|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Characterization of Minerals, Metals, and Materials
||Fatigue Fracture Surface Morphologies in Controlled Crack Growth Rail Steel Specimens
||Donato Firrao, Roberto Doglione, Paolo Matteis, Stefano Rossi, Raffaella Sesana
|On-Site Speaker (Planned)
Fatigue fracture surfaces of R260 rail steels have been examined and their morphology interpreted at the light a micro-mechanical model previously developed by the authors. Rail steels have an almost complete pearlite structure, for which the model calls for a rupture of cementite lamellae when the crack tip approaches a pearlite colony leaving a network of ferrite platelets to stand the incoming cyclic stress/strain field. Depending on the crack growth rate, a single resisting ferrite lamella, already strained and cross area reduced by the incoming stress concentration, can be overcome in a single jump or in a few cycles of the fatigue process. Tests with varying da/dN values have been performed on rail steels samples under different applied ΔK’s. Fatigue fracture morphologies and the application of the above reported model to the present case have been related with Paris Law curves pertaining to the examined type of steel.
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