Showing papers on "Butt joint published in 1998"

CO{sub 2} laser beam welding of magnesium-based alloys

Abstract: Magnesium has gained increased attention in recent years as a structural metal--especially in the automotive industry--necessitating the development of welding techniques qualified for this new application. Lasers are known to be an excellent tool for joining metals. This paper presents results of recent investigations on the weldability of several cast and wrought magnesium-based alloys. Plates with a thickness of 2.5--8 mm were butt joint welded with and without filler metal using a 2.5-kW CO{sub 2} laser. The investigations showed that magnesium alloys can be easily laser welded in similar and dissimilar joints. The beam characteristics of the laser leads to small welds and a deep penetration depth. Crackfree welds exhibiting low porosity and good surface finish can be achieved with appropriate process parameters. Generally, the laser welding leads to either no change or a small increase in hardness in the fusion zone (FZ) and in the heat-affected zone (HAZ) relative to the base metal. Less promising results were obtained for the cast alloy QE22, in which cracking in the age-hardened condition and a significant decrease in hardness occurred. Laser welded die cast alloys showed an extremely high level of porosity in the weld.

Fatigue failure criterion of adhesively bonded CFRP/metal joints under multiaxial stress conditions

Abstract: In order to investigate the fatigue failure criterion of adhesively bonded CFRP/metal joints under multiaxial stress conditions, a series of fatigue tests was carried out on three kinds of adhesively bonded joint specimens; butt joint, scarf joint and thick-adherend lap-shear joint, where these joints have considerably uniform stress distributions in the adhesive layer. In addition, stress distributions of these joints were analysed by the finite element method. The results show that the fatigue limits of respective joints are governed by the maximum principal stress except when negative hydrostatic pressure acts on the adhesive.

Effects of joint configuration for the arc welding of cast Ti-6Al-4V alloy rods in argon

Abstract: Statement of problem. Titanium and its alloys are more commonly used in prosthodontics and welding has become the most common modality for their joining. Studies on the welding of titanium and its alloys have not quantified this value, though its importance has been suggested. Purpose. This study compared the strength and properties of the joint achieved at various butt joint gaps by the arc-welding of cast Ti-6Al-4V alloy tensile bars in an argon atmosphere. Material and methods. Forty of 50 specimens were sectioned and welded at four gaps. All specimens underwent tensile testing to determine ultimate tensile strength and percentage elongation, then oxygen analysis and scanning electron microscopy. Results. As no more than 3 samples in any group of 10 actually fractured in the weld itself, a secondary analysis that involved fracture location was initiated. There were no differences in ultimate tensile strength or percentage elongation between specimens with weld gaps of 0.25, 0.50, 0.75, and 1.00 mm and the as-cast specimens. There were no differences in ultimate tensile strength between specimens fracturing in the weld and those fracturing in the gauge in welded specimens; however, as-cast specimens demonstrated a higher ultimate tensile strength than welded specimens that fractured in the weld. Specimens that fractured in the weld site demonstrated less ductility than those that fractured in the gauge in both welded and as-cast specimens, as confirmed by scanning electron microscopy examination. The weld wire showed an oxygen scavenging effect from the as-cast parent alloy. Conclusions. The effects of the joint gap were not significant, whereas the characteristics of the joint itself were, which displayed slightly lower strength and significantly lower ductility (and thus decreased toughness). The arc-welding of cast titanium alloy in argon atmosphere appears to be a reliable and efficient prosthodontic laboratory modality producing predictable results, although titanium casting and joining procedures must be closely controlled to minimize heat effects and oxygen contamination. (J Prosthet Dent 1998;79:291-7.)

Two-Dimensional Thermal Stress Analysis in Adhesive Butt Joints Containing Hole Defects and Rigid Fillers in Adhesive Under Non-Uniform Temperature Field

Abstract: This study is concerned with the thermal stress analysis of an adhesive butt joint which contains circular holes and rigid fillers in an adhesive and is under a non-uniform temperature field. In the analysis, the adherends are assumed to be rigid and the adhesive is replaced with a finite strip having holes and rigid fillers in it and the thermal stress distribution in the adhesive is analyzed using a two-dimensional theory of elasticity. The effects of size and location of the circular holes and rigid fillers on the stress distributions at the interface and at the hole and filler peripheries are clarified by numerical calculations. For verification, photoelastic experiments were performed using an epoxide resin plate with small holes and fillers in it, to model and adhesive in the joint. The analytical results are fairly consistent with the experimental ones.

Autogenous laser welding of austenitic stainless steel to copper alloy

Abstract: A technique for the autogenous laser welding of stainless steel to copper alloy in a butt joint has been developed, by which microfissuring in the heat affected zone of stainless steel can be eliminated. The impinge direction and the offset of the laser beam played the dominant roles in achieving this. The sound weld of AISI 316L–C18100 contained 3·0 wt-% copper in the fusion zone with dendrite structures. However, banding and spherical structures were present in the fusion zone with a high percentage of copper and microfissuring was strongly related to the distribution of copper in this region. A model is proposed for achieving a sound butt joint and the mechanism of microfissuring is also discussed.

CO2 Laser Welding of Zinc-Coated Steel Sheets

Abstract: Welding of zinc-coated steel sheets for the automotive industry has been investigated experimentally and theoretically, using a continuous wave 2 kW CO2 laser. The specimens of 0.8, 1.0 and 1.2 mm thickness were welded as butt joint and lap joint. Argon gas was shielded co-axially to reduce the plasma and to protect the molten, pool from atmosphere. The mechanical tests of specimens were carried out to investigate the ductility of welds in butt joint and lap joint, using the Erichsen test, ball punch test and tensile shear test. The value of transverse weld pattern is higher than others. The fatigue life of longitudinal weld is superior, but that of circular weld pattern is inferior due to the high tensile residual stresses in the weld. The maximum Erichsen value was obtained as 96% and the deformability of zinc coated steel butt-welded was found to be 80% in the ball punch test. The high pressure formed by vaporization of zinc with the low boiling temperature during laser lap-joint welding splattered the molten pool and created porosities in the weld. The optimum gap was calculated to be 0.1 mm in the lap joint welding of zinc-coated steel sheet which was a good agreement with the experimental result.

The gap bridging capability in laser tailored blank welding

Abstract: The demand for the use of tailor welded blanks in the automotive industry continues to grow. Like in any other laser welding applications, the requirement for an intimate fit-up is a key in laser tailored blank welding. In the case of edge preparation is not sufficient, alternative laser welding method can be applied. A study on the bridging capability of co2 laser welding with a twin spot optic was done. It shows that gaps with a maximum width of 0.45 mm can be bridged using a co2 laser twin spot optic with the 8 kw laser power and a maximum welding speed of 4.75 m/min for 3.0 mm-1.9 mm and 3.0 mm - 1.2 mm butt joint combinations. By placing the center of the twin-spot a little more on the thicker blank about 0.15 mm away from the abutted line, the maximum gap which can be tolerated becomes approximately 0.2mm larger compared to that aligning the center of the twin spot on the abutted line. The changing in the incidence angle from 0° to 45°, the maximum width of the gap which can be bridged increases by 0.1 mm and the speed of welding by 1 m/min for 1.2-0.6 and 1.9-1.2 butt joint combinations. The changing in the orientation of the twin spot, angle θ, from 0° to 60°, the speed increased by 0.5 m/min, whereas the position accuracy for tolerating a variation in position (laser beam and weld seam alignment) decreases by 0.15 mm compared to 0.3 mm.The demand for the use of tailor welded blanks in the automotive industry continues to grow. Like in any other laser welding applications, the requirement for an intimate fit-up is a key in laser tailored blank welding. In the case of edge preparation is not sufficient, alternative laser welding method can be applied. A study on the bridging capability of co2 laser welding with a twin spot optic was done. It shows that gaps with a maximum width of 0.45 mm can be bridged using a co2 laser twin spot optic with the 8 kw laser power and a maximum welding speed of 4.75 m/min for 3.0 mm-1.9 mm and 3.0 mm - 1.2 mm butt joint combinations. By placing the center of the twin-spot a little more on the thicker blank about 0.15 mm away from the abutted line, the maximum gap which can be tolerated becomes approximately 0.2mm larger compared to that aligning the center of the twin spot on the abutted line. The changing in the incidence angle from 0° to 45°, the maximum width of the gap which can be bridged increases by ...

Method for laser welding of butt joints

Abstract: FIELD: welding technology SUBSTANCE: this can be used for welding metals of high thickness, for example large-diameter pipelines for gas and oil According to method, filler band material is fed to gap of butt joint Edges of band are welded to edges of weldable joint Process is repeated by applying several layers of filler band material until complete filling of joint in thickness is achieved Layer of upper filler band material is pressed against lower layer so as to ensure strong joining of layers between themselves Third laser ray is directed to line of contact of layers Laser ray is linearly polarized in parallel to band plane EFFECT: high efficiency 3 cl, 3 tbl, 4 dwg ooo1

Non-destructive test for butt-joint quality between welded plastics pipes

Abstract: A non-destructive test for the quality of butt-welded plastics pipes involves the use of heat sensitive reversible or irreversible rapid transition materials, e.g. those which change colour on heating or have a precise melting point and form an isothermal image during the welding. The transition materials are applied either directly onto the electrical welding socket or onto an indicator carrier of film, paper or fleece which is then bonded or loosely placed around the whole socket circumference to cover the heating coils. Broad, parallel isothermal images on both sides of the joint indicate a fault-free weld quality while geometrically unequal isothermal fronts indicate a faulty weld. The breadth of the isothermal indicates the energy input.

The effect of an air gap on the properties of high power Nd:YAG laser welds

Abstract: Laser welding gives designers increased freedom in material selection and joint design, in comparison with many conventional joining techniques. Butt, lap and T -joints are typically used when laser welding sheet materials. The presence of an air gap between the sheets affects weld quality - it is recommended that no air gap is present in a butt joint, if an acceptable weld is to be produced. Although an air gap should be avoided in lap and T – joints, to avoid weld defects, an air gap is necessary in some cases, e.g. when welding zinc-coated sheets. Data for acceptable air gaps are also needed in order to be able to specify appropriate fixturing, based on economic and technical criteria. If a small air gap is acceptable, expensive fixturing that ensures no air gap is not necessary.The results of an investigation into high power Nd:YAG laser welding of low strength mild steel, in sheet thicknesses of 0.75 and 1 mm, using lap and T-joints (welded in a stake joint configuration), are reported and discussed. Some of the specimens were zinc-coated. The effect of an air gap on the weld properties was studied in both joint configurations, in order to establish the fixturing accuracy required in practical applications, as well as its effect on the formation of pores when welding zinc-coated sheets. Laser power levels up to 3 kW, and welding speeds up to 10 m/min were used. The focal plane position was varied in order to control the weld bead profile to ensure a satisfactory weld section in the joint. The following were characterized from transverse weld sections: penetration and bead profile; geometry of the bead root and face; effective weld area in the joint with regard to the accommodation of weld defects. Tensile tests and hardness profiles were also made on some of the welds.The results show that in the case of a stake-welded T-joint, the most important factors controlling weld quality are the size of the air gap between the web and the flange, and the alignment of the laser beam with the web sheet. An air gap of 0.1 mm can be tolerated with a sheet thickness of 1 mm, provided that the laser beam is aligned with sufficient accuracy. The same air gap can be tolerated in a lap joint configuration with a sheet thickness of 1 mm. A zinc coating density of 100 g/m2 was used. No pores were found from a macroscopic examination of sections.Laser welding gives designers increased freedom in material selection and joint design, in comparison with many conventional joining techniques. Butt, lap and T -joints are typically used when laser welding sheet materials. The presence of an air gap between the sheets affects weld quality - it is recommended that no air gap is present in a butt joint, if an acceptable weld is to be produced. Although an air gap should be avoided in lap and T – joints, to avoid weld defects, an air gap is necessary in some cases, e.g. when welding zinc-coated sheets. Data for acceptable air gaps are also needed in order to be able to specify appropriate fixturing, based on economic and technical criteria. If a small air gap is acceptable, expensive fixturing that ensures no air gap is not necessary.The results of an investigation into high power Nd:YAG laser welding of low strength mild steel, in sheet thicknesses of 0.75 and 1 mm, using lap and T-joints (welded in a stake joint configuration), are reported and discussed....

Experimental results at pulse test Facility (PTF) of butt joint used in ITER CS model coil outer module

Abstract: A butt type joint is used for electrical connections between layers in the outer module of the ITER-CS model coil. The AC loss, joint resistance, stability and quench current were investigated using a prototype butt joint sample in the Pulse Test Facility (PTF) at MIT. The experimental results of the AC loss and joint resistance are reported in this paper. The AC loss is measured to be sufficiently low, about 7 W, for magnetic field pulses with a ramp rate of 0.4 T/s. The joint resistance is evaluated to be about 8 nΩ at 4.5 T and 40 kA.

Butt joint for electron-beam welding

Abstract: PROBLEM TO BE SOLVED: To eliminate occurrence of the fault of welding part caused by a residual air or metallic vapour of arcing porosity or burn out and blow hole of welding part, etc, by communicating the space through an exhaust passage formed at a fixed interval from the depth part to be electron-beam welded to the surface of a welded member SOLUTION: On a welding member 2a, a back up member 5 is installed in one body In a welding member 11a, a fitting space 11h in machine so that it is made in close contact with the welding member 2a and the back up member 5 A through hole 5h as an exhaust passage with the fitting space 11h is formed at a fixed interval L corresponding to the size of the fitting space 11h on the back-up member 5 With this through hole 5h, the fitting space 11h is communicated with a vacuum part outside the welding member with a small air resistance Therefore, in a butt welding joint with the back up member being able to be positioned precisely, the metallic vapour generated in the electron-beam welding is also sucked immediately to the vacuum and the fault is not generated on the welding part

Fatigue strength characteristics of A6061/SUS304 friction welded butt joints.

Abstract: Friction welded butt joints have come into wider use because of their easiness to fabricate composed shafts such as steering shaft, rear axle shaft and so forth. However, the welding condition optimum to obtain high joint efficiency in terms of fatigue strength has not yet been established because of a scarcity of fatigue strength data. Accordingly, it is indispensable to accumulate fatigue strength data on a variety of joints fabricated under different friction welding conditions. In this study, the rotating bending fatigue behavior of butt joints of aluminum alloy A6061 and austenitic stainless steel SUS304 which were friction welded at three different upset pressures are discussed. The results indicate that the butt joints friction welded at the highest upset pressure give almost the same fatigue strength as that of the aluminum alloy specimen. But the distribution of the fatigue lives of this kind of joint is larger than that of the joint of similar aluminum alloy, presumably depending on the scatter of fatigue crack initiation life.

Full bamboo butt-joint artificial grooved and tongued floor

Abstract: A tongue-and-groove bamboo floor with aligia of joint to joint is made up of Mao bamboo through cutting short, cutting open to obtain small pieces, coarse milling, bleaching, digestion, baking fine milling, adhering by joint to joint, hot pressing, planting, planing, making tongue, groove and back slots, and painting, and features clear grains, beautiful appearance, and warming in water and cooling in summer.

Welding method for two different types of steel

Abstract: The method provides a way of welding together two different types of steel forgings which are suitable for turbine rotor blades. The first forging is preferably made of X12CrMoWVNbN1011 steel and the second forging is preferably made of a low alloy 26NiCrMoV145 steel. The first forging 4 is machined and a layer of weld metal 6 is deposited on a surface, and is heat treated. The weld metal is preferably 12%CrNiMoCoV. The deposit is machined and the surface of the second forging 8 is similarly machined. A butt joint is formed having a gap which is filled with a weld metal wire filler 10. A welding process is performed and the joint is heat treated to remove stresses and temper the area of the joint. The welding process may be performed using tungsten inert gas welding, submerged arc welding or laser welding.

Insulating sleeve for chimneys

Abstract: A thermal insulating jacket of mineral wool includes insulating layer (2) surrounded by a mantle (4) with at least one butt joint (3) closed by the use of an adhesive band (5), which includes a thermosetting adhesive, covering both edges.

Butt joint of monolithic reinforced concrete slab and steel girder of steel-reinforced concrete bridge span structure

Abstract: FIELD: construction engineering SUBSTANCE: this relates to bridge-building industry and can be used for joining together monolithic reinforced concrete slab and metal structure Butt joint of slab and steel girder has stops welded to girder and embedded in slab body Stops are made in the form of continuous steel strips having slots Located in aforesaid slots are reinforcement bars Slots are elongated and create comb which is inclined in direction of acting major stresses in slab concrete at angle equal to 10-60 deg to vertical plane Reinforcement bars seated in slots create together lower working reinforcing net of reinforced concrete slab In this case, diameter d of reinforcement bars, pitch f and width b of slot, distance h from slot edge to lower edge of strip, and thickness of strip are determined according to following relation: b = (11-16)d; f = (5-10)b; h = (1-3)t Aforesaid embodiment of comb with inclined slots for anchoring reinforcing members located close to center of gravity of slab ensures taking not only shearing forces but breaking forces as well and what is particularly important it occurs uniformly over entire length EFFECT: higher efficiency 2 dwgh

Method for increasing length of continuous welded rails

Abstract: FIELD: railway transport; permanent way; laying rail lengths to block-section. SUBSTANCE: method of increasing the length of rails of continuous welded rails comes to unloading the lengths to be welded from vehicle, aligning the lengths and butts to be welded, welding of rail lengths first to previously laid length and then to each other and machining of welded joints. Prior to welding each rail length, only end part of length is unloaded from vehicle to base, leaving the rest of length on vehicle. In process of welding vehicle with unloading part of length is moved in direction of joint under welding. After welding and machining of welded butt joint the remaining part of length is lowered to base. EFFECT: reduced labour input, cut down interruptions of traffic.

Method of and device for consumable electrode electric arc welding

Abstract: FIELD: mechanical engineering; welding. SUBSTANCE: flat insulated electrode with lead is fixed in joint between pipes to be welded. Electrode is made in form of part of ring with mean radius equal to mean radius of pipes to be welded. Width of electrode is equal to thickness of pipe walls. Electrode is shunted through easily melting jumpers by highly conducting bus. Electric arc is started between electrode and pipes to be welded. Power source is adjusted to required current and voltage according to desired power. Core and end face surfaces of pipes are melted. Power output is found by formula depending on required value of metal vapor gauge pressure. Electric arc is displaced automatically along end face of core. Weld metal melt is cooled. Sections of butt joint remaining unwelded are welded by stick electrode. Welding device has flat consumable insulated electrode with lead. Easily melting jumper connect electrode and shunting bus with lead. Electrode and bus are made in form of part of ring with central angle of where N is number of electrodes placed on one butt joint of pipes. Values of electrical resistance of shunting bus R b ,, jumper R j and electrode R e are related by expression (R b +R j ) e /n where n is number of jumpers per electrode. EFFECT: simplified process of pipe welding, enhanced quality of welds. 3 cl, 3 dwgs

Method for calculating rotating spring constant in butt joint part

Abstract: PROBLEM TO BE SOLVED: To obtain a calculation method, in which a beam spring can be analyzed properly so as to match with an actual state, by using a joint part, in which joint faces on side faces in the ring direction of block pieces regarding identical rings as a rotating spring, and analizing the beam spring by using a rotating spring constant expressed by a specific expression. SOLUTION: A plurality of longitudinal ribs 9 are installed so as to be stridden in corresponding parts on inside faces of opposite main beam plates 6, and reinforcing bars for crack prevention are arranged at the inside of hearting concrete plates 7. In addition, rod-shaped protrusion couplings 10 are installed near butt joint plates on outside faces of the main beam plates 6. Then, when a butt joint part in which joint faces are butted is used as a rotating spring so as to analyze a beam spring, a rotating spring constant Kθ (tf.m/ rad) is calculated by using an expression. In the expression, N represents an axial force (tf) acting on a butt face, M represents a bending moment (tf.m) acting on the butt face, E' represents a conversion elastic coefficient (tf/m2) in a joint contact part, and b' represents a contact with (m) on the joint face.

Superconducting Butt Joint of Bi-2212/Ag Multi Filamentary Tapes

Abstract: Superconducting properties of butt joints for Bi-2212/Ag multifilamentary tapes were studied in relation to the crystal orientation. The multifilamentary Bi-2212/Ag tapes with 19 and 55 filaments were prepared by a powder-in-tube technique. The tapes were butt jointed, followed by partial melting in a flowing oxygen atmosphere. The typical dimensions of the tapes used in the experiments were 3–5 mm in width, 0.15–0.25mm in thickness, and 30–40mm in length. The critical current Ic of the joint reached around 500A, showing a high possibility for use in persistent magnets. The crystal alignment of the butt jointed tape was analysed by means of a transmission X-ray diffraction method, and it was found that the preferred orientation was observed with in the joint. The marked angular dependence of Jc of the joint also proved the excellent c-axis alignment.

A Study on Characteristics of Echoes from Planar Defects by the Ultrasonic Testing of Angle Beam Technique

Abstract: The application of field-welded butt joints of flanges and web plates for steel girder bridges has been on the increase in Japan. Figure 1 is an illustration of such a field-welded joint. The thickness of the flange plate may at times be in excess of 75 mm. Radiographic testing has been used to inspect the quality of welded joints in the shop; however, taking into account material having a thickness that is beyond the capacity of the radiographic testing and the risk of using X-rays in the field, ultrasonic testing is applied to field-welded joints [1,2].

A mathematical model to predict fatigue notch factor of butt joints

Abstract: A mathematical model is developed to predict the fatigue notch factor of butt welds subject to number of parameters such as weld geometry, residual stresses under dynamic combined loading conditions (tensile and bending). Linear elastic fracture mechanics, finite element analysis, dimensional analysis and superposition approaches are used for the modelling. The predicted results are in good agreement with the available experimental data. As a result, scatters of the fatigue data can be significantly reduced by plotting S-N curve as (S . K-f) vs. N.

Utility vehicle loading surface

Abstract: not available for EP0956231Abstract of corresponding document: WO9833696The invention concerns a utility vehicle loading surface which is spanned by extruded sections (24, 42, 42a) which are rigidly connected to one another in non-thermal manner and form a base plate (18) which comprises at least two extruded sections (24, 42, 42a). The extruded sections (24, 42, 42a) of the base plate (18) are bonded to the loading surface (12), and in each case two adjacent extruded sections (24, 42, 42a) form a butt joint (46) which is closed at the bottom and on which a layer of adhesive (52) is superimposed. These extruded sections (24, 42, 42a) can comprise mould grooves (32) parallel to the butt joint (46), the adhesive layer (52) engaging at least in the mould grooves (32) adjacent the two butt joints (46). A solvent- and softener-free two-component elastic material is to be used to form the adhesive layer (52) for the butt joint (46).