Showing papers on "Submerged arc welding published in 2010"

The effects of metal vapour in arc welding

Abstract: Metal vapour is formed in arc welding processes by the evaporation of molten metal in the weld pool, and in the case of gas–metal arc welding, in the wire electrode and droplets. The presence of metal vapour can have a major influence on the properties of the arc and the size and shape of the weld pool. Previous experimental and computational works on the production and transport of metal vapour in welding arcs, in particular those relevant to gas–metal arc welding and gas–tungsten arc welding, are reviewed. The influence of metal vapour on the thermodynamic, transport and radiative properties of plasmas is discussed. The effect of metal vapour on the distributions of temperature, current density and heat flux in arcs is examined in terms of these thermophysical properties. Different approaches to treating diffusion of metal vapour in plasmas, and the production of vapour from molten metal, are compared. The production of welding fume by the nucleation and subsequent condensation of metal vapour is considered. Recommendations are presented about subjects requiring further investigation, and the requirements for accurate computational modelling of welding arcs.

The dynamic effects of metal vapour in gas metal arc welding

Abstract: Numerical simulations for the dynamic effects of metal vapour in gas metal arc welding (GMAW) suggest that vapour from the welding droplet at the tip of the welding wire has a significant influence on the plasma properties. It is found that for the evaporation rates calculated for arcs in pure argon, the dynamic effects of metal vapour markedly cool down the plasma in the central region of the arc, leading to the formation of a low temperature zone centred on the arc axis, in agreement with experimental measurements in the literature. Radiation effects, omitted in this paper, may produce further cooling of the plasma gas. The results highlight major deficiencies in the common approach to modelling the GMAW process and suggest that accurate description of GMAW must include the influence of metal vapour on the plasma.

Numerical and experimental study on prediction of thermal history and residual deformation of double-sided fillet welding

Abstract: Distortions occur in almost every arc welded joint. The nature of the created distortion depends on several parameters including the welding speed, plate thickness, welding current, voltage, and restraints applied to the job. The distortions and thermal history of a joint can be measured experimentally but the measurement procedure may be costly and time-consuming. In the present work a numerical elasto-plastic thermomechanical model has been developed for predicting the thermal history and resulting angular distortions of submerged arc welded double-sided fillet joints. A moving distributed heat source was used in the finite element modelling of the double-sided fillet welding to create a realistic simulation of the process. The effect of filler metal deposition was taken into account by implementing a birth-and-death process for the elements. The transient temperature distributions were predicted using temperature-dependent material properties. The angular distortion profiles were predicted base...

Effects of shielding gas compositions on arc plasma and metal transfer in gas metal arc welding

Abstract: This article presents the effects of shielding gas compositions on the transient transport phenomena, including the distributions of temperature, flow velocity, current density, and electromagnetic force in the arc and the metal, and arc pressure in gas metal arc welding of mild steel at a constant current input. The shielding gas considered includes pure argon, 75% Ar, 50% Ar, and 25% Ar with the balance of helium. It is found that the shielding gas composition has significant influences on the arc characteristics; droplet formation, detachment, transfer, and impingement onto the workpiece; and weld pool dynamics and weld bead profile. As helium increases in the shielding gas, the droplet size increases but the droplet detachment frequency decreases. For helium-rich gases, the current converges at the workpiece with a “ring” shape which produces non-Gaussian-like distributions of arc pressure and temperature along the workpiece surface. Detailed explanations to the physics of the very complex but interesting transport phenomena are given.

Research on the activating flux gas tungsten arc welding and plasma arc welding for stainless steel

Abstract: A systematic study of the effects of activating flux in the weld morphology, arc profile, and angular distortion and microstructure of two different arc welding processes, namely, Gas Tungsten Arc Welding (GTAW) and Plasma Arc Welding (PAW), was carried out. The results showed that the activating fluxes affected the penetration capability of arc welding on stainless steel. An increase in energy density resulting from the arc constriction and anode spot reduction enhanced the penetration capability. The Depth/Width (D/W) ratio of the weld played a major role in causing angular distortion of the weldment. Also, changes in the cooling rate, due to different heat source characteristics, influenced the microstructure from the fusion line to the centre of the weld.

Thermomechanical finite element analysis and experimental investigation of single-pass single-sided submerged arc welding of C—Mn steel plates

Abstract: Determination of distortions are important while designing the arc-welded joints. These distortions occur in a varied way in almost every type of welded joint, depending on several parameters, i.e. welding speed, plate thickness, welding current and voltage, restraints applied to the job while welding, thermal history, etc. In the present work a numerical model based on the finite element package ANSYS was developed for single-pass single-sided submerged arc welding of square butt joints. Suitable macros were developed to simulate the situation of a moving distributed heat source, metal deposition to account for top and bottom reinforcements, a time step, and a meshing scheme. In this model the effect of bead geometry was incorporated. The effect of filler metal deposition was taken into account by implementing the element birth and death technique.Submerged arc welding (SAW) can be conveniently used to weld a range of plate thicknesses in a single run using a suitable backing strip achieving adeq...

Argon-Hydrogen Shielding Gas Mixtures for Activating Flux-Assisted Gas Tungsten Arc Welding

Abstract: Using activating flux for gas tungsten arc welding (GTAW) to improve penetration capability is a well-established technique. Argon is an inert gas and the one most widely used as a shielding gas for GTAW. For the most austenitic stainless steels, pure argon does not provide adequate weld penetration. Argon–hydrogen mixtures give a more even heat input to the workpiece, increasing the arc voltage, which tends to increase the volume of molten material in the weld pool as well as the weld depth-to-width ratio. Great interest has been shown in the interaction between activating flux and the hydrogen concentration in an argon-based shielding gas. In this study, the weld morphology, the arc profile, the retained delta ferrite content, the angular distortion, and the microstructures were examined. The application of an activating flux combining argon and hydrogen for GTAW is important in the industry. The results of this study are presented here.

Hybrid Laser Arc Welding Process Evaluation on DH36 and EH36 Steel: This study characterizes the effects laser power, arc power, and laser-arc separation have on weld macrostructure, microstructure, and welding arc

Abstract: The effects of laser power, arc power, and laser-arc separation on the macrostructure, microstructure, and welding arc were characterized in hybrid laser arc welds on DH36 and EH36 steels. Experiments were done to study a range of arc and laser powers at a constant laser-arc separation and a range of laser powers and laser-arc separation at a constant arc power. High-speed video captured images of the welding in process, and arc voltage and current were also measured. Two distinct weld macrostructure morphologies were observed. The first had a uniform fusion zone, and the second had a two- part fusion zone with an upper laser and arc combined region and a lower laser-only penetration region at the root. This two-part fusion zone was only observed for partial joint penetration welds, and process parameter maps were made to define the windows for both morphologies. Complete penetration welds always exhibited a uniform fusion zone. Decreasing the laser-arc separation increased the total penetration of the uniform fusion zone welds and reduced the size of the laser-only penetration region in the two-part fusion zone welds. The formation of acicular ferrite was promoted by increasing the arc power and increasing the laser-arc separation. Laser power did not have a major effect on the weld metal microstructure. Small laser-arc separations and low laser powers added a low-frequency large globular/short circuiting metal transfer mode to the predominately spray arc. Welding with larger laser-arc separations and higher lasers powers did not exhibit this low-frequency transfer but did have a mid frequency small globular free-flight transfer that was not observed in the gas metal arc welding (GMAW) only arc.

Probing influence of welding current on weld quality in two wire tandem submerged arc welding of HSLA steel

Abstract: Two wire tandem submerged arc welding (SAW-T) involves application of two electrode wires to form a single weld pool with one wire leading the other along the weld interface. Realisation of the inf...

Study of the welding gas influence on a controlled short-arc GMAW process by optical emission spectroscopy

Abstract: The controlled short-arc processes, variants of the gas metal arc welding (GMAW) process, which have recently been developed, are used to reduce the heat input into the workpiece. Such a process with a wire feeding speed which varies periodically, using a steel wire and a steel workpiece to produce bead-on-plate welds has been investigated. As welding gases CO2 and a mixture of Ar and O2 have been used. Depending on the gas, the properties of the plasma change, and as a consequence the weldseams themselves also differ distinctly. Optical emission spectroscopy has been applied to analyse the plasma. The radial profiles of the emission coefficients of an iron line and an argon line or an atomic oxygen line, respectively, have been determined. These profiles indicate the establishment of a metal vapour arc core which has a broader profile under CO2 but is more focused in the centre for argon. The measured iron line emission was near to its norm maximum in the case of CO2. From this fact, temperatures around 8000 K and a metal vapour molar fraction above 75% in the arc centre could be roughly estimated for this case. Estimations of the electrical conductivity and the arc field indicate that the current path must include not only the metal vapour arc core but also outer hot regions dominated by welding gas properties in the case of argon.

Butt joint submerged-arc welding method of bridge steel with tensile strength more than 690Mpa grade

Abstract: The invention relates to a butt joint submerged-arc welding method of bridge steel with tensile strength more than 690Mpa grade, overcoming the defects that at the present, bridge steel and other engineering structural steel which are in 690Mpa strength grade needs preheating before welding and heat treatment after welding and has severe welding environment and the like during manual and gas protective welding. The butt joint submerged-arc welding method comprises the following steps: adopting steel with tensile strength Rm of between 690Mpa and 745Mpa, the yield strength ReL of between 550 and 690Mpa, the extension rate A of between 19 percent and 21 percent, KV2 ballistic work of between 165J and 180J at 40 DEG C below zero and the thickness of 40mmm, and adopting same-thickness butting;adopting matched welding wires with the tensile strength more than 690Mpa and diameter phi of 4.0mm, and using CHF105 as a welding flux; adopting a double-sided X-type asymmetrical submerged-arc welding groove with the angle of 60 degrees and the truncated edge of 5mm; continuously welding until welding seams are full, and under the conditions that the welding current is 570A, the voltage is 31V,the speed is 35cm/min and the linear energy is 30kj/cm; baking the welding flux for 1 hour at 350DEG C and keeping the temperature of welding layers between 100 DEG C and 150DEG C.

Opening Electrical Contacts: The Transition from the Molten Metal Bridge to the Electric Arc

Abstract: This paper presents a comprehensive explanation of the formation of the electric arc between opening contacts in a current carrying electric circuit. As the contacts begin to open a molten metal bridge forms between them. The rupture of this bridge and the initial formation of the electric arc are studied in both atmospheric air and vacuum using experiments to determine the direction of metal transfer between the contacts as a function of time after the rupture of the molten metal bridge. High speed streak photography is also used to show the rupture of the molten metal bridge and the initial formation of the electric arc. Analysis of these data show that a very high-pressure, high-temperature metal vapor zone exists between the contacts after the rupture of the molten metal bridge. Under this condition a pseudo-arc forms where current is carried by metal ions and an anomalous, high net transfer of metal to the cathodic contact occurs. The pressure in this region decreases rapidly and there is a transition to the usual electric arc, which still operates in the metal vapor. In this arc the current is now mostly carried by electrons. The data shows that there is still a net transfer of metal to the cathode, but now its volume is a function of the arcing time.

Thermal Modeling of Multipass Narrow Gap Pulse Current GMA Welding by Single Seam per Layer Deposition Technique

Abstract: A thermal model has been developed for production of multipass single seam per layer narrow gap pulse current gas metal arc (GMA) weld joint of thick plates free from lack of groove wall fusion under no angle of attack to groove wall. The model considers the fusion of groove wall as well as a part of earlier deposited weld based on the geometrical aspects and temperature of weld pool, which primarily arises out of initial arc heating and heating by droplets of superheated filler metal transferred to the weld pool. The geometrical aspects of weld pool are considered as its width and height appeared under narrow weld groove. For prduction of a sound weld joint, the favorable role of pulse current gas metal arc welding (P-GMAW) has been amply justified. But the selection of pulse parameter is quite complex due to involvement of relatively large number of pulse parameters simultaneously interactive in nature, which has been solved by considering a summarized influence of pulse parameters defined by a dimensio...

Submerged-arc welding process of stainless steel composite steel plate

Abstract: The invention discloses a submerged-arc welding process of a stainless steel composite steel plate, which has the advantages that the labour intensity of welders can be effectively reduced, the labour condition, production efficiency and the welding quality are improved, the production cost is reduced, and the like. The invention comprises the following processes of: (1) processing a groove, i.e., processing the welding end of the stainless steel composite steel plate to be welded into a groove; (2) using the weld bead in the middle part of the groove as a bottoming weld line, using the weld bead at the upper part of the base layer bottoming weld line close to the stainless steel composite steel plate composite layer as the multicoat weld line and using the weld bead at the lower part of the base layer bottoming weld line as the base layer filling cap weld; (3) welding the base layer bottoming weld line by a traditional process; (4) welding the base layer filling cap weld by a traditional process; and (5) welding the multicoat weld line, wherein the welding current ranges from 350A to 400A, the welding voltage ranges from 28V to 30V and the welding speed ranges from 40cm/min to 50cm/min.

Hybrid welding with multiple heat sources

Abstract: A method of welding a joint includes directing a first output from a high energy density heat source, such as a laser, against a first side of the joint. The method further includes directing a second output from an arc welding heat source, such as a gas metal arc welding torch, against a second side of the joint. The first output produces a keyhole surrounded by a molten metal pool which extends from the first side of the joint toward the second side of the joint. In some embodiments a third output from a second arc welding heat source may also be directed at the first side of the joint. A second molten metal pool produced by the arc welding heat source joins with the first molten metal pool and the third molten metal pool to form a common molten metal pool which solidifies to form the weld.

Investigation into Arc Behavior during Twin-Wire Submerged Arc Welding

Abstract: Behavior of leading and trailing arcs in twin-wire submerged arc welding has been investigated with help of transient heat transfer analysis. An appropriate heat transfer model with dissimilar heat sources at leading and trailing arcs has been considered. The model has been simulated with different combinations of model parameters. Computed and experimentally measured temperatures have been compared and geometrical and heat distribution differences between leading and trailing heat sources have been suggested. The behavior of leading and trailing arcs along with comparison between the current and the conventional approach has been presented and discussed. The simulation indicates that the leading arc has a major share in producing penetration where as the trailing arc is more responsible for melting.

Twin arc submerged arc welding method for thick plate box beam/pillar

Abstract: The invention relates to a method for butt joint and corner joint of a medium plate in the field of steel structure manufacturing, in particular to a production method of a twin arc submerged arc welding method for a thick plate box beam/pillar. A computer is adopted to assist a plate and a flange plate for blanking; a single groove is opened at the same side of two long sides of the plate along the thickness direction, a bevel angle is 20+/-2 degrees, the depth is 1/3 of the plate thickness; a truncated edge is reserved, a bevel groove of 25+/-2 degrees is opened at the single plane of the same side of the two long sides of the flange plate; the groove depth of the flange plate is equal to the groove depth of the plate; during the welding, the box beam/pillar are put on a work platform parallel to welder rails; two welding guns are respectively adopted to weld four assembly main weld lines of the box beam/pillar at the same time in the same direction; and the single side twin arc submerged arc welding process is adopted for welding molding in one step. The welding of the invention has high first time through and low production cost, solves the problem that welding deformation of the traditional box components, improves the automaticity of the box beam/pillar production, and has promotion and application value in the field of steel structure manufacturing.

Improving the Life of Continuous Casting Rolls Through Submerged Arc Cladding with Nitrogen-Alloyed Martensitic Stainless Steel

Abstract: Continuous casting rolls are subjected to extreme temperature fluctuations and harsh environmental conditions during service. High slab contact pressures, high surface temperatures, adhesive or abrasive wear by slag or oxides and thermal fatigue all contribute towards deterioration of the roll surface. Rolls may also suffer surface degradation as a result of corrosion. The slab is cooled using water spray, often containing hydrofluoric acid as product of the reaction between water and the mould flux powder used to keep the molten metal from adhering to the copper mould plate. This results in an aggressive low pH environment that may promote pitting or crevice corrosion and stress corrosion cracking failures. In order to prolong the life of continuous casting rolls in service, the rolls are surfaced using martensitic stainless steel weld cladding. After surfacing, the roll may be given a post-weld heat treatment to temper the martensite to the required hardness level, or to relieve thermally-induced stresses. This investigation examined the submerged arc cladding of continuous casting rolls using nitrogen-alloyed martensitic stainless steel, and focused on the effect of the weld thermal cycle and post-weld heat treatment on carbide precipitation in the clad layer. The precipitation of chromium-rich carbides during welding or post-weld heat treatment may lead to weld decay due to chromium depletion, rendering the roll surface susceptible to pit nucleation and crack initiation.

Two phase stainless steel submerged-arc welding SAW welding procedure

Abstract: The invention relates to an economic and practical submerged arc welding procedure applicable to welding of common two phase stainless steel 022CrNi5Mo3(S31803 and S2205). The invention is characterized in that the procedure includes the following steps: 1) the performance characteristics of two phase stainless steel are researched; 2) welding material is selected and welding procedure is determined; 3) welding edge preparation is carried out; 4) clean-up and final inspection are carried out on the surface of work piece to be welded; 5) submerged arc welding is carried out on the common two phase stainless steel. The invention is based on research of chemical constituents and performance characteristics of common two phase stainless steel, economic and practical domestic submerged arc welding material combination applicable to common two phase stainless steel and reasonable submerged arc welding procedure are selected, and the invention has the advantage that efficient welding of two phase stainless steel is realized by adopting high line energy submerged arc welding. Welding of common two phase stainless steel is carried out by adopting the invention, the chemical constituents of welding line can be ensured to meet standard requirement, ferrite content of welding joint (including welding line and heat affected zone) is controlled to be 30-65%, and the welding joint has good mechanical properties and pitting corrosion resistance.

Welding method of thick steel plate

Abstract: PROBLEM TO BE SOLVED: To provide a welding method of a thick steel plate which is suitable for pipe making welding of large diameter steel pipes such as UOE steel pipe with a thickness of ≥30 mm and spiral steel pipe. SOLUTION: In welding a steel material with a thickness of ≥30 mm or more from both sides, an electrode for gas shielded arc welding is arranged, as multi-electrode welding as necessary, in the front in the welding direction of the first electrode in multi-electrode submerged arc welding for hybrid welding. In the hybrid welding, the multi-electrode submerged arc welding is performed with a heat input to satisfy an expression (1) while, desirably, the gas shielded arc welding is performed with a heat input to satisfy an expression (2). If the gas shielded arc welding is multi-electrode welding, the wire diameter to be applied for the first electrode is ≥1.4 mm, with a current density set at ≥500 A/mm 2 . Provided that 0.18t-3≤Q S ≤0.35t-5.5 (1), where t is the thickness (mm) of the steel material and Q S is a welding heat input (KJ/mm) of multi-electrode submerged arc welding, and that Q G ≤0.17t-1.5 (2), where t is the thickness (mm) of the steel material and Q G is a welding heat input (KJ/mm) of gas shielded arc welding. COPYRIGHT: (C)2011,JPO&INPIT

Submerged-arc welding process of large-size cylinder body

Abstract: The invention relates to a submerged-arc welding process of a large-size cylinder body, comprising the following steps of: firstly laying a standard operation platform at a construction field, erecting a submerged-arc welding bracket and installing an electric rotator on the standard operation platform, and arranging an automatic welding operation platform on the submerged-arc welding bracket; then horizontally placing the cylinder body to be welded on the electric rotator, wherein the electric rotator drives the cylinder body to rotate during rotation; installing a travelable submerged-arc welding trolley at the lower part of an inner ring welding line when the inner ring welding line is welded, wherein the traveling speed of the submerged-arc welding trolley is equal to the rotating speed of the electric rotator, and the submerged-arc welding trolley and the electric rotator are inversed in motion directions so that the submerged-arc welding trolley is positioned on the welding line position of a starting point of the lower part of the cylinder body all the time; and placing the submerged-arc welding trolley on the automatic welding operation platform when an outer ring welding line is welded, wherein the electric rotator drives the cylinder body to rotate, and the submerged-arc welding trolley is in a static state The invention realizes the purpose of automatic welding through the rotation of the cylinder body and the coordination of the submerged-arc welding trolley, greatly reduces the labor intensity of welders, also enhances the welding efficiency and the welding quality and has very high practical value

Submerged arc welding wire of high tensile pipeline steel

Abstract: The invention discloses a submerged arc welding wire of a high tensile pipeline steel. The welding wire material comprises the following chemical components in percentage by weight: not more than 0.10 of C, not more than 0.6 of Si, 1.3-1.8 of Mn, 1.4-2.5 of Ni, 0.25-0.55 of Mo, not more than 0.12 of Ti, not more than 0.05 of V, not more than 0.35 of Cr, 0.0005-0.005 of B, not more than 0.015 of S, not more than 0.015 of P, and the balance of Fe and other inevitable impurities. The submerged arc welding wire of the high tensile pipeline steel provided by the invention has the yield strength of deposited metals of more than 690MPa and the tensile strength of more than 785Mpa, has attractive welding formation, high intensity, high flexibility and high crack resistance without defects of cracking, undercut and the like, and has favorable matching effect with X100 level pipeline steel plates, and meets the requirement on the welding of oil-gas transmission pipelines under the condition of higher pressure.

Plasma-arc-through apparatus and process for submerged electric arcs

Abstract: An application for a recycler includes a pressure and temperature resistant metal vessel that is filled with a liquid. Within the vessel is at least one submerged electric arc between a pair of carbon base electrodes powered by either a DC or AC current. The vessel has mechanical systems that maintain and optimize the electric arc. The electric arc produces a combustible gas. The liquid is pumped through a bore in one or more of the electrodes, delivering the liquid directly to the location of the arc, thereby reducing or eliminating any ignition of the gas by the arc.

SMAW, FCAW, and SAW High-Strength Ferritic Deposits: The Challenge Is Tensile Properties

Abstract: The objective of this work was to analyze the influence of chemical composition and welding parameters on microstructure and mechanical properties of medium- and high-strength steel all weld metals of both C-Mn-Ni-Mo and C-Mn-Ni-Mo-Cr ferritic types produced with coated electrodes, flux cored arc welding electrodes, and wire/flux combinations for submerged arc welding and compare these results with AWS requirements. Chemical composition of the deposits was varied and welding parameters were changed in the production of all-weld-metal samples according to the relevant AWS standards of the consumables employed. Tensile properties, hardness, and Charpy-V impact toughness of the all-weld-metal specimens were assessed and metallographic studies were conducted with light microscopy in order to correlate mechanical properties with resulting microstructures. From the analysis of the results it was concluded that achieving the toughness required by the standards was not a problem. On the contrary, consistently satisfying the minimum requirements for tensile strength turned out to be much more difficult, demanding a rigorous approach to welding parameter selection in order to obtain repeatable results. On the other hand, for a given type of weld deposit, the requirements to be met differ according to the welding process employed, thus adding another variable to the difficulties in satisfying the tensile requirements of the different standards.

Seawater corrosion resistance submerged arc welding wire rod, welding wire and application thereof

Abstract: The invention provides a seawater corrosion resistant submerged arc welding wire rod and a welding wire thereof. Both the wire rod and the welding wire comprise the following elements (according to the weight percent): C is equal to or less than 0.12, Si is equal to or less than 0.3, Mn is 1.0 to 1.8, S is equal to or less than 0.020, P is equal to or less than 0.020, Cr is 0.60 to 1.50, Ni is 0.15 to 0.50, Mo is 0.10 to 0.30, Cu is 0.05 to 0.30, Ti is 0.01 to 0.08, B is equal to or less than 0.005, Al is equal to or less than 0.030, and the rest is Fe and inevitable impurity elements. The invention also provides the application of the welding wire on the submerged arc welding wire matched with the seawater corrosion resistant steel Q345C-NHY3. The deposited metal of the welding wire provided by the invention has the advantages of excellent dynamic performance, welding performance and seawater corrosion resistant performance, which can be used for welding the seawater corrosion resistant steel. The welding wire rod and the welding wire of the invention are applicable to the structure with high corrosion resistance requirement on the immersion zone and the splash zone of the sea.

Hybrid laser arc welding system and method for railroad tank car fabrication

Abstract: A system for welding a tub of a railroad tank car includes a manipulator boom adapted to move with respect to the interior surface of the tank shell. A hybrid laser arc welding head mounted to the manipulator. A supplemental gas metal arc welding head includes dual wires of welding material and is mounted to the manipulator adjacent to the hybrid laser arc welding head. An inductive heating coil is mounted adjacent to the supplemental gas metal arc welding head. The hybrid laser arc welding head welds a seam of the railroad tank car shell with the supplemental gas metal arc welding head following to generally complete filling of a resulting weld joint with welding metal. The supplemental gas metal arc welding head is followed with the inductive heating coil to provide heat to normalize the resulting weld joint.

Finite element analysis of JCO forming process for longitudinal seam submerged arc welded pipes

Abstract: This paper presents a study of spring-back in the JCO forming process for welded pipe with diameter 1067 mm, wall thickness of 19.1 mm of X70 based on the plate bending theory by the method of FEM analysis combining with production practice. The true stress-true strain curve from a tensile test is used as the material description. Springback has been studied for five different bending angles of varying punch displacement. The results from the simulations compared with those from practical production, good correlation being achieved. The work shows that the finite-element method can be used to predict JCO geometry. The relationship between punch displacement, the bending angle under loading and after springback, and springback angle is deduced and can be used to optimise process parameters and guide the production practice.