Showing papers on "Shielded metal arc welding published in 1992"

Effects of chemistry, density and size distribution of inclusions on the nucleation of acicular ferrite of CMn steel shielded-metal-arc-welding weldments

Abstract: The influence of inclusions on the nucleation of acicular ferrite of six as-deposited CMnTi welds prepared by the shielded-metal-arc-welding process was studied. The microstructure of the welds, the inclusion size distribution, the density and the average chemical composition were characterized. It was found that a titanium-rich phase which partially covers the inclusions is responsible for the nucleation of acicular ferrite. It is estimated that a titanium content of about 39 wt.ppm in the weld metal is necessary for the formation of this titanium-rich phase. However, even if the presence of the titanium-rich phase in the inclusions is necessary, it is not the only factor affecting the nucleation of acicular ferrite (AF). After correcting for the effect of austenite grain size, it was found that the efficiency of the inclusions for the nucleation of AF is related to the total external surface area of the titanium-rich phase covering the inclusions per unit area of weld metal. This is in turn related to the density, the size distribution and the titanium level of the inclusions.

Electrode and flux for arc welding stainless steel

Abstract: A flux for use in arc welding of a stainless steel workpiece with a consumable metal electrode having a precentage of chromium, which welding flux comprises a silica containing system for forming a slag on the surface of the deposited chromium-bearing alloy weld metal and a bismuth containing slag releasing agent selected from the class consisting of elemental bismuth, bismuth fluoride, bismuth sulfide, bismuth titanate, bismuth oxy carbonate, bismuth oxy-chloride and mixtures thereof. Also, there is provided an electrode employing this flux.

Method and apparatus for depositing molten metal

Abstract: A collector electrode and adjacent electric weld torch are placed at a selected distance from a work surface or substrate. An electric welding current is generated so that a welding current arc forms between the collector electrode and the weld torch. A feed metal is then fed into the welding current arc and is melted into molten metal adjacent to the collector electrode. The molten metal is then deposited onto a work surface. The collector electrode and weld torch are positioned so that the welding current arc between the weld torch and the collector electrodes does not penetrate the work surface or the already-deposited metal.

Chemical composition and morphology of welding fume particles and grinding dusts.

Abstract: Elemental composition and morphology of pure manual metal arc (MMA) welding fumes, pure grinding dust, and combined fume/dust air samples were collected and determined separately under semilaboratory conditions. The base material was stainless steel. The purpose of the present study was to create a “synthetic” work situation under semilaboratory conditions by combining one grinding period and two MMA welding periods and comparing these results with results during welding in a workshop. The duty cycles of pure welding and of pure grinding were also observed. A comparison was also made between metal inert gas (MIG) and MMA welding on stainless steel as well as a nickel-rich alloy under regular conditions. The amount of collected material was determined by weighing the membrane filters before and after exposure, and the element contents were determined by atomic spectroscopy. Other transmission electron microscopy (TEM) filters were used for TEM and computer-image analysis, in which the amount of collected m...

Gun for gas metal arc welding

Abstract: A gas arc metal welding gun has a handle which may be rotated freely with respect to a conduit containing a current transfer wire and a gas tube and with respect to an adapter and tip assembly.

The interface below stainless steel and nickel-alloy claddings

Abstract: The formation of microstructures across cladding interfaces was examined with an emphasis on the fused region as-welded and after postweld heat treatment (PWHT). The strip submerged arc and shielded metal arc welding processes were used to deposit austenitic stainless steel and nickel-alloy consumables on to 2 1/4 Cr-1 Mo steel. Optical and electron microscopy were employed, with energy dispersive x-ray and electron probe microanalysis for examining major alloying elements and carbon. The observations were related to the results of hardness, bend and crack tip opening displacement (CTOD) toughness testing

Method of welding nickel or nickel alloy products

Abstract: A method of welding metal products, at least one of which being made of nickel or a nickel alloy, comprises the steps of generating an arc between the products to be welded serving as a positive pole and a tungsten electrode held by a welding torch serving as a negative pole, emitting a shielding gas consisting of an argon-based mixed gas containing one or both of hydrogen and helium from a confining gas nozzle concentric with the tungsten electrode, thus confining the apparent flaring angle of the arc within 80 degrees, and moving the welding torch along the weld line while feeding the tip of a filler wire to a part of the molten pool directly below the arc. This method is applicable to the welding of metal products, at least one of which is made of nickel or a nickel alloy.

Arc welding method using special protecting gas

Abstract: The invention relates to a protective-gas arc welding method using a melting electrode for relatively highly and highly alloyed, corrosion resistant steels, especially nickel materials and special steels, in which the welding process is carried out under protective gas. Welding methods of this type are associated, owing to the normally present oxygen contents or the contents of oxygen-carrying compounds in the protective gases, with undesirable oxidation at the welding point. Said oxidising proportions, on the other hand, do contribute to effective welding. According to the invention, a welding process is now proposed in which a protective gas having a proportion of carbon dioxide or a proportion of oxygen or a proportion of a mixture of said gases of from 0.01 to 0.5% by volume, preferably from 0.02 to 0.1% by volume is used. This results in an advantageous welding outcome while welding proceeds surprisingly well.

High temperature, low cycle fatigue behaviour of AISI type 316LN base metal, 316LN-316 weld joint and 316 all-weld metal

Abstract: Studies on the strain-controlled low cycle fatigue (LCF) behaviour of type 316LN stainless steel (SS) base material, type 316 SS all-weld metal and 316LN-316 weldments prepared by the shielded-metal-arc-welding (SMAW) process at 873 K have been conducted at a strain rate of 3 × 10 −3 s −1 . The results indicated that the LCF resistance of all-weld metal was better than that of the base material while weldments displayed the least fatigue resistance. The better fatigue resistance of all-weld metal has been attributed to the beneficial effects associated with fine distribution of δ-ferrite in the austenite matrix while the poor fatigue resistance of the weldment has been ascribed to the detrimental effects associated with coarse grain size and surface intergranular cracking in the heat-affected zone. The cyclic stress amplitude varied with the material condition and strain amplitude in the LCF test.

Double gas shielded metal arc welding method

Abstract: PURPOSE:To perform stable welding and to increase the welding speed by more than double in the past by changing argon into a mixture of helium with a small quantity of inert gas and using a flux-cored wire. CONSTITUTION:The occurrence and scattering of spatters are reduced and nozzle clogging is prevented by regulating a welding current, the arc voltage and the gas flow rate of inside and outside nozzles to values in the specified ranges. In addition, the welding speed is increased and penetration is increased without deteriorating a preventive effect of nozzle clogging by using mixed gas at the specified ratio of argon and helium as the inert gas of the inside nozzle. In addition, the occurrence and scattering of spatters can be suppressed by using the specified flux-cored wire for a welding electrode. This proposal is more excellent in points of the welding speed, penetration and the spatter quantity than results attained by the already-known DMA welding process.

Gas tungsten arc welding of a powder metallurgy aluminum alloy

Abstract: A thin sheet of the powder metallurgy aluminum alloy Al-10Fe-5Ce (wt-%) was fusion welded with the gas tungsten arc welding process. The effects of preweld vacuum heat treatment of the base metal, filler metal, and the type of welding current were investigated. The gross porosity of welds made with untreated base metal was virtually eliminated by the use of a combination of preweld vacuum heat treatment and a direct current electrode negative (DCEN) welding arc with helium shielding gas

Method for gas-shield arc welding of a pipe and weld wire for use in the welding method

Abstract: Disclosed is a gas-shield arc welding method in which chemi-cal components of base material and weld material (gas-shield arc welding wire), chemical component ranges of weld metal based on the base material and the weld material, especially, difference (DELTA(Cu+Ni), DELTAMo) of Cu, Ni and Mo between the weld metal and the base material, and welding conditions are limited for the purpose of improvement selective corrosion resistance, toughness and crack resistance of the weld metal in circumferential welding of a pipe exposed into a corrosion environment including CO2

Shielded Metal Arc Welding Consumables for Advanced High Strength Steels

Abstract: : To achieve the goal of developing adequate shielded metal arc (SMA) welding consumables for advanced high strength steels, the complex relationship between flux coating and base metal must be understood. This report is concerned with the effect of flux ingredients on high strength steel welding. Submerged arc (SA) welding was first used to investigate the performance of 45 experimental flux compositions chosen from the CaCO3-SiO2-K2SiO3-CaF2-Fe system. Bead-onplate welds were produced on 3/4 in. (19.1 mm) thick HSLA-100 steel plates using a 1/16 in. (1.59 mm) diameter Airco AX-140 welding wire. A 1.5 kj/ mm (38.1 kJ/in.) linear heat input was maintained for all welds. To evaluate the effect of the experimental fluxes, two empirical basicity indexes were used: the basicity index (BI) and the Zeke basicity index (Bz). Experimental results showed definite influences of the flux ingredients, both on weld bead morphology and chemical composition of the weld metal. As the basicity of the flux increases, the weld metal oxygen content decreases and the weld metal carbon equivalent (Pcm.) increases. As weld metal oxygen content decreases, the amount of acicular ferrite and Charpy-V-notch impact toughness of the weld metal are observed to increase. The submerged arc welding results also showed that while BI can describe satisfactorily the behavior of basic fluxes, Bz is more appropriate for the acidic fluxes. Using the submerged arc welding data, four fluxes were selected for the extrusion of experimental SMA electrodes. Welding was performed at similar conditions as the submerged arc welds. Slag coverage, weld bead morphology, and weld metal microstructures confirmed the results obtained in submerged arc welding.

Structure morphology effect of Ti and Nb stabilized austenitic stainless steel welds on corrosion properties

Abstract: In this preliminary study the microstructure morphology of the austenitic stabilized stainless steel deposited by manual metal arc (MMA) welding on corrosion has been investigated as part of a study attempting to establish a quantitative correlation between the morphology and corrosion properties. It was found that corrosion resistance of the developed complex microstructure depends on the particular structure morphology at the parent metal-weld bead interface. For a given composition, the developed morphology is controlled by the interrelated parameters of heat input, cooling rate and joint geometry. Extensive precipitation of δ-ferrite results in a significant reduction of corrosion resistance.

Procedure for build-up arc weld and device therefor

Abstract: Method of build-up arc welding, of the type comprising an operation which consists in continuously dispensing a metal welding wire (11) forming a consumable welding electrode through a passage (31) made in an electrical contact tube (30). According to the invention, the said method furthermore comprises an operation which consists in dispensing a metal welding powder (41) through the said passage by means of an entrainment gas (51), the said metal wire and the said metal powder forming a weld bead by melting under the action of the said welding arc. Application to the build up of bronze glass-making moulds with nickel- or cobalt-based alloys.

Ar-O2, Ar-CO2およびCO2-O2雰囲気における鋼溶接金属の酸素吸収について

Abstract: In an oxidizing gas welding atmosphere of Ar-O2, Ar-CO2 or CO2-O2 gas mixture, oxygen absorption behavior by steel weld metal has been investigated metallurgically, using a popular Fe-Si-Mn electrode wire and two types of base metal, that is, pure iron and rolled steel for welded structure. As an addition of oxygen to argon-based mixture, the oxygen content in steel weld metal extremely increases and the losses of alloying elements such as silicon and manganese steadily increase. As an addition of carbon-dioxide to argon-based mixture, the oxygen content in steel weld metal increases somewhat and limited amount of alloying elements losses. As an addition of oxygen to carbon-dioxide-based mixture, only a little amount of oxygen is absorbed into the steel weld metal. Despite the active gas of CO2 instead of Ar adds into the welding atmosphere, unexpectedly, the oxygen content of steel weld metal under CO2-O2 is lower than that of the weld metal under Ar-O2 for the same oxygen partial pressure over the range of 0.01 MPa. The losses of alloying elements are not so significant in this atmosphere.

An Enclosed-arc Welding Process for High Strength Rails and Welded Joint Performance. Study on Rail Welding with High-C Welding Materials Report 2.

Abstract: This paper describes the use of high-C welding materials for enclosed-arc welding of high strength rail. Experiments have been done to improve the facility of manipulation of the high-C electrodes to find the optimum welding procedures and to find weld joint performances of high-C welds.The experimental results are as follows :1) It is necessary to keep the flux weight ratio to core electrode between 22 and 23%, the ratio of CaO/ CaF2 in flux around 1.6, and carbon content in weld metal less than 0.5% so that welders can preferably manipulate electrodes to remove molten slag swiftly out of molten weld pool.2) The welding conditions and the pass sequences specific to the high-C welding have been found so that sound welds free from solidification cracks in weld metal and liquation cracks in HAZ can be obtained.

Manufacture of High-C Welding Materials and Development of High-C Welding Techniques. Study on Rail Welding with High-C Welding Materials Report 1.

Abstract: This paper describes the use of high-C welding materials for rail welding, which provide rail weld metal with improved wear resistance. The high-C weld metal prevents liquation cracking at rail HAZ caused by the significant difference in the melting points between weld metal and HAZ when using conventional low carbon low alloy electrodes.Fundamental studies have been made on how to manufacture electrodes with carbon up to 1% and how to avoid solidification cracking likely to occur in high carbon weld metal.The results of this study are as follows :1) The high-C electrodes have been successfully manufactured2) The microstructure of high-C weld metal is of fine lamellar pearlite which is known to be highly wear-resistant.3) The liquation cracking at HAZ can be avoided by the use of weld metal with carbon higher than 0.4%.4) The occurrence of weld metal solidification cracking is facilitated in high-C weld metal. This cracking can be prevented by a control of molten pool configuration through appropriate manipulation of electrodes.

Ar-CO2-O2雰囲気における鋼溶接金属の酸素吸収について

Abstract: In an oxidizing gas welding atmosphere of Ar-CO2-O2 gas mixture, oxygen absorption behavior by steel weld metal has been investigated metallurgically, using a popular Fe-Si-Mn electrode wire and two types of base metal, that is, pure iron and rolled steel for welded structure. The oxygen content in steel weld metal is controlled by the partial pressure of oxygen, and the partial pressure of carbon-dioxide has the both different effects of gain and decrease of the oxygen content. The silicon and manganese contents in steel weld metal depend on the degree of deoxidation reaction. Thus, the more the oxygen in steel weld metal, the less the silicon and manganese content. The carbon content in steel weld metal decreases as the result of the deoxidation reaction and increases depending on the absorption of carbon from the CO2 in welding atmosphere. Finally, the diagram of oxygen, silicon, manganese and carbon cuntent of steel weld metal have been produced as the function of the ternary welding atmosphere of Ar-CO2-O2.

Conductive nozzle for gas shielded metal-arc welding

Abstract: The utility model provides a conductive nozzle for gas shielded metal-arc welding, which belongs to an element for arc-welding equipment. The utility model is characterized in that the front end of the conductive nozzle is provided with a concave cambered surface; the hole diameters of center through holes which are variable diameter holes are gradually increased from a front end to a back end. The length of arcs can be kept enough because of the function of the concave cambered surface of the conductive nozzle for gas shielded metal-arc welding; the flashback of the arcs can be blocked by compressed gases which are generated by the concave cambered surface in the process of gas shielded metal-arc welding, and the phenomenon of cementing between welding wires and the conductive nozzle can be effectively prevented; variable diameter holes are adopted by the center through holes, the electric currents can be uniformly conducted, and the arcs are stable; the problem that people can be scratched and pricked by the welding wires is solved. The use is reliable, and the service life is enhanced.