Metallurgical Examination of a Cast Armor Turret T23 Produced by Ordnance Steel Foundry.
Final memorandum rept.,
WATERTOWN ARSENAL LABS MA
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This report covers the investigation of two inches thick sections from Ordnance Steel Foundry Cast Turret No. T23 drawing No. 7054366 which had been subjected to ballistic tests at the Ordnance Research Center, Aberdeen with two other turrets made by another manufacturer. The results show that this casting did not possess satisfactory toughness as measured by fracture and notched bar impact tests although the ballistic test was not sufficiently severe to reveal this weakness. The ballistic tests did bring out an inferiority in the ballistic efficiency of the casting at an obliquity of 45 deg. which was probably a result of its low hardness. A re-solution of some of the carbides and formation of bainite on cooling from the temper indicates that an excessively high tempering temperature was used resulting in the casting being heated above the lower critical temperature. This casting made from a manganese-molybdenum type steel had a bordeline hardenability for the 2 12 inches thick section.
- Metallurgy and Metallography