SUBSTITUTION OF MANGANESE FOR NICKEL IN NI-CR-MO STEELS.
UNITED STATES STEEL CORP MONROEVILLE PA
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A laboratory study was initiated in which the manganese content of six Ni-Cr-Mo steels was increased from 0.5 to 3.0 and the nickel content was decreased from 4.5 to 0.5 to maintain a calculated hardenability index of 15 to 20. The evaluation consisted of hardenability, mechanical-property, and temperability studies on water-quenched and on blower-cooled 12-in.-thick plates of the six vacuum-melted, vacuum-carbondeoxidized Mn-Ni-Cr-Mo steels. The results showed that the hardenability of the highermanganese steels 1.0 to 3.0 Mn was less than that predicted from the calculations, and the notch toughness of the water-quenched and of the blower-cooled plates decreased continuously as the manganese content increased. Author