Mechanical Properties in Ultrahigh Strength Secondary Hardening Steels Bearing Co and Ni
Applying the severe deformation, the mechanical properties related to secondary hardening were investigated. The Mo-Cr-Co-Ni steels containing (5-13)wt% Co and (8-14)wt% Ni were severely rolled at 850 °C, followed by direct quenching(DQ). DQ specimens were then isothermally aged at 475°C. Ni additions promoted aging kinetics, accompanied by a little enhancement in hardness. In contrast, Co additions enhanced the peak hardness, but did not induce a remarkable aging acceleration. In the 13Co addition group, an actual secondary hardening, that is, the peak hardness is higher than the as-quenched hardness. Variation in peak hardness(Rc) in alloys is summarized as follows; 14Ni-13Co(57.2) ≒ 11Ni-13Co(57.1) > 8Ni-13Co(56.5) > 11Ni- 9Co(56.2) > 8Ni-9Co(54.4) > 11Ni-5Co(53.4).
T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran
H. S. Sim et al., "Mechanical Properties in Ultrahigh Strength Secondary Hardening Steels Bearing Co and Ni", Materials Science Forum, Vols. 539-543, pp. 4417-4421, 2007