Patent ID: 8007603
Filing Date: 2011-08-30
Classification: C21D,C22C

Abstract:
1. A weldable high strength seamless pipe comprising an alloy steel containing, 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% Mo >0.27% Ca <0.035% V <0.09% Nb <0.030% Ti <0.009% N <0.011% the balance being Fe and incidental impurities, wherein the microstructure of the steel is more than 30% martensite and wherein the yield stress is greater than 690 MPa, and wherein the mean subgrain size is smaller than 1.5 μm and wherein the packet size is smaller than 4.8 μm, and wherein the 50% fracture appearance transition temperature (FATT) is <−30° C as measured in accordance with ASTM E23.