| 摘要 |
A high-strength steel machined product giving excellent hardenability has a metal microstructure with excellent balance of strength and toughness and high stability of retained austenite. The product is composed of an ultra-high low-alloy TRIP steel having a metal microstructure which contains an appropriate quantity of two or more of Cr, Mo, and Ni, and an appropriate quantity of one or more of Nb, Ti, and V, and having an appropriate value of carbon equivalent; the metal microstructure has a mother-phase structure composed mainly of lathy bainitic ferrite with a small amount of granular bainitic ferrite and polygonal ferrite, and has a secondary-phase structure composed of fine retained austenite and martensite. |
