Evaluation of the HCF-behavior of 42CrMoS4 by means of strain, temperature and electrical measurements

Single step tests were performed on quenched and tempered specimens of the steel 42CrMoS4. Strain, temperature and electrical resistance measurements yielded an empirical evaluation of fatigue life according to Coffin [L.F. Coffin, A Study of Cyclic Thermal Stress in a Ductile Metal, Trans. ASME, 76 (1954) 931], Manson [S.S. Manson, Behavior of Materials under Conditions of Thermal Stress, NACA TN-2933, 1953] and Morrow [J. Morrow, Cyclic plastic strain energy and fatigue of metals. In: Internal Friction, Damping and Cyclic Plasticity, ASTM STP 378, 45/87, American Society of Testing and Materials, Philadelphia, PA, 1964]. All the measured values are based on physical processes and therefore show a strong interrelation. A new testing procedure was developed permitting hysteresis measurements to be used for the characterization and description of fatigue behavior under variable amplitude loading. The basic idea is to combine fatigue tests with any kind of load spectrum with single step tests. This offers the possibility to apply lifetime prediction methods normally used for single step tests to those with random or service loading.