MICROSTRUCTURE AND CYCLIC DEFORMATION-BEHAVIOR OF PLAIN CARBON AND LOW-ALLOYED STEELS

Stress- and strain-controlled push-pull tests have been performed to study fatigue phenomena in several plain carbon steels and a low-alloyed steel after different heat treatments with special consideration being given to the microstructural processes. The cyclic deformation behaviour is characterized in terms of plastic strain amplitudes which can be regarded as the basic condition for fatigue damage. Depending on the loading amplitudes and temperatures, the cyclic deformation curves reveal characteristics of cyclic softening and cyclic hardening. In stress-controlled tests with non-zero mean stresses, normalized as well as quenched and tempered material states show cyclic creep effects. TEM investigations indicate distinct differences in the dislocation structures of materials which have been fatigued under different loading and temperature conditions. © 1990.