CREEP-BEHAVIOR OF HEAT-RESISTANT STEELS . 1. CREEP EQUATIONS FOR INDIVIDUAL TEST MATERIALS

For finite element calculations of high temperature components a conti nuous description of the creep behaviour in the material's whole field of application is required. For several long term tested heats of ste els 2.25 Cr - 1 Mo, 1 Cr - 1 Mo - 0.5 Ni - 0.25 V and 12 Cr- 1 Mo - 0. 3 V creep equation were established.They contain the initial plastic s train as well as the primary-. secondary- and tertiary-creep strain an d are valid in the interesting range of temperature, stress and time f or these steels. The test results are well interpreted by the correspo ndent values calculated according to the creep equations. Additionally . an equation of the recovery strain is proposed. Moreover, the creep equations can be applied to incremental calculations with true strain and true stress and in a certain extent, a transformation of the creep equations to similar steels seems to be possible.