Ultra-high strength, weldable steels with excellent ultra-low temperature toughness

A technology of tensile strength and finish rolling temperature, applied in the field of weldable low-alloy pipeline steel and pipeline pipes, can solve the problems of not meeting the weldability requirements of pipeline pipes and lack of toughness of pipeline pipes.

Inactive Publication Date: 2000-09-06
EXXONMOBIL UPSTREAM RES CO +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although ultra-high-strength steels with yield strengths of 830 MPa (120 ksi) or higher have been produced, these steels generally lack the toughness necessary for line pipe and cannot meet the we

Method used

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  • Ultra-high strength, weldable steels with excellent ultra-low temperature toughness
  • Ultra-high strength, weldable steels with excellent ultra-low temperature toughness
  • Ultra-high strength, weldable steels with excellent ultra-low temperature toughness

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Embodiment Construction

[0058]According to one aspect of the invention, a steel slab is treated by heating the slab to a substantially uniform temperature at which substantially all of the carbides and carbonitrides of vanadium and niobium are sufficiently dissolved, said temperature Preferably about 1000-1250°C (1832-2282°F), and more preferably about 1050-1150°C (1922-2102°F); The slab is hot-rolled for the first time, wherein the reduction is preferably about 20-60% (thickness direction), so as to be rolled into a plate through one or more passes; in the second temperature range, one or more In the pass, the second hot rolling is carried out with a reduction of preferably about 40-80% (thickness direction), the second temperature range is slightly lower than the first temperature range, and austenite cannot occur at this time recrystallized, but more than Ar 3 High transition point; hardening of the rolled plate by quenching with a cooling rate of at least about 10°C / sec (18°F / sec), preferably at...

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Abstract

A steel plate having a tensile strength of at least about 930 MPa (135 ksi) and a toughness of at least about 120 Joules (88 ft-lbs) as determined by the Charpy V-notch impact test at -40°C (-40°F), and Its microstructure comprises at least about 90% by volume of a mixture of fine-grained lower bainite and fine-grained lath martensite, wherein at least about 2/3 of the mixture consists of particles having an average grain size of less than about 10 microns The composition of fine-grained lower bainite transformed from unrecrystallized austenite, and wherein the steel plate contains iron and specific weight percentages of added elements: carbon, silicon, manganese, copper, nickel, niobium, Titanium, aluminum, calcium, rare earth metals and magnesium, the preparation process of the steel is: heating a steel slab to an appropriate temperature; within the first temperature range where austenite can recrystallize, using one or more One hot rolling pass (10), the slab is rolled into a plate; in the second temperature range where austenite does not recrystallize, one or more hot rolling passes (10) are used to further roll the slab The plate; quenching the plate (12) to an appropriate quenching termination temperature (16); stopping the quenching and air cooling the plate (18) to room temperature.

Description

field of invention [0001] The invention relates to an ultra-high strength, weldable steel plate with good toughness, and a line pipe manufactured using the steel plate. More particularly, the present invention relates to a weldable low alloy pipeline steel having ultrahigh strength and high toughness, wherein the strength loss in the HAZ is minimized relative to the rest of the pipeline, and to a steel used as A production method of a steel plate for a pipe base material for a pipeline. Background of the invention [0002] A number of terms are defined in the description that follows. For convenience, a glossary is given directly in front of the claims. [0003] Currently, the highest yield strength line pipe in industrial applications has a yield strength of about 550 MPa (80 ksi). Higher strengths, eg up to about 690 MPa (100 ksi), are also commercially available, but to our knowledge, such steels have not been used commercially for pipelines. Additionally, as disclose...

Claims

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Application Information

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IPC IPC(8): C21D1/19C21D8/02C22C38/00C22C38/04C22C38/08C22C38/12C22C38/14C22C38/58
CPCC22C38/14C21D2211/008C21D8/0226C21D1/19C22C38/12C22C38/04C22C38/08C21D2211/002
Inventor 为广博朝日均原卓也寺田好男M·J·鲁汤J·考N-R·V·班加鲁C·W·彼特森
Owner EXXONMOBIL UPSTREAM RES CO
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