Fracture Toughness Master Curve of bcc Steels

The Master Curve methodology has been developed as an advanced, direct technique for characterizing the fracture toughness of ferritic structural steels. The application of the methodology has increased during the last decade and spread worldwide extending beyond the initial applications associated with nuclear power plant surveillance and integrity assessment programs. Today, the methodology is well acknowledged and increasingly accepted by regulators and safety authorities as a standardized method for application in integrity assessments. Methods based on conventional approaches, such as the Charpy V-notch test, are still widely used, and probably will be used in parallel into the foreseeable future. Once a sufficient amount of reference data have been measured using the Master Curve method, it will gain even further acceptance. Also, further understanding of the limits of applicability for different steels and different size/geometry test specimens will be obtained. The overall trend in fracture mechanics testing is toward characterization and methods which allow the use of small and/or moderate-size specimens simulating the true loading conditions and accounting for the expected micromechanisms of fracture. The Master Curve approach and its implementation into the ASTM E 1921 methodology have proven to be a valuable and powerful analysis tool for a wide variety of applications involving ferritic steels.