Elastic-plastic fracture toughness and acoustic emission of rolled steel for reactor pressure vessel (A533B)

In this paper, the results of the elastoplastic fracture toughness test on A 533B Cl. 1 steel for reactor pressure vessels and the evaluation by AE are reported. For this test, the compact test pieces of 1 in thickness taken in L-T and S-L directions were used, and the elastoplastic fracture toughness value was measured in accordance with ASTM-24 tentative rule (R-curve method) and JSME S781 tentative rule (R-curve method, stretch zone method). At the same time, AE measurement was carried out, and the effectiveness of the AE method was examined by the comparison with the test results, Also the influence that the direction of taking test pieces exerts on the fracture toughness and AE was investigated. The chemical composition and mechanical properties of A 533B Cl. 1 steel are shown. The test of the pre-cracked test pieces was interrupted at respective stages of the load-displacement curve, and the test pieces were fractured by fatigue, then the fractured surfaces were observed, and the length of crack developemt and stretch zone width were measured. Also the number of AE events, amplitude and energy were recorded. The determination of the fracture toughness value by the AE method was difficult in the range of this test, but the AE characteristics were remarkably dependent on the direction of taking test pieces due to the difference in the ductile fracture. (Kako, I.)