1. Forming

Such an operation is feasible as long as the metal is sufficiently deformable. The curve shown in figure 1 defines the three temperature ranges in which this condition can be considered to be met:

• hot: at a temperature above Ac ₃ , the steel is in the austenitic state;

• cold, i.e. at room temperature or slightly above;

• but also lukewarm or medium-hot: between about 550 °C and Ac ₁ .