Abstract: Nickel-base precipitation hardenable alloys with enhanced hydrogen embrittlement resistance and desired yield strength have critical ranges of titanium and iron, among other elements. One of the nickel-base precipitation hardenable alloys has a composition, in wt.%, of Cr from about 18.0% to about 23.0%, Fe from about 7.0% to about 12.0%, Mo from about 6.5% to about 9.5%, Nb from about 3.2% to about 5.2%, Ti from about 0.3% to about 1.3%, Al up to about 0.4%, with a balance of Ni and incidental impurities. This alloy has a yield strength (0.2% offset) greater than or equal to 120 ksi (827 MPa), a plastic strain ratio greater than or equal to 0.35, and a plastic strain to failure greater than or equal to 9.0%.

Abstract: An ultra-high strength, high toughness alloy steel comprising, by weight, 0.24% to 0.32% carbon, 1.0% manganese or less, 0.45% silicon or less, 1.60% to 1.85% chromium, 2.5% to 3.1% nickel, 0.40% to 0.65% molybdenum, and 0.025% to 0.05% vanadium, the balance being iron and unavoidable impurities; or 0.23% to 0.28% carbon, 1.0% manganese or less, 0.45% silicon or less, 2.05% to 2.4% chromium, 0.35% or less nickel, 0.85% to 1.15% molybdenum, and 0.03% or less vanadium, the balance being iron and unavoidable impurities; or 0.27% to 0.32% carbon, 1.0% manganese or less, 0.45% silicon or less, 0.7% to 1.0% chromium, 0.7% to 1.0% nickel, 0.7% to 1.0% molybdenum, 0.05% or less vanadium, and 0.05% or less niobium, the balance being iron and unavoidable impurities.