EURO PM2001, in Nice, France. Authors: Anders Bergmark, Sven Bengtsson. A full factor test of the axial fatigue properties of Cu + C alloyed PM steel is performed. The three variables are: density (approx 7.15 and 7.4 g/cm³ obtained by single and double compaction), Cu content (0 and 2%) and C content (0.2% and 0.8%). The greatest influence on the fatigue endurance limit was found for Cu (+53 MPa) followed by density (+33.5 MPa) and C (+25 MPa). The greatest combined influence was found for Cu and C (+12.5 MPa in addition to the individual effects). The high cycle fatigue properties of cold compacted double pressed and sintered Fe2Cu0.8C are compared with warm compacted material with the same composition. Fractography, displaying the sizes and origins of the initial faults, is performed on double pressed/sintered and warm compacted Fe2Cu0.8C.