Evaluating a valid fracture specimen geometry for predicting geometry independent SZWc and JSZW value in SA333 Gr. 6 carbon steel material

• Studied the geometry independent evaluation of critical SZW and JSZW for SA333 Gr. 6 carbon steel material.
• Variation of critical SZW due to standard and non standard fracture specimen geometries is predicted.
• Variation of critical SZW due to a/W ratio and thickness is also predicted for the material.
• Possible reasons for the variation of SZWc parameter due to geometric variation of fracture specimens are evaluated.
• The minimum thickness criteria available in literature are also checked for the studied material.

To obtain geometry independent critical stretch zone width there is a need to understand its variation with fracture specimen thickness, initial crack size, fracture specimen geometries and the type of loading. It comes out that minimum tri-axiality quotient value on the un-cracked ligament and the plastic zone size contained within fracture specimen geometry are the two criteria to be considered while choosing the fracture specimen shape and its geometry for the evaluation of valid critical SZW value of the material. The present study also showed the possibility of further improving the minimum thickness criterion of fracture specimen.