Effect of short-term tempering on microstructure and mechanical properties of high-strength FeCrMoVC

The present work describes a systematic investigation of the influence of short-term tempering on the microstructure and mechanical properties of a fast solidified Fe84.3Cr4.3Mo4.6V2.2C4.6 (at.%) alloy. The applied casting conditions promote the formation of non-equilibrium phases such as martensite, retained austenite and a complex network of fine carbides already in the as-cast state. Additional short-term tempering further increases the strength and hardness of the alloy along with significantly improved ductility under compressive and tensile loading. By this procedure an extremely high ultimate compression strength of almost 4500 MPa combined with a compressive fracture strain of ∼22% and an ultimate tensile strength of over 1600 MPa can be achieved. The interacting mechanisms appearing due to short-term tempering were investigated by different X-ray diffraction methods and Auger electron spectroscopy, and a transformation of austenite into martensite as well as the formation of nano-carbides and a change in residual stresses during tempering was detected. Altogether, the outstanding properties of the material combined with the energy-efficient manufacturing process for Fe84.3Cr4.3Mo4.6V2.2C4.6 open up a new possibility to obtain a high-strength and simultaneously adequately ductile alloy for advanced tool design.