MANUFACTURE OF BODIES FROM CAST IRON SCRAP BY POWDER METALLURGY

摘要

1285186 Compressing scrap GKN SCREWS & FASTENERS Ltd 30 Oct 1969 [6 Nov 1968] 52604/68 Heading B3H [Also in Division C7] Cast iron scrap is cold pressed to a green compact with a contoured surface which is then heated and hot pressed in a die with tools matching the contoured surface. The scrap may be turnings, flakes or chips, and the carbon content may be reduced by heating at 400- 1000‹ C. in an oxidizing and then a reducing atmosphere. Mill scale may be added to the scrap and decarburization effected when heating after cold pressing iron oxide or powder cast iron may be added to adjust the carbon content. The decarburized scrap is milled to 0À05-1 mm. minimum diameter, pressed e.g. isostatically at 5-30 t.s.i., heated to 1090-1100‹ C. and hot pressed in a die which may be preheated to 250‹ C. The compact e.g. a pulley is slowly cooled in a protective atmosphere.