SYNERGY EFFECTS OF STATIC AND CYCLIC STRE SS ON CREEP OF STEEL EI-268-S

This work deals with a synergy effect of cyclic stress part on creep b ehaviour of stainless steel EI 268 S. Due to the effect of the cyclic stress part with frequency 20 kHz, the time to fracture is shortened, the stable creep rate increases, and the value of apparent activate en ergy of creep loading is changed slightly. The cyclic stress part has a significant influence on the lifetime. The higher is this part, the shorter is the total lifetime. The activate energy for pure creep was 385 kJ/mol, while at the stress 340 +/- 45 MPa and temperature 500 deg rees C, it was 361,7 kJ/mol.