The Influence of Structural Parameters on the Yield Strength of Tempered Martensite and Lower Bainite

摘要

The contributions to the yield strength of tempered martensitic and bainitic structures was examined in 4340 steel. The principal factors that contribute to the reduction in yield strength with tempering in the range from 600 to 1000F are carbide coarsening and enlargement of the cellular substructure. The yield strength of both tempered martensitic and bainitic structures can be described in terms of cell size and dispersoid distribution by a single relationship in which the Orowan model is employed for the contribution from dispersion hardening and the Langford-Cohen model for that from cell size. (Author)