Process for producing sintered-iron molded parts with pore-free zones

A process for producing from iron materials a sintered molded part which is pore-free in individual zones or boundary zones but porous in the other zones. The process is based on a molded part brought to a residual porosity of about 10% by volume by conventional powder pressing and sintering processes. By additional process steps such as zonal introduction of additional materials or local mechanical recompacting, certain zones or local areas are brought to a residual porosity of 5% by volume or less; at the same time, a closed pore structure is produced in these zones. Under these preconditions, in a final HIP or sintering HIP process step the sintered molded part can be brought to 100% material density in the pretreated zones so that they substantially completely free from pores. The major advantages include local improvement in material properties and calibratability of the finished sintered molded part.