Showing papers on "Submerged arc welding published in 2011"

Optimization of parameters of submerged arc weld using non conventional techniques

Abstract: In submerged arc welding (SAW), weld quality is greatly affected by the weld parameters such as welding current, welding speed; arc voltage and electrode stickout since they are closely related to the geometry of weld bead, a relationship which is thought to be complicated because of the non-linear characteristics. However, trial-and-error methods to determine optimal conditions incur considerable time and cost. In order to overcome these problems, non-traditional methods have been suggested. Bead-on-plate welds were carried out on mild steel plates using semi automatic SAW machine. Data were collected as per Taguchi's Design of Experiments and regression analysis was carried to establish input-output relationships of the process. By this relationship, an attempt was made to minimize weld bead width, a good indicator of bead geometry, using optimization procedures based on the genetic algorithm (GA) and particle swarm optimization (PSO) algorithm to determine optimal weld parameters. The optimized values obtained from these techniques were compared with experimental results and presented.

Marine engineering large thick steel plate submerged arc welding process method in low-temperature environment

Abstract: The invention belongs to the field of welding, in particular to a process method applicable to marine engineering large thick steel plate submerged arc welding in low-temperature environment, which comprises a welding method, welding material selection, a welding order, a welding process and the selection and control of various welding process parameters. The method renders with carbon dioxide gas protection welding, and fills and faces through an automatic submerged arc welding; stops welding when the welding reaches more than two thirds of the thickness of a large groove during the welding process, clears chips on the back side and completes the welding of the other side; finally completes the welding of the first side; strictly controls all relevant process parameters of the welding during the welding process, and solves the problems of poorer anti-crack toughness of welding seams and heat affected zones caused by too high cooling speed of the welding seams and too high temperature; can ensure good anti-crack toughness of a welding seam connector without heat treatment after welding; and can meet the requirements of welding of an E36 plate with the thickness of 35 to 77mm underthe working environment at the temperature of above -30DEG C, simplifies the production process, shortens the production cycle and reduces the cost.

Solder wire for submerged arc welding of X100 pipeline steel and preparation method thereof

Abstract: The invention discloses a solder wire for submerged arc welding of X100 pipeline steel, which consists of the following components in percentage by weight: 0.03 to 0.06 percent of C, 0.1 to 0.3 percent of Si, 1.0 to 2.0 percent of Mn, 0.7 to 1.0 percent of Ni, 0.3 to 0.6 percent of Mo, 0.3 to 0.6 percent of Cr, 0.01 to 0.04 percent of Nb, 0.1 to 0.3 percent of Ti, 0.0015 to 0.005 percent of B, 0.1 to 0.3 percent of Cu, 0.1 to 0.3 percent of Ce, 0.01 to 0.05 percent of Al, less than 0.01 percent of S, less than 0.01 percent of P and the balance of Fe. The solder wire has the advantages of high strength of welding lines, good impact property and the like. The invention also discloses a preparation method for the solder wire, which comprises the following steps of: smelting Fe, Nb and the like in a vacuum induction furnace, raising the temperature to 1,540 DEG C, keeping the temperature, and after the molten steel is calm, cooling and exhausting; refining, reducing temperature, performing fine adjustment on Ti content, introducing a protective gas Ar before tapping, simultaneously adding components such as Mn, Fe and the like, stirring, tapping and casting to obtain steel ingots; and performing subsequent forging, rolling and drawing on the steel ingots, and finally obtain solder wires. The preparation method for the solder wire is stable in smelting process and easy to implement; and the product has good properties.

Welding flux for X100 pipe line steel submerged arc-welding and preparation method thereof

Abstract: The invention discloses a welding flux for X100 pipe line steel submerged arc-welding and a preparation method thereof. The welding flux comprises, in percentage by weight, main components including 5-13% of SiO2, 26-40% of MgO, 15-24% of Al2O3, 18-25% of CaF2, 1-4% of CaO, 4-8% of MnO, 1-2% of Na2O, 1-2% of K2O and 1.0-6.0% of TiO2, and a bonder accounting for 15-20wt% of the total weight. The preparation method comprises the steps of: uniformly mixing the main components according to proportions; then adding the bonder for pelleting; and baking at low temperature, sintering at high temperature and sifting. When the welding flux is matched with a special welding wire CHW-SG10, a soldered seam has excellent performances, such as high strength, high toughness, better corrosion resistance, lower rigidity and the like approaching to those of an X100-level steel pipe body, and the welding flux can be used for carrying out single or multiple-wire welding and internal and external high-speed welding; and a multiple-wire large-line energy welding speed can reach 120 m/h, and the soldered seam performance and air holes, slag inclusions, cracks, appearance edge, undercut and the like of the soldered seam all meet the requirements of the technical standard of the X100 pipe line steel submerged arc-welding.

Three-dimensional Heat Transfer Analysis of Two Wire Tandem Submerged Arc Welding

Abstract: Two wire tandem submerged arc welding process facilitates high rate of joint filling with little increase in the overall rate of heat input due to the simultaneous deposition from two electrode wires. Since the lead wire is usually connected to a DC welding arc and the trail wire to a pulsed AC arc, the tandem process requires appropriate selection of a large number of process variables. A quantitative understanding of the effect of the welding conditions on weld joint dimensions and weld thermal cycle is difficult through experimental studies only. Here we present a three-dimensional heat transfer analysis based on finite element method using two independent volumetric heat sources to account for heat input from two welding arcs. The shapes of the heat sources are estimated based on the original joint geometry and welding conditions. The results show that the trail wire current pulses significantly influences the reinforcement height and weld width while lead wire current affects the depth of penetration. For a constant trail wire effective current, increase in the negative pulse time results in greater reinforcement height and reduced weld width with very little influence on the cooling rate and weld strength. In contrast, increase in trail wire negative current pulse increases both reinforcement height and weld width while reduces cooling rate and weld strength.

Hybrid arc/laser-welding method for aluminized steel parts using gammagenic elements and a gas containing less than 10 % of nitrogen or oxygen

Abstract: The invention relates to a hybrid laser/arc-welding method using an electric arc and a laser beam that are combined together within a single welding melt to which molten metal is supplied by melting a filler wire, wherein the welding melt is provided on at least one steel part including an aluminum surface coating, and a protective gas is used, characterized in that the filler wire contains at least 3 wt % of one or more gammagenic elements, in particular the gammagenic elements selected from C, Mn, Ni and N, and the protective gas consists of helium and/or argon with the addition of at least 10 vol % of nitrogen or oxygen. The method of the invention is particularly suitable for welding end-welded flanks used in the field of manufacturing automobiles or for tube welding.

Modeling of Weld Bead Geometry and Shape Relationships in Submerged Arc Welding using Developed Fluxes

Abstract: To automate a welding process, which is the present trend in fabrication industry, it is essential that mathematical models have to be developed to relate the process variables to the weld bead parameters. Submerged arc welding (SAW) is characterized by its high reliability, deep penetration, smooth finish and high productivity especially for welding of pipes and boiler joints. In the present work mathematical models have been developed for SAW using developed fluxes. Response surface methodology has been used to predict critical dimensions of the weld bead geometry and shape relationships. The models developed have been checked for their adequacy and significance by using the F-test and the t-test, respectively. Main and interaction effects of the process variables on bead geometry and shape factors are presented in graphical form and using which not only the prediction of important weld bead dimensions and shape relationships but also controlling the weld bead quality by selecting appropriate process parameter values are possible.

Some myths about DC arc furnaces

Abstract: DC arc furnaces are widely used for steel scrap melting as well as for reductive smelting of ore fines. Industrial smelting applications include the smelting of chromite to produce ferrochromium, the smelting of ilmenite to produce titania slag and pig iron, and the recovery of cobalt from non-ferrous smelter slags. A number of myths and misconceptions are widely held, especially regarding: the age of the technology, the use of a hollow electrode, arc stability and shape, arc and bath radiation, interaction between the arc and molten slag, electrical behaviour of arcs and slags, a comparison between AC and DC furnaces, DC reactors, the lifespan of bottom electrodes, and the applicability of DC arc furnaces to various metallurgical systems. DC arc furnaces have been known by various names over the years. In this paper, a 'DC arc furnace' refers to a pyrometallurgical vessel that comprises a cylindrical steel shell with either a domed or flat base, and a roof that is typically conical. It is lined inside with a refractory material in order to contain the molten materials being processed. The furnace usually has a central graphite electrode (maybe more than one, but that is not the specific focus of this paper), and an anode imbedded in the hearth. It is usual that the molten metal in the furnace is in electrical contact with the anode. Energy is supplied to the furnace by means of an open plasma arc that impinges on the upper surface of the molten material. The arc in a DC (direct current) furnace is a sustained high-velocity high-temperature jet, driven by electromagnetic acceleration (the Maecker effect) in the constricted region near the arc's root on the electrode surface. The arc is generated by the interaction between the fluid flow, the thermal field, and the electromagnetic fields. The self-constricting electromagnetic forces keep this supersonic super-heated plasma jet reasonably coherent. A DC reactor is used to stabilize the arc further. Furthermore, the surface of the molten bath (or at least a portion of the surface in the arc- attachment zone) is open, i.e. essentially uncovered by unreacted feed material.

The influence of heat treatment by annealing on clad plates residual stresses

Abstract: The influence of applied clad procedure as well as heat treatment by annealing (650 °C/2h) on level and nature of residual stresses was researched. Three clad procedure are used i.e. hot rolling, submerged arc welding (SAW) with strip electrode and explosion welding. The relaxed deformation measurement on clad plate surfaces was performed by applying centre-hole drilling method using special measuring electrical resistance strain gauges (rosettes). After performed measuring, size and nature of residual stresses were determined using analytical method. depending of residual stresses on depth of drilled blind-hole is studied.

Two-electrode arc welding device and two-electrode arc welding method

Abstract: A two-electrode arc welding device and two-electrode arc welding method are provided for performing welding with improved penetration performance using two non-consumable electrodes. In a two-electrode arc welding device 1, a power-supply unit 11 outputs a straight-polarity voltage and a reverse-polarity voltage, which has a different electrical potential than the straight-polarity voltage. The straight-polarity voltage output from the power-supply unit 11 is applied to a non-consumable electrode 41 of a straight-polarity arc torch 14, whereby an arc is formed. The reverse-polarity voltage output from the power-supply unit 11 is applied to a non-consumable electrode 41 of a straight-polarity arc torch 15, whereby an arc is formed. An arc spacing distance L1, which is a distance between the ends of both the straight-polarity arc torch 14 and the reverse-polarity arc torch 15, is set to be at least a minimum distance at which an arc will not occur therebetween (arc spacing critical distance).

Submerged arc-welding method of steel for high strength pressure vessel

Abstract: The invention discloses a submerged arc-welding method of thick steel slab for large pressure vessel with tensile strength of 610-670 MPa, which solves the currently existing defects that the impact energy of deposited metal and the actual joint tenacity can not meet the welding requirements for the production of large high-strength thick steel slab structure. A measure adopted by the invention is as follows: the method comprises the following steps of: adopting pressure vessel steel with tensile strength of 610-670 Mpa and thickness of 44mm to 55mm; using matched welding materials: the tensile strength of a welding wire is 610-670 Mpa with diameter of 4.0mm and welding flux SJ105Q is adopted; adopting an unsymmetrical double-side V-shaped groove with an angle of 60 degrees as the groove of submerged arc-welding and a blunted edge of 4mm; continuously welding at the butt joint till weld seams are filled up under the conditions of 700A welding current, 36V voltage, 30cm/min speed and 50kJ/cm energy input; using a welding flux roasting system of 350 DEG C multiplied by 1h; and adopting interlayer temperature of 100 DEG C to 150 DEG C. In the invention, preheating is not required before welding and heat treatment is not needed after welding and joints have good low temperature impact toughness and safety storage.

Fabricating process of full-web welding H-type steel member

Abstract: The invention relates to a fabricating process of a full-web welding H-type steel member, which mainly comprises the following steps of: 1, discharging a jointed board; 2, assembling an H-shaped member; 3, carrying out automatic submerged arc welding; 4, correcting; 5, making holes; 6, sawing; 7, drilling a preliminary shaft; 8, sparking-out; and 9, processing an end face. The invention has the advantages of simple steps and easiness of operation, and can save a large quantity of labor resources; and the machined H type steel member has the advantages of stable quality, good end face flatness, good bearing capacity and steel consumption reduction.

Method for manufacturing X70 steel-level large deformation-resistant longitudinally submerged arc welding pipe

Abstract: The invention discloses a method for manufacturing X70 steel-level large deformation-resistant longitudinally submerged arc welding pipes, which is applied to the manufacture of special welding pipes for oil and gas transmission In the method, a controllable rolled steel plate is used, wherein the controllable rolled steel plate has a ferrite-bainite double-phase metallurgical microstructure and contains the following chemical components: 004 to 007 percent of C, 160 to 185 percent of Mn, 015 to 030 percent of Si, not more than 0003 percent of S, not more than 0010 percent of P, 015 to 030 percent of Ni, not more than 0020 percent of Ti, 0015 to 0040 percent of Al, 0010 to 0065 percent of Nb, not more than 0006 percent of N, not more than 030 percent of Cu, 010 to 025 percent of Cr, and not more than 00005 percent of B The method comprises the following steps: (1) milling edges of the steel plate; (2) pre-bending bended edges; (3) performing JCO forming; (4) pre-welding joint seams; and (5) performing finish-welding on the inner and the outer sides of the joint seams The method is applied to the manufacture of large-deformation-resistant welding pipes which are used in seismic belts, frozen soil areas, landslide area and other areas with high risk of deformation The method has the advantages as follows: in the JCO forming process, the local deformation amounts and straight edge sizes of the steel plate in different rolling passes are analytically acquired according to the width, thickness and strength of the steel plate and the size of a die so as to determine the rolling passes and ensure uniform deformation at all parts of the steel plate after forming; and in the diameter expansion process, the minimum diameter expansion amount is determined according to the size and shape of the formed steel pipe, so as to ensure the size, shape and physiochemical properties of the steel pipe after diameter expansion

Effect of process parameters on microhardness and microstructure of heat affected zone in submerged arc welding

Abstract: The aim of the present work was to study the effect of flux, welding current, arc voltage, and travel speed on changes in microhardness and microstructure of the heat-affected zone (HAZ) and to optimize the process so that minimal changes occur in the material properties after completion of a submerged arc welding (SAW) process following suitable Taguchi experimental design. Micrographs of the welded samples were studied to analyse the changes in the microstructure of the material and the resultant changes in ferrite percentage, pearlite, bainite, and martensite formations. Welding current and type of flux were found to be the most significant factors leading to changes in microhardness and metallurgical properties. The microhardness tended to increase significantly with the increase of welding current from 350 to 450 Amp whereas higher hardness was observed when flux type I (basicity index 0.8) was used. Travel speed and arc voltage were found to be insignificant in relative comparison. Flux with basicit...

Hardness and microstructural gradients in the heat affected zone of welded low-carbon quenched and tempered steels

Abstract: This paper concentrates on the form of the hardness gradient in the heat affected zones (HAZs) produced by submerged arc welding of two low-carbon Q & T steels. The results show unequivocally that the gradient differs from that found in steels of lower carbon equivalent in that the peak HAZ hardness is displaced from the grain coarsened heat affected zone (GCHAZ) into the grain refined heat affected zone (GRHAZ). Weld thermal cycle simulation has been used to confirm the results obtained from actual welds and to clarify the cause of this unexpected phenomenon.

Thick-wall chromium-molybdenum steel pipeline submerged arc welding technology

Abstract: The invention discloses a thick-wall chromium-molybdenum steel pipeline submerged arc welding technology, which is characterized in that an automatic submerged arc welding is used for filling and welding a cover: a pipeline is placed on a rolling tire, an automatic submerged arc welder is used for welding the pipeline, the rolling tire is rotated to drive the pipeline to rotate during welding, and a welding gun is located at a flat welding position and always keeps still; welding parameters are as follows: the welding current is 240-500A, the voltage is 30-36.5V, the welding speed is 36-46.5 cm/min, the extension length of a welding wire is 8-12 mm, and a distance from a tail end of the welding wire to a weld surface is 5-6 mm. The average working efficiency by using the submerged arc welding technology to weld the thick-wall chromium-molybdenum steel pipeline is more than 4-6 times that of the manual welding, the thickness theta of a welding wall is more than the thick-wall pipeline of 30 mm, and the working efficiency is 8-12 times that of the manual welding.

Hybrid welding apparatus and system and method of welding

Abstract: A hybrid welding apparatus, and a system and method for welding at least two adjacent components having a large gap of approximately 30 millimeters that results in a full-penetration weld is provided The welding system includes a hybrid welder having a defocused laser beam, an electric arc welder, and at least one bridge piece adjacent to one or more of the at least two adjacent components The defocused laser beam and the electric arc welder are arranged and disposed to direct energy onto the at least two adjacent components to create a common molten pool operable to provide a full penetration weld to bridge the gap at a high constant weld speed, thereby joining the two adjacent components with a weld

Prediction of Transient Temperature Distribution, HAZ Width and Microstructural Analysis of Submerged Arc-Welded Structural Steel Plates

Abstract: Critical investigation of the transient temperature distribution is important for maintaining the quality of the Submerged Arc Welding of structural steel plates. The aim of this paper is to derive an analytical solution to predict the transient temperature distribution on the plate during the process of Submerged Arc Welding. An analytical solution is obtained from the 3D heat conduction equation. The main energy input that is applied on the plate is taken as the heat lost from the electric arc. The kinetic energy of filler droplets, electromagnetic force and drag force are also considered as input to the process. The electric arc is assumed to be a moving double Central Conicoidal heat source which follows approximately the Gaussian distribution. It is observed that the predicted values are in good agreement with the experimental results. The heat-affected zone (HAZ) width calculation is also done with the help of the analytical solution of the transient 3D heat conduction equation. Analysis of microstructural changes is critically investigated to comprehend the HAZ softening phenomenon and for the validation of the predicted HAZ width.

Thick steel plate buried arc welding method for high-strength bridge

Abstract: The invention relates to a submerged arc welding butt welding technique for high intensity bridge steels, which is used for solving problems at present that in the submerged arc welding butt welding of making large span bridge structures by the bridge steels with low alloy and high intensity, the bridge steels need to be heat treated and back-gouged after being welded. The measure is as following: the method of the invention includes that the bridge steels with the tensile strength of 570MPa to 650MPa and the thickness of 36 to 60mm are used; the matched welding material meet the requirementsthat the tensile strength of welding wires is 600MPa, the diameter Phi of the welding wires is 5.0mm, the welding flux is SJ105Q; a submerged arc welding groove adopts a double-sided V shape asymmetrical groove, the groove angle is 60 degrees, the blunted edge is 6mm; the flame before the welding is preheated to 80 DEG C to 100 DEG C; the welding parameter includes that the welding current is 680A to 700A, the welding voltage is 29V to 30V, the welding speed is 22m/h to 23m/h, the welding line energy is 32kJ/cm to 35kJ/cm, the baking system of the welding flux is 350 DEG C multiplied by 1h; the submerged arc welding adopts the multi-layer and multi-channel continuous welding, and the interlayer temperature is controlled to be 100 DEG C to 160 DEG C. The submerged arc welding butt welding technique for the high intensity bridge steels is simple in procedure and low in energy consumption without the heat treating and the back gouging after being welded.

Special flux-cored wire for carrying out preheating-free and heat treatment-free surfacing repair and reproducing on shaft and gear parts

Abstract: The invention belongs to the field of material science and engineering and relates to a special flux-cored wire for carrying out preheating-free and heat treatment-free surfacing repair and reproducing on shaft and gear parts. The special flux-cored wire comprises the following chemical compositions in percentage by weight: 5 to 10 percent of fluorite, 20 to 40 percent of high-carbon ferrochrome, 5 to 10 percent of high carbon ferromanganese, 5 to 10 percent of ferrosilicon, 5 to 10 percent of ferromolybdenum, 10 to 15 percent of rare earth oxide, 15 to 20 percent of metallic nickel, 2 to 5 percent of ferrovanadium, 2 to 5 percent of ferrocolumbium, 2 to 5 percent of ferrotitanium, 0.1 to 0.5 percent of graphite, 5 to 15 percent of iron powder, 0.5 to 2 percent of nitride and 1 to 3 percent of aluminum magnesium alloy. A sheath of the special flux-cored wire is a low-carbon steel strip. The special flux-cored wire can be suitable for open arc welding or submerged arc welding. The series flux-core wire for surfacing can carry out surfacing repair and reproducing on the shaft and gear parts under the conditions that preheating is free before surfacing and heat treatment is free after surfacing. The surfacing metal has high crack resistance. The performance of the repaired parts is equal to or even superior to that of the original parts. The special flux-cored wire is convenient to use on site. The hardness range is between HRC20 and HRC45. The service life of the repaired parts is about 3 times longer than that of the original parts.

Submerged arc welding method of bridge steel of different intensity scale

Abstract: The invention discloses a hidden arc welding method for bridge steel at different levels of strength, which adopts two steel types with different tensile strengths, namely 510-550MPa and 570-650MPa as the subject of hidden arc welding; an X-type asymmetric divided edge is adopted as the divided edge of hidden arc welding; the adopted steel types are 14MnNbq steel and WNQ5709 steel; the yield strength ReL of the 14MnNb steel is 370-415MPa, the tensile strength Rm thereof is 510-550MPa, the unit extension A thereof is 20-35%, and the -40 DEG C AKV impact energy thereof is 120-290J; the yield strength Rel of the WNQ570 steel is 420-560MPa, the tensile strength Rm thereof is 570-650MPa, the unit extension A thereof is 18-27%, and the -40 DEG C AKV impact energy thereof is 120-270J; the thickness of steel plates is 32-60mm; the angle of the divided edge is 60 DEG; and the length of the truncated edge is 6mm. The hidden arc welding method meet the requirements for using the key hidden arc welding technique to manufacture dissimilar steel joints with a novel bridge structure of large-span, heavy-duty, high-speed, high-strength and high-tenacity. The joints made through hidden arc weldinghave good tensile strength and cold-bending performance; the impact energy of the three areas of the joint reaches a high level; and the joints have relatively high impact tenacity reserve and safetymargin.