This paper discusses fracture toughness and temperature rise for JJ1 austenitic stainless steel forged plate at liquid helium temperature for fusion reactor magnets of next generation. Elastic-plastic fracture toughness (JIC) testing was conducted in general accordance with ASTM standards E813-81 and E813-87, and unloading-compliance technique was applied using compact specimens 25.0 mm and 12.5 mm thick. Thermocouples were used to measure the temperature rise near the crack tip. The effects of specimen size and side-groove on the cryogenic fracture properties of this alloy are examined. Examination of the fracture surface of CT specimens by scanning electron microscopy showed ductile failure by microvoid coalescence. The effect of inclusion on fracture mechanics parameters (JQ, JIC) is also discussed using energy dispersive X-ray analyser.
