PSI - Issue 18

Mehdi Mokhtarishirazabad et al. / Procedia Structural Integrity 18 (2019) 457–471 M. Mokhtarishirazabad / Structural Integrity Procedia 00 (2019) 000–000

470 14

 Considerable plastic deformation in the un-cracked ligament of the specimens showed that the failure occurred by plastic collapse in all cases (as shown by fully plastic J and FAD analysis).  Plastic collapse occurred before the cracks start to grow (during the early loading unloading sequences in crack tip blunting regime) These observations suggest that austenitic stainless steel, particularly AISI type 316L, which shows an extraordinary strain hardening capacity is not suitable for studying the constraint effect. Further study is currently in progress to examine the effect of long-term aging treatment on mechanical properties and fracture behaviour of this type of steel.

Fig. 17. Failure Analysis Diagram for samples with thicknesses of 10 mm and 5 mm with a/W =0.5. The highlighted marks show the Lr at J 0.2 .

Acknowledgements This work was supported by the Department of Business, Energy and Industrial Strategy (BEIS) Nuclear Innovation Programme. The views expressed in the paper are those of the authors and should not be interpreted as BEIS or wider Government policy. Financial support of the University of Malaga through the program of “Doctor Internacional” and the University of Bristol’s Impact Acceleration Fund is greatly acknowledged.

References

Adams, Lai, M. O., and W. G. Ferguson. 1986. “Effect of Specimen Thickness on Fracture Toughness of Bovine Patellar Cartilage.” Engineering Fracture Mechanics 23 (4): 649–59. Anderson, T. L. 2017. Fracture Mechanics, Fundamentals and Applications . 4th ed. Boca Raton, FL, USA.: CRC Press. ASTM-E8/E8M. 2016. “Standard Test Methods for Tension Testing of Metallic Materials.” https://doi.org/10.1520/E0008. Dzugan, Jan. 2003. “Crack Lengths Calculation by Unloading Compliance Technique for Charpy Size Specimen.” (FZR--385) . Germany. Hioe, Y, S Kalyanam, G Wilkowski, S Pothana, and J Martin. 2017. “Fracture Toughness Variation with Flaw Depth in Various Specimen Geometries and Role of Constraint in Material Fracture Resistance.” In ASME 2017 Pressure Vessels and Piping Conference , 1–12. Landes, J. D. 1995. “The Blunting Line in Elastic - Plastic Fracture.” Fatigue & Fracture of Engineering Materials & Structures 18 (11): 1289–97. https://doi.org/10.1111/j.1460-2695.1995.tb00855.x. Mills, W. J. 1997. “Fracture Toughness of Type 304 and 316 Stainless Steels and Their Welds.” International Materials Reviews 42 (2): 45–82. https://doi.org/10.1179/imr.1997.42.2.45. Moreton, D. N., and D. P. Sellings. 1989. “The Nature of Room Temperature Creep.” Strain . Vol. 25. Mostafavi, M., D. J. Smith, and M. J. Pavier. 2010. “Reduction of Measured Toughness Due to Out-of-Plane Constraint in Ductile Fracture of Aluminium Alloy Specimens.” Fatigue and Fracture of Engineering Materials and Structures 33 (11): 724–39. https://doi.org/10.1111/j.1460-2695.2010.01483.x. Murakami, Y. 1987. Stress Intensity Factors Handbook . Oxford: Pergamon Press. Paris, P.C., H. Tada, A. Zahoor, and H. Ernst. 1979. “The Theory of Instability of the Tearing Mode of Elastic-Plastic Crack Growth.” In Elastic-