Abstract: A process for manufacturing high strength deep well casing, tubing, and drill pipes, which have improved resistance to stress corrosion cracking is disclosed. The process comprises the steps of preparing an alloy composition which is:______________________________________ C .ltoreq.0.05% Si .ltoreq.1.0% Mn .ltoreq.2.0% P .ltoreq.0.030% S .ltoreq.0.005% N 0-0.30% Ni 25-60% Cr 15-35% Mo 0-12% W 0-24% Cr (%) + 10Mo (%) + 5W (%) .gtoreq. 50% 1.5% .ltoreq. Mo (%) + 1/2W (%) .ltoreq. 12% Cu 0-2.0% Co 0-2.0% Rare Earths 0-0.10% Y 0-0.20% Mg 0-0.10% Ti 0-0.5% Ca 0-0.10% and incidental impurities balance; ______________________________________applying, after hot working, the solid solution treatment to the alloy at a temperature of from the lower limit temperature (.degree.C.) defined by the following empirical formula: 260 log C(%)+1300 to the upper limit temperature (.degree.C.

Abstract: An alloy useful for manufacturing high strength oil-well casing, tubing and drill pipes for use in oil-well operations is disclosed. The alloy exhibits improved resistance to stress corrosion cracking in the H.sub.2 S--CO.sub.2 --Cl.sup.- environment, which comprises the following alloy composition:______________________________________ C: .ltoreq. 0.1% Si: .ltoreq. 1.0% Mn: 3-20% P: .ltoreq. 0.030% S: .ltoreq. 0.005% N: 0-0.30% sol. Al .ltoreq. 0.5% Ni: 20-60% Cr: 15-35% Mo: 0-12% W: 0-24% Cr(%) + 10 Mo(%) + 5 W(%) .gtoreq. 50% 1/2 Mn(%) + Ni(%) .gtoreq. 25% 1.5% .ltoreq. Mo(%) + 1/2 W(%) .ltoreq. 12% Cu: 0-2.0% Co: 0-2.0% Rare Earths: 0-0.10% Y: 0-0.20% Mg: 0-0.10% Ti: 0-0.5% Ca: 0-0.10% Fe and incidental impurities: balance.

Abstract: An alloy useful for manufacturing high strength deep well casing, tubing and drill pipes for use in oil-well operations is disclosed. The alloy exhibits improved resistance to stress corrosion cracking in the H.sub.2 S--CO.sub.2 --Cl.sup.- environment, which comprises the following alloy composition:______________________________________ C: .ltoreq. 0.1% Si: .ltoreq. 1.0% Mn: .ltoreq. 2.0% P: .ltoreq. 0.030% S: .ltoreq. 0.005% N: 0-0.30% Ni: 25-60% Cr: 22.5-40% Mo: 0-3.5% (excl.) W: 0-7% (excl.) Cr (%) + 10Mo (%) + 5W (%) .gtoreq. 50%, 1.0% .ltoreq. Mo (%) + 1/2W (%) < 3.5% Cu: 0-2.0% Co: 0-2.0% Rare earths: 0-0.10% Y: 0-0.20% Mg: 0-0.10% Ca: 0-0.10% one or more of Nb, Ti, Ta, Zr and V in the total amount of 0.5-4.0, if necessary, Fe and incidental impurities: balance.

Abstract: An alloy useful for manufacturing high strength deep well casing, tubing and drill pipes for use in oil-well operations is disclosed. The alloy exhibits improved resistance to stress corrosion cracking in the H.sub.2 S-CO.sub.2 -Cl.sup.- environment, which comprises the following alloy composition:______________________________________ C: .ltoreq.0.1% Si: .ltoreq.1.0% Mn: .ltoreq.2.0% P: .ltoreq.0.030% S: .ltoreq.0.005% N: 0-0.30% Ni: 30-60% Cr: 15-35% Mo: 0-12% W: 0-24% Cr(%) + 10Mo(%) + 5W(%) .gtoreq. 110% 7.5% .ltoreq. Mo(%) + 1/2W(%) .ltoreq. 12% Cu: 0-2.0% Co: 0-2.0% rare earths: 0-0.10% Y: 0-0.20% Mg: 0-0.10% Ca: 0-0.10% one or more of Nb, Ti, Ta, Zr and V in the total amount of 0.5-4.0%, if necessary Fe and incidental impurities: balance.

Abstract: An alloy useful for manufacturing high strength deep well casing, tubing and drill pipes for use in oil-well operations is disclosed. The alloy exhibits improved resistance to stress corrosion cracking in the H.sub.2 S--CO.sub.2 --Cl.sup.- -environment, which comprises the following alloy composition:______________________________________ C: .ltoreq.0.1% Si: .ltoreq.1.0% Mn: .ltoreq.2.0% P: .ltoreq.0.030% S: .ltoreq.0.005% N: 0-0.30% Ni: 25-60% Cr: 22.5-35% Mo: 0-7.5% (excl.) W: 0-15% (excl.) Cr (%) + 10Mo (%) + 5W (%) .gtoreq. 70% 3.5% .ltoreq. Mo (%) + 1/2W (%) < 7.5% Cu: 0-2.0% Co: 0-2.0% Rare earths: 0-0.10% Y: 0-0.20% Mg: 0-0.10% Ca: 0-0.10% ______________________________________one or more of Nb, Ti, Ta, Zr and V in the total amount of 0.5-4.0%, if necessary,Fe and incidental impurities: balance.

Abstract: A method of producing a tube with an ultra-high tensile strength over 255 kg/mm.sup.2 and remarkably improved ductility and toughness is provided, which comprises preparing a mother tube through hot extrusion of a steel consisting essentially of 15.0 - 18.5% by weight of Ni, 12.5 - 15.0% by weight of Co, 5.0 - 6.9% by weight of Mo, 1.00 - 1.28% by weight of Ti, 0.01 - 0.20% by weight of Al and the balance essentially iron, cold working the mother tube with a reduction in wall thickness of 5 - 25%, then raising the temperature of the resulting tube to a temperature of 800 - 950.degree. C in a period of from 20 minutes to 2 hours and maintaining the heated tube at this temperature for from 30 minutes to 3 hours, and, after cooling to or below room temperature, ageing the cooled tube at a temperature of 450.degree. - 550.degree. C for 1 - 10 hours.