Impact of Oxygen on The Microstructure and Fracture Morphology of Fe(Cr,Mo)-PM Steels  (1,47MB)
Lorenz S. Sigl and Patrice Delarbre
2003 PM2-Tec Conference, Las Vegas

A number of (Cr,Mo)-alloyed PM-steels was prepared from commercial powder (3 wt.% Cr, 0.5 wt.% Mo) are sintered to various oxygen levels. The microstructures and the fractographic appearance of these materials were analyzed. Oxygen being generally precipitated as particulate Cr2O3 was found to be concentrated in planes along former particle boundaries. This spatial configuration controls the nucleation and spacing of micro-voids during plastic deformation of sintering necks and significantly reduces ductility and fatigue resistance upon increasing oxygen content. Finally it is shown that (Cr,Mo)-PM-steels combining both high strength and good ductility can be obtained by high temperature sintering which reduces the oxygen content of such materials below 0.05 wt.%.