Oo Structural Diagram of Austenitic 25%Cr-20%Ni-Fe-C Type Alloys

Abstract

To establish the structural diagram of 25%Cr-20%Ni-Fe-Calloys in which carbon content is lower than2.4wt%, were studied thermal characteristics such as melting temperature, carbide solubility in austenitic phase, and stability of carbides and sigma phase. In addition to the sectional diagram shown in Fig. 16 in the text, the remarkable results are as follows.
(1) The solubility of M₂₃C₆type carbide in austentitc phase is shown by where C is the carbon content (wt%) in solid solution and T the absolute temperature
(2) Sigma phase precipitates within austenite phase in the alloys of lower carbon content. On the other hand, in the case above about 0.25%C, it is likely that M₂₃C₆type carbide transforms to sigma phase.