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

A technology of austenite and austenite grains, applied in the production field of this 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 hydrogen induced cracking at the HAZ, especially when welding with low heat input

Method used

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

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Embodiment Construction

[0030] 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. Toughening of the microstructure is achieved by obtaining a very small equivalent grain size and promoting the formation of a microlamellar structure. refer to Figure 2B, The microlamellar structure of the steel according to the invention is preferably composed of laths 28 dominated by fine-grained lower bainite or fine-grained martensite alternately with austenite thin film layers 30 . Preferably, the average thickness of the austenitic film...

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Abstract

An ultra-high strength, weldable, low alloy steel with excellent cryogenic temperature toughness in the base plate and in the heat affected zone (HAZE) when welded, having a tensile strength greater than 830 MAP (120 KS) and a micro-laminate microstructure comprising austenite film layers and fine-grained marten site/lower bainite laths, is prepared by heating a steel slab comprising iron and specified weight percentages of some or all of the additives carbon, manganese, nickel, nitrogen, copper, chromium, 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 to a suitable Quench Stop Temperature (QST); stopping the quenching; and either, for a period of time, holding the plate substantially isothermally at the QST or slow-cooling the plate before air cooling, or simply air cooling the plate to ambient temperature.

Description

field of invention [0001] The present invention relates to ultra-high strength, weldable, low alloy steel plates with excellent low temperature toughness both in the parent plate and in the heat affected zone (HAZ) during welding. Furthermore, the present invention relates to a production method of 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 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 ot...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/19C21D8/04C21D1/20C21D6/00C21D8/00C21D8/02C22C38/00C22C38/04C22C38/08C22C38/12C22C38/14C22C38/16
CPCC22C38/14C21D2211/008C21D8/0226C21D1/20C21D1/19C22C38/12C22C38/04C22C38/08C22C38/16C21D2211/001C21D6/001C21D2211/002C21D8/0263
Inventor 具滋荣N-R·V·班加鲁G·A·沃根
Owner EXXONMOBIL UPSTREAM RES CO
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