Static and fatigue properties of high strength PM-steels

The static, dynamic and fatigue properties of two high-alloyed Fe-(Mo)-Ni-Cu PM steels are compared with two Fe-(Cr,Mo) PM steels. All materials were processed in a typical industrial environment. The Fe-(Mo)-Ni-Cu materials were sintered in endo-gas ar 1120°C, while the Fe-(Cr,Mo) was consolidated in 90/10 N2 -H2 at 1160°C and 1140°C respectivly. All materials were finally sinterhardened under similar conditions (cooling rate 2 Ks-1) and annealed at 200°C for 60 minutes. The material were characterized by evaluatingtheir static properties (Vickers hardness HV5, yield strength, tensile strength, strain to fructure), dynamic properties (Charpy impact energy) and fatigue properties under constant amplitude axial loading (Woehler-curve) using conventional specismens and testing procedures. The result for the four PM steels are presented and compared. Specificially, the Fe-(Cr,Mo) based materials SIRON® P1150 and P820, with an axial fatigue strength Sigma f,50%, of 258 and 244 MPa respectivly, clearly outperform conventional Fe-(Mo)-Ni-Cu PM steels at a similar carbon content.