Micro Fatigue Crack Propagation Behavior in a Duplex Stainless Steel Studied Using In Situ SEM/EBSD Method

Abstract:

Fatigue crack propagation behaviors in a duplex stainless steel have been studied using an in-situ SEM/EBSD fatigue test and a conventional da/dN test. Crack propagation behaviors in grain, effect of Schmid factor, propagation cross the grain or phase boundaries have been discussed. Crack propagation occurs mainly in the grains with a high Schmid factor, but the crack can also propagate in the grains with very small Schmid factor. Crack deflection occurs mainly at the phase boundaries, but crack branching occurs mainly in the grains due to the dislocation slip. In-situ SEM/EBSD fatigue test confirms that crack propagation deflection can lead to a decrease in crack propagation rate. Formation of crack branches can significantly reduce the crack propagation rate, which can cause crack growth retardation in the main crack path in the worst case. The crack branches formed are usually not ideal. They can propagate almost transversely to the main crack direction with a mode II stress intensity factor, SIF, and a rate that is much higher than that of the main crack.

• Periodical: Advanced Materials Research (Volumes 891-892)
• Pages: 313-318
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.891-892.313
• Online since: March 2014
• Authors: Guo Cai Chai, Ru Lin Peng, Sten Johansson
• Keywords: Crack Branching, Crack Deflection, Fatigue, Fatigue Crack Propagation, In Situ SEM/EBSD

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