Method for producing high-strength welded joint for cryogenic environments
A welding joint and manufacturing method technology, applied in the field of manufacturing high-strength welded joints, can solve the problems of low tensile strength, poor weldability, unfavorable economy, etc., and achieve the effect of excellent impact toughness at extremely low temperature
Pending Publication Date: 2021-11-09
JFE STEEL CORP +1
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Problems solved by technology
However, aluminum alloys have problems in that the thickness of the structure needs to be designed to be large due to the low tensile strength, and the weldability is poor.
In addition, 9% Ni steel requires the use of expensive Ni-based materials as welding materials, so it is economically unfavorable
In addition, austenitic stainless steel has the problem of being expensive and having low base material strength
Method used
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Embodiment
[0109] Molten steel was smelted in a vacuum melting furnace, cast into a mold, and then billet-rolled to produce a slab (wall thickness: 150 mm) with the composition (steel composition) shown in Table 1 to obtain a billet. Next, the obtained billet material is loaded into a heating furnace, heated to 1250° C., and after hot rolling at a finishing temperature of 850° C., immediately, water cooling treatment is carried out to obtain a steel plate with a thickness of 12 mm (high Mn content steel material ).
[0110] In addition, molten steel having the composition (wire rod composition) shown in Table 2 was melted in a vacuum melting furnace and cast to obtain a steel ingot. The obtained steel ingot was heated to 1200 degreeC in the heating furnace, and it hot-rolled, and the bar-shaped steel billet material was obtained. The obtained bar-shaped billet material was further subjected to multiple cold rolling through annealing to obtain a solid wire for welding (1.2 mmφ).
[0111...
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Abstract
The present invention provides a method for producing a welded joint for cryogenic welded steel structures. In the production method, cryogenic high-strength high-Mn steel materials having a predetermined steel composition are welded using a solid wire having a predetermined wire composition, for example, preferably using gas metal arc welding to form a multi-layer weld metal portion. Welding conditions are adjusted such that the weld aspect ratio (dilution ratio) of the steel material in the first layer weld metal is in the range of 35-60%. The solid wire used has a wire composition having Mn and Cr contents lower than the Mn and Cr contents contained in the steel material used. Accordingly, a welded joint that has a weld metal portion having high strength and excellent cryogenic impact toughness can be easily produced.
Description
technical field [0001] The present invention relates to a welded steel structure made of high Mn content steel used in an extremely low temperature environment, such as a tank body for a liquefied gas storage tank, and particularly relates to a high-strength welded metal part having excellent extremely low temperature impact toughness Method of manufacture of strength welded joints. Background technique [0002] In recent years, environmental regulations have become increasingly stringent. Liquefied natural gas (hereinafter also referred to as LNG) is known as a clean fuel that does not generate air pollutants such as sulfide oxides because it does not contain sulfur, and its demand is increasing. For transportation or storage of LNG, containers (tanks) for transportation or storage of LNG are required to maintain excellent cryogenic impact toughness at the liquefaction temperature of LNG, that is, -162° C. or lower. [0003] Since it is necessary to maintain excellent low...
Claims
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IPC IPC(8): B23K35/30B23K9/23C22C38/00C22C38/38
CPCB23K35/30C22C38/00C22C38/38B23K9/23B23K35/3073
Inventor 仲道治郎石田伦教高田充志高山直树植田圭治山下贤韩鹏
Owner JFE STEEL CORP