Formation of Free Graphites during Sintering Green Compact Made of Mixture of Iron Powder Including Boron any Graphite

The sintered steel made of a green compact of the iron powder containing b oron and sulfur and 1.4mass% graphite consisted of ferrite microstructure and free carbon more than 1.0mass%. The X-ray diffraction analysis of the residue made by dissolving the sintered steel into nitric acid proved that free carbon has been graphitized. The graphite in the, sintered steel orientated higher than the added graphite powder. The free graphite precipitated in the pore sites of the sintered steel on cooling after sintering.