Forging forming

In addition, this volume also contains processing information such as forging, forming, casting, powder metallurgy, and welding. Recommended procedures/hmits in these areas are provided, and where appropriate, the affects of some of these processing variables on the final properties are discussed. 

Pig-iron or cast iron contains impurities, chiefly carbon (up to 5 ). free or combined as iron carbides. These impurities, some of which form interstitial compounds (p. I I3i with the iron, make it hard and brittle, and it melts fairly sharply at temperatures between 1400 and 1500 K pure iron becomes soft before it melts (at 1812 K). Hence cast iron cannot be forged or welded. 

Magnesium alloys are available in a variety of metal forms, including cast ingots, slabs, and billets sand, permanent-mold, die, and investment castings forgings extmded bars, rods, tubes, stmctural and special hoUow and soHd shapes and roUed sheet and plate. Magnesium alloys are used widely in a great variety of appHcations. 

For ordinary materials and higher production rates, P/M forging can be used (26,28). After parts are compacted and sintered to medium density, they are reheated, lubricated, and fed into a hot-forming or P/M-forging press. The part is formed by one stroke of the press in a closed precision die. A typical hot-forming press setup includes die sets, automatic die cooling and lubrication, transfer mechanism, an induction heating unit for preforms, and controls. 

Metal-Matrix Composites. A metal-matrix composite (MMC) is comprised of a metal ahoy, less than 50% by volume that is reinforced by one or more constituents with a significantly higher elastic modulus. Reinforcement materials include carbides, oxides, graphite, borides, intermetahics or even polymeric products. These materials can be used in the form of whiskers, continuous or discontinuous fibers, or particles. Matrices can be made from metal ahoys of Mg, Al, Ti, Cu, Ni or Fe. In addition, intermetahic compounds such as titanium and nickel aluminides, Ti Al and Ni Al, respectively, are also used as a matrix material (58,59). P/M MMC can be formed by a variety of full-density hot consolidation processes, including hot pressing, hot isostatic pressing, extmsion, or forging. 

Conventional thermoforming of sheet and film is appHcable to the production of skylights, radomes, signs, curved wiadshields, prototype production of body parts for automobiles, skimohiles, boats, etc. Because BPA polycarbonate is malleable, it can be cold-formed like metal, and may be cold-roUed, stamped, or forged. 

Aluminum alloys are commercially available in a wide variety of cast forms and in wrought mill products produced by rolling, extmsion, drawing, or forging. The mill products may be further shaped by a variety of metal working and forming processes and assembled by conventional joining procedures into more complex components and stmctures. 

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