Low-cost steelmaking process of S420GD + ZAM zinc-aluminum-magnesium steel plate

Abstract

The invention discloses a low-cost steelmaking process of an S420GD + ZAM zinc-aluminum-magnesium steel plate. The process route is converter smelting LD-LF refining-continuous casting CCM. According to the low-cost steelmaking process of the S420GD + ZAM zinc-aluminum-magnesium steel plate, the RH refining procedure is omitted, the process route is optimized, it is guaranteed that the Ti component of a product is stable, the mechanical property reaches the standard, and meanwhile the production cost is remarkably reduced.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel smelting technology, and in particular relates to a low-cost steelmaking process for S420GD+ZAM zinc-aluminum-magnesium steel plates. Background Technology

[0002] S420GD+ZAM zinc-aluminum-magnesium steel plate is a high-strength weather-resistant steel plate widely used in construction, automobiles, home appliances, photovoltaic brackets, and other fields due to its excellent mechanical properties and corrosion resistance. Currently, the mainstream steelmaking process for producing this type of steel plate in the industry is LD-LF-RH-CCM, namely converter smelting-LF refining-RH refining-continuous casting. The RH refining process is mainly used for deep dehydrogenation, composition homogenization, and temperature fine-tuning. While it can further improve the purity of the molten steel, it also has problems such as complex process, high energy consumption, and high production costs.

[0003] With increasing competition in the steel industry, reducing production costs and improving product economic efficiency have become core needs for enterprise development. Optimizing process routes and eliminating unnecessary steps, while ensuring product quality meets standard requirements, is an effective way to reduce costs. Existing research on the optimization of S420GD+ZAM zinc-aluminum-magnesium steel plate processes mainly focuses on composition adjustment or rolling process improvements, with limited research on simplifying the steelmaking process. There is no clear process scheme proving that omitting the RH refining step still ensures the product's compositional stability and mechanical properties meet usage requirements. Therefore, developing a simplified, cost-effective, and quality-assured steelmaking process for S420GD+ZAM zinc-aluminum-magnesium steel plate has significant practical implications. Summary of the Invention

[0004] In order to overcome the problems of complex and high cost in the existing steelmaking process of S420GD+ZAM zinc-aluminum-magnesium steel plate, the purpose of this invention is to provide a low-cost steelmaking process for S420GD+ZAM zinc-aluminum-magnesium steel plate. This process significantly reduces production costs by eliminating the RH refining process and optimizing the process route, while ensuring the stability of Ti composition and meeting the mechanical properties of the product.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] This invention discloses a low-cost steelmaking process for S420GD+ZAM zinc-aluminum-magnesium steel plates. The process route is converter smelting (LD-LF refining-continuous casting CCM), specifically:

[0007] 1) Converter smelting LD: Molten iron is added to the converter according to the conventional ratio, and oxidation reaction is carried out by top blowing oxygen. At the same time, quicklime and dolomite slagging agent are added to remove harmful impurities such as carbon, phosphorus and sulfur in the molten iron. The tapping temperature is controlled at ≥1620℃ to obtain molten steel with preliminary qualified composition.

[0008] 2) LF Refining: The molten steel after tapping from the converter is transferred to the LF refining furnace, stirred with argon gas, and heated to 1580-1590℃ using graphite electrodes. Ferrosilicon and ferromanganese alloys are added for fine-tuning of the composition, and aluminum blocks are added for deoxidation. During this process, the Ti content in the molten steel is carefully controlled to maintain the Ti content in the refined steel within the range of 0.058-0.064, ensuring uniform and stable composition.

[0009] 3) Continuous Casting CCM: The molten steel that has passed the LF refining process is transferred to the ladle turret of the continuous casting machine. The temperature of the molten steel in the tundish is controlled at 1530-1540℃. A protective casting method is adopted to prevent secondary oxidation of the molten steel. The billet is drawn and cooled by the continuous casting machine to obtain the billet of S420GD+ZAM zinc-aluminum-magnesium steel plate. The billet can be made into finished steel plates through subsequent rolling processes.

[0010] Furthermore, the converter smelting LD involves adding molten iron to a 240t converter, top-blowing oxygen for 29 minutes, adding 7.4t of lime and 3.6t of dolomite for slag formation, and tapping at a temperature of 1627℃ to obtain preliminarily qualified molten steel.

[0011] Furthermore, the LF refining process involves: transferring molten steel to the LF refining furnace, heating it to 1587°C using graphite electrodes, adding 0.26t of ferrotitanium and 0.22t of ferromanganese to adjust the composition, adding 0.15t of aluminum blocks for deoxidation, refining the Ti composition to 0.058, and refining for 52 minutes.

[0012] Furthermore, the continuous casting CCM involves transferring the refined molten steel to a continuous casting machine, with the molten steel temperature in the tundish at 1544℃, using protective casting, and a billet pulling speed of 1.35m / min to obtain the cast billet.

[0013] Furthermore, specifically:

[0014] LD (Leading Die) in Converter: Molten iron is added to a 240t converter, oxygen is blown from the top for 34 minutes, 8.1t of lime and 2.8t of dolomite are added to form slag, and the tapping temperature is 1632℃ to obtain preliminarily qualified molten steel;

[0015] LF Refining: The molten steel is transferred to the LF refining furnace, heated to 1580℃ by graphite electrodes, and 0.26t of ferrotitanium and 0.26t of ferromanganese are added to adjust the composition. 0.15t of aluminum blocks are added for deoxidation. The refined Ti composition is 0.058, and the refining time is 48min.

[0016] Further, in the continuous casting CCM: the refined molten steel is transferred to the continuous casting machine, the temperature of the molten steel in the tundish is 1542℃, protective casting is used, and the billet pulling speed is 1.35m / min to obtain the billet.

[0017] Furthermore, specifically:

[0018] LD (Leading Die) in Converter: Molten iron is added to a 240t converter, oxygen is blown from the top for 33 minutes, 7.6t of lime and 2.5t of dolomite are added to form slag, and the tapping temperature is 1626℃ to obtain preliminarily qualified molten steel.

[0019] LF Refining: The molten steel is transferred to the LF refining furnace, heated to 1582℃ by graphite electrodes, and 0.28t of ferrotitanium and 0.37t of ferromanganese are added to adjust the composition. 0.10t of aluminum blocks are added for deoxidation. The refined Ti composition is 0.058, and the refining time is 48min.

[0020] Continuous casting CCM: The refined molten steel is transferred to the continuous casting machine. The temperature of the molten steel in the tundish is 1540℃. Protective casting is used, and the billet pulling speed is 1.35m / min to obtain the billet.

[0021] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0022] 1. This invention optimizes the process route, eliminates the RH refining step, simplifies the production process, shortens the production cycle, and improves production efficiency.

[0023] 2. Under the premise of ensuring the stability of Ti composition and the compliance of mechanical properties of S420GD+ZAM zinc-aluminum-magnesium steel plate, the cost can be reduced by RMB 48.18 per ton of steel, which significantly enhances the market competitiveness of the product.

[0024] 3. This process does not require large-scale modification of existing production equipment; it can be achieved simply by adjusting the process flow, making it easy to promote and apply, and suitable for large-scale industrial production. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments.

[0026] Example 1

[0027] A steelmaking process for S420GD+ZAM zinc-aluminum-magnesium steel plate, comprising the following steps:

[0028] 1. Converter smelting (LD): Molten iron is added to a 240t converter, oxygen is blown from the top for 29 minutes, 7.4t of lime and 3.6t of dolomite are added to form slag, and the tapping temperature is 1627℃ to obtain preliminarily qualified molten steel.

[0029] 2. LF Refining: The molten steel is transferred to the LF refining furnace, heated to 1587℃ by graphite electrodes, and 0.26t of ferrotitanium and 0.22t of ferromanganese are added to adjust the composition. 0.15t of aluminum blocks are added for deoxidation. The refined Ti composition is 0.058, and the refining time is 52min.

[0030] 3. Continuous Casting (CCM): The refined molten steel is transferred to the continuous casting machine. The temperature of the molten steel in the tundish is 1544℃. Protective casting is used, and the billet pulling speed is 1.35m / min to obtain the cast billet. Testing shows that the Ti content of the finished product from the tundish is 0.058. The resulting steel plate has a yield strength of 460MPa, a tensile strength of 552MPa, and an elongation after fracture of 16.0%, all meeting the standard requirements.

[0031] Example 2

[0032] A steelmaking process for S420GD+ZAM zinc-aluminum-magnesium steel plate, comprising the following steps:

[0033] 1. Converter smelting (LD): Molten iron is added to a 240t converter, oxygen is blown from the top for 34 minutes, 8.1t of lime and 2.8t of dolomite are added to form slag, and the tapping temperature is 1632℃ to obtain preliminarily qualified molten steel.

[0034] 2. LF Refining: The molten steel is transferred to the LF refining furnace, heated to 1580℃ by graphite electrodes, and 0.26t of ferrotitanium and 0.26t of ferromanganese are added to adjust the composition. 0.15t of aluminum blocks are added for deoxidation. The refined Ti composition is 0.058, and the refining time is 48min.

[0035] 3. Continuous Casting (CCM): The refined molten steel is transferred to the continuous casting machine. The temperature of the molten steel in the tundish is 1542℃. Protective casting is used, and the billet pulling speed is 1.35m / min to obtain the cast billet. Testing shows that the Ti content of the finished product from the tundish is 0.062. The resulting steel plate has a yield strength of 602MPa, a tensile strength of 668MPa, and an elongation after fracture of 24.5%, all meeting the standard requirements.

[0036] Example 3

[0037] A steelmaking process for S420GD+ZAM zinc-aluminum-magnesium steel plate, comprising the following steps:

[0038] 1. Converter smelting (LD): Molten iron is added to a 240t converter, oxygen is blown from the top for 33 minutes, 7.6t of lime and 2.5t of dolomite are added to form slag, and the tapping temperature is 1626℃ to obtain preliminarily qualified molten steel.

[0039] 2. LF Refining: The molten steel is transferred to the LF refining furnace, heated to 1582℃ by graphite electrodes, and 0.28t of ferrotitanium and 0.37t of ferromanganese are added to adjust the composition. 0.10t of aluminum blocks are added for deoxidation. The refined Ti composition is 0.058, and the refining time is 48min.

[0040] 3. Continuous Casting (CCM): The refined molten steel is transferred to the continuous casting machine. The temperature of the molten steel in the tundish is 1540℃. Protective casting is used, and the billet pulling speed is 1.35m / min to obtain the cast billet. Testing shows that the Ti content of the finished product from the tundish is 0.060. The resulting steel plate has a yield strength of 530MPa, a tensile strength of 605MPa, and an elongation after fracture of 21.0%, all meeting the standard requirements.

[0041] To verify the feasibility of the process of this invention, the applicant conducted a comparative experiment. A total of 18 heats of S420GD+ZAM products were produced in 150308 castings. Of these, 12 heats used the traditional LD-LF-RH-CCM process (control group), and 6 heats used the LD-LF-CCM process of this invention (experimental group). The Ti composition and mechanical properties of the two groups of products were compared, and the results are as follows:

[0042] 1. Comparison of Ti composition: In the control group, the Ti composition of the packaged product ranged from 0.055 to 0.064, with an average of 0.060; in the experimental group, the Ti composition ranged from 0.056 to 0.062, with an average of 0.059. Both groups' Ti compositions were within the control range of 0.052 to 0.065, and the experimental group showed no significant fluctuations in Ti composition, indicating good stability.

[0043] 2. Comparison of Mechanical Properties: The control group had an average yield strength of 535 MPa, an average tensile strength of 611 MPa, and an average elongation after fracture of 21.0%; the test group had an average yield strength of 530 MPa, an average tensile strength of 605 MPa, and an average elongation after fracture of 21.0%. Both groups of products met the standard requirements of "yield strength ≥ 420 MPa, tensile strength ≥ 480 MPa, and elongation after fracture ≥ 15%", indicating comparable performance.

[0044] 3. Cost Analysis: According to cost accounting, the process of this invention can save 48.18 yuan per ton of steel by eliminating the RH refining process. Based on an annual output of 100,000 tons of this product, the annual cost savings can reach 4.818 million yuan, which is a significant economic benefit.

[0045] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A low cost steelmaking process of S420GD+ZAM zinc-aluminum-magnesium steel sheet, characterized in that: The process route is converter smelting-LD-LF refining-continuous casting CCM, in particular: 1). Converter smelting LD: The molten iron is added into a 240t converter, oxygen is blown from the top, the blowing time is 29min, 7.4t of lime and 3.6t of dolomite are added as slagging agent, the tapping temperature is 1627℃, and the molten steel is obtained; 2). LF refining: The molten steel is transferred to the LF refining furnace, the graphite electrode is heated to 1587℃, 0.26t of titanium iron and 0.22t of manganese iron are added to adjust the composition, 0.15t of aluminum block is added for deoxidation, the off-site Ti component is 0.058, and the refining time is 52min. 3). Continuous casting CCM: The molten steel after refining is transferred to the continuous casting machine, the tundish steel temperature is 1544℃, protective casting is adopted, and the casting speed is 1.35m / min, and the casting blank is obtained.

2. The low cost steelmaking process of S420GD+ZAM zinc-aluminum-magnesium steel sheet according to claim 1, characterized in that: In particular:

3. The low cost steelmaking process of S420GD+ZAM zinc-aluminum-magnesium steel sheet according to claim 2, characterized in that: Converter smelting LD: The molten iron is added into a 240t converter, oxygen is blown from the top, the blowing time is 34min, 8.1t of lime and 2.8t of dolomite are added as slagging agent, the tapping temperature is 1632℃, and the molten steel is obtained; 4. The low cost steelmaking process of S420GD+ZAM zinc-aluminum-magnesium steel sheet according to claim 3, characterized in that: LF refining: The molten steel is transferred to the LF refining furnace, the graphite electrode is heated to 1580℃, 0.26t of titanium iron and 0.26t of manganese iron are added to adjust the composition, 0.15t of aluminum block is added for deoxidation, the off-site Ti component is 0.058, and the refining time is 48min.

5. The low cost steel making process of S420 GD+ZAM Zinc Aluminum Magnesium steel sheet as claimed in claim 1, wherein: Continuous casting CCM: The molten steel after refining is transferred to the continuous casting machine, the tundish steel temperature is 1542℃, protective casting is adopted, and the casting speed is 1.35m / min, and the casting blank is obtained. In particular: Converter smelting LD: The molten iron is added into a 240t converter, oxygen is blown from the top, the blowing time is 33min, 7.6t of lime and 2.5t of dolomite are added as slagging agent, the tapping temperature is 1626℃, and the molten steel is obtained; 6. The low cost steelmaking process of S420 GD+ZAM zinc-aluminum-magnesium steel sheet according to claim 5, characterized in that: ​ 7. The low cost steelmaking process of S420 GD+ZAM zinc-aluminum-magnesium steel sheet according to claim 1 characterized in that: ​ ​ LF refining: the molten steel is transferred to the LF refining furnace, graphite electrode heating is warmed to 1582℃, 0.28t of titanium iron and 0.37t of manganese iron are added to adjust the composition, 0.10t of aluminum block is added to deoxidize, the Ti composition after refining is removed is 0.058, and the refining time is 48min; Continuous casting CCM: the refined molten steel is transferred to the continuous casting machine, the molten steel temperature in the tundish is 1540℃, protective casting is adopted, and the blank drawing speed is 1.35m / min, so that the casting blank is obtained.