Metallurgical Examination of Japanese Face Hardened Cast Armor.
WATERTOWN ARSENAL LABS MA
Pagination or Media Count:
The 1 12 in. thick sample of Japanese cast armor face hardened by an experimental high frequency induction method contained C .69, Mn .37, Si .33, Cr 1.04, and Mo 0.51. The depth of case was 0.21 inch. The case had a fine martensitic structure with areas of undissolved carbides present. The microstructure of the steel base consisted of fine pearlite resulting from a normalizing treatment. The Vickers hardness of the outer layers of the case was about 812 while the Vickers hardness of the steel base averaged about 312. It is believed that the steel base employed by the Japanese would possess poor ballistic shock properties due to the fact that the carbon content is very high and also since the steel base had been given an improper heat treatment, namely, a normalizing treatment resulting in a fine pearlitic structure. The sample investigated which contains a high percentage of carbon and molybdenum may not be representative of Japanese armor. It is believed, however, that a steel of high carbon content was employed for induction hardening in order to produce a maximum face hardness.
- Properties of Metals and Alloys