Analysis of Orientation Relationships, Carbon Partitioning and Strengthening Mechanism of a Novel Ultrahigh Strength Steel

The orientation relationships, carbon partitioning and strengthening mechanism of a novel ultrahigh strength steel were analyzed in depth during the complex process of heat treatment. The experimental results reveal that the (011)α//()γ, [100]α//[011]γ orientation relationships can be drawn between martensite and retained austenite. The position and angle of martensite and retained austenite are shown more clearly from the stereographic projections. Moreover, the calculated results show that the carbon content near the austenite interface is the highest in the shorter carbon allocation time. With the further increase of time, its carbon content gradually decreases. Furthermore, a model of the relationship between yield strength and strengthening mechanism was established. It was proved that the main strengthening components contributing to the yield strength include Orowan strengthening, grain-size strengthening and dislocation hardening. The main strengthening mechanism of steel in this experiment is dislocation strengthening.