Creep Rupture Behavior and Microscopic Analysis of 304HCu Austenitic Stainless Steel Under Multiaxial State of Stresses at 973 K

• Published in: Transactions of the Indian Institute of Metals 2016-03, Vol.69 (2), p.451-455
• Main Authors: Sahoo, Kanhu Charan, Ravi, S., Goyal, Sunil, Parameswaran, P., Laha, K.
• Format: Article
• Language: English
• Subjects: Chemistry and Materials Science; Corrosion and Coatings; Materials Science; Metallic Materials; Technical Paper; Tribology
• ISSN: 0972-2815; 0975-1645
• DOI: 10.1007/s12666-015-0788-1

As a part of materials development for the application of 304HCu SS in advanced ultra super critical power plants, an experimental study has been carried out to understand the response of material under various states of stresses at 973 K. In order to introduce the multiaxial state of stress, notches of different root radii ranging from 0.25 to 2.5 mm were incorporated in smooth specimens. The comparison of rupture life of the smooth and notched specimen revealed the ability of the steel to ‘notch-strengthen’. In order to understand and substantiate the above observations, detailed FE analysis has been carried out. The decrease in von-Mises stress below the net applied stress resulted in notch strengthening in the steel in presence of a notch. The rupture life of the steel was found to increase with notch sharpness. Detailed scanning electron microscopy investigation carried out on fracture surfaces of smooth and notched specimens exhibited ductile fracture for smooth and shallow notches; whereas mixed mode fracture for relatively sharper notches. Further, the effect of different stresses on fracture morphology has also been discussed.