EFFECTS OF STRESS LEVEL IN PRE-CRACKING ON FRACTURE TOUGHNESS OF SUS 304L STEEL IN AN 8 TESLA MAGNETIC FIELD AT 4K

摘要

The effects of an 8 tesla magnetic field on fracture toughness of SUS 304L steel were examined at 4K in order to clarify conflicting results among previous reports on the magnetic effects. In order to make clear the reason for the conflict between the results at Toshiba Corporation and at the University of Tokyo, the mean maximum stress in the ligament region during pre-cracking was controlled as similarly low as possible as that in the previous work at Toshiba Corporation. The decrease in the mean maximum stress down to the value of that in pre-cracking at Toshiba Corporation did not affect Jic value and tearing modulus in zero magnetic field. And the decrease showed no magnetic effect on Jic value and tearing modulus, whereas Jic value and tearing modulus was increased and decreased respectively by the application of an 8 tesla field in the previous tests at Toshiba Corporation.