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

For finite element calculations of high temperature components a continuous description of the creep behaviour in the material's whole field of application is required. For several long term tested heats of steels 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 strain as well as the primary-. secondary- and tertiary-creep strain and are valid in the interesting range of temperature, stress and time for these steels. The test results are well interpreted by the correspondent 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.