In situ neutron diffraction study of internal strain evolution around a crack tip under variable-amplitude fatigue-loading conditions

In situ neutron diffraction measurements were performed to investigate the lattice-strain evolution around a fatigue crack under five different loading conditions (i.e. fatigued, tensile overloaded, compressive underloaded, tensile overloaded-compressive underloaded, and compressive underloaded-tensile overloaded) during fatigue crack growth. The results show that different crack-growth behaviors are closely related to the distinct strain distributions developed near the crack tip under the various loading conditions. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.