FRACTURE TOUGHNESS BEHAVIOR OF A STRUCTURAL STEEL WITH YIELD STRENGTH 960 MPa

摘要

For ferritic steels the FITNET procedures and the Master Curve approach are good methods for evaluating the integrity of structures against fracture. It is not clear however, whether existing procedures are suitable for weldable high-strength steels with yield strengths as high as 960 MPa. Such steels have been tested according to ASTM E1921-03 and E1820-05 and the resultant master curves have been compared to the test results. The Master Curve cannot be used above certain cut-off temperature, but for designer this boundary is difficult to define. A better approach is to express measured fracture toughness data in the form of polynomial fitted function covering the range of temperature that is of practical interest, for example. In this way, structural design becomes easier, as the problem of locating the brittle-ductile transition temperature is included in K_(IC) curve.