Journal article
Microstructural influence on small fatigue cracks in a ferritic-martensitic steel
Publication Details
Authors: | Brückner-Foit, A.; Motoyashiki, Y.; Sugeta, A. |
Publication year: | 2008 |
Journal: | Engineering Fracture Mechanics |
Pages range : | 768-778 |
Volume number: | 75 |
Start page: | 768 |
End page: | 778 |
ISSN: | 0013-7944 |
Abstract
Microstructure effects on fatigue crack initiation and propagation in ferritic-martensitic dual phase steel were investigated. Slip bands were formed in ferrite grains after several thousand cycles with ensuing crack initiation due to dislocation pile-up. Subsurface observations using a focused ion beam (FIB) and crystallographic analyses using electron backscatter diffraction (EBSD) measurements showed that crack initiation occurred as a result of the activation of a slip system having a high Schmid factor. Surface crack nucleation occurred quite frequently at ferrite/martensite and ferrite/ferrite boundaries, with crack propagation in the ferrite grains. This initiation mode can be attributed to the mismatch stresses at ferrite/martensite phase boundaries and at high angle grain boundaries. (C) 2007 Published by Elsevier Ltd.
Microstructure effects on fatigue crack initiation and propagation in ferritic-martensitic dual phase steel were investigated. Slip bands were formed in ferrite grains after several thousand cycles with ensuing crack initiation due to dislocation pile-up. Subsurface observations using a focused ion beam (FIB) and crystallographic analyses using electron backscatter diffraction (EBSD) measurements showed that crack initiation occurred as a result of the activation of a slip system having a high Schmid factor. Surface crack nucleation occurred quite frequently at ferrite/martensite and ferrite/ferrite boundaries, with crack propagation in the ferrite grains. This initiation mode can be attributed to the mismatch stresses at ferrite/martensite phase boundaries and at high angle grain boundaries. (C) 2007 Published by Elsevier Ltd.
