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RH (Ruhrstahl Heraeus) refining process for inhibiting 20CrMnTi steel from generating large-size TiN-containing composite inclusions

A composite inclusion, large-scale technology, applied in the field of steel smelting, can solve problems such as insolvency, achieve fine distribution, reduce heterogeneous nucleation rate, and inhibit generation.

Active Publication Date: 2022-03-25
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above methods have some effects in reducing the size of TiN inclusions, but they cannot solve the problem of heterogeneous nucleation to form large-sized TiN composite inclusions

Method used

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  • RH (Ruhrstahl Heraeus) refining process for inhibiting 20CrMnTi steel from generating large-size TiN-containing composite inclusions
  • RH (Ruhrstahl Heraeus) refining process for inhibiting 20CrMnTi steel from generating large-size TiN-containing composite inclusions
  • RH (Ruhrstahl Heraeus) refining process for inhibiting 20CrMnTi steel from generating large-size TiN-containing composite inclusions

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0059] Example of the present invention is a typical test result in industrial production, wherein the RH refining process is:

[0060] The RH refining treatment time is 40 minutes, and the refining process follows the three-stage system shown in Figure 1. The RH pre-, mid-, and post-treatment times are 10 min, 20 min, and 10 min, respectively. At the beginning of RH refining, ω[Al] in molten steel t The content is 0.045%, the pressure of the vacuum chamber in the early stage of RH is gradually reduced, the liquid level of the vacuum chamber is steadily increased, and the flow rate of argon is maintained at 14NL / min / ton of steel; min / ton of steel; the pressure of the vacuum chamber in the later stage of RH refining is kept at 3kPa, and the flow rate of argon gas is kept at 14NL / min / ton of steel. CaFe alloy with a Ca content of 10-15% is fed first for calcium treatment, and the target ω[Ca] is 0.0008%, titanium alloy is added after adding calcium and iron for 5 minutes, the ta...

Embodiment 2

[0067] Example of the present invention is a typical test result in industrial production, wherein the RH refining process is:

[0068] The RH refining treatment time is 44 minutes, and the refining process follows the three-stage system shown in Figure 1. The RH pre-, mid-, and post-treatment times are 11 min, 22 min, and 11 min, respectively. At the beginning of RH refining, ω[Al] in molten steel t The content is 0.048%, the pressure of the vacuum chamber in the early stage of RH is gradually reduced, the liquid level of the vacuum chamber is steadily increased, and the flow rate of argon is maintained at 15NL / min / ton of steel; min / ton of steel; the pressure of the vacuum chamber in the later stage of RH refining is kept at 2.5kPa, the flow rate of argon gas is kept at 15NL / min / ton of steel, and CaFe alloy with a Ca content of 10-15% is fed first for calcium treatment. The target ω[Ca] 0.0007%, calcium and iron are added 6 minutes before adding titanium alloy, the target ω[...

Embodiment 3

[0074] Example of the present invention is a typical test result in industrial production, wherein the RH refining process is:

[0075] The RH refining treatment time is 48 minutes, and the refining process follows the three-stage system shown in Figure 1. The RH pre-, mid- and post-treatment times are 12 minutes, 24 minutes and 12 minutes respectively. At the beginning of RH refining, ω[Al] in molten steel t The content is 0.042%, the pressure of the vacuum chamber in the early stage of RH is gradually reduced, the liquid level of the vacuum chamber is steadily increased, and the flow rate of argon is maintained at 16NL / min / ton of steel; min / ton of steel; the pressure of the vacuum chamber in the later stage of RH refining is kept at 4kPa, the flow rate of argon gas is kept at 16NL / min / ton of steel, and the CaFe alloy with a Ca content of 10-15% is fed first for calcium treatment, and the target ω[Ca] is 0.0006%, add calcium and iron 7 minutes before adding titanium alloy, t...

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Abstract

The invention discloses an RH (Ruhrstahl Heraeus) refining process for inhibiting 20CrMnTi steel from generating large-size TiN-containing composite inclusions. The total treatment time of the RH refining process is 30-50 min, and the maximum argon blowing flow is 15-25 NL / min per ton of steel; the whole process is divided into an RH early stage, an RH middle stage and an RH later stage; and the treatment time, vacuum pressure, argon blowing flow and alloying of the three periods are controlled, and strict control over the content of elements such as Al, Mg, O, Ca, Ti and N in the 20CrMnTi molten steel is achieved. According to the method, generation of MgO-Al2O3-TiOx oxides in the smelting and solidification process is inhibited, TiN is effectively prevented from growing on MgO-Al2O3-TiOx oxide inclusions, the effect of remarkably reducing the number and mutual aggregation of the oxides and TiN composite large-size inclusions is achieved, the TiN inclusions are fine and evenly distributed, and the size is smaller than 5 micrometers.

Description

technical field [0001] The invention mainly belongs to the field of steel smelting, and in particular relates to an RH refining process for suppressing the formation of large-sized TiN-containing composite inclusions in 20CrMnTi steel. Background technique [0002] 20CrMnTi gear steel is a kind of gear steel with large production volume and wide application in my country. The Ti content is controlled within the range of 0.04-0.1%, and the TiN precipitates of tens of nanometers are mainly used to pin the grain boundary and inhibit the grain growth. effect. [0003] In actual production, due to the complex smelting process and solidification segregation, two kinds of harmful inclusions of TiN will be formed in steel. The first type is a single TiN inclusion, formed in a homogeneous nucleation manner, with a size in the range of a few microns, relatively small, and more uniformly distributed, so it is less harmful. The other is composite TiN inclusions, which are formed in a h...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C7/10C21C7/072
CPCC21C7/10C21C7/072Y02P10/20
Inventor 成国光李尧鲁金龙
Owner UNIV OF SCI & TECH BEIJING
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