Joint Preparation in Arc Welding

December 23, 2011

Joint Preparation in Arc Welding  The principal basic types of joints used in arc welding are the butt, lap, corner, edge and Tconfigurations. Selection of the proper design for a particular application will depend primarily on the following factors: • The mechanical properties desired in the weld • The type of grade being welded • The size, shape and appearance […]

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Selecting Shielded Gases for Welding of Stainless Steels

December 23, 2011

Selecting Shielding Gases for Welding of Stainless Steels (1) Influence of the Shielding Gas on: GTAW, PAW, GMAW, FCAW and LBW The choice of shielding gas has a significant influence on the following factors: • Shielding Efficiency (Controlled shielding gas atmosphere) • Metallurgy, Mechanical Properties (Loss of alloying elements, pickup of atmospheric gases) • Corrosion Resistance (Loss of alloying elements, pickup of atmospheric […]

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Electron Beam Welding

December 23, 2011

Electron beam welding uses energy from a high velocity focussed beam of electrons made to collide with the base material. With high beam energy, a hole can be melted through the material and penetrating welds can be formed at speeds of the order of 20 m/min. EBW can produce deep and thin welds with narrow heat affected zones. The depth to width […]

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Laser Beam Welding

December 23, 2011

The laser effect (Light Amplification by Stimulated Emission of Radiation) was discovered in the optical wavelength range by Maiman in 1958. The possibility immediately appeared of using a laser beam as a small area contact–free high intensity power source for welding applications. The continuous power levels available are particularly high for carbon dioxide lasers, although it must be remembered that the effective […]

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High Frequency Induction Welding

December 23, 2011

High frequency induction welding is essentially used for making tubes from strip. The process is performed by a multiple roll forming system. On leaving the last rolling stand, the tube comprises a longitudinal slit which is closed by welding. The joint is formed by solid-solid contact, with intermediate melting, as the strip edges are brought together by a pair of horizontal rolls […]

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Flash Welding

December 23, 2011

This technique is used essentially for long products, e.g. rods, bars, tubes and shaped sections. Although apparently similar to upset welding, flash butt welding is in fact quite different. Indeed, during upset welding, it has been observed that when the abutting surfaces are not in perfect contact, the current passes only in a few small areas, leading to intense local heating and […]

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Electroslag Welding

December 23, 2011

The electroslag welding process was developed at the E.O. Paton Welding Institute (Ukraine) in the early 1950s. Electroslag welding is a single pass process used to produce butt joints in the vertical position. Joints thicker than 15mm (with no upper thickness limit) can be welded in one pass, and a simple square-edged joint preparation is required. The process is similar to […]

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Projection Welding

December 23, 2011

In this process, small prepared projections on one of the two workpiece surfaces are melted and collapse when current is supplied through flat copper-alloy electrodes. The projections are formed by embossing (sheet metal parts) or machining (solid metal parts) usually on the thicker or higher electrical conductivity workpiece of the joint. The projections are shaped and positioned to concentrate the […]

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Resistance Seam Welding

December 23, 2011

The principle of resistance seam welding is similar to that of spot welding, except that the process is continuous. The major difference is in the type of electrodes, which are two copper-alloy wheels equipped with an appropriate drive system. The wheel edges usually have either a double chamfer or a convex profile. Compared to spot welding, where the principal process parameters are […]

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Resistance Spot Welding

December 23, 2011

This process is still extensively used and is particularly suited to the welding of thin stainless steel sheets. Melting is induced by resistance heating due to the passage of an electric current through the work-piece materials at the joint. Five different stages are generally distinguished in the spot welding process, namely: • Positioning of the sheets to be joined • […]

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