The Effects of Low-Temperature Tempering on the Properties of 0.25 Percent Carbon Ni-Cr-Mo Steels

摘要

Five selected steels (3Ni-Cr-Mo-Cb, 3Ni-Cr-Mo, 5Ni-Cr-Mo, and two 5Ni-Cr-Mo-V steels) containing 0.22 to 0.27 percent carbon were evaluated after tempering at appropriate temperatures to determine their suitability as HY-180/210 steels. The results indicated generally that the five steels had adequate hardenability for 4-inch-thick plates and that yield strengths of about 185 ksi were attained at a carbon content of 0.25 percent carbon when the steels were tempered at temperatures in the range 400 to 1000 F. In addition, none of the steels was significantly embrittled by tempering. At a yield strength of 185 ksi, none of the steels met the tentative minimum toughness (50 ft-lb at 0 F) for an HY-180/210 base metal. However, the 3Ni-Cr-MoCb steel and the 0.22C 5Ni-Cr-Mo-V steel appear capable of meeting the toughness requirement at a yield strength of about 182 ksi in 1/2-inch-thick plates and of about 175 ksi in 4-inch-thick plates. (Author)