Phase stability of reduced-activation Mn-stabilized austenitic steels

The thermal aging response of three Mn-stabilized austenitic alloys: Fe15Cr15Mn, Fe10Cr30Mn and Fe30Mn, is characterized as a function of aging time and temperature using optical metallography, analytical electron microscopy, microhardness, and magnetic susceptibility measurements. The alloys were aged in the 20% cold-worked state from 1000 to 30 000 h between 300 and 700°C. Isothermal sections at 300, 500 and 600°C are constructed for the FeCrMn system from the experimental data. Results indicate that Mn-stabilized austenitics are significantly more prone to form secondary phases during thermal aging than their Ni-stabilized counterparts.