Tenaris Connections Limited

Andrea Di Schino

Ettore Anelli

Alfonso Izquierdo Garcia

Héctor Manuel Quintanilla Carmona

Marco Mario Tivelli

Hector Manuel Quintanilla Carmona

A low-alloy steel containing, by weight percent, C 0.03-0.13%, Mn 0.90-1.80%, Si&#x2266;0.40%, P&#x2266;0.020%, S&#x2266;0.005%, Ni 0.10-1.00%, Cr 0.20-1.20%, Mo 0.15-0.80%, Ca&#x2266;0.040%, V&#x2266;0.10%, Nb&#x2266;0.040%, Ti&#x2266;0.020% and N&#x2266;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&#x2266;0.40%, P&#x2266;0.020%, S&#x2266;0.005%, Ni 0.10-1.00%, Cr 0.20-1.20%, Mo 0.15-0.80%, Ca&#x2266;0.040%, V&#x2266;&#x2266;0.10%, Nb&#x2266;0.040%, Ti&#x2266;0.020% and N&#x2266;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).

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Bergamo, Italy

Andrea Di Schino