4. Hot rotors

4.1 Choice of materials

The materials selected for hot compressor and turbine rotor discs must have high mechanical strength properties: burst strength, low-cycle fatigue strength (disc bore) and creep-elongation strength (disc rim), over a temperature range from 450 ˚C for the first disc, up to 700 ˚C for the last high-pressure compressor disc or high-pressure turbine disc.

The alloys chosen by engine manufacturers are exclusively from the nickel superalloy family (table 2 ), and are processed by hot forging, which enables the development of fine, fatigue-resistant microstructures. These nickel-matrix alloys are both strengthened by solid solution (Co, Cr, Mo, Hf...), for creep resistance, and by...