TABLE OF CONTENTS The jointing of metals by processes employing fusion of some kind may be classified as follows:
Temperature range: 1130 1550 C approximately. Processes: oxy-acetylene welding, manual metal arc welding, inert gas metal arc welding.
Temperature range: 620 950 C approximately. Processes: flame brazing, silver soldering, aluminium brazing, bronze welding.
Temperature range: 183 310 C approximately. Process: soft soldering.
In total fusion the parent metal and, if used, the filler metal are completely melted during the jointing. Thin sheet metal edges can be fused together without additional filler metal being added. Oxy-acetylene welding and manual metal arc welding were the first processes to employ total fusion. In recent years they have been supplemented by methods such as inert-gas arc welding, metal inert-gas (MIG/MAG) and tungsten inert-gas (TIG) welding, carbon dioxide welding and atomic hydrogen welding. Welding is normally carried out at high temperature ranges, the actual temperature being the melting point of the particular metal which is being joined. The parent metal is totally melted throughout its thickness, and in some cases molten filler metal of the correct composition is added by means of rods or consumable electrodes of convenient size. A neat reinforcement weld bead is usually left protruding above the surface of the parent metal, as this gives good mechanical properties in the completed weld. Most metals and alloys can be welded effectively, but there are certain exceptions which, because of their physical properties, are best joined...
