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CN-118932140-B - Molten steel cleanliness improving process for 20CrMnTi

CN118932140BCN 118932140 BCN118932140 BCN 118932140BCN-118932140-B

Abstract

The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a process for improving the cleanliness of molten steel of 20CrMnTi, which adopts carbon pre-deoxidation and carbon-containing ferrochrome deoxidation alloying during converter tapping to carry out refining slag modification in an LF furnace so as to reduce oxidized chromium elements and re-enter the molten steel. Compared with the traditional Al deoxidization process, the process can greatly reduce the Al consumption, thereby reducing the generation amount of alumina inclusions, further reducing the feeding amount of calcium wires and having good metallurgical effect.

Inventors

  • BAO YANPING
  • ZHANG XIAOHUA
  • YU FEI
  • LI HAOZHE
  • GAO FANG
  • ZHOU ZHIWEI
  • LI HAITAO
  • GU CHAO
  • LI LIKAI
  • SUN YUCHUN
  • WANG ERQING

Assignees

  • 北京科技大学
  • 常州东方特钢有限公司

Dates

Publication Date
20260512
Application Date
20240724

Claims (8)

  1. 1. The process for improving the cleanliness of the molten steel for 20CrMnTi is characterized in that carbon pre-deoxidation and carbon-containing ferrochrome deoxidation alloying are carried out in the converter tapping process, the traditional Al deoxidation process is replaced, refining slag modification is carried out in LF refining, so that oxidized chromium elements are reduced and re-enter the molten steel; The process comprises the following steps: S1, finishing converter smelting and oxygen determination; s2, tapping through a converter; S3, carbon pre-deoxidizing, namely adding carbon powder to pre-deoxidize molten steel in the tapping process, and starting to add when the tapping amount reaches 1/4; s4, deoxidizing and primarily alloying the carbon-containing ferrochrome, and adding the carbon-containing ferrochrome to deoxidize and alloy when the tapping amount reaches 1/2; S5, modifying the refining slag, namely adding a modifier into the ladle to reduce the oxidability of the refining slag to produce reducing white slag after the ladle enters an LF refining process, wherein the modifier is selected from calcium carbide, silicon carbide and aluminum particles; S6, LF secondary alloying; s7, carrying out micro-calcium treatment on molten steel, wherein the feeding amount of a calcium line is 0.35-0.6 m/t Steel and method for producing same ; s8, soft blowing.
  2. 2. The process for improving the cleanliness of molten steel for 20CrMnTi according to claim 1, wherein in the step S2, the tapping temperature is 1610-1650 ℃ and the tapping time is 3-4 min.
  3. 3. The process for improving the cleanliness of molten steel for 20CrMnTi according to claim 1, wherein in the step S3, the carbon powder is added in an amount of 0.70-0.95 kg/t Steel and method for producing same .
  4. 4. The process for improving the cleanliness of molten steel for 20CrMnTi according to claim 1, wherein in the step S4, when the carbon-containing ferrochrome is low-carbon ferrochrome, the addition amount of the low-carbon ferrochrome is 17.5-18.8 kg/t Steel and method for producing same , and when the carbon-containing ferrochrome is high-carbon ferrochrome and low-carbon ferrochrome, the addition amount of the low-carbon ferrochrome is 10-12 kg/t Steel and method for producing same , the addition amount of the high-carbon ferrochrome is 4-5 kg/t Steel and method for producing same , and carbon powder is 0.3-0.5 kg/t Steel and method for producing same .
  5. 5. The process for improving the cleanliness of molten steel for 20CrMnTi according to claim 1, wherein in the step S4, after deoxidizing and alloying, a slag former is added through a storage bin, the slag former is synthetic refining slag and lime, the addition amount of the synthetic refining slag is 5-6 kg/t Steel and method for producing same , and the addition amount of the lime is 2-3 kg/t Steel and method for producing same .
  6. 6. The process for improving the cleanliness of molten steel for 20CrMnTi according to claim 1, wherein in the step S5, the calcium carbide addition amount is 0.95-1.2 kg/t Steel and method for producing same , the silicon carbide addition amount is 0.6-0.85 kg/t Steel and method for producing same , the calcium carbide and silicon carbide addition amount is more than or equal to 1.8kg/t Steel and method for producing same , and aluminum particles of 0.23-0.35 kg/t Steel and method for producing same are paved on the slag surface.
  7. 7. The process for improving the cleanliness of molten steel for 20CrMnTi according to claim 1, wherein in the step S6, after the refining slag is made into the reducing white slag, the secondary alloying is performed by adding silicomanganese and ferrotitanium through an alloy bin.
  8. 8. The process for improving the cleanliness of molten steel for 20CrMnTi according to claim 1, wherein in said step S8, after feeding the calcium wire, the ladle is subjected to a soft blowing operation for at least 10 minutes before being hung up to continuous casting.

Description

Molten steel cleanliness improving process for 20CrMnTi Technical Field The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a molten steel cleanliness improving process for 20 CrMnTi. Background The 20CrMnTi gear steel is carburizing steel with good performance, higher hardenability, higher strength and toughness, particularly higher low-temperature impact toughness, good machinability, small special machining deformation, quite good fatigue resistance and good machinability after normalizing. For manufacturing important parts, such as gears, gear rings, gear shaft crosses, etc., which are subjected to high, medium or heavy loads, impacts and friction. At present, the deoxidizer mainly adopted in the smelting of the gear steel at home and abroad is aluminum particles, and the deoxidized product Al 2O3 produced by the deoxidizer has high inclusion melting point and low deformability, belongs to high-melting point non-deformable inclusions, is easy to gather at a water gap in the pouring process of a tundish, causes the water gap to be blocked due to nodulation, reduces the service life of the water gap and even affects the smooth production. In addition, in the subsequent rolling, due to the characteristic that the Al 2O3 inclusion is not easy to deform, the steel matrix is scratched, and the stress is easy to concentrate around the inclusion, so that gaps or cracks are formed, the material is damaged and broken in the using process, and the fatigue performance is reduced. Disclosure of Invention In order to solve the problems in the prior art, the main purpose of the invention is to provide a molten steel cleanliness improving process for 20 CrMnTi. In order to solve the technical problems, according to one aspect of the present invention, the following technical solutions are provided: A process for improving the cleanliness of molten steel of 20CrMnTi includes such steps as pre-deoxidizing carbon, deoxidizing and alloying carbon-contained ferrochrome, and refining in LF refining to make the oxidized Cr element reduced and reentered molten steel. As a preferable scheme of the molten steel cleanliness improving process for 20CrMnTi, the smelting process comprises the following steps: S1, finishing converter smelting and oxygen determination; s2, tapping through a converter; s3, carbon pre-deoxidation; s4, deoxidizing carbon-containing ferrochrome and performing primary alloying; s5, modifying refining slag; S6, LF secondary alloying; s7, treating micro calcium; s8, soft blowing. As a preferable scheme of the process for improving the cleanliness of the molten steel for the 20CrMnTi, in the step S1, an oxygen analyzer is adopted for oxygen determination before tapping of a converter. As a preferable scheme of the process for improving the cleanliness of the molten steel for 20CrMnTi, in the step S2, the tapping temperature is 1610-1650 ℃ and the tapping time is 3-4 min. In the step S3, carbon powder is added to pre-deoxidize the molten steel in the tapping process, carbon reacts with free oxygen in the molten steel to generate CO and then is separated from a molten steel system, and deoxidized products cannot pollute the molten steel. The carbon powder is added in an amount of 0.70-0.95 kg/t Steel and method for producing same , and the carbon powder is added when the tapping amount reaches 1/4. The preferable scheme of the molten steel cleanliness improving process for 20CrMnTi comprises the steps of starting adding carbon-containing ferrochrome to deoxidize and alloy when the tapping amount reaches 1/2 in the step S4, adding 17.5-18.8 kg/t Steel and method for producing same when the carbon-containing ferrochrome is low-carbon ferrochrome, adding 10-12 kg/t Steel and method for producing same when the carbon-containing ferrochrome is high-carbon ferrochrome and low-carbon ferrochrome, adding 4-5 kg/t Steel and method for producing same when the carbon-containing ferrochrome is low-carbon ferrochrome, and adding 0.3-0.5 kg/t Steel and method for producing same of carbon powder. The preferable scheme of the molten steel cleanliness improving process for 20CrMnTi comprises the following steps of adding a slag former through a feed bin after deoxidizing and alloying, wherein the slag former is synthetic refining slag and lime, the adding amount of the synthetic refining slag is 5-6 kg/t Steel and method for producing same , the adding amount of the lime is 2-3 kg/t Steel and method for producing same , the synthetic refining slag comprises 40-50wt% of CaO, 30-45wt% of Al 2O3, and more than or equal to 95wt% of CaO in the lime, the alkalinity of the final refining slag is 5-7, 50-60wt% of CaO, 25-35wt% of SiO 2：9～13wt％,Al2O3, 3-5wt% of MgO, and the sum (FeO+MnO) is less than or equal to 1wt%. The preferable scheme of the molten steel cleanliness improving process for 20CrMnTi comprises the steps that in the step S5, after a ladle enters an LF refining proce