Initiation and growth behavior of very-long microstructurally short fatigue cracks
Journal Title: Frattura ed Integrità Strutturale - Year 2013, Vol 7, Issue 25
Abstract
The present paper describes a novel experimental technique recently presented that allows one to study interactions between the crack and microstructural barriers with an unprecedented level of ease and detail. The method consists in increasing the grain size of Al1050 Aluminium alloy until the centimetre scale by applying a series of mechanical and heat treatments. Once the thermo-mechanical treatment is completed and the desired microstructure obtained, a circular notch is machined on each specimen, and the samples are subjected to push-pull fatigue loading. Several combinations of notch and microstructural sizes have been tested. This method provides an easy way to record and analyse the effect of the microstructure upon crack growth rate. It was observed that the space between successive crack-tip arrests correlates well with the material grain size. Another interesting observation is that in the majority of the cases studied the cracks did not initiate at the point of maximum stress concentration. This is surprising since the classical methods of notched fatigue limit analysis clearly indicate the horizontal symmetry axis as the initiation and propagation direction for push-pull loading.
Authors and Affiliations
P. Lorenzino, A. Navarro
Keywords
Related Articles
- EP ID EP156664
- DOI 10.3221/IGF-ESIS.25.20
- Views 63
- Downloads 0
Fatigue crack micromechanisms in a Cu-Zn-Al shape memory alloy with pseudo-elastic behavior
Shape memory property characterizes the behavior of many Ti based and Cu based alloys (SMAs). In Cu-Zn-Al SMAs, the original shape recovering is due to a bcc phase that is stable at high temperature. After an...
Ductile cast irons: microstructure influence on fatigue crack propagation resistance
Microstructure influence on fatigue crack propagation resistance in five different ductile cast irons (DCI) was investigated. Four ferrite/pearlite volume fractions were considered, performing fatigue crack propagation t...
Fatigue crack growth in additive manufactured products
Additive Manufacturing (AM) is a new innovative technique that allows the direct fabrication of complex, individual, delicate and high-strength products, based on their 3D data. Selective Laser Melting (SLM) ...
On the applicability of multi-surface, two-surface and non-linear kinematic hardening models in multiaxial fatigue
In this work, a comparison between NLK and Mróz-Garud’s multi-surface formulations is presented. A unified common notation is introduced to describe the involved equations, showing that the Mróz-Garud model can b...
L’infragilimento da idrogeno. Un caso di studio in una barra di comandi di un velivolo dell’aviazione generale.
La degradazione delle caratteristiche meccaniche di un materiale di impiego aeronautico ha pesanti ricadute sulla sicurezza del volo. Tale degradazione si può manifestare sia per l’effetto combinato tra l’ambiente...