welding surface films of aluminum alloys used consisted of the alumina. Mg oxide and Li oxide were more detected with the increase in the content of Mg and Li in the aluminum alloys. The alumina film on the welded surface of the the aluminum alloys reacted with the alloying element Mg during diffusion welding and changed to MgAl2O4. On the intimate contact zone, the reaction formed the metallic bonding, when aluminum alloys contained 0.1-2 mass%Mg. The joints of A6N01 and A3003 alloy were most soundest in the aluminum alloys tested.
Microstructure of titanium joint made with developed Ti-Zr base alloy brazing fillers has been investigated by observation and microanalysis with TEM, STEM/EDX, SEM/EDX, and X-ray diffraction test. Effect of heating time on the structure of the joint area was also examined in connection with diffusion of alloy elements in the fillers. TEM microscopy revealed that the acicular structure at the joint area consists of more fine lamellar and cellular structures which form colonies similar to those commonly observed in eutectic and eutectoid. The configurations and diffraction patterns suggseted that these fine structures were eutectoid of α-Ti and Ti2Cu containing Zr, and that the joint area was made of proeutectoid α-phase and the eutectoid. Joint structure was remarkably affected by heating time. Particualrly the width of the region of these acicular structure at the joint area varies with heating time; firstly it increases to some extent, then decreases and finally disappears. According to the observation and analysis with SEM/EDX, the area of acicular structure was considered to correspond to such area as containing more amount of Cu and Ni than the solubility in Ti base metal. On this discussion, the width was also calculated by diffusion theory.
Diffusion brazeability of β-type Ti alloy (Ti-21V-4Al) using newly developed Ti-20Zr-2OCu-2ONi amorphous filler has been investigatedd by electron microscopy, EDX microanalyses, and tensile tests of the joints. The brazeability was compared with solid state diffusion bondability of the same material, and the effect of aging heat treatments of the joint generally carried out for the alloy was also examined. Results of metallurgical examination of the joints indicated that the liquid layer at the joint interface became to disappear during holding at the joining temperature, and that the joint structure and composition finally became similar to those of the base metal. As for mechanical properties of the joint, even the joint made at 850C for 15 min under the joining pressure of 0.6 MPa, which is fairly lower than that required in solid state diffusion bonding of the same material, was fractured in the base metal with tensile strength of 680 MPa. Furthermore, the joint strength could be increased up to 1400MPa by aging heat treatment after joining. These results demonstrate that the use of developed Ti-base filler metal improves the diffusion weldability, and make it possible to produce the joint equivalent to the base metal even under a fairly low joining pressure.
A visual sensing system for in-process control of arc welding process is constructed by the combination of He-Ne laser and interference filter with narrow width at half maximum (WHM: 1.0 nm). By adopting a polygonal mirror in this visual sensing system for scanning of laser spot light, the variation in intensity of laser slit-like light has been decreased by a large margin. Using this visual sensing system, the gap width of I groove and weld line can be detected easely near molten pool without disturbance of powerful arc light, and the time for detection of groove information is only 36 ms. The error in detection of groove information is less than 0.05 mm, and the limit of detection is about 0.1 mm. On the other hand, it is proved experimentally that the detection is not influenced very much by the errors in measurment or angle in making I groove is proved experimentally. This visual sensing system has been applied to automatic weld line tracking at TIG arc welding process in real time. In this case, one cycle of weld line tracking is about 0.2 second and the error in tracking is less than ±0.4 mm.
The numerical solution technique for the dynamics of a viscous incompressible fluid with a free surface, which is called the Marker And Cell (MAC) method, is applied to the problem of the stability in the electromagnetic fluid cylinder. Numerical stability and accuracy of the MAC method, which is based on Finite-Difference Method, are examined as the first step for an analytical study of the kinetics of the metal transfer in the arc welding processes. In the growth rate of instability of the fluid cylinder, the numerical solutions by MAC method agree with the analytical solutions by Rayleigh, Murty and Chandrasekhar within the numerical error.
Electric current and time required to break up the conducting liquid bridge between the electrode and the pool are theoretically and experimentally investigated. Time-dependent deformation and breakup of the mercury bridge is observed by high speed photography. In the instability of the bridge due to electromagnetic pinch force, it is possible to simulate the initial stage in the necking process and evalutea the time to breakup, using the numerical solution technique for the dynamics of a viscous incompressible fluid with a free surface (MAC method) based on Finite-Difference Method. It is shown that there exists the critical current level responsible for occurring the instability of the bridging liquid and the time to breakup varies inversely as increasing current.
The corrosion resistance and weld hot cracking of high silicon containing stainless steels were investigated from a metallurgical point of view. A stainless steel has good corrosion resistance due to the passive film. However the stainless steels differ from the intergranular corrosion in the high potential region, for example, in the boiling nitric acid solution containing strongly oxidizing ions. The addition of silicon into stainless steels is effective for the improvement of corrosion resistance in these evnironment. However, it has been reported that in the weld metals containing high level of silicon the selective corrosion and weld hot cracking very often occur. The effect of the solidification mode of weld metals on the weld hot cracking and the selective corrosion in the boiling solution of 8MHNO3 containing 0.2 g/l Cr6+ ion was investigated. The both of weld hot cracking and selective corrosion occurred due to the silicon enriched phase, which tended to form under the primary austenitic solidification, and can be prevented by the fully ferritic solidification even though with a silicon content of approx. 3.5%.
It was cleared in the previous report that phosphorus is one of the main influence factors to enhance the crack susceptibility of quenching crack type cold cracking because of the grain boundary segregation. In this report, the variation of phosphorus segregation to grain boundaries during weld thermal cycle has been studied by calculation method for JIS SNCM 447 (0.47 wt.%C-Ni-Cr-Mo steel) containing 0.015 and 0.030 wt.%P. Grain boundary concentration enriched by the grain boundary liquation is further increased with solidification of the liquated part. The concentration decreased rapidly due to homogenization with subsquent cooling, reaching a constant value at about 1273 K. The concentration is increased by equilibrium segregation, reaching a constant value at about 800 K. However, the tendency of the final concentrations under the various cooling conditions did not agree with the result of AES having a tendency to decrease with increasing in cooling time discussed in the previous paper. In Fe-C-P ternary alloy, the phosphorus concentration was decreased to be caused by the rapid carbon segregation at the temperature range below Ms. Moreover, the degree of decrease was observed to be large in case of the lower cooling rate. This suggested that competition segregation of carbon at grain boundaries should be considered for decreasing of the phosphorus concentration with increasing cooling time
Influence of alloying elements in the matrix of the Heat-Affected Zone on the stress relaxation behavior during the reheat treatment process was studied. Reheat cracking tests on 3 type High Tensile strength steels (2 type H.T. 80 and H.T. 100) were carried out by means of ring type specimens and three point bending method. Influence of microstructure of synthetic HAZ at high temperature during the reheat treatment process was investigated by atomic absorption spectrometry and scanning electron microscopic observation. The relation between alloying elements concentration of the precipitated carbides and their concentration in the matrix of synthetic HAZ were investigated. The results are summarized as follows. 1) The critical stress of Lath-martensitic structure specimens (Water Quenched) was higer than that of Bainitic-Ferritic structure specimens (Air Cooled). 2) The reheat cracking susceptibility could be explained by the stress relaxation behavior of specimens and change of alloying elements concentration in the matrix during the reheat treatment process. 3) Air cooled specimens which showed the higher cracking susceptibility had not so many alloying carbides and showed a poor deformability. Water quenched specimens, lower cracking susceptibility had many precipitates and showed a good deformability. 4) The concentration of alloying elements (Mo+V) in the matrix showed a good correspondence to the stress relaxation behavior. Decreasing of (Mo+V) concentration in the matrix leads to a good deformability of the matrix.
Effect of ambient pressure on mechanical properties of mild steel welded joints obtained by gravity arc welding process was investigated. Welding was executed by low hydrogen type electrode of 4 mm in diameter under pressure range from 0.1 to 5.1 MPa (abs.). As base metals, SM41A steel plates of 6 and 9 mm in thickness were used. Main results obtained are summarized as follows: 1) Charpy impact value of weld metal decreases considerably with an increasing pressure. The tensile strength and the elongation decrease somewhat and the average hardness increases slightly with it. 2) As the pressure increases, volume of pearlite in weld metal increases and the structure tends to be bainitic. The grain size of dendrite tends to decrease. 3) As the pressure increases, content of diffusible hydrogen in deposited metal (HD) increases up to about I MPa, however, it tends to decrease over that pressure. 4) As the pressure increases, content of Si and Mn in weld metal decreases and content of C and O increases considerably. Content of P and S is approximately constant regardless of pressure. 5) Mechanical properties of weld metal decrease with an increasing pressure, because the content of C, O and H in weld metal increases with it.
The strength of electron beam welded joint of the ultra high tensile steel was investigated. This steel has the chemical composition of 0.2%C-7.5%Ni-4%Co-2%Cr-2%Mo-0.1%V and tensile strength of 1470 MPa (150 kgf/mm2) lebel, made by cold rolling, hot rolling or forging. The tension tests, impact tests and fracture toughness tests were made on each king of steels prepared by various processing: as for welding processes, EB welding and TIG wedling, and as for the procedure of welding and heat treatment, W-HT (Welding then Heat Treatment) and HT-W (Heat Treatment then Welding). Then various mechanical properties were compared to thoes examined on base metal. Summerized results obtained from this investigation are as follows. (1) For the tensile properties of welded joint; They are almost similar to those of base metal in all cases tested. (2) For the fracture toughness values of weld zone; In the W-HT condition, weld metal and HAZ show alomst the same value of around 100 MPa √m as that of base metal. But in the HT-W condition, weld metal shows higher value of around 130 MPa √m and HAZ shows lower value of around 60 MPa √m than that of base metal.The lower value of fracture toughness of HAZ is probably due to the precipitation generated by welding heat.
The stress corrosion cracking (SCC) resistance of non equlibrium duplex stainless steel weldment was investigated. Non equlibrium duplex stainless steel developed by mixing the powders of both Type 316L and 444 has excellent SCC resistance because the ferritic phase of 444 is nickel free. The welded joints of this steel revealed higher resistance to SCC in MgCl2 solution than conventional duplex stainless steels. However, the SCC occurred in HAZ in the severe environment of 42% MgCl2 boiling solution. The effect of weld thermal cycle on the SCC resistance of the non equlibrium duplex stainless steel was tested using the simulated HAZ. The HAZ showed the SCC susceptibility in the narrow region heated up to the high temperature because the nickel diffused into ferritic phase from austenitic one. The nickel diffusion between the two phases was investigated. The effect of heating conditions on the SCC susceptibility can be explained by the nickel diffusion theory considering the phase transeformation at the phase interface.
In this study, an improved technique of ultrasonic testing with an immersion-type focusing probe is applied to various types of soldered lap joints of copper and brass thin sheet of 0.3 to 1.0 mm in thickness. This method is based on a composite effect of convergence of ultrasonic beam and its attenuation due to multiple reflections between surface and near surface flaw. The sound soldered region is evaluated by the appearance of backwall echo or interface echo on the oscilloscope screen and echo height variation on scanning graphs. Moreover, the echo height topography and C-scan colour display are tried to image the soldered region. The results show that by this method, it is able to distinguish between surface echo, interface echo within the non-soldered region and backwall echo within the sound soldered region, since the interface echo produces higher amplitude than the backwall echo. Although solder affects the echo pattern, its effect on the echo height is minor. The echo height topography and C-scan colour display both deduced from scanning detection of this process indicate an image of the soldered region precisely.
Bonding of Si3N4 to W using Cu-5%Cr, Cu-1%Nb, Cu-3%V, Cu-5%Ti and Cu-10%Zr insert metals was conducted in a vacuum furnace. The reaction layer existed at the interface between Si3N4 and insert layers in Si3N4-W joints. Cr, Nb, V, Ti or Zr was concentrated in the region adjacent to Si3N4, and Cu was enriched in the center region of insert layer for all insert metals used. From the results of X-ray diffraction analysis, it was found that Cr2N, CrN and CrSi2, NbN and Nb3Si, VN and V6Si5, TiN and Ti5Si3, ZrN and Zr5Si3 existed in thee reaction layer. The thermodynamics calculation suggested that these nitrides and silicides could be formed by the reaction between Si3N4 and Cr, Nb, V, Ti or Zr containing in the melted insert metal in the first stage of reaction layer formation.
Bonding of Si3N4 to W using Cu-5%Cr, Cu-1%Nb, Cu-3%V, Cu-5%Ti and Cu-10%Zr insert metals was conducted in a vacuum chamber. Thickness of the reaction layer formed at the interface between Si3N4 and insert layers was increased with increasing bonding temperature and holding time. SEM observation revealed that reaction layer grew toward the both sides of bonding interface. Growth of reaction layer toward the Cu enriched layer was attributed to the reaction between N and Cr, Nb, V, Ti or Zr, and that toward Si3N4 was attributed to the solid state reaction between Si3N4 and Cr, Nb, V, Ti or Zr in the reaction layer. Formation of Cu enriched layer was explained as a consequence of decrease in the contents of Cr, Nb, V, Ti and Zr in the melted insert metal by the reaction with Si3N4.
Kinetics of the reaction layer growth in Si3N4-W brazed joints was investigated using Cu-5%Cr, Cu-I%Nb, Cu-3%V, Cu-5%Ti and Cu-10%Zr liquid insert metals. It was elucidated that the reaction layer growth could be expressed by Johnson-Mehl type equation with time exponent 'n' of 1/2. EPMA analysis of elements in the reaction layer revealed that Cr, Nb, V, Ti and Zr contents slightly decreased toward Si3N4, and that N content was almost constant. From the consideration of activation energy for reaction layer growth, it may be deduced that the reaction layer growth was controlled by diffusion of Cr, Nb, V, Ti and Zr in the reaction layer from the melted insert metal to Si3N4.
This paper is concerned with the theoretical evaluation of residual stresses in multilayered structures fabricated on substrates, such as evaporated films and plating films. Firstly, the analysis of thermal stresses in multilayered elastic thin films is carried out by using the method of strain suppression. Next, the theoretical formulas for evaluation of residual stresses arising in thin films and substrates are derived by the use of combining the results of the thermal stress analysis and those of stresses due to the inherent strains of the thin film. Furthermore the controlling parameters of residual stresses are derived theoretically. Experimental results of residual stresses in evaporated Ag films and hard chrominum plating films agree approximately with theoretical ones.