Q390D steel plate and production method thereof

A steel plate and stage technology, applied in the field of Q390D steel plate and its production, can solve the problems of easy cracks in the slab, poor surface quality of the steel plate, high alloy cost, etc., and achieve good surface quality, low cost, and good matching between strength and toughness Effect

Inactive Publication Date: 2020-06-26
BAOTOU IRON & STEEL GRP
9 Cites 1 Cited by

AI-Extracted Technical Summary

Problems solved by technology

However, this method needs to add micro-alloys such as Nb, V, Ti, etc., and the cost of the alloy is high
After t...
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Method used

Ti content is higher in composition design, therefore in production process, continuous casting slab adopts higher heating temperature and longer heating time, when heating like this, Ti in steel can fully solid solution go in, so that rolling When cooling after casting and rolling, the carbon and nitride of Ti can be fully analyzed to improve the structure of the steel plate; the purpose of using a longer heating time in the soaking section is to make the temperature of the continuous casting slab uniform, so that the load of the rolling mill is uniform during rolling. It can achieve a larger single-pass reduction rate, which is beneficial to improve the microstructure of the steel plate. According to the chemical composition and mechanical performance requirements of the steel grade, the heated continuous casting slab is subjected to controlled rolling in the austenite recrystallization zone and non-recrystallization zone. The steel grade adopts two-stage controlled rolling. The first-stage controlled rolling belongs to the austenite recrystallization controlled rolling in the high-temperature zone. This stage adopts a low-speed, high-pressure rolling strategy. Large single-pass reduction rate can fully penetrate the rolling deformation to the center of the steel plate, fully refine the austenite grain and uniform austenite structure, and at the same time, the high-temperature welding produced by rolling largely eliminates the Defects such ...
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Abstract

The invention discloses a Q390D steel plate and a production method thereof and belongs to the field of structural steel. The Q390D steel plate comprises the chemical components in percent by mass: 0.16-0.18% of C, 0.24-0.34% of Si, 0.5-0.6% of Mn, 0.06-0.07% of Ti, less than or equal to 0.015% of P, less than or equal to 0.004% of S, 0.0011-0.0002% of Ca, 0.02-0.035% of Als and the balance iron and inevitable impurities. By means of proper smelting, continuous casting, heating, rolling and controlled cooling processes, for the obtained Q390D steel plate, the yield strength is between 413 MPaand 456 MPa, the tensile strength is between 522 MPa and 573 MPa, the yield ratio is less than or equal to 0.80, the ductility is between 21.5% and 28%, and the ballistic work at 20 DEG C below zero is between 153 J and 195 J.

Technology Topic

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  • Q390D steel plate and production method thereof
  • Q390D steel plate and production method thereof
  • Q390D steel plate and production method thereof

Examples

  • Experimental program(6)

Example Embodiment

[0027] Example 1:
[0028] The molten steel undergoes RH treatment. The time required for the vacuum to be below 122 Pa during the treatment is 17 minutes, the frequency of electromagnetic stirring during slab continuous casting is 6.5 Hz, the current is 295 A, the reduction positions are 6, 7, and 8, and the reduction is 2.4mm, 2.4mm, 2.2mm, the thickness of the obtained continuous casting billet is 250mm. When the continuous casting billet is heated, a walking heating furnace is used. The continuous casting billet discharge temperature is 1235°C, the total heating time is 280 minutes, and the heating time in the soaking section is 30 minutes. The chemical composition of the slab (weight percentage) is: C0.16%, Si 0.24%, Mn 0.6%, Ti 0.07, P 0.015%, S 0.004%, Als 0.02%, Ca 0.0011%, the balance is Fe and unavoidable 的impurities. Rolled into a steel plate with a thickness of 14mm, the detailed rolling and cooling process is shown in Table 1, the mechanical properties of the obtained steel plate are shown in Table 2, and the metallographic structure of the obtained steel plate is shown in Table 1. figure 1 , The organization is fine ferrite + pearlite.
[0029] Table 1: Rolling and cooling process
[0030]
[0031] Table 2: Mechanical properties of steel plate
[0032]

Example Embodiment

[0033] Example 2:
[0034] The molten steel undergoes RH treatment. The time required for the vacuum to be below 122 Pa during the treatment is 18 minutes, the frequency of electromagnetic stirring during slab continuous casting is 6.5 Hz, the current is 295 A, the reduction positions are 6, 7, and 8, and the reduction is 2.4mm, 2.4mm, 2.2mm, the thickness of the continuous casting billet is 250mm. The continuous casting billet is heated by a walking-type heating furnace, the furnace temperature is 1215°C, the total heating time is 220 minutes, and the heating time in the soaking section is 33 minutes. The chemical composition of the slab (weight percentage) is: C 0.18%, Si 0.34%, Mn 0.5%, Ti 0.06%, P 0.014%, S 0.003%, Als 0.035%, Ca 0.0026%, the balance is Fe and non-volatile Impurities to avoid. Rolled into a steel plate with a thickness of 21mm, the detailed rolling and cooling process is shown in Table 3, the mechanical properties of the obtained steel plate are shown in Table 4, and the metallographic structure of the steel plate is shown in Table 3. figure 2.
[0035] Table 3: Rolling and cooling process
[0036]
[0037] Table 4: Mechanical properties of steel plate
[0038]

Example Embodiment

[0039] Example 3
[0040] The molten steel undergoes RH treatment. The time required for the vacuum to be below 122 Pa during the treatment is 18 minutes, the frequency of electromagnetic stirring during slab continuous casting is 6.5 Hz, the current is 295 A, the reduction positions are 6, 7, and 8, and the reduction is 2.4mm, 2.4mm, 2.2mm, the thickness of continuous casting billet is 250mm. The continuous casting slab is heated by a walking-type heating furnace, the furnace temperature is 1228℃, the total heating time is 245 minutes, and the heating time in the soaking section is 35 minutes. The chemical composition (weight percentage) of the slab is: C 0.17%, Si 0.31%, Mn 0.56%, Ti 0.063%, P 0.013%, S 0.002%, Als 0.033%, Ca 0.0022%, and the balance is Fe and Inevitable impurities. Rolled into a steel plate with a thickness of 18mm, the detailed rolling and cooling process is shown in Table 5, and its mechanical properties are shown in Table 6, and the metallographic structure is as image 3 Shown.
[0041] Table 5: Rolling and cooling process
[0042]
[0043] Table 6: Mechanical properties of steel plate
[0044]
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Description & Claims & Application Information

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