Cr-Mo ASTM A387 Gr22CL2 pressure vessel steel and production method thereof

Abstract

The invention provides a limit-thickness Cr-Mo ASTM A387 Gr22CL2 pressure vessel steel and a production method thereof. The Cr-Mo ASTM A387 Gr22CL2 pressure vessel steel comprises the following chemical components in percentage by mass: 0.08-0.16 wt% of C, 0.20-0.50 wt% of Si, 0.30-0.60 wt% of Mn, at most 0.015 wt% of P, at most 0.005 wt% of S, 0.020-0.060 wt% of Als, 2.0-2.5 wt% of Cr, 0.9-1.1 wt% of Mo and the balance of Fe and residual element. The production method comprises the following steps: pretreatment of high-quality molten iron and KR molten iron, 120t top / bottom blown converter, argon blowing by Ar station, LF (ladle furnace) refining, VD (vacuum degasser) vacuum degassing, water-cooled die casting, dead soaking pit heating, 3800mm rolling mill, ACC laminar cooling, straightening, cooling in pile, heat treatment, finishing, outer inspection, flaw detection and warehousing. The steel plate is cast by a 48t water-cooled ingot die, so the cooling and solidifying time is shortened by 1 / 3 as compared with the conventional foundry ingot die, the defect of severe loosening or segregation at the center of the steel ingot is reduced or avoided, and the internal quality of the steel plate is improved.

Description

technical field [0001] The invention belongs to the technical field of production of wide and thick steel plates, and in particular relates to a Cr-Mo ASTM A387 Gr22CL2 pressure vessel steel with a thickness of 120-150 mm and a production method thereof. Background technique [0002] ASTM A387 Gr22CL2 belongs to the pressure vessel steel in American Standard ASTM A387 / A387M-06a. It is widely used in petroleum, chemical industry, nuclear power plant, boiler and other industries, and is used to make reactors, heat exchangers, boiler drums, nuclear reactor pressure shells, and hydropower plants. High-pressure water pipes, turbine volute and other equipment components. It is required to have good mechanical properties, good process performance, good corrosion resistance and oxidation resistance. [0003] At present, traditional production adopts mold casting and pouring. Patent CN102080187A discloses a method for producing 12Cr2Mo1R container steel using 33t flat ingots. Howeve...

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Problems solved by technology

[0003] At present, traditional production adopts mold casting and pouring. Patent CN102080187A discloses a method for producing 12Cr2Mo1R container steel using 33t flat ingots. However, conventional ingot molds are used for production, and the molten steel is naturally and slowly cooled after pouring, especially in the middle and late stages of solidification. After absorbing a large amount of heat, it relies on the conduction between the ingot mold and the air to dissipate heat outward, and the heat dissipation speed is extremely slow, which tends to be consistent with the heat dissipation speed of the molten steel at the cap mouth, which is not conducive to forming a "bell mouth" feeding in the center of the steel ingot. channel, the narrow and long liquid phase cavity affects the feeding effect of the center of the ingot body

At the same time, due to the prolongation of solidification time, the separation crystallization and composition segregation inside the steel ingot are intensified, and the central looseness and shrinkage cavity phenomenon in conventional casting production cannot be avoided, and the internal quality is difficult to guarantee.

[0004] Produced with conventional ingot molds, the average number of uses of each set of conventional ingot molds is about 60 times (the maximum is no more than 80 times), and the ingot molds will be scrapped due to cracks on the inner wall of the mold, and the cost of using ingot molds is relatively high; and conventional scale casting The loose defect of the ingot extends to the body part of the lower part of the cap mouth, and may even extend to the middle part of the body. In order to ensure the quality of the steel plate, the part of the steel ingot body near the cap mouth also needs to be cut off. The yield rate is low, which directly leads to an increase in production costs.

[0005] After the pouring is completed, the conventional ingot mold relies on heat dissipation for natural cooling, the production cycle is long, and it is difficult to meet the demand for product delivery

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