Notch sensitivity of Sanicro 25 in small punch creep test

• Published in: Theoretical and applied fracture mechanics Vol. 100; pp. 383 - 389
• Main Authors: Dymáček, P., Dobeš, F., Andrés, D.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.04.2019; Elsevier BV
• Subjects: Austenitic stainless steels; Crack initiation; Creep; Creep tests; Displacement; Ductility; Ductility tests; Fracture; Fracture mechanics; Geological time; Notch; Notch sensitivity; Notches; Rupture; Small Punch Test; Fracture; Small Punch Test; Creep; Notch
• ISSN: 0167-8442; 1872-7638
• DOI: 10.1016/j.tafmec.2019.02.003

•Sanicro 25 small punch specimens with Lacalle's type of notch were tested in SP creep.•Different notch lengths showed influence on time to rupture and displacement rate.•The crack initiation was not clearly identified from the SPC curves and interrupted test.•Intergranular fracture of all specimens was confirmed by SEM. Small punch creep tests of unnotched and notched 8 mm discs of new austenitic steel Sanicro 25 were performed at 700 °C. Side notches through the disc thickness proposed by Lacalle of different lengths ranging from 3.0 to 4.5 mm were applied for this study. It was found that the notch length influences the time to rupture and the minimum displacement rate, however no apparent signs of crack initiation were observed on the recorded time-displacement and time-displacement rate curves at 400 N force. The shortest time to rupture and fastest displacement rate were obtained for notch length of 3.5 mm, while the longest time to rupture and slowest displacement rate were obtained for notch length of 4.25 mm. The fracture of Sanicro 25 discs had signs of a “star” shape, with multiple cracks, which indicates lower ductility. A larger circular cap which is obvious for materials with high ductility was not present in all the small punch tests performed.