Effect of loading rate on fracture toughness of pressure vessel steels

The master curve method has recently been developed to determine fracture t oughness in the brittle-to-ductile transition range. This method was succes sfully applied to numerous fracture toughness data sets of pressure vessel steels. Joyce (Joyce, J. A. 1997, "On the utilization of High Rate Charpy T est Results and the Master Curve to Obtain Accurate Lower Bound Toughness P redictions in the Ductile-to-Brittle Transition, Small Specimen Test Techni ques," Small Specimens Test Technique, ASTM STP 1329, W. R. Corwin, S.T. Ro sinski, and E. Van Walle, eds., ASTM, West Conshochocken, PA) applied this method to high loading rate fracture toughness data for SA-515 steel and sh owed the applicability of this approach to dynamic fracture toughness data. In order to investigate the shift in fracture toughness from static to dyn amic data, B&W Owners Group tested five weld materials typically used in re actor vessel fabrication in both static and dynamic laoding. The results we re analyzed using ASTM Standard E 1921 (ASTM, 1998, Standard E 1921-97, "St andard Test Method for the Determination of Reference Temperature, T-0, for Ferritic Steels in the transition Range," 1998 Annual book of ASTM Standar ds, 03.01, American Society for Testing and Materials, West Conshohocken, P A). This paper presents the data and the resulting reference temperature sh ifts in the master curves from static to high loading rate fracture toughne ss data. This shift in the toughness curve with the loading rate selected i n this test program and from the literature is compared with the shift betw een K-1c and K-1a curves in ASME Boiler and Pressure Vessel Code. In additi on data from the B&W Owners Group test of IAEA JRQ material and dynamic fra cture toughness data from the Pressure vessel Research Council (PVRC) datab ase (Van Der Sluys, W. A. Yoon, K K., Killian D. E., and Hall J. B. 1998, " Fracture Toughness of Ferritic Steels and ASTM Reference Temperature (T-0), "BAW-2318, framatome Technologies. Lynchburg, VA) are also presented. It i s concluded that the master curve shift due to loading rate can be addresse d with the shift between the current ASME Code K-1c and K-1a curves. [S0094 -9930(00)01302-0].