A method for refining a steel for automotive drive shafts

Abstract

This invention discloses a refining method for steel used in automotive drive shafts, including the design of an alloying model for electric furnace tapping, a low-basicity slag system process, a refining combined deoxidation method, a pre-process for adjusting easily oxidized elements such as Al, S, and Ti, and a post-vacuum calcium treatment process. This invention focuses on a pure metallurgical route, exploring the patterns of easily oxidized elements, and breaking through the traditional processes of aluminum deoxidation and vacuum composition adjustment. It designs a proprietary alloying model, slag system, deoxidation, and composition adjustment process, meeting the requirements for steady-state casting and water immersion testing of this type of steel.

Description

Technical Field

[0001] This invention relates to the field of iron and steel smelting, and more particularly to a refining method for steel used in automobile drive shafts. Background Technology

[0002] The steel used for automotive driveshafts is a low-silicon, sulfur-containing, and aluminum-containing steel. It has a narrow pouring window, and the first heat, in particular, requires overcoming adverse conditions such as oxygen absorption and temperature loss. Accumulated materials easily form on the stopper rod and nozzle. As pouring progresses, these accumulated materials fall off, causing significant fluctuations in the liquid level and increasing the risk of inclusions in the cast billet. The driveshaft market has a promising outlook, and with increasing order volumes, customers are placing higher demands on the purity of the steel, making the resolution of steel purity a crucial issue.

[0003] Currently, most steel mills use traditional aluminum deoxidation and vacuum process to adjust the composition, which cannot meet the requirements for steady-state casting and water immersion testing of this type of steel. Summary of the Invention

[0004] Purpose of the invention: To address the shortcomings and defects of existing technologies, this invention provides a refining method for steel used in automotive drive shafts. Taking a purification metallurgical route as the main line, it explores the rules of easily oxidized elements and breaks through the traditional aluminum deoxidation and vacuum air conditioning process. It designs a proprietary alloying model, slag system, deoxidation and composition adjustment process, which meets the requirements for steady-state casting and water immersion testing of this type of steel.

[0005] Technical solution: The present invention provides a refining method for steel used in automotive drive shafts, characterized by: designing an alloying model for electric furnace steel tapping, a low-basicity slag system process, a refining combined deoxidation method, a pre-adjustment process for easily decaying elements such as Al, S, and Ti, and a calcium treatment process after vacuum treatment.

[0006] This refining method is used in the EAF+LF+VD process for producing steel for automotive drive shafts.

[0007] The refining method specifically includes the following steps:

[0008] 1) In the electric furnace smelting process, aluminum alloys with a yield of 1.8 kg / t-2.0 kg / t per ton of steel and silicon-containing alloys with a yield of ≤0.1 kg / t per ton of steel are used; the slag basicity is between 2.5 and 3.5.

[0009] 2) In the LF refining process, a strong deoxidation method is adopted, with a deoxidizer dosage of 2 kg / t per ton of steel; the easily degraded elements Al, S, and Ti are adjusted before refining, specifically 1 kg / t-1.2 kg / t for aluminum alloys, 3 kg / t-4 kg / t for S alloys, and 1 kg / t-1.2 kg / t for Ti alloys;

[0010] 3) In the VD process, use 0.15kg / t-0.3kg / t of pure calcium.

[0011] The number of consecutive casting furnaces in this refining method is 8 or more.

[0012] In step 1), 1.8 kg / t of aluminum alloy and 0.1 kg / t of silicon alloy are used per ton of steel; the slag basicity is 2.5. In step 2), specifically, 1 kg / t of aluminum alloy, 3 kg / t of silicon alloy, and 1.2 kg / t of silicon alloy are used; in step 3), 0.15 kg / t of pure calcium is used.

[0013] In step 1), 2.0 kg / t of aluminum alloy and 0.1 kg / t of silicon alloy are used per ton of steel; the slag basicity is 3.5. In step 2), specifically, 1.2 kg / t of aluminum alloy, 4 kg / t of silicon alloy, and 1.0 kg / t of silicon alloy are used; in step 3), 0.30 kg / t of pure calcium is used.

[0014] In step 1), 1.9 kg / t of aluminum alloy and 0.1 kg / t of silicon alloy are used per ton of steel; the slag basicity is 3.5. In step 2), specifically, 1.1 kg / t of aluminum alloy, 3.5 kg / t of silicon alloy, and 1.1 kg / t of silicon alloy are used; in step 3), 0.20 kg / t of pure calcium is used.

[0015] Beneficial Effects: Compared with the prior art, the present invention has the following significant advantages: Based on the characteristics of steel used in automotive drive shafts and following the EAF-LF-VD process flow, the present invention designs a special process for this type of steel. Taking the purification metallurgical route as the main line, it explores the rules of easily oxidized elements and breaks through the traditional aluminum deoxidation and vacuum composition process. It designs a proprietary alloying model, slag system, deoxidation and composition adjustment process, including low alkalinity slag system process, refining combined deoxidation method, and pre-adjustment process for easily decaying elements such as Al, S, and Ti, as well as calcium treatment process after vacuum. This meets the requirements for steady-state casting and water immersion testing of this type of steel. Detailed Implementation

[0016] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0017] Example 1:

[0018] The refining method for automotive driveshaft steel in this embodiment includes the design of an electric furnace steelmaking alloying model, a low-basicity slag system process, a refining combined deoxidation method, a pre-treatment process for easily decaying elements such as Al, S, and Ti, and a post-vacuum calcium treatment process. Specifically, it includes the following steps:

[0019] 1) In the electric furnace smelting process, aluminum alloy with a content of 1.8 kg / t of steel and 0.1 kg of silicon alloy are used; the slag basicity is 2.5.

[0020] 2) In the LF refining process, a strong deoxidation method is adopted, with a deoxidizer dosage of 2 kg / t per ton of steel. Pre-refining adjustment is adopted for easily degraded elements such as Al, S, and Ti, specifically 1 kg / t for aluminum alloys, 3 kg / t for S alloys, and 1.2 kg / t for Ti alloys.

[0021] 3) In the VD process, use 0.15 kg / t of pure calcium.

[0022] This refining method was used in the EAF+LF+VD process for producing steel for automotive drive shafts. After testing, it met the requirements for steady-state casting and water immersion testing of this type of steel.

[0023] Example 2:

[0024] The refining method for automotive driveshaft steel in this embodiment includes the design of an electric furnace steelmaking alloying model, a low-basicity slag system process, a refining combined deoxidation method, a pre-treatment process for easily decaying elements such as Al, S, and Ti, and a post-vacuum calcium treatment process. Specifically, it includes the following steps:

[0025] 1) In the electric furnace smelting process, aluminum alloy with a yield of 2.0 kg / t of steel and 0.1 kg of silicon alloy are used; the slag basicity is 3.5.

[0026] 2) In the LF refining process, a strong deoxidation method is adopted, with a deoxidizer dosage of 2 kg / t per ton of steel. Pre-refining adjustment is adopted for easily degraded elements such as Al, S, and Ti, specifically 1.2 kg / t for aluminum alloys, 4 kg / t for S alloys, and 1.0 kg / t for Ti alloys.

[0027] 3) In the VD process, use 0.30 kg / t of pure calcium.

[0028] This refining method was used in the EAF+LF+VD process for producing steel for automotive drive shafts. After testing, it met the requirements for steady-state casting and water immersion testing of this type of steel.

[0029] Example 3:

[0030] The refining method for automotive driveshaft steel in this embodiment includes the design of an electric furnace steelmaking alloying model, a low-basicity slag system process, a refining combined deoxidation method, a pre-treatment process for easily decaying elements such as Al, S, and Ti, and a post-vacuum calcium treatment process. Specifically, it includes the following steps:

[0031] 1) In the electric furnace smelting process, aluminum alloy with a yield of 1.9 kg / t of steel and 0.1 kg of silicon alloy are used; the slag basicity is 3.5.

[0032] 2) In the LF refining process, a strong deoxidation method is adopted, with a deoxidizer dosage of 2 kg / t per ton of steel. Pre-refining adjustment is adopted for easily degraded elements such as Al, S, and Ti, specifically 1.1 kg / t for aluminum alloys, 3.5 kg / t for S alloys, and 1.1 kg / t for Ti alloys.

[0033] 3) In the VD process, use 0.20 kg / t of pure calcium.

[0034] This refining method was used in the EAF+LF+VD process for producing steel for automotive drive shafts. After testing, it met the requirements for steady-state casting and water immersion testing of this type of steel.

[0035] In summary, the fluidity qualification rate of this type of steel has increased from 92% to over 99.6%; the number of consecutive casting heats has increased from 3 heats to an average of over 8 heats; the inclusions of Class A and Class B have decreased by 0.5 levels; and the water immersion testing requirements of some customers have been met with a 100% qualification rate.

Claims

1. A method for refining a steel for automotive drive shafts, characterized in that: This includes the design of an alloying model for electric arc furnace steelmaking, a low-basicity slag system process, a refining combined deoxidation method, a pre-adjustment process for easily decaying elements such as Al, S, and Ti, and a calcium treatment process after vacuum treatment; this refining method is used in the EAF+LF+VD process for producing steel for automotive drive shafts. The refining method specifically includes the following steps: 1) In the electric furnace smelting process, aluminum alloys with a yield of 1.8 kg / t-2.0 kg / t per ton of steel and silicon-containing alloys with a yield of ≤0.1 kg / t per ton of steel are used; the slag basicity is between 2.5 and 3.

5. 2) In the LF refining process, a strong deoxidation method is adopted, with a deoxidizer dosage of 2 kg / t per ton of steel; the easily degraded elements Al, S, and Ti are adjusted before refining, specifically 1 kg / t-1.2 kg / t for aluminum alloys, 3 kg / t-4 kg / t for S alloys, and 1 kg / t-1.2 kg / t for Ti alloys; 3) In the VD process, use 0.15 kg / t - 0.3 kg / t of pure calcium; The refining method requires a continuous casting of 8 or more furnaces.

2. Refining process of a steel for automotive propeller shafts according to claim 1, characterized in that: In step 1), 1.8 kg / t of aluminum alloy and 0.1 kg / t of silicon alloy are used; the slag basicity is 2.

5.

3. Refining process of a steel for automotive propeller shafts according to claim 2, characterized in that: In step 2), the specific dosage is 1 kg / t of aluminum alloy, 3 kg / t of S alloy, and 1.2 kg / t of Ti alloy; in step 3), 0.15 kg / t of pure calcium is used.

4. The steel for automotive propeller shaft according to claim 1, characterized in that: In step 1), 2.0 kg / t of aluminum alloy and 0.1 kg / t of silicon alloy are used; the slag basicity is 3.

5.

5. The refining method for automotive driveshaft steel according to claim 4, characterized in that: In step 2), the specific dosage is 1.2 kg / t for aluminum alloys, 4 kg / t for S alloys, and 1.0 kg / t for Ti alloys; in step 3), 0.30 kg / t of pure calcium is used.

6. The refining method for automotive driveshaft steel according to claim 1, characterized in that: In step 1), an aluminum alloy with a strength of 1.9 kg / t and a silicon alloy with a strength of 0.1 kg / t are used; the slag basicity is 3.

5.

7. The steel for automotive propeller shaft according to claim 6, characterized in that: In step 2), the specific dosage is 1.1 kg / t for aluminum alloys, 3.5 kg / t for S alloys, and 1.1 kg / t for Ti alloys; in step 3), the dosage is 0.20 kg / t of pure calcium.