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US 2020/0370152 A1Published application
Ultra-fine grained steels having corrosion-fatigue resistance
AssigneeTenaris Connections Limited
InventorsMartin Bühler, Matias Gustavo Pereyra
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Abstract
Embodiments of an ultra-fine-grained, medium carbon steel are disclosed herein. In some embodiments, the ultra-fine grained steel can have high corrosion fatigue resistance, as well as high toughness and yield strength. The ultra-fine grained steels can be advantageous for use as sucker rods in oil wells having corrosive environments.
Claims20
A method of manufacturing a steel sucker rod, the method comprising:
- providing a steel composition comprising iron and:
- 0.15-0.4 wt. % carbon;
- 0.1-1.0 wt. % manganese;
- 0.5-1.5 wt. % chromium;
- 0.2-0.35 wt. % silicon;
- 0.1-1.0 wt. % molybdenum;
- 0.01-0.05 wt. % niobium;
- 0.005-0.03 wt. % titanium;
- 0.0001 to 0.0025 wt. % boron;
- 0.01 to 0.1 wt. % aluminum;
- hot rolling the steel composition at a forging ratio greater than about 15;
- austenitizing the hot rolled steel composition at a temperature between the critical temperature (Ac3) and a maximum temperature that satisfies the formula T max=1025° C.-210° C.*sqrt(wt % C)+50° C.*wt % Mo;
- quenching the steel composition below about 100° C. at a rate to produce a martensitic microstructure;
- and
- tempering at a temperature between 565° C. and a lower critical temperature (Ac1) to form tempered martensite;
- wherein a time between a maximum austenitizing and quenching is between 1 second and 10 seconds;
- and
- wherein an austenitic grain size prior to quenching is 5 microns or less.
15 more elements
A steel sucker rod formed from a steel composition comprising iron and, by weight:
- 0.15-0.4% carbon;
- 0.1-1.0% manganese;
- 0.5-1.5% chromium;
- 0.01-0.1% aluminum;
- 0.2-0.35% silicon;
- 0.1-1.0% molybdenum;
- 0.01-0.05% niobium;
- 0.005-0.03% titanium;
- and
- 0.0001-0.005% boron;
- wherein the steel has a final microstructure comprising tempered martensite;
- and
- wherein an average grain size of the final microstructure is between about 2 and about 5 micrometers.
10 more elements
A steel formed from a steel composition comprising iron and, by weight:
- 0.15-0.4% carbon;
- 0.1-1.0% manganese;
- 0.5-1.5% chromium;
- 0.01-0.1% aluminum;
- 0.2-0.35% silicon;
- 0.1-1.0% molybdenum;
- 0.01-0.05% niobium;
- 0.005-0.03% titanium;
- and
- 0.0001-0.0025% boron;
- wherein the steel has a final microstructure comprising tempered martensite;
- and
- wherein an average grain size of the final microstructure is between about 2 and about 5 micrometers.
10 more elements
Dependencies are inferred from the claim text.