Mechanical Properties in Ultrahigh Strength Secondary Hardening Steels Bearing Co and Ni

Abstract:

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).

• Periodical: Materials Science Forum (Volumes 539-543)
• Pages: 4417-4421
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.539-543.4417
• Online since: March 2007
• Authors: Ho Sup Sim, Ki Seop Cho, Kon Bae Lee, Hyung Ryul Yang, Hoon Kwon
• Keywords: Co-Ni Steel, Mechanical Property, Secondary Hardening, Severe Deformation, Ultra High-Strength Steel

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