Creep behavior of a new cast austenitic alloy

A new cast austenitic alloy, CF8C-Plus, has been developed by Oak Ridge National Laboratory (ORNL) and Caterpillar for a wide range of high temperature applications including diesel exhaust components and turbine casings. The creep strength of the CF8C-Plus steel is much greater than that of the standard cast CF8C stainless steel and is comparable to the highest strength wrought commercial austenitic stainless steels and alloys, such as NF709. The creep properties of CF8C-Plus are discussed in terms of the alloy design methodology and the evaluation of some long-term creep tested specimens (over 20,000 h). Microcharacterization shows that the excellent creep strength is due mainly to the precipitation of very fine nano-scale and stable MC carbides, without the formation of deleterious intermetallic phases.