Further aspects on J-evaluation demonstrated with EDM notched round bars and double-edged plates between 300 and 7 K

Based on recent experiences with respect to JETT (J_-E_valuation on T_ensile T_est) several materials were measured to investigate the potential of this novel technique with the aim to determine the fracture toughness of materials. The investigated materials covered a wide field of toughness levels ranging from ∼2 MPa√m to ∼300 MPa√m. These materials were as follows; OFHC annealed copper, CuNiSi, sintered NdFeB, FeCo, 9Ni steel, Al 6061-T6, wrought 316LN, and modified Type 316LN cast steels. The tests comprised measurements of EDM notched round bars as well as double edged flat tensile specimens between 300 K and 7 K. Wherever possible the tests were cross checked with ASTM standard compact tension or single edged notched specimens using the standard procedures. Main attention was paid to seek a solution towards a realistic integration path focusing the materials fracture point, comprising tests with high ductility and medium toughness materials represented by copper and copper alloys. Scanning electron m...