INSPECTION OF SINTERED PARTS SUBJECTED TO STEAM TREATMENT

摘要

PURPOSE:To select the propriety of steam treatment in an iron-based sintered alloy by measuring an electric resistance between two points of a sintered part subjected to the steam treatment. CONSTITUTION:When a sintered alloy being porous is subjected to a surface treatment such as carburizing, nitriding and plating, it is necessary to seal pores on the surface thereof beforehand and a steam treatment is employed for the purpose. The sintered material subjected to the steam treatment changes noticeably in the electric resistance depending on the propriety of the treatment. When the generation of an oxide film by the steam treatment is sufficient, the electric resistance indicates a high value. When it is not suficient or a carbon substance is attached to the surface thereof, the electric resistance indicates a low value. The measured value of the electric resistance is checked upon with the proper range of an electric resistance value as previously obtained by comparison of the electric resistance value to the results of the surface treatment for the same kind of parts to select the propriety of the steam treatment applied to the parts.