METHOD FOR CONTROLLING DIMENSIONAL CHANGE OF POWDER METALLURGICAL IRON SINTERED COMPACT

摘要

PURPOSE: To make it possible to obtain a sintered compact with which the variations in the dimensional accuracy of products are decreased by suppressing specific iron oxide to a specific amt. in a mixture and controlling the dimensional change of the iron sintered compact. ;CONSTITUTION: The control of the dimensional change rate at the time of sintering is made possible if a slight amt. of the fine powder of the iron oxide powder having a large oxygen quantity is mixed with iron powder subjected to finish reduction. The iron powder subjected to the finish reduction refers to the iron powder produced by further subjecting the resulted powder to reduction to an oxygen content of ≤0.5% regardless of the process for production thereof. The iron oxide powder in which the powder of a grain size of ≤45μm occupies ≥80wt.% is used. Such iron oxide powder is suppressed to ≤10wt.% (including 0%) in the mixture to control the dimensional change in the iron sintered compact. As a result, the dimensional change of the powder metallurgical iron sintered compact is easily and stably controlled.;COPYRIGHT: (C)1996,JPO