The microstructure as crack initiation point and barrier against fatigue damaging

Interaction effect of adjacent small defects on the fatigue limit of a medium carbon steel

“…Major studies have been undertaken in the past about the manner in which small cracks behave in inhomogeneous microstructures, for example, in ferritic–pearlitic structures . However, discussions about microstructural effects gain greater importance with regard to crack interaction because of their undisputed effect on crack closure, where cracks penetrate different microstructures and produce the various characteristics of non‐propagating cracks.…”

An efficient stress intensity factor evaluation method for interacting arbitrary shaped 3D cracks

“…Major studies have been undertaken in the past about the manner in which small cracks behave in inhomogeneous microstructures, e.g., in ferritic-pearlitic structures [70][71][72][73][74]. However, discussions about microstructural effects gain greater importance with regard to crack interaction, because of their undisputed effect on crack closure, where cracks penetrate different microstructures and produce the various characteristics of non-propagating cracks.…”

Recent Developments in Assessing Microstructure-Sensitive Early Stage Fatigue of Polycrystals (Postprint)

“…Szczepanski and collaborators [35] employed micro-notches with length corresponding to several grain sizes in Ti alloys and deduced that the variability of MSC growth rates is much lower than the variability of total fatigue life; therefore, most variability is attributed to the process of forming and growing MSC cracks in very early stages. Marx and coworkers [36][37][38][39] performed novel studies on the effects of grain boundaries on Stage I (crystallographic) fatigue crack growth in a directionally-solidified CMSX-4 Ni-base superalloy by introducing FIB notches (30-60 lm, semi-circular) within selected surface grains, oriented along the slip system with the highest Schmid factor, attempting to mimic naturally occurring cracks. By measuring the crack length periodically via a replication technique, the authors quantified a decreasing crack growth rate as the crack approached a grain boundary.…”