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AssigneeTenaris Connections Limited
InventorsAlfonso Izquierdo Garcia, Héctor Manuel Quintanilla Carmona, Marco Mario Tivelli, Ettore Anelli, Andrea Di Schino
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A low-alloy steel containing, by weight percent, C 0.03-0.13%, Mn 0.90-1.80%, Si≦0.40%, P≦0.020%, S≦0.005%, Ni 0.10-1.00%, Cr 0.20-1.20%, Mo 0.15-0.80%, Ca≦0.040%, V≦0.10%, Nb≦0.040%, Ti≦0.020% and N≦0.011% for making high-strength, weldable steel seamless pipe, characterized in that the microstructure of the alloy steel is a mixture of bainite and martensite and the yield stress is at least 621 MPa (90 Ksi). It is a second object of the present invention to provide a high-strength, weldable steel seamless pipe, comprising an alloy steel containing, by weight percent, C 0.03-0.13%, Mn 0.90-1.80%, Si≦0.40%, P≦0.020%, S≦0.005%, Ni 0.10-1.00%, Cr 0.20-1.20%, Mo 0.15-0.80%, Ca≦0.040%, V≦≦0.10%, Nb≦0.040%, Ti≦0.020% and N≦0.011% also characterized in that the microstructure of the alloy steel is predominantly martensite and the yield stress is at least 690 MPa (100 ksi).
A weldable high strength seamless pipe comprising an alloy steel containing, by weight percent,
A method for producing a weldable high-strength seamless pipe, comprising:
An alloy steel comprising, by weight percent, C 0.07-0.13% Mn 0.90-1.40% Si <0.40% P <0.020% S <0.005% Ni 0.15-0.50% Cr 0.25-0.60% Mo 0.27-0.60% Ca <0.035% V <0.09% Nb <0.030Ti <0.012% N <0.011% the balance being Fe and incidental impurities, wherein the microstructure of the steel is more than 60% martensite and wherein the yield stress is greater than 750 MPa, and wherein the mean subgrain size is smaller than 1.1 μm and wherein the packet size is smaller that 3 μm, and wherein the 50% fracture appearance transition temperature (FATT) is <-80° C. as measured in accordance with ASTM E23.
Dependencies are inferred from the claim text.