On the crystallographic, stage I-like, character of fine granular area formation in internal fish-eye fatigue cracks

The crystallographic character of fine granular area (FGA) formation from internal particles in martensitic high strength steel has been revealed by an assessment of the plastic zone size at the FGA border. This plastic zone size corresponded to about 3 times the martensite lath width. Tests at different temperatures (20°C, 200°C and 400°C) revealed a decreasing FGA size with increasing temperature at constant applied stress amplitude. As a consequence, the critical stress intensity factor varied as the FGA decreased with temperature. In contrast, the critical plastic zone size remained constant and equal to the sizes of microstructural features. This represents a strong similarity between crystallographic, stage I-like, crack propagation and FGA formation in a vacuum. ….Read the article

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Failure analysis of re-bars during bending operations

Failure_analysis_of_Rebar

An article published in « Case Studies in Engineering Failure Analysis« , october 2014.

This  paper highlights failure investigation of a failed rebar during bending operations. From fractography and microstructural analysis it is confirmed that the rebar sample failed in brittle manner due to through harden martensitic structure and which indicates that there is some anomaly in water box resulting in these premature failures.

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