Effect of back-stress on cyclic stress-strain behaviour of a quenched and tempered low alloy steel

Low cycle fatigue was considered in relation to back-stress hardening. Cyclic stress-strain behaviours under controlling strain and stress conditions were investigated for a quenched and tempered low alloy steel which contained cementite particles. The cyclic stress-strain states obtained by the two prescribed tests were uniquely described using a parameter which reflected the cumulative reversible plastic work associated with the back-stress hardening. It was suggested that the effect of back-stress hardening on cyclic deformation should appear directly on the cyclic stress-strain curves defined as the loci of the tips of stable hysteresis loops. The initial slopes of the cyclic stress-strain curves for several steels were demonstrated to coincide with the theoretical work-hardening rates calculated on the basis of back-stress hardening due to the included carbide particles. Finally, the Manson-Coffin law was explained from the view that the surface damage would progress in parallel with the structure change in the bulk according to the persistency of slips resulting from the reversible back-stress hardening.