SR-125 was initiated for the purpose of surveying notch-toughness properties of ship plate procured by various shipyards for merchant ship construction under ABS rules. The main objective was to determine the ex-tent to which post World War II steels have been improved, based princi-pally on a comparison of their Charpy V-notch properties with those estab-lished by the National Bureau of Standards for fractured plates from World War II ships.nThe initial part of the program (prior to 1956) covered plate procured to the requirements of the 1948 ABS Rules and included 37 samples of Class A, 81 of Class B andl4of Class C. In view of the 1956 changes in the ABS Rules, the sampling program was extended to coyer primarily the new Class Btype but some additional samples of Class G were included to supplement the relatively small number received in the previous sampling. The extended program included 76 samples of Class B and 12 of Class C.nThe results of the survey indicate that since the 1956 revision of the ABS Rules for Ship Steel, the range and average transition temperatures (15 ft-lb Charpy V) for the new material have been found to be -40 to 29 F and 2 F, respectively, for ABS Class B plates, and -46 to 13 F and -13 F, re¬spectively, for ABS Class C plates, as compared with an average of 90 F forWorldWar II fracture-source plates and 68 F for fracture-through plates.
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