THE CYCLIC STRESS-STRAIN CURVE AND EQUATI ON OF FATIGUE LIFETIME WHENCHANGING RAMP LOADING FOR CARBON-STEELS

In the paper the dependencies of the cyclic stress-strain curve parame ters and parameters of the new equation of fatigue life time on ramp l oading values and carbon content in non-alloyed steers are presented. It is proved that, an increase of loading ramp develops a decrease of th factor of cyclic strength and of the exponent of cyclic strengtheni ng. An increase of ramp loading causes a decrease of the factor H-x an d an increase of the fatigue lifetime exponent. Increasing the carbon content in non-alloyed steel, the factor of cyclic strength, exponent of cyclic strengthening as well as the factor H-x is decreasing while the exponent of fatigue lifetime is increasing.