| Elastic-plastic fracture toughness(J_(IC)) of Ni-Cr-Mo-V steel with different yield strengths has been evaluated by two different testing methods (ASTM E8l3 JSME S001) and compared with K_(IC) and Charpy V-notch (CVN) impart value. At high yield strength levels, J_(IC) values measured by ASTM and JSME method are almost equal, however, at low yield strength levels, J_(IC) values by the ASTM method exceed those by the JSME method. This difference in J_(IC) values is due to variation in the method of considering crack extension on the specimen fracture surface. The comparison of K_(IC) with J_(IC) and CVN impact values shows that a very good correlation, exists between 93- 144 ㎏/㎟ yield strength levels. Therefore, it is possible to predict K_IC value with J_(IC) and CVN impact test. |
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