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Method for precisely controlling nitrogen content in nitrogen-containing steel smelting in vacuum induction furnace

A vacuum induction furnace and precise control technology, applied in the field of steelmaking and smelting, can solve the problems of difficult precise control of composition, difficult control of nitrogen increase, unstable nitrogen yield, etc., to achieve stable smelting and precise control of nitrogen content in molten steel , Nitriding rate stabilization effect

Active Publication Date: 2016-07-20
HEBEI IRON AND STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Vacuum argon filling and nitrogen alloy, the nitrogen recovery rate is unstable, and the amount of nitrogen increase is not easy to control; after nitrogen filling, nitrogen alloy is added for alloying, and the nitrogen content of liquid steel is affected by the two effects of gas phase nitriding and nitrogen alloy nitrogen increase. The composition is not easy to control accurately; and both methods require the use of more expensive nitrided alloys, which increases the cost of steelmaking

Method used

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  • Method for precisely controlling nitrogen content in nitrogen-containing steel smelting in vacuum induction furnace
  • Method for precisely controlling nitrogen content in nitrogen-containing steel smelting in vacuum induction furnace
  • Method for precisely controlling nitrogen content in nitrogen-containing steel smelting in vacuum induction furnace

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Embodiment 1

[0025] The equipment adopts a 500kg vacuum induction furnace with an ultimate vacuum of 6.67×10 -2 , Smelting 00Cr13Ni5Mo stainless steel. Charge 480kg, vacuumize to 10Pa and start power supply heating. After melting, control the temperature at 1550°C and keep it warm. Fill it with argon to 30000Pa and carry out alloying. After alloying, vacuumize to 100Pa, and then fill it with nitrogen to Keep it for 30 minutes for vapor phase nitriding alloying, then fill it with nitrogen gas again, raise the pressure in the furnace to 31000Pa and then pour it. The composition requirements of 00Cr13Ni5Mo stainless steel and the composition of smelted products are shown in Table 1.

[0026] Table 100Cr13Ni5Mo stainless steel composition requirements and smelting finished product composition (wt%)

[0027]

Embodiment 2

[0029] The equipment adopts a 100kg vacuum induction furnace with an ultimate vacuum of 6.67×10 -2 , smelting electrical pure iron. Charge 100kg, vacuumize to 10Pa, start power supply heating, control temperature 1650°C after melting, and carry out alloying after filling argon to 5000Pa, vacuumize to 10Pa after alloying, and then fill with nitrogen to Keep for 5 minutes for vapor phase nitriding alloying, then fill with nitrogen again, raise the pressure in the furnace to 11200Pa and then pour. The composition requirements of electrical pure iron and the composition of smelted products are shown in Table 2.

[0030] Table 2 Requirements for the composition of electrical pure iron and the composition of smelted products (wt%)

[0031]

Embodiment 3

[0033] The equipment adopts a 50kg vacuum induction furnace with an ultimate vacuum of 6.67×10 -2 , Smelting vanadium nitrogen steel. Charge 45kg, vacuumize to 8Pa, start power supply heating, control temperature 1600°C after melting, fill with argon to 10000Pa and carry out alloying, after alloying, vacuumize to 8Pa, then fill with nitrogen to Keep for 25 minutes for vapor phase nitriding alloying, then fill with nitrogen again, raise the pressure in the furnace to 60000Pa and then pour. The composition requirements of vanadium nitrogen steel and the composition of smelted products are shown in Table 3.

[0034] Table 3 Composition requirements of vanadium nitrogen steel and composition of smelted products (wt%)

[0035]

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Abstract

The invention discloses a method for precisely controlling the nitrogen content in nitrogen-containing steel smelting in a vacuum induction furnace. The method comprises the following steps that an iron and steel stock of which the surface is clean is placed into a crucible of the vacuum induction furnace, and power is supplied for heating when the vacuum induction furnace is vacuumized to be below 10 Pa; after the iron and steel stock is molten down completely, the temperature is raised to 1550-1650 DEG C, and then heat preservation is performed; vacuumizing is stopped, and then argon is introduced in for alloying; after contents of other alloy elements except nitrogen reach target values, and the vacuum degree is smaller than or equal to 100Pa, nitrogen is introduced into the furnace; after the pressure of nitrogen in the furnace reaches a preset value, inflation is stopped, and nitrogen alloying is performed in a nitrogen atmosphere in the furnace by maintaining a certain gas nitriding time period; after nitrogen alloying is finished, the temperature of molten steel is adjusted; and nitrogen is introduced in the furnace again, and after the pressure in the furnace is increased to 10000-20000 Pa, pouring is performed, so that an ingot casting which is precise in content and compact and uniform in inner part is obtained. The method is applicable to smelting of steel types of which the nitrogen content is 0.005%-0.05%; by utilizing the method, the nitrogen content in steel can be precisely controlled in a range of a target value + / -5PPm; and the molten steel is high in cleanness, and the ingot casting is compact and uniform.

Description

technical field [0001] The invention belongs to the technical field of steelmaking and smelting, and in particular relates to a method for precisely controlling nitrogen content in smelting nitrogen-containing steel in a vacuum induction furnace. Background technique [0002] Nitrogen is one of the permanent elements of steel, which is usually related to various brittle fractures of steel, but nitrogen also has many beneficial effects in steel. Nitrogen has the effects of solid solution strengthening and grain refinement, which can not only increase the strength of steel, improve wear resistance, but also improve its corrosion resistance, so stainless steel, oriented silicon steel, micro-alloyed steel and some non-quenched and tempered steel Need to add a small amount of nitrogen to improve its steel properties. For this reason, it is necessary to carry out nitrogen alloying and nitrogen addition to molten steel when nitrogen-containing steel is smelted. Since the high vac...

Claims

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Application Information

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IPC IPC(8): C21C5/52C21C7/10C22C33/04
CPCC21C5/5241C21C7/10C22C33/04
Inventor 李博斌翟永臻高宇董廷亮窦磊王海明
Owner HEBEI IRON AND STEEL
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