A study on the fracture toughness of heavy section steel plates and forgings for nuclear pressure vessels produced in Japan, 1

Recently, reactor pressure vessels have become very large, and those with plate thickness of 250 mm are seen in Japan. It is very important to grasp the strength and fracture toughness of the materials for such heavy section structures. In USA, reference fracture toughness curves were set up as one of the results of the Heavy Section Steel Technology Program. In Japan, the experimental research mainly aiming at the research on the strength and fracture toughness of the materials produced in Japan was carried out for three years from 1977 by the Japan Welding Engineering Society. Moreover, the research on the thermal shock in the nozzles of LWR pressure vessels was carried out for additional three years from 1981. The materials tested were JIS SQV 2A steel (ASTM A 533B, Class 1) and JIS SFVQ 1A steel (ASTM A 508, Class 3), and the method of manufacture, and the fundamental test results of these steels are reported. Also the welded joints of these steels were tested. The anisotropy of the mechanical properties and impact characteristics, the change of properties in the direction of thickness and the correlation among the characteristic values were examined. Also the comparison with foreign materials was made. (Kako, I.)