MECHANICAL-PROPERTIES OF FULLY DENSIFIED INJECTION-MOLDED CARBONYL IRON-POWDER

The mechanical properties of carbonyl iron powder shaped by injection molding techniques are affected by the grain size, sintered density, and carbon content. Control of the carbon level depends on several factors, including the binder composition, debinding approach, and sintering conditions (atmosphere, temperature, time, and furnace design). Sintered compacts were densified by containerless hot isostatic pressing, giving smaller grain sizes and superior properties than were possible by pressureless sintering at a high temperature. A quick hot isostatic pressing route (gas forging) with a peak pressure higher than 500 MPa for 1 minute helps retain carbon and results in excellent properties due to a high final density and small grain size. This approach resulted in a final strength of 732 MPa with extensive ductility (23 pct reduction of area) for injection-molded carbonyl iron. © 1990 The Metallurgical of Society of AIME.