Change characteristics of static mechanical property parameters and dislocation structures of 45(#) medium carbon structural steel during fatigue failure process

A series of experiments at both macroscopic and microscopic levels were car ried out to investigate the variation in static mechanical property paramet ers (yield stress sigma (0.2), elastic modulus E, reduction of area phi, el ongation delta, strain hardening exponent n, ultimate strength sigma (b)) o f 45(#) medium carbon structural steel during fatigue damage process. The p ossible reasons for the variation of the static mechanical property paramet ers are qualitatively discussed through analyzing the evolution of dislocat ion substructures in the steel during cycling. A composite parameter of the static mechanical property called static toughness is proposed for charact erizing comprehensively the variation of the static mechanical property par ameters, and a quantitative relationship between the variation of static to ughness and the dissipation of cyclic plastic strain energy is established. (C) 2001 Elsevier Science B.V. All rights reserved.