EFFECTS OF COMPOSITION VARIATIONS ON THE PROPERTIES OF 5NI-CR-MO-V STEEL.
UNITED STATES STEEL CORP MONROEVILLE PA
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Four composition modifications of a 0.10 percent carbon 5Ni-Cr-Mo-V steel and three modifications of a 0.15 percent carbon 5Ni-Cr-Mo-V steel were investigated. Among the 0.10 percent carbon steels, the standard 5NiCr-Mo-V steel and a 0.9 Mn, 0.04 Si modification exhibited the best combination of yield strength 140 to 150 ksi and notch toughness 80 to 120 ft-lb at 0 F. Severe embrittlement occurred when the chromium content was increased to 1.25 percent and a general loss in toughness resulted when aluminum was eliminated. Increasing the carbon content of the 5Ni-Cr-Mo-V steel from 0.10 percent to 0.15 percent increased the yield strength after appropriate tempering from the 130150 ksi range to the 150165 ksi range, but decreased the notch toughness at 0 F to the 50 to 90 ft-lb range. At the higher carbon content, the notch toughness was somewhat improved when the manganese and silicon contents were reduced. The results indicate that the standard 0.10 percent carbon 5Ni-Cr-Mo-V steel has the best composition for a steel capable of developing a yield strength of 140 to 150 ksi and exceptional notch toughness. A 0.15 percent carbon 5Ni-Cr-Mo-V steel also exhibits good notch toughness at yield strrengths of 150 to 165 ksi. Author