MECHANICAL AND MICROSTRUCTURAL CHANGES IN QUENCH-AGED FE-C ALLOYS SUBJECTED TO CYCLIC STRAINING

An Fe-0·04 wt.% C alloy was quenched and aged to produce precipitate particles of varying size and spacing. Specimens were fatigued at constant plastic strain over a range of strain amplitudes. In the as-quenched condition the alloy exhibited pronounced cyclic hardening which was attributed to strain ageing. The alloy containing fine carbide particles showed high primary cyclic hardening followed by softening. The softening was associated with the formation of precipitate free channels observed by electron microscopy. When larger, more widely spaced noncoherent particles were present in the lattice, primary cyclic hardening was slight even at high strain amplitudes. © 1969 Czechoslovak Academy of Sciences.