Fatigue Crack Growth Study in P91 and 316LN Steels Using Acoustic Emission

• Published in: Transactions of the Indian Institute of Metals 2019-12, Vol.72 (12), p.3067-3080
• Main Authors: Nani Babu, M., Mukhopadhyay, C. K., Sasikala, G.
• Format: Article
• Language: English
• Subjects: Acoustic emission testing; Acoustic fatigue; Ambient temperature; Austenitic stainless steels; Chemistry and Materials Science; Correlation; Corrosion and Coatings; Crack propagation; Emission analysis; Fatigue failure; Ferritic stainless steels; Fracture mechanics; Materials Science; Metal fatigue; Metallic Materials; Steel; Stress intensity factors; Technical Paper; Tribology
• ISSN: 0972-2815; 0975-1645
• DOI: 10.1007/s12666-019-01773-2

Fatigue crack growth (FCG) behavior of ferritic steel P91 and austenitic stainless steel 316LN (SS 316LN) has been studied at ambient temperature. Acoustic emission (AE) signals generated during FCG tests were captured using 375 kHz resonant transducer. The FCG and AE results were compared for both steels in Paris and threshold regimes. The AE results indicated five and four substages of FCG for P91 steel and SS 316LN, respectively. Several parameters of AE signals such as rise time, peak amplitude and event duration were used to differentiate between various substages of the FCG. AE cumulative count was correlated with stress intensity factor range (Δ K ) in Paris regime for both the steels. For SS 316LN, the exponent of the correlation of AE cumulative count with Δ K is in good agreement with Paris exponent. For P91 steel, higher value of the exponent of the AE cumulative count—stress intensity factor range correlation compared to Paris exponent is observed. Monitoring of AE continuously during fatigue crack growth of these two steels enables understanding the mechanisms of crack growth operative at different regions of the FCG curve.