Thermodynamic calculations for precipitation in maraging steels

In the present work, thermodynamic calculations for several maraging system s have been carried out, and the results are compared with experimental dat a. The calculations were conducted using ThermoCalc. Excellent agreement is obtained between calculation and experimental measurements using mainly th e atom probe, As a highlight, calculated equilibrium phases and their mole fractions in 1RK91 steel recently developed by Sandvik compare extremely we b with atom probe microchemistry data, which showed the presence of copper rich particles, mixed Ni3Al and Ni3Ti, and molybdenum rich precipitates, Ca lculations also indicate the thermodynamic stability of mu phase in the Fe- Ni-Mo and Fe-Ni-Co-Mo systems, Ni3Al and Ni3Ti in a chromium containing ste el, and NiMn in a Fe-Ni-Mn system. However, it should be noted that thermod ynamic calculations may only be used as a guideline for systems not in equi librium. MST/4807.