Metallurgical Examination of Two 4 inch Sections of Cast Armor Manufactured by Pittsburgh Steel Foundry

摘要

A metallurgical examination including fracture tests, microscopic examination, Brinell hardness surveys, Charpy impact tests and chemical analyses was made on two samples of 4 in. thick cast armor manufactured by the Pittsburgh Steel Foundry from different basic open hearthheats. Plate No. 68 failed the ballistic requirements due to poor steelmaking practice as revealed by segregation of Type II sulphide inclusions (eutectic type) and other complex nonmetallic inclusions in the primary austenite grain boundaries, thereby resulting in conchoidal patches in the fracture. Plate No. 60 passed the ballistic requirements although the heat from which this plate was cast had metallurgical properties which were not typical of the best quality basic open hearth steels.