Showing papers on "Shielded metal arc welding published in 1996"

Structural stability of super duplex stainless weld metals and its dependence on tungsten and copper

Abstract: Three different superduplex stainless weld metals have been produced using manual metal arc welding under identical welding conditions. The concentration of the alloying elements tungsten and copper corresponded to the concentrations in commercial superduplex stainless steels (SDSS). Aging experiments in the temperature range 700 °C to 1110 °C showed that the formation of intermetallic phase was enhanced in tungsten-rich weld metal and also dissolved at higher temperatures compared with tungsten-poor and tungsten-free weld metals. It could be inferred from time-temperature-transformation (TTT) and continuous-cooling-transformation (CCT) diagrams produced in the present investigation that the critical cooling rate to avoid 1 wt pct of intermetallic phase was 2 times faster for tungsten-rich weld metal. Microanalysis in combination with thermodynamic calculations showed that tungsten was accommodated in χ phase, thereby decreasing the free energy. Experimental evidence supports the view that the formation of intermetallic phase is enhanced in tungsten-rich weld metal, owing to easier nucleation of nonequilibrium χ phase compared with σ phase. The formation of secondary austenite (γ2) during welding was modeled using the thermodynamic computer program Thermo-Calc. Satisfactory agreement between theory and practice was obtained. Thermo-Calc was capable of predicting observed lower concentrations of chromium and nitrogen in γ2 compared with primary austenite. The volume fraction of γ2 was found to be significantly higher in tungsten-rich and tungsten + copper containing weld metal. The results could be explained by a higher driving force for precipitation of γ2 in these.

Stress corrosion crack repair by plasma arc welding underwater welding

Abstract: Stress corrosion cracking damage to stainless steels and nickel base superalloys is repaired by underwater plasma transferred arc welding which under conditions which reduce residual tensile stresses in the weld and adjacent portions of the repaired structure.

Effects of moisture contamination and welding parameters on diffusible hydrogen

Abstract: Two experiments were conducted on gas-shielded flux cored arc welding. The first one tested the effects of shielding gas moisture contamination and welding parameters on the diffusible hydrogen content. The second compared the hydrogen levels of various unused electrodes with the diffusible hydrogen they produced in the weld. An empirical equation has been developed that can predict the diffusible hydrogen in weld metal for gas-shielded flux cored arc welding. Estimating diffusible hydrogen is possible using measured welding parameters, shielding gas dew point, and total hydrogen of the consumable. The equation is suitable for small-diameter electrodes and welding parameter ranges commonly used for out-of-position welding.

The effect of welding on the properties of advanced 9–12%Cr steels

Abstract: There are strong environmental and economic pressures to increase the thermal efficiency of fossil fuel fired power stations, and this has led to a steady increase in steam temperatures and pressures resulting in worldwide plans for ultrasupercritical power plants. Basic investigations on the weldability of advanced 9–12%Cr steels which are either currently in use or which are intended to fulfil this requirement were performed on pipes of P91, E911 and a tungsten containing cast steel G-X 12 CrMoWVNbN 10 1 1. Gleeble simulations representing the manual metal arc welding process were applied to produce HAZ simulated microstructures. After different post-weld heat treatments they were tested using hardness tests, metallographic investigations, constant strain rate tests, and creep tests. Particular attention was given to the softening effect in the HAZ and its influence on the creep resistance of the welded material. This decrease, shown by simulated and manufacturing welded samples, seems to be les...

Advanced consumable electrodes for gas metal arc (GMA) welding of high strength low alloy (HSLA) steels

Abstract: This invention relates to solid, bare, consumable wire electrodes for gas metal arc (GMA) welding of high strength low alloy (HSLA) steels. The electrodes require little or no preheat, interpass and post soak temperature controls. The invention also relates to the method of welding and weld deposits produced therefrom.

Welding process for drawn ARC stud welding

Abstract: The invention relates to a welding process for drawn arc stud welding wherein after ignition of the main current electric arc, the latter's voltage (U) is measured and, depending upon the measured voltage, the current flow of the continued main current electric arc and/or the dipping movement of the parts which are to be welded together, is regulated or controlled.

Gas tungsten arc welding flux

Abstract: An easy to apply flux for increasing the penetration of gas tungsten arc welding of stainless steel substantially independent of flux thickness and variations in composition from heat to heat of stainless steel includes a flux consisting of reagent or laboratory grade TiO or TiO 2 (about 50%), Cr 2 O 3 (about 40%), and SiO 2 (about 10%) in a liquid carrier, preferably of methyl ethyl ketone. The flux is easy to apply, increases penetration of the weld, decreases bead width, and increases weld cross sectional area.

Friction Welding of 2017 and 6061 Aluminum Alloys to S45C Carbon Steel.

Abstract: Joint performance of two types of friction welded butt joints, A2017/S45C and A6061/S45C, fabricated under several welding conditions was investigated. In the case of A2017/S45C joint, the joint strength decreased with an increase in forging pressure, and the intermetallic compounds of Al7Cu2Fe and iron -aluminum alloy were observed at the weld interface. On the other hand, in the case of A6061/S45C joint, the joint strength increased with an increase in forging pressure, and iron-aluminum alloy was observed at the weld interface. Such a difference in the effect of forging pressure on microstructure at the weld interface depends on the deformation property of each aluminum alloy at elevated temperature. And the thinner was the intermetallic compound or the iron-aluminum alloy, the higher was the joint strength.

Study of the mechanism of spatter produced by basic welding electrodes

Abstract: In this work a device was made to control the current at three stages of short circuiting welding: at the beginning of short circuiting, during the overall period of short circuiting, including the breaking stage, and at the arc reinitiating stage. By investigating the effects of these currents on the spatter produced by basic welding electrodes, the decisive parameter which determined spatter quantities was identified as the current at the short circuit breaking stage. On the basis of the experimental results from the combined effect of short circuiting current and the oxygen potential in the covering, it was found that the major process causing spatter was the explosion of CO gas bubbles, which resulted in the breakage of the short circuiting bridge. The high density of current intensified this explosion and increased the spatter quantity. The spatter mechanism caused by the explosion of gases was identified by studying the metal transfer using laser back-light, high-speed photography and x-ray, high-speed photography to record two images simultaneously, along with arc sound and arc voltage oscillographs.

Process and gaseous mixture for arc welding of aluminium components

Abstract: The arc welding, with a refractory electrode, using alternating current, is performed with a gaseous protective mixture employing, at the location of the weld, at least 60%, typically between 70 and 80% of helium and more than 1000 vpm, typically between 1100 and 1200 vpm, of carbon dioxide, the remainder being argon. Application to manual or automatic welding of aluminium components.

Nitrogen Content of 316L Weld Metal and Its Fine Particle by Means of High-pressure MIG Arc Welding

Abstract: The suitability of the high nitrogen pressure Metal Inert Gas (MIG) ARC welding process (constant arc length condition) for high nitrogen containing stainless steel was investigated. The formation of the stainless steel fine particles by the high nitrogen pressure MIG arc welding process was examined. The welding atmosphere consisted of pressurized N2 gas. Nitrogen absorption of 316L stainless steel weld metal and its fine particle in the high nitrogen pressure MIG process was studied. The effect of nitrogen contents in remelted weld metal and changes in teh microstructure of the weld metal were observed. The nitrogen content of weld metal and the number of fine particles increased with increasing pressure of N2. Approximately 0.6 and 2.4 mass% nitrogen was absorbed in the weld metal and fine particles at pressure of N2 6 MPa and 3 MPa nitrogen, respectively. Nitrogen content of the weld metal was lower than that representing equilibrium solubility of 316L stainless steel at colse to the melting point.

Shielding gas mixture and process for arc welding of stainless steel workpieces

Abstract: The shielding gas mixture for the TIG or GTAW arc welding of stainless steels, in particular of duplex or super duplex steels, comprises, in argon, from 3 to 18%, advantageously approximately 10%, of helium and from 1 to 3%, advantageously approximately 2%, of nitrogen. This gas mixture makes it possible to ensure good corrosion resistance of the metal deposited, acceptable solidity of the welds and excellent arc stability, as well as a suitable viscosity of the molten metal appropriate to manual welding in all positions.

The Effect of Welding Process on the Chi Phase Precipitation in As-welded 317L Weld Metals

Abstract: Three multipass 317L welds were prepared using submerged arc welding (SAW), flux-cored arc welding (FCAW) and manual metal arc welding (MMA), respectively. A microstructural study was undertaken by trepanning 3 mm discs from specific positions in the weld gap, and examining the thinned specimens by transmission electron microscopy (TEM). It was found that, in addition to Chi phase precipitation detected in the regions where overlapping of the welding passes occurred, the large heat input for each welding pass can also induce Chi phase precipitation during the cooling of the welding pool. The mechanical properties showed that there were few differences resulting from the three processes. The intermetallics which formed due to high heat input passes did not appear to have a particularly harmful effect on the mechanical properties.

Shielding gas oxygen equivalent in weld metal microstructure optimization

Abstract: One of the compositional variables that strongly influence low-carbon structural steel weld metal microstructure and mechanical properties is the weld metal oxygen content. As the weld metal oxygen content varies, a change in microstructure occurs. At low concentrations of oxygen, ferrite with aligned or nonaligned second phases may become predominant, slightly higher oxygen levels may result in the formation of the desired acicular ferrite, and further increases in the oxygen content promote the formation of grain boundary ferrite. The start of austenite decomposition and ferrite nucleation are very sensitive to variations in the amount of oxygen present in the weld metal. Consequently, for a given cooling rate and chemical composition, the final weld metal microstructure can be fine-tuned by proper control of the weld metal oxygen concentration. Thus, in gas metal arc welding, adjusting the shielding gas oxygen potential provides a means of controlling the weld metal oxygen content. Bead-in-groove gas metal arc welding experiments were performed on HSLA steel coupons using three different welding wires and two heat inputs. A total of 17 different argon-based oxygen and carbon dioxide shielding gas mixtures was used. Complete metallographic and chemical analyses were carried out to evaluate the weld specimens. Sub-size Charpy V-notch toughness testing was performed on selected welds. A shielding gas-related parameter named oxygen equivalent was developed for the discussion of the effects of the shielding gas composition on weld metal chemical composition, microstructure and toughness. The results showed that the shielding gas oxygen equivalent strongly influenced the pyrometallurgical reactions that occurred during welding, giving rise to significant changes in weld metal chemical composition, and thus, weld metal microstructure. The Ito-Bessyo P cm index was modified by incorporating the weld metal oxygen content to allow for better prediction of weld metal phase transformation behavior and cracking susceptibility.

Hydrogen content of underwater wet welds deposited by rutile and oxidizing electrodes

Abstract: Shielded metal arc wet welding, due to its flexibility and ease of mobilization, is one of the most attractive methods for repair of underwater structures. However, the quality of the weld metals deposited by this process is detrimentally affected by the direct contact of the welding arc with the aqueous environment. Oxygen and hydrogen generated by the decomposition of water in the arc are responsible for the main problems related to this specific process: loss of deoxidizers, oxygen pickup, increase in oxide inclusions content, hydrogen-induced cracking, and porosity. Rutile electrodes are recognized in the literature as being able to deposit welds with adequate mechanical properties but with high hydrogen content. Oxidizing electrodes, on the other hand, are able to deposit welds with lower hydrogen content but higher oxygen content. Welds deposited by rutile electrodes presented approximately 90 ml/100g of diffusible hydrogen while oxidizing electrodes produced welds with diffusible hydrogen contents varying from 40 to 50 ml/100g. It was found that the measured diffusible hydrogen contents of underwater wet welds are more dependent on the type of electrode covering than on the weld metal oxygen content. The residual hydrogen content of underwater welds showed a tendency to increase to a constantmore » level of approximately 5 ml/100g as the oxygen content of the weld increased to the saturation value (0.22 wt.pct.). It seems, therefore, that the diffusible hydrogen content of underwater wet welds is more influenced by the amount of total hydrogen absorbed by the liquid metal before solidification than by the amount of inclusions, acting as hydrogen traps, in the weld metal.« less

Gas shielded metal arc welding method which enhances corrosion resistance after coating of weld zone and near this zone

Abstract: PURPOSE:To enhance corrosion resistance after coating of a weld zone and near this zone by a shielding gas making mainly consist of Ar, etc., including CO2, etc., therein as the oxidizing gas which amount satisfies specific conditions and using pulse currents in arc generation. CONSTITUTION:Weld slag is the oxide contg. Si, Mn and Fe generated by deoxidation reaction in molten iron and the oxygen constituting this oxide is supplied mainly from the inside of the shielding gas into the molten iron. The shielding gas is mainly composed of Ar or He or a gaseous mixture composed thereof and includes CO2 or O2 or both thereof as the oxidizing gas. The gas shielded metal arc welding is, thereupon, executed at the amt. in the shielding gas satisfying the equation I and using the pulse currents in arc generation. In the formula I, X: the amt. of the CO2, Y: the vol.% of the amt. of the O2. The slag is, therefore, prevented and electrodeposition coatability is improved. The oxidation in a heat affected zone is suppressed and phosphate treatability is improved as well.

Method of igniting a welding arc

Abstract: A method is indicated for igniting a welding arc between a fixed electrode and a metal workpiece to be welded, whereby a covering protective gas is supplied by a nozzle that extends into the welding area. Before a welding power source is switched on for the welding arc, an auxiliary arc supplied by an auxiliary power source is ignited, which ignites the welding arc after the welding power source is switched on. To better ionize the welding area and ensure the ignition of the auxiliary welding arc, a high-frequency electric arc is produced in the welding area between the nozzle and the workpiece by means of a pulse generator which produces high-frequency high-voltage pulses.

The effect of welding parameters on high-strength SMAW all-weld-metal : Part 1: AWS E11018-M

Abstract: Three AWS A5.5-81 all-weld-metal test assemblies were welded with an E110180-M electrode from a standard production batch, varying the welding parameters in such a way as to obtain three energy inputs: high heat input and high interpass temperature (hot), medium heat input and medium interpass temperature (medium) and low heat input and low interpass temperature (cold). Mechanical properties and metallographic studies were performed in the as-welded condition, and it was found that only the tensile properties obtained with the test specimen made with the intermediate energy input satisfied the AWS E11018-M requirements. With the cold specimen, the maximal yield strength was exceeded, and with the hot one, neither the yield nor the tensile minimum strengths were achieved. The elongation and the impact properties were high enough to fulfill the minimal requirements, but the best Charpy-V notch values were obtained with the intermediate energy input. Metallographic studies showed that as the energy input increased the percentage of the columnar zones decreased, the grain size became larger, and in the as-welded zone, there was a little increment of both acicular ferrite and ferrite with second phase, with a consequent decrease of primary ferrite. These results showed that this type of alloy ismore » very sensitive to the welding parameters and that very precise instructions must be given to secure the desired tensile properties in the all-weld-metal test specimens and under actual working conditions.« less

Shielding gas and heat transfer effeciency in plasma arc welding

Abstract: Variable polarity plasma arc welding is widely used in the aerospace industry for producing high-quality welds on aluminum. In plasma welding the arc is produced in a narrow stream of plasma gas while workpiece shielding is accomplished by a lower velocity but higher flow rate stream of shielding gas that surrounds the arc. This paper will show that on aluminum welds both the melt zone and the heat-affected zone are appreciably decreased by this flow of shielding gas. Moreover, the amount of cooling is changed by the detailed shape of this flow as well as the flow rate. On the other hand, it will be shown that excessively high shielding flow rates can cause undercutting from contamination in the shielding gas.

Metal and method for shielded metal arc welding of high strength cr-mo steel

Abstract: PROBLEM TO BE SOLVED: To provide a metal and a method for shielded metal arc welding of high strength Cr-Mo steel excellent in room temperature and high temperature strength after SR treatment, toughness, creep strength, annealing resistant brittle property, high temperature cracking resistance, and low temperature cracking resistance, and SR cracking resistance. SOLUTION: The weld metal to be formed by the shielded metal arc welding has the composition consisting of, by weight, 0.04-0.15% C, 0.15-0.50% Si, 0.50-1.40% Mn, 2.00-3.25% Cr, 0.90-1.20% Mo, and 0.20-0.70% V, and the balance Fe with inevitable impurities. In the inevitable impurities, P is regulated to be ≤0.15%, Cu ≤0.50%, Ni ≤0.50%, B ≤0.0050%, Al ≤0.050%, Ti ≤0.050%, and N ≥0.0200%. The composition of the residue to be sampled through the electrolytic extraction only from the original part of the weld metal treated at the temperature of 625°C for 10 hours is Fe to be ≤35%, and V to be ≥10%. COPYRIGHT: (C)1998,JPO

Gas shielded metal-arc welding wire

Abstract: PURPOSE: To well feed a wire even in the case of using a long size conduit cable and being welded in the state of being applied with a bending load. CONSTITUTION: In this gas shielded metal-arc welding wire, the surface of the wire whose average interval H of projections is <=150μm, the average roughness Ra of the projections is 0.4 to 3.0μm, and the highest height Ry of the projections is <=15μm is coated with a lubricating agent. Further, the lubricating agent to be applied on the wire surface is a liquid lubricating agent, and the amount thereof is defined as 0.2 to 1.5g per 10kg wire.

Gas shielded metal-arc welding method

Abstract: PURPOSE:To provide a highly efficient joint excellent in the mechanical proper ties by substantially eliminating the root gap of the groove, setting the wire deviation position at the first pass to the prescribed region, and arranging a surface plate in a groove by the prescribed dimension. CONSTITUTION:The solid wire or flux-cored wire of 1.2-2.0mm in diameter is combined with the shielding gas and a backing plate 3. A groove 4 of V- or Y-shape where the root gap is substantially zero and the surface plate side is open is provided, and a surface plate 5 interposed at the lower half part of the groove at the surface side with the length of 10-25mm is provided. The wire deviation position at the first pass is set in the range of 2-12mm along the groove surface of the second half back surface on the groove of a lower plate 2 to achieve the stringer welding or the weaving welding with the welding current of >=280A. The wire deviation position at the first pass is set to the prescribed region thereby, and the surface plate 5 is arranged in the groove with projection of the prescribed dimension to obtain the joint excellent in the cracking resistance, the bead appearance and shape, the mechanical properties of the weld metal.

Process monitoring and on-line modelling of the gas metal arc welding process

Abstract: PROCESS MONITORING AND ON-LINE MODELING OF THE GAS METAL ARC WELDING PROCESS This Abstract is brief description o f a thesis on the development o f methods for the Process Monitoring and On-line Modeling o f the Gas Metal Arc Welding Process (GMAW). Progress in development o f Advanced Process and Equipment for GMAW, especially in Automated and Mechanised Welding, requires clear understanding o f the physical phenomena o f the Welding Process [1]. The objective o f this thesis is to design and develop modem experimental facilities capable o f providing instrumentation and photography to record welding phenomena, so as to allow a thorough study o f die physical welding processes. The thesis initially describes the development o f an Experimental Facility for Monitoring die Gas Metal Arc Welding (GMAW) Process. The Facility described consists o f : a) Weld Testing Facilities. b) A Physical Testbed with a Weld Table moving under a stationary GMAW Gun. c) Electronic Monitoring o f the GMAW Parameters including Weld Voltage (V), Weld Current (I), Wire Feed Rate(WFR) and Weld Travel Speed (TS). d) Computer Control o f GMAW Parameters including Weld Voltage, Wire Feed Rate and Weld Travel Speed. e) Weld Visualisation using High Speed Photography with a Communications Link from the High Speed Camera to the Electronic Monitoring System allowing the Camera, when it commences its diming run, to trigger the Electronic Monitoring System, thereby enabling time-correlated Electronic Data and Visual Images to be obtained. The thesis next describes in detail the Weld Testbed and Electronic Monitoring System in terms o f Electronic Hardware, Software Algorithms for Weld Monitoring, Algorithms for Weld Parameter Control and two Graphical User Interface (GUI’s) Packages developed for the Viewing and Analysis o f Weld Data. These Software Packages are: a) ‘Shortmon’: A package for Viewing and Analysing the Parameter Traces o f short bursts o f Welding Data ( < 2 seconds). b) ‘Longmoir : A package for Viewing and Analysing the behaviour and stability o f Weld Parameter Settings over longer welding periods (up to 120 seconds). Both o f the above described Packages also include Computer Controlled Setting o f Weld Parameters. ‘Longmon’ also allows in-weld alteration o f Weld Parameters thus enabling the effects o f Weld Parameter variation to be studied. The verifification o f the MWEF as a facility for GMAW Control Strategy development was achieved through a series o f experimentation in which process irregularities were induced and monitored in Real-time. The next Stage o f the thesis describes the development o f a Graphical User Interface (GUI) for On-line Modeling o f the Welding Process in a single weld run utilising Weld Parameter Feedback for a range o f Computer Controlled Weld Parameter Settings. An important research interest is the development o f Strategies and Models for die effective Real-time Control o f the Welding Gun Standoff (L) (also often referred to as ‘Contact-tip to Workpiece Distance’). The On-line Modeling Package has therefore been initially developed to generate Least-Squares Models of: I = ffV,W FR,L) and also L = f(V,I,WFR) which are intended for use as Real-time Estimators for Current and Standoff Control. This work is funded by die Cooperative Research Centre (CRC) for Materials Welding and Joining as part o f Project 93/12 which is a collaborative research effort in the area o f Welding Automation between the University o f Wollongong, The University o f Sydney and the CSIRO Division o f Applied Physics (Sydney). Please Note that Welding Visualisation with High Speed Photography was developed by Dr. Wee King Soh and Mr. Heman Ratio whilst the Welding Testbed and the Electronic Monitoring and Control o f the Welding Process was developed by the Author under the supervision o f Professor Michael W est

Tig welding method of high tensile steel and solid wire for tig welding

Abstract: PROBLEM TO BE SOLVED: To provide a TIG welding method of high-tensile steel and a solid wire for TIG welding capable of improving the welding efficiency and the welding environment, excellent in the mechanical property, and capable of preventing development of the weld cracking SOLUTION: In a TIG welding method of high tensile steel which contains, by weight, ≤013% C and whose tensile strength is 760 to 980N/mm 2 , a solid wire is used in which the martensitic transformation start temperature of the fully-deposited metal obtained by the method specified in JIS-Z-3111 is ≤400°C, 75 to 120% Ni is contained to the total weight of the wire, and the composition of ≤010% C and ≤2wtppm H is regulated, and the wire feeding speed is 5-40g/min for welding COPYRIGHT: (C)1997,JPO

Flux cored wire for 9% ni steel

Abstract: PROBLEM TO BE SOLVED: To enhance deposited metal performance such as high-temperature cracking resistance in a gas shielded metal arc welding by composing the flux to be filled in an outer shell made of Ni-based alloy of Mo powder and the slug forming agent containing TiO2 , Al2 O3 , CaO, SiO2 , carbonate and metallic fluoride. SOLUTION: In thus flux-cored wire for 9% Ni steel, the flux of 10-35% to the total weight of the wire is filled in an outer shell made of N-based alloy. The flux has the composition consisting of, to the total weight of the wire, 5-14% Mo powder of >44 μm in grain size, 1-10% metallic powder in total except Mo, 5-15% slag forming agent containing TiO2 , Al2 O3 , CaO, SiO2 , carbonate, and metallic fluoride, and the balance inevitable impurities. As for the grain size distribution of the total flux, >=85% of the total weight of the flux is 44-500 μm, and >15% is 44 μm, preferably. The wire is welded by the gas- shielded metal arc welding with Ar-CO2 mixture and the backstep welding of 10-50 cm/min in speed.

Visualisation study of metal transfer in gas metal arc welding (GMAW)

Abstract: This Abstract briefly describes a thesis on the development of techniques for the purpose of viewing Gas Metal Arc Welding (GMAW) metal transfer. The thesis also describes an elaborate investigation into the physics associated with metal transfer of this welding process. An understanding of the physical process that is GMAW metal transfer has yet to be fully realised. Many factors are thought to contribute to this phenomenon and a number of theories have been proposed and counter proposed by a multitude of welding researchers. Thus, the thesis is an attempt to better comprehend the process to hopefully lead the way to a complete understanding. The thesis firstly looks into what a weld actually is and presents the associated problems and terminology of welding so the reader may grasp the complex considerations that must be taken into account in order to produce a sound weld. A sound weld is obviously one that exhibits the properties that a designer expects from it during its applied life time. It then moves on to describe the components and materials utilised in such a welding plant. Once these welding fundamentals are shown to provide an understanding of the process, the actual metal transfer is investigated. The metal transfer types are shown together with the forces thought to play an important part in metal removal and transportation to the weld. Various parameters which are known to alter the metal transfer are also presented and discussed. From this one receives a good overall view on what changes metal transfer and also the consequences of the changes. As the title of the thesis suggests, visualisation of the electrode as it melts and travels across the welding arc is a major aim of this work. Visualisation techniques for viewing this are sought and discussed. The necessity of implementing such techniques are pointed out as well. These visualisation methods are then employed in our study. The equipment chosen and used is described in detail and the corresponding results presented. An analysis of GMAW metal transfer theories is undertaken to try and predict what is seen in the pictures produced with the visualisation methods. A comprehensive mathematical analysis is given utilising the ‘Static Force Balance Theory’ and the ‘Mathematica’ computing package. The theory is also modified to allow for tapering of the wire electrode. The results are discussed to test the validity of the theory. A discussion on possible improvements and direction for further research is also undertaken. This work is generously funded by the Co-operative Research Centre (CRC) for Materials and Joining as a component of Project 93.12. Project 93.12 is a collaborative research venture in the area of Welding Automation between the Universities of Wollongong and Sydney and the Sydney based CSIRO Division of Applied Physics. Please note that the electrical data acquired and presented in this thesis was obtained from the welding test bed facility at the University of Wollongong whose development is attributed to Professor Michael West and Mr. Lawrence Sanders.