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Pouring method for large-scale vacuum steel ingot

A pouring method, vacuum steel technology, applied in the field of steel ingot pouring, can solve the problems of poor flow of molten steel, failure to achieve trickle pouring, low pass rate of forgings, etc., and achieve the effect of improving the purity of molten steel

Active Publication Date: 2020-08-14
SHANGHAI ELECTRIC SHMP CASTING & FORGING CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem that in the pouring process of the existing large-scale vacuum steel ingot process, the molten steel flow is poor, and the effect of trickle pouring cannot be achieved, resulting in excessive defect equivalents and relatively low pass rate of forgings

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  • Pouring method for large-scale vacuum steel ingot

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Embodiment 1

[0026] Refer to attached figure 1 , a pouring method for a large vacuum steel ingot in this embodiment, nitrogen blowing at the bottom of the ladle is used before the end of refining. Then break the vacuum. In the large-scale vacuum steel ingot manufactured by the manufacturing method of the present invention, the purity of molten steel is greatly improved, the content of C-type inclusions is reduced from 1-1.5 levels in the past to 0.5-1 level, and the contents of other types of inclusions are reduced from 0.5-1 level to 0-0. 0.5 level, some plate products, the pass rate of flaw detection has increased from less than 70% in the past to more than 95%.

[0027] Specifically include the following steps:

[0028] S100, pre-blowing nitrogen, using nitrogen blowing at the bottom of the ladle before refining;

[0029] S200, pouring, argon blowing is carried out through the nozzle or stopper during the pouring process, and the initial pressure of argon blowing is greater than 0.6M...

Embodiment 2

[0038] The steel grade SA508Gr.3Cl.1 of this embodiment has an ingot size of 300t and is hydrated with 3 packs of steel. The nitrogen content of the product is required to be controlled at 90-120ppm, and the target value is 105ppm. After vacuum treatment in the refining furnace, nitrogen is blown at the bottom, the nitrogen blowing flow rate is 200L / min, and the nitrogen blowing time is 25min. Samples are taken before pouring. The nitrogen content of 3 bags of molten steel is: 208, 215, 212ppm.

[0039] When pouring, the vacuum degree is 40Pa. When pouring starts, the argon pressure is 1.0Mpa, and the injection speed is controlled at 3t / min. After 2 minutes, the argon pressure is reduced to 0.2Mpa, and the pouring is at full speed. The whole pouring process is well diffused and the molten steel It drips into the ingot mold in the form of drizzle.

[0040] After the molten steel is poured to the target position of the riser, the nozzle is closed, the vacuum is broken, and the ...

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Abstract

Provided is a pouring method for a large-scale vacuum steel ingot. Nitrogen is blown at the bottom of a steel ladle before refining is finished, after nitrogen blowing is finished, the temperature iscontrolled to be 30-40 DEG C higher than the pouring temperature, steel tapping is performed to be prepared for pouring, and vacuum is damaged after pouring is finished. According to the large-scale vacuum steel ingot manufactured by the manufacturing method, the purity of molten steel is greatly improved, the content of C-type inclusions is reduced to 0.5-1 grade from 1-1.5 grade in the past, thecontent of other types of inclusions is reduced to 0-0.5 grade from 0.5-1 grade, and the qualification rate of flaw detection of partial plate products is improved to more than 95% from less than 70%in the past.

Description

technical field [0001] The invention belongs to the technical field of pouring steel ingots, in particular to a pouring method for large vacuum steel ingots. Background technique [0002] For some large vacuum steel ingots, due to their limited composition (need to add Si, Al, etc.), the vacuum carbon deoxidation (VCD) casting process cannot be used, and the vacuum dripping (MSD) casting process is usually used. Poor, can not achieve the effect of trickle pouring, even if the plug rod or slide argon blowing technology is used, the steel flow droplets are relatively large, in the form of flakes, and the effect of degassing and removing inclusions is not obvious. Moreover, due to equipment limitations, the intensity of argon blowing is often not very high, especially in the later stage of pouring, and the diffused flow effect is even worse. Seriously affect the purity of such large steel ingots, especially after forging with a large forging ratio, the C-type and Ds-type inclu...

Claims

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Application Information

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IPC IPC(8): C21C7/072B22D7/00B22D27/04
CPCC21C7/072B22D7/00B22D27/04
Inventor 杨海石王志刚朱伟伟高峰王紫林乔麟淞
Owner SHANGHAI ELECTRIC SHMP CASTING & FORGING CO LTD
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