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CN-121992284-A - 40Cr steel smelting process based on synergistic effect of C deoxidation and rare earth

CN121992284ACN 121992284 ACN121992284 ACN 121992284ACN-121992284-A

Abstract

The invention discloses a 40Cr steel smelting process based on the synergistic effect of C deoxidation and rare earth, which comprises the following steps of S1, oxygen determination after converter smelting, S2, converter tapping, S3, carbon pre-deoxidation, S4, refining slag modification, S5, rare earth deoxidation and S6, secondary alloying. Aiming at the deoxidization alloy adopted in the smelting process of 40Cr steel in the traditional industry and the existing deoxidization method adopting carbon powder for deoxidization, the invention provides a method combining the clean deoxidization capability of carbon powder for deoxidization and the deep deoxidization capability of rare earth.

Inventors

  • QU ZHIBO
  • LU BIN
  • MA XIAOGUANG
  • ZHANG HUAIJUN
  • Diao Wangcai
  • HAN CHUNPENG
  • ZHANG YIN
  • CHEN JIANXIN

Assignees

  • 内蒙古包钢钢联股份有限公司

Dates

Publication Date
20260508
Application Date
20260306

Claims (7)

  1. 1. A40 Cr steel smelting process based on the synergistic effect of C deoxidation and rare earth is characterized by comprising the following steps: S1, finishing converter smelting and oxygen determination; S2, tapping through a converter; s3, carbon pre-deoxidation; S4, modifying refining slag; s5, rare earth deoxidization; S6, secondary alloying; in the step S3, carbon powder starts to be added when tapping is carried out 1/4, and the adding is finished when tapping is carried out 3/4; in the step S4, adding rare earth alloy for deep deoxidation, wherein the addition amount of the rare earth alloy is 0.3kg-2kg/t steel; In the step S6, after the rare earth alloy is added, carbon powder, silicon manganese, aluminum blocks and high-carbon ferrochrome alloy materials are sequentially added according to the component requirements of molten steel, so that the alloying operation of the molten steel is completed. Wherein the carbon powder addition amount is 0.3-0.5 kg/t steel, the silicon-manganese alloy addition amount is 5-7kg/t steel, the aluminum block addition amount is 0.6-0.7 kg/t steel, and the high-carbon ferrochrome is 14-15kg/t steel.
  2. 2. The 40Cr steel smelting process based on the synergistic effect of C deoxidation and rare earth according to claim 1, wherein in the step S1, oxygen is measured by an oxygen analyzer before tapping of the converter.
  3. 3. The 40Cr steel smelting process based on the synergistic effect of C deoxidation and rare earth according to claim 1, wherein in the step S2, the tapping operation is started according to the components, the tapping time is 3-8min, and the tapping temperature is 1630-1650 ℃.
  4. 4. The 40Cr steel smelting process based on the synergistic effect of C deoxidation and rare earth according to claim 1, wherein in the step S3, in order to avoid the excessive adding speed of carbon powder, the boiling of the liquid level of molten steel caused by excessive adding amount of single time, the adding of carbon powder is divided into a small amount and a plurality of times, and the adding process is totally called to start argon bottom blowing operation.
  5. 5. The 40Cr steel smelting process based on the synergistic effect of C deoxidation and rare earth according to claim 1, wherein in the step S3, the carbon powder added under normal pressure removes the oxygen content to 100ppm, and the carbon content adding amount calculating method is as follows: Wherein W steel is the tapping amount of the converter, [ O ] Tapping steel wt.% is the oxygen content in steel during tapping, k is the carbon powder addition coefficient for deoxidization, and the value range is 1-12.
  6. 6. The 40Cr steel smelting process based on the synergistic effect of C deoxidation and rare earth according to claim 1, wherein in the step S4, 3kg-6kg of lime is added to ton of steel after the carbon powder addition in the step S3 is finished, 2 kg-5 kg of synthetic slag is refined to form refining slag with good fluidity, and the floating and removal of inclusions are promoted.
  7. 7. The 40Cr steel smelting process based on the synergistic effect of C deoxidation and rare earth according to claim 1, wherein in the step S4, the addition amount W RE of the rare earth alloy is calculated as follows: wherein W steel is the amount of molten steel, M RE is the relative atomic mass of rare earth elements, M O is the relative atomic mass of oxygen elements, a is the rare earth content in the rare earth alloy, the value range is 5% -50%, b is the addition coefficient of the rare earth alloy for deoxidization, and the value range is 1-15.

Description

40Cr steel smelting process based on synergistic effect of C deoxidation and rare earth Technical Field The invention belongs to the technical field of steel smelting, and particularly relates to a 40Cr steel smelting process based on the synergistic effect of C deoxidation and rare earth. Background The 40Cr steel is a widely used alloy structural steel with excellent comprehensive performance, and is mainly applied to manufacturing mechanical parts such as automobiles, tractors, machine tools, mines, petrochemical machinery and the like. The effective control of the oxygen content and the morphology of inclusions in the steel is a key link in determining the mechanical properties (especially fatigue strength, impact toughness) and the processability of the final product. At present, al is mainly used for deoxidizing when 40Cr steel is smelted at home and abroad. However, the process has a series of remarkable technical pain points and limitations in practical application, and directly affects the purity, mechanical properties, processability and product stability of the steel, and is mainly characterized in that: The aluminum deoxidized product is mainly solid Al2O3 inclusion with high melting point (about 2050 ℃). These Al2O3 inclusions are clustered or clusters in the molten steel, and have a large size, irregular morphology, and high hardness. In the subsequent casting and solidification processes, the steel is difficult to float up and remove sufficiently, a large amount of steel remains, and the purity of the steel is remarkably deteriorated. In Al deoxidized steel, sulfur (S) is generally present in the form of elongated or chain MnS inclusions. The MnS inclusions in this form extend in the deformation direction during hot working (rolling and forging) of the steel. The extended MnS not only obviously cracks the matrix and becomes a fatigue crack source, but also can cause serious deterioration (anisotropy) of mechanical properties such as transverse impact toughness, area shrinkage, fatigue strength and the like of steel, and is difficult to meet the severe requirements of high-end 40Cr components (such as high-strength connecting rods, gear shafts and the like) on comprehensive properties. To ensure the deoxidizing effect, it is often necessary to add an excessive amount of aluminum, resulting in a high acid-soluble aluminum (Als) content in the steel. High Als content increases the viscosity of the molten steel and is unfavorable for floating up the inclusions. Under certain conditions, an excess of Al may promote precipitation of AlN, adversely affecting the toughness and aging properties of the steel. Disclosure of Invention Aiming at the problems existing in the prior art, the invention provides a method combining the clean deoxidization capability and the rare earth deep deoxidization capability of carbon powder deoxidization aiming at the deoxidization alloy adopted in the 40Cr steel smelting process in the traditional industry and the existing deoxidization method adopting carbon powder deoxidization. In order to solve the technical problems, the invention adopts the following technical scheme: the invention discloses a 40Cr steel smelting process based on the synergistic effect of C deoxidation and rare earth, which comprises the following steps: S1, finishing converter smelting and oxygen determination; S2, tapping through a converter; s3, carbon pre-deoxidation; S4, modifying refining slag; s5, rare earth deoxidization; S6, secondary alloying; in the step S3, carbon powder starts to be added when tapping is carried out 1/4, and the adding is finished when tapping is carried out 3/4; in the step S4, adding rare earth alloy for deep deoxidation, wherein the addition amount of the rare earth alloy is 0.3kg-2kg/t steel; In the step S6, after the rare earth alloy is added, carbon powder, silicon manganese, aluminum blocks and high-carbon ferrochrome alloy materials are sequentially added according to the component requirements of molten steel, so that the alloying operation of the molten steel is completed. Wherein the carbon powder addition amount is 0.3-0.5 kg/t steel, the silicon-manganese alloy addition amount is 5-7kg/t steel, the aluminum block addition amount is 0.6-0.7 kg/t steel, and the high-carbon ferrochrome is 14-15kg/t steel. Further, in the step S1, oxygen is measured by an oxygen meter before tapping of the converter. In the step S2, the tapping operation is started when the components meet the requirements, the tapping time is 3-8min, and the tapping temperature is 1630-1650 ℃. Further, in the step S3, in order to avoid boiling of the molten steel liquid surface caused by too high carbon powder adding speed and too high single adding amount, the carbon powder is added in small amounts for many times, and the argon bottom blowing operation is fully started in the adding process. Further, in the step S3, the carbon powder added under normal pressure removes the oxygen content t