Austenitic decomposition and tensile properties of Fe-7Al-31Mn-1C steel were studied. This austenitic steel whose oxidation resistance is derived from aluminum has a possibility to replace conventional stainless steels in certain applications.
The mechanical strength of the properly heat-treated state was higher than that of conventional stainless steels such as AISI 304, but formability was considered not necessarily inferior to that of commercial austenitic stainless steels because the difference between yield strength and ultimate tensile strength was large.
When the alloy was aged for a long time in the temperature range between 600℃ and 700℃, carbides precipitated in the grain boundaries, and successively pearlites also formed. Because of the decomposition of austenite, ductility was markedly decreased. In the case of 500℃ and 400℃ aging only small particle carbides precipitated and the related strength was raised.
The study also considered the effect of non-metallic inclusions on the properties of the alloy and of cold working on the austenitic decomposition rate.
It seemed that the successive pearlitic formation stages were somewhat different from Hillert's mechanism because this hyper-eutectoid alloy contained high austenitic stabilizing elements.