Experimental 3 Inch Thick Cast Armor Program Heat Treatment of Fracture Blocks from Heats Numbers 1903, 1917, 1968, and 2244, Produced by Continental Foundry and Machine Company

摘要

As the result of heat treatments performed at Continental and at Watertown Arsenal it is concluded that heats 1917 and 1968 do not respond satisfactorily to suitable heat treatment. Dendritic fractures and lowered impact properties in these two heats are traceable to segregations of sulfide inclusions at the primary austenite grain boundaries. These segregations are believed associated with the deoxidation practice which involved the addition of 2 of aluminum per ton of metal. It is concluded that heats 1917 and 1968 should not be included in the experimental program. Heats 1903 and 2244 are capable of responding satisfactory to heat treatment and are considered of sufficiently good quality for retention in the experimental program. Heat 1903 was not deoxidized with aluminum, while heat 2244 was deoxidized with a smaller amount of aluminum than was used in heats 1917 and 1968. The higher carbon content of heat 1903 makes the material susceptible to quench cracking and may introduce some difficulty during heat treatment.