The Effects of Ferrite Content and Morphology on the Mechanical Properties and Room Temperature Creep of Quenched and Tempered SAE 4340 Steel

Abstract

The room temperature creep behavior is investigated for a commercial SAE 4340 steel containing small amounts of ferrite. Significant creep deformation occurs at stress levels below 1/3 σ_0.2 (The yield strength at 0.2% offset strain). Small amounts of ferrite (0% to 4%) have no influence on the hardness and yield strength. However, these small amounts of ferrite play an important role in controlling the creep resistance. The presence of any ferrite leads to a reduction in the creep resistance. The creep deformation at room temperature increases with an increase in the amount of ferrite. The effects of ferrite morphology and an inhomogeneous microstructure on the creep resistance are discussed.