4. Choosing creep-resistant steel

To prepare the selection of a creep-resistant steel, it is useful to characterize its creep resistance level by comparing, on the same graph, the evolution of its hot yield strength and that of two performance levels capable of globally delimiting its field of use in the presence of a creep phenomenon; here we can arbitrarily choose :

• the unit load that causes creep failure in 10,000 h, representing the maximum stress that the metal can practically withstand (up to 1,000 h is possible);

• the unit load that causes 1% creep elongation in 100,000 h, representing the minimum stress under which the metal in question can still be used.