Ultra-high strength steels with excellent cryogenic temp. toughness

A temperature range and tensile strength technology, applied in the production field of the steel plate, can solve problems such as hydrogen-induced cracking

Inactive Publication Date: 2001-01-31
EXXONMOBIL UPSTREAM RES CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Another problem encountered with standard commercial HSLA steels is hydrog

Method used

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  • Ultra-high strength steels with excellent cryogenic temp. toughness
  • Ultra-high strength steels with excellent cryogenic temp. toughness

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Embodiment Construction

[0018] The present invention relates to the development of a new type of HSLA steel satisfying the above requirements. The basis of the present invention is to produce intrinsic toughening and microstructure toughening through a new combination of chemical composition and treatment method of steel, thereby reducing DBTT and improving toughness under the condition of high tensile strength. Intrinsic toughening is achieved by a proper balance of important alloying elements in the steel, which is described in detail in this specification. The microstructure is toughened by obtaining a very small equivalent grain size and forming fine-grained martensite and / or lower bainite plates in small bundles with an average size much smaller than prior austenite grains article to achieve. In addition, in the present invention, the strength and toughness of the martensite / bainite microstructure during tempering can be achieved by utilizing fine copper precipitates and dispersion strengthenin...

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Abstract

An ultra-high strength, weldable, low alloy steel, containing less than 9 wt.% nickel, with excellent cryogenic temperature toughness in the base plate and in the heat affected zone (HAZ) when welded, having a tensile strength greater than 830 MPa (120 ksi) and a microstructure comprising predominantly fine-grained lath martensite and/or fine-grained lower bainite, is prepared by heating a steel slab comprising iron and some or all of the additives carbon, manganese, nickel, nitrogen, copper, chrominum, molybdenum, silicon, niobium, vanadium, titanium, aluminum, and boron; reducing the slab to form plate in one or more passes in a temperature range in which austenite recrystallizes; finish rolling the plate in one or more passes in a temperature range below the austenite recrystallization temperature and above the Ar3 transformation temperature; quenching the finish rolled plate (10''') to at a suitable Quench Stop temperature; stopping the quenching; and tempering the plate (10''') at a suitable temperature for a period of time sufficient to cause precipitation of hardening particles.

Description

field of invention [0001] The present invention relates to ultra high strength, weldable, low alloy steel plates having excellent low temperature toughness in both the base plate and the heat affected zone (HAZ) when welded. Furthermore, the present invention relates to a method for producing the steel sheet. 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] Frequently, it is desirable to store and transport pressurized volatile fluids at cryogenic temperatures, ie, temperatures below about -40°C (-40°F). For example, pressurized liquefied liquids need to be stored and transported at pressures ranging from about 1035 kPa (150 Psia) to 7590 kPa (1100 Psia) and at temperatures ranging from about -123°C (-190°F) to -62°C (-80°F). Containers for natural gas (PLNG). There is also a need for containers that safely and economically store and transport...

Claims

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Application Information

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IPC IPC(8): C21D1/19C21D6/02C21D8/02C22C38/00C22C38/04C22C38/06C22C38/08C22C38/12C22C38/14C22C38/16C22C38/58
CPCC22C38/14C21D6/02C21D2211/008C22C38/06C21D8/0226C22C38/12C22C38/04C22C38/16C22C38/08C22C38/001C21D2211/002C21D1/19C21D6/005C21D6/001
Inventor 具滋荣N-R·V·班加鲁
Owner EXXONMOBIL UPSTREAM RES CO
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