3. Production and Working of Metals and Alloys

Metals are produced from ores that exist in nature mostly as oxides or sulphides. Steel has the largest use of any metal and is extracted from iron ore. Initially liquid iron extracted from ore in blast furnace contains substantial amounts of C, Si, Mn, S and P which is further purified by blowing with oxygen to reduce the C, Mn, S and P content within specified levels and cast into ingots or used for producing semi-finished shapes directly from molten steel by continuous casting. Advanced processes are also used to meet the demand of clean steel containing low sulphur, phosphorus, inclusion and dissolved gases. Steel thus produced is converted into blooms, slabs and billets and these semi-finished shapes are further worked to get the desired products. The chapter includes broad outline of production of steel from iron ore and various forming techniques used like rolling, forging, extrusion along with the production of seamless and welded tubular products. Also included is the process of cladding higher strength cheaper carbon or low alloy steels with a comparatively thinner layer of corrosion-resistant alloy using the techniques like sheet lining, hot rolling, weld cladding and explosion cladding. There are some equipments like pump, valves, etc., of intricate shape alloys, which are not amenable to deformation, are produced by casting. Activities like cutting and bending required for fabrication of different equipment have been described.