Ultra high strength steel having good toughness

摘要

Embodiments of the present disclosure comprise carbon steels and methods of manufacture. In one embodiment, a double austenizing procedure is disclosed in which a selected steel composition is formed and subjected to heat treatment to refine the steel microstructure. In one embodiment, the heat treatment may comprise austenizing and quenching the formed steel composition a selected number of times (e.g., 2) prior to tempering. In another embodiment, the heat treatment may comprise subjecting the formed steel composition to austenizing, quenching, and tempering a selected number of times (e.g., 2). Steel products formed from embodiments of the steel composition in this manner (e.g., seamless tubular bars and pipes) will possess high yield strength, at least about 175 ksi (about 1200 MPa) while maintaining good toughness.

主权项

1. A steel tube, comprising:
about 0.25 wt. % to about 0.35 wt. % carbon; about 0.30 wt. % to about 0.70 wt. % manganese; about 0.10 wt. % to about 0.30 wt. % silicon; about 0.90 wt. % to about 1.70 wt. % chromium; about 0.60 wt. % to about 1.00 wt. % molybdenum; about 0.050 wt. % to about 0.150 wt. % vanadium; about 0 wt. % to about 0.15 wt % copper and about 0.01 wt. % to about 0.04 wt. % aluminum; the remainder of the composition comprising iron and impurities; wherein the steel tube is processed to have a yield strength greater than about 175 ksi and wherein a Charpy V-notch energy is greater or equal to about 50 J/cm2 in a transverse direction and 65 J/cm2 in a longitudinal direction at about room temperature.