Study of 'Woody' Fractures in Rolled Armor Plate
WATERTOWN ARSENAL LABS MA WATERTOWN ARSENAL United States
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This 1944 report investigates a series of 34 in., 1 in., and 1 12 in. thick steel plates which showed a marked tendency toward woody fractures. The woody fracture usually has a fine striated appearance and shows occasionally evidence of ruptured fibres. The woody condition develops when the fracture plane is parallel to the major rolling direction and is caused by the presence of fine nonmetallic inclusions in the planes of rupture which have a stepped appearance. The types of inclusions generally found in the steels investigated which exhibit woody fractures are silicates or complex oxide-sulphide-silicates. Occasionally, streaks of titanium nitride or complex oxides associated with zirconium nitrides are found which also result in the same effect. The nonmetallic inclusions are occasionally associated with metallic banding. The degree of woody appearance increases with the quantity of nonmetallic inclusions as well as the inequality-in-reduction in the two rolling directions.