Control method for low-melting-point plastic inclusions of tire cord steel

Abstract

The invention relates to the technical field of steel and iron smelting, and provides a tire cord steel low-melting-point plastic inclusion control method which comprises the following steps: S1, pretreatment: pretreating molten iron to obtain molten steel; s2, smelting: after the molten steel is smelted, tapping to obtain smelted molten steel; s3, refining: carrying out component adjustment on the smelted molten steel, and carrying out slagging, deoxidation and soft argon blowing treatment to obtain refined molten steel; s4, continuous casting: continuously casting the refined molten steel to obtain tire cord steel; during tapping, a modifier is added, and the modifier comprises, by weight, 30-40 parts of sodium fluoride, 10-20 parts of calcium oxide, 10-35 parts of a ferrous compound and 3-6 parts of cryolite; based on the weight of the molten steel, the adding amount of the modifier is 1-2 kg / t. According to the technical scheme, the problem that the content of Al2O3 in the inclusion of the tire cord steel in the related technology is high is solved.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and in particular to a method for controlling low-melting-point plastic inclusions in cord steel. Background Art

[0002] As an important metal material, cord steel is mainly used to manufacture the skeleton material of radial tires. Its quality is crucial to the performance and safety of tires. In the production and use of cord steel, the nature and content of inclusions have a profound impact on its quality, especially low-melting-point plastic inclusions. The deformation ability of inclusions can be characterized by plastic deformation. The main factor affecting the plastic deformation of non-metallic inclusions is their melting point, which has a certain relationship with the composition of inclusions, especially the Al2O3 content in the inclusions. The less Al2O3 content in the inclusions, the more conducive it is to the later processing of cord steel.

[0003] However, traditional inclusion control methods often focus on the number and size of inclusions, and largely ignore the control of inclusion composition. This limitation makes it difficult to effectively reduce the Al2O3 content in cord steel inclusions in actual production, which in turn affects the processing performance of cord steel. Therefore, it is of great significance to develop a control method for reducing the Al2O3 content in cord steel inclusions. Summary of the invention

[0004] The present invention provides a method for controlling low-melting-point plastic inclusions in cord steel, which solves the problem of high Al2O3 content in cord steel inclusions in the related art.

[0005] The technical solution of the present invention is as follows: The present invention provides a method for controlling low-melting-point plastic inclusions in cord steel, comprising the following steps: S1. Pretreatment: After pretreatment, molten iron is obtained to obtain molten steel; S2, smelting: after smelting, the molten steel is tapped to obtain smelted molten steel; S3, refining: adjusting the composition of the smelted molten steel, and obtaining refined molten steel after slagging, deoxidation, and soft argon blowing; S4, continuous casting: the refined molten steel is continuously cast to obtain cord steel; When tapping the steel, a modifier is added, wherein the modifier comprises the following components in parts by weight: 30-40 parts of sodium fluoride, 10-20 parts of calcium oxide, 10-35 parts of ferrous compound, and 3-6 parts of cryolite; The amount of the modifier added is 1-2 kg / t based on the weight of the molten steel.

[0006] As a further technical solution, the weight ratio of the ferrous compound to cryolite is 4-5:1.

[0007] In the present invention, when the weight ratio of ferrous compound to cryolite is 4-5:1, it helps to further reduce the content of Al2O3 in the inclusions.

[0008] As a further technical solution, the ferrous compound includes one or both of ferrous sulfide and ferrous oxalate.

[0009] In the present invention, compared with ferrous oxide, when the modifier contains ferrous sulfide and / or ferrous oxalate, it helps to further reduce the content of Al2O3 in the inclusions.

[0010] As a further technical solution, when the ferrous compound includes ferrous sulfide and ferrous oxalate, the weight of the ferrous sulfide is less than the weight of the ferrous oxalate.

[0011] In the present invention, when the ferrous compound includes ferrous sulfide and ferrous oxalate, and the weight of ferrous sulfide is less than the weight of ferrous oxalate, it helps to further reduce the content of Al2O3 in the inclusions.

[0012] As a further technical solution, in step S1, in the molten steel, S≤0.01% and P≤0.01% by weight.

[0013] In the present invention, the influence of harmful elements on the performance of cord steel is reduced to the greatest extent by limiting the contents of S and P in molten steel.

[0014] As a further technical solution, in step S2, the end point composition of the smelting is controlled to be: C ≥ 0.06%, P ≤ 0.009%, S ≤ 0.006%, in weight percentage.

[0015] In the present invention, the problem of high initial inclusion content caused by overoxidation of molten steel is avoided by controlling the end point composition of smelting.

[0016] As a further technical solution, in step S2, low-aluminum ferrosilicon is added during steel tapping, and the amount of low-aluminum ferrosilicon added is 4-8 kg / t based on the weight of the molten steel.

[0017] As a further technical solution, in step S3, during slag making, the slag basicity is 0.95-1.1.

[0018] As a further technical solution, in step S3, during the deoxidation, silicon carbide is added, and the amount of silicon carbide added is 1-2 kg / t based on the weight of the molten steel after smelting.

[0019] As a further technical solution, in step S3, the soft argon blowing treatment is performed for a time of ≥20 min.

[0020] In the present invention, by ensuring that the soft argon blowing treatment time is ≥20 minutes, it can be ensured that the inclusions can effectively float up.

[0021] As a further technical solution, the cord steel is composed of the following components in weight percentage: C 0.8%~0.85%, Si 0.16%~0.25%, Mn 0.45%~0.6%, P≤0.016%, S≤0.015%, Als≤0.003%, Ti≤0.0015%, and the rest is Fe and other inevitable impurities.

[0022] The working principle and beneficial effects of the present invention are: In the present invention, by adding a modifier during steel tapping, the content of Al2O3 in inclusions can be reduced, and the inclusions can be controlled to be low-melting plastic inclusions, so that the cord steel can still maintain good plasticity during subsequent processing. The modifier contains ferrous compounds and cryolite, and the combination of the two can promote the transformation of high-melting-point Al2O3 to low-melting-point aluminum compounds, thereby reducing the content of Al2O3 in inclusions. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Example 1 A method for controlling low-melting-point plastic inclusions in cord steel comprises the following steps: S1. Pretreatment: After pretreatment, molten iron is obtained to obtain molten steel; Among them, by weight percentage, S 0.01%, P 0.01% in molten steel; S2. Smelting: After smelting, the molten steel is tapped to obtain smelted molten steel; Among them, in terms of weight percentage, the end-point composition of smelting is controlled as follows: C 0.06%, P 0.009%, S 0.006%; Based on the weight of molten steel, 1kg / t of modifier and 4kg / t of low-aluminum ferrosilicon (FeSi75-A) are added during tapping. The modifier includes the following components in parts by weight: 30 parts of sodium fluoride, 10 parts of calcium oxide, 10 parts of ferrous sulfide, and 3 parts of cryolite; S3, refining: adjusting the chemical composition of the smelted molten steel according to the target composition, and obtaining the refined molten steel after slagging, deoxidation, and 20 minutes of soft argon blowing; Among them, during slag making, the slag basicity is 0.95; during deoxidation, the amount of silicon carbide added is 1kg / t based on the weight of molten steel after smelting; S4, continuous casting: the refined molten steel is continuously cast to obtain cord steel; The cord steel is composed of the following components in weight percentage: C 0.8%, Si 0.16%, Mn 0.45%, P 0.016%, S0.015%, Als 0.003%, Ti 0.0015%, and the rest is Fe and other inevitable impurities.

[0025] Example 2 A method for controlling low-melting-point plastic inclusions in cord steel comprises the following steps: S1. Pretreatment: After pretreatment, molten iron is obtained to obtain molten steel; Among them, by weight percentage, S 0.008%, P 0.008% in molten steel; S2. Smelting: After the molten steel is smelted, the steel is tapped to obtain the smelted molten steel; Among them, in terms of weight percentage, the end-point composition of smelting is controlled as follows: C 0.08%, P 0.007%, S 0.005%; Based on the weight of molten steel, 2kg / t of modifier and 8kg / t of low-aluminum ferrosilicon (FeSi75-A) are added during tapping. The modifier includes the following components in parts by weight: 40 parts of sodium fluoride, 20 parts of calcium oxide, 35 parts of ferrous sulfide, and 6 parts of cryolite; S3, refining: adjusting the chemical composition of the smelted molten steel according to the target composition, and obtaining the refined molten steel after slagging, deoxidation, and 25 minutes of soft argon blowing; Among them, during slag making, the slag basicity is 1.1; during deoxidation, the amount of silicon carbide added is 2kg / t based on the weight of molten steel after smelting; S4, continuous casting: the refined molten steel is continuously cast to obtain cord steel; The cord steel is composed of the following components in weight percentage: C 0.85%, Si 0.25%, Mn 0.6%, P 0.015%, S0.01%, Als 0.001%, Ti 0.001%, and the rest is Fe and other inevitable impurities.

[0026] Example 3 The only difference between this embodiment and embodiment 2 is that in this embodiment, the modifier includes the following components in parts by weight: 35 parts of sodium fluoride, 15 parts of calcium oxide, 16.5 parts of ferrous sulfide, and 6 parts of cryolite.

[0027] Example 4 The only difference between this embodiment and embodiment 2 is that in this embodiment, the modifier includes the following components in parts by weight: 35 parts of sodium fluoride, 15 parts of calcium oxide, 19.5 parts of ferrous sulfide, and 3 parts of cryolite.

[0028] Example 5 The only difference between this embodiment and embodiment 2 is that in this embodiment, the modifier includes the following components in parts by weight: 35 parts of sodium fluoride, 15 parts of calcium oxide, 18 parts of ferrous sulfide, and 4.5 parts of cryolite.

[0029] Example 6 The only difference between this embodiment and embodiment 2 is that in this embodiment, the modifier includes the following components in parts by weight: 35 parts of sodium fluoride, 15 parts of calcium oxide, 18.75 parts of ferrous sulfide, and 3.75 parts of cryolite.

[0030] Example 7 The only difference between this embodiment and embodiment 6 is that in this embodiment, the ferrous sulfide in the modifier is replaced by an equal amount of ferrous oxalate.

[0031] Example 8 The only difference between this embodiment and embodiment 6 is that in this embodiment, the ferrous sulfide in the modifier is replaced by an equal amount of ferrous oxide.

[0032] Example 9 The only difference between this embodiment and embodiment 6 is that, in this embodiment, the ferrous sulfide in the modifier is replaced by equal amounts of ferrous oxide and ferrous oxalate in a weight ratio of 2:1.

[0033] Example 10 The only difference between this embodiment and embodiment 9 is that in this embodiment, the ferrous oxalate in the modifier is replaced by an equal amount of ferrous sulfide.

[0034] Embodiment 11 The only difference between this embodiment and embodiment 9 is that in this embodiment, the ferrous oxide in the modifier is replaced by an equal amount of ferrous sulfide.

[0035] Example 12 The only difference between this embodiment and embodiment 11 is that, in this embodiment, the weight ratio of ferrous sulfide to ferrous oxalate is 1:1.

[0036] Example 13 The only difference between this embodiment and embodiment 11 is that, in this embodiment, the weight ratio of ferrous sulfide to ferrous oxalate is 1:2.

[0037] Comparative Example 1 The only difference between this comparative example and Example 1 is that in this comparative example, the modifier includes the following components in parts by weight: 30 parts of sodium fluoride, 10 parts of calcium oxide, and 13 parts of ferrous sulfide.

[0038] Comparative Example 2 The difference between this comparative example and Example 1 is that in this comparative example, the modifier includes the following components in parts by weight: 30 parts of sodium fluoride, 10 parts of calcium oxide, and 13 parts of cryolite.

[0039] Comparative Example 3 The only difference between this comparative example and Example 1 is that in this comparative example, the modifier includes the following components in parts by weight: 30 parts of sodium fluoride and 10 parts of calcium oxide.

[0040] Zeiss EVO18-21-57 and the attached Phoenix+OIM integrated spectrometer were used to test the Al2O3 content in the cord steel inclusions of Examples 1 to 13 and Comparative Examples 1 to 3. The results are shown in Table 1 below.

[0041] Table 1 Al2O3 content in cord steel inclusions

[0042] Comparison between Example 1 and Comparative Examples 1-3 shows that when the modifier contains ferrous compounds and cryolite, the content of Al2O3 in the inclusions can be significantly reduced.

[0043] Comparison between Examples 3-4 and 5-6 shows that when the weight ratio of ferrous compounds to cryolite is 4-5:1, it helps to further reduce the content of Al2O3 in inclusions. Comparison between Examples 8-10 and Examples 6-7, 11-13 shows that when the modifier contains ferrous sulfide and / or ferrous oxalate compared to ferrous oxide, it helps to further reduce the content of Al2O3 in inclusions. Comparison between Example 6 and Examples 11-13 shows that when the ferrous compound includes ferrous sulfide and ferrous oxalate, it helps to further reduce the content of Al2O3 in inclusions. Comparison between Example 13 and Examples 11-12 shows that when the weight of ferrous sulfide is less than the weight of ferrous oxalate, it helps to further reduce the content of Al2O3 in inclusions.

[0044] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for controlling low-melting-point plastic inclusions in cord steel, characterized in that: The following steps are involved: S1. Pretreatment: After pretreatment, molten iron is obtained into molten steel; S2, smelting: after smelting, the molten steel is tapped to obtain smelted molten steel; S3, refining: adjusting the composition of the smelted molten steel, and obtaining refined molten steel after slagging, deoxidation, and soft argon blowing; S4, continuous casting: the refined molten steel is continuously cast to obtain cord steel; When the steel is tapped, a modifier is added, wherein the modifier comprises the following components in parts by weight: 30-40 parts of sodium fluoride, 10-20 parts of calcium oxide, 10-35 parts of ferrous compound, and 3-6 parts of cryolite; Based on the weight of molten steel, the amount of the modifier added is 1-2 kg / t.

2. A method for controlling low-melting-point plastic inclusions in cord steel according to claim 1, characterized in that: The weight ratio of the ferrous compound to cryolite is 4-5:

1.

3. A method for controlling low-melting-point plastic inclusions in cord steel according to claim 1, characterized in that: The ferrous compound includes one or both of ferrous sulfide and ferrous oxalate.

4. A method for controlling low-melting-point plastic inclusions in cord steel according to claim 3, characterized in that: When the ferrous compound includes ferrous sulfide and ferrous oxalate, the weight of the ferrous sulfide is less than the weight of the ferrous oxalate.

5. A method for controlling low-melting-point plastic inclusions in cord steel according to claim 1, characterized in that: In step S1, in the molten steel, S≤0.01% and P≤0.01% by weight.

6. A method for controlling low-melting-point plastic inclusions in cord steel according to claim 1, characterized in that: In step S2, the end point composition of the smelting is controlled to be: C ≥ 0.06%, P ≤ 0.009%, S ≤ 0.006%, by weight percentage.

7. A method for controlling low-melting-point plastic inclusions in cord steel according to claim 1, characterized in that: In step S2, when tapping the steel, low-aluminum ferrosilicon is added, and the amount of low-aluminum ferrosilicon added is 4-8 kg / t based on the weight of the molten steel.

8. A method for controlling low-melting-point plastic inclusions in cord steel according to claim 1, characterized in that: In step S3, during the slag making, the slag basicity is 0.95-1.

1.

9. A method for controlling low-melting-point plastic inclusions in cord steel according to claim 1, characterized in that: In step S3, during the deoxidation, silicon carbide is added, and the amount of silicon carbide added is 1-2 kg / t based on the weight of the molten steel after smelting.

10. A method for controlling low-melting-point plastic inclusions in cord steel according to claim 1, characterized in that: In step S3, the soft argon blowing treatment lasts for ≥ 20 min.

Images