Forge sintering

Sintering processes have been used since antiquity to alter the properties of ores and ore concentrates, powdered metals and alloys such as bloomery iron, ceramics, and glass. Bloomery iron, for example, was sintered in a forge, and the operation was often referred to as forge sintering. 

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. 

There is a material to process compatibility risk for impact extrusion, cold forging, cold extmsion, sheet metalworking, machining and powder metal sintering processes because their respective process capability maps relate to the ideal material case. 

In different forms (bar, casting such as sand, centrifugal, die, pernianenl mould, etc., extrusion, forging, impact extrusion, pressing, sintered, powder pressing)... 

Rolling and swaging Vacuum-sintered bar can be cold rolled, and reductions up to 90% between anneals are possible. Arc-cast and electron-beam-melted material is generally forged at room temperature prior to rolling and swaging. 

A PM preform could be made using recently developed prealloyed steel powders, and full densification could be achieved by hot precision forging to final configurations after the sintering operation... 

Ta powder is recovered by leaching the reaction product. The Ta powder purified may be compacted and then sintered by passing an electric current (at 2500°C) or by arc melting, and finally shaped by forging, rolling, extruding or wire drawing. 

Fabrication techniques include compaction and sintering, direct compression molding, hot stamping, forging, and hot plate or spin welding (13). 

Another technique makes use of ultra-fine powders sintered under stress-assisted conditions so the sintering temperature is reduced,38 for instance hot-isostatic pressing, hot pressing, sinter forging, or techniques with fast... 

Kondo, N., Suzuki, Y., and Ohji, T., Superplastic sinter-forging of silicon nitride with anisotropic microstructure formation , J. Am. Ceram. Soc., 1999, 82, 1067-9. 

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