Preparation method of rare earth treated hot-rolled armored steel plate

Abstract

The steel plate comprises the following chemical components in percentage by mass: less than or equal to 0.50% of C, less than or equal to 1.0% of S , less than or equal to 1.85% of Mn, less than or equal to 0.020% of P, less than or equal to 0.015% of S, less than or equal to 1.00% of N , less than or equal to 1.5% of Cr, less than or equal to 1.0% of Mo, less than or equal to 0.1% of Nb + V + Ti, less than or equal to 0.005% of B, more than or equal to 0.015% of Al < t >, 0.0010-0.0100% of Ce and the balance of Fe and inevitable impurities. The preparation method comprises the steps of molten iron pretreatment, converter steelmaking, LF external refining, RH vacuum degassing, continuous casting, heating, phosphorus removal, rough rolling, finish rolling and cooling. By means of the effect of adding the rare earth elements and the influence of the rare earth elements on the hardness, cleanliness, structure and grain size of the armor steel, the strength grade of the produced armor bulletproof steel plate meets the requirement.

Description

Technical Field

[0001] The invention belongs to the technical field of bulletproof steel plate materials, and in particular relates to a method for preparing a rare earth treated hot-rolled armor steel plate. Background Art

[0002] Patent 1, application number 202110479480.4, relates to a 1800MPa grade high-strength self-toughening protective steel plate and its manufacturing method. The manufacturing method includes rolling and heat treatment processes. The invented 1800MPa grade steel plate can be manufactured in a thickness range of 4 to 25mm, but the steel plate composition does not contain rare earth elements.

[0003] Patent 2, application number 201910160548.5, discloses a heat treatment method for civilian bulletproof steel, followed by quenching + two-phase zone quenching + tempering heat treatment. The invention also does not describe the specific smelting and rolling process, but only provides a heat treatment method.

[0004] Patent 3, application number 201510539848.6, discloses a bulletproof steel plate with a tensile strength of 2000 MPa and a Brinell hardness of 600, and accordingly provides a manufacturing method thereof. The bulletproof performance of the bulletproof steel plate can meet the standard requirements, and a bulletproof steel plate with high tensile strength and high Brinell hardness is obtained. However, no rare earth elements are added. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a rare earth treated hot rolled armor steel plate, utilizing the effect of rare earth element addition and the influence of rare earth elements on the hardness, cleanliness, organization and grain size of armor steel, so as to produce armor bulletproof steel plates with strength levels that meet requirements.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The invention discloses a method for preparing a rare earth treated hot rolled armor steel plate, wherein the chemical composition of the steel plate by mass percentage is C: ≤0.50%, Si: ≤1.0%, Mn ≤1.85%, P: ≤0.020%, S: ≤0.015%, Ni ≤1.00%, Cr ≤1.5%, Mo ≤1.0%, Nb+V+Ti ≤0.1%, B ≤0.005%, Alt ≥0.015%, Ce: 0.0010-0.0100%, and the rest is Fe and Inevitable impurities; the total mass fraction is 100%; the preparation method comprises: molten iron pretreatment - converter steelmaking - LF refining - RH vacuum degassing - continuous casting - heating - dephosphorization - rough rolling - finishing rolling - cooling; wherein, the heating temperature is 1250±15℃ to reach the complete austenitization temperature, so that the slab structure is completely austenitized; the rough rolling adopts high temperature and large reduction rolling to ensure that the columnar crystals are fully crushed; the final rolling temperature is 900±15℃ to ensure that the finishing rolling is rolled in the completely non-recrystallization temperature area.

[0008] Furthermore, the preparation method specifically comprises the following steps:

[0009] (1) Hot metal pretreatment: After hot metal desulfurization pretreatment, the S content is ≤ 0.003%;

[0010] (2) Converter steelmaking: The converter adopts single slag process to ensure the successful carbon extraction in one go; the steel tapping process adopts bottom blowing argon operation. To ensure the effect, the bottom blowing mode of nitrogen and argon switching is adopted; the steel tapping temperature is less than 1670℃;

[0011] (3) LF refining: mainly for the addition of Si, Mn, Nb, Ni, Cr, and Mo, and adding appropriate amounts of alloys according to the requirements of internal control components; LF refining is carried out for no less than 40 minutes;

[0012] (4) RH refining: vacuum treatment is performed for no less than 30 minutes in the RH stage; 50 kg of rare earth alloy is added for microalloying in the later stage of RH treatment; the molten steel after RH treatment is first subjected to soft argon blowing to ensure uniform composition and sufficient floating of inclusions for more than 15 minutes, and then allowed to stand and steel is added, wherein the standing time is no less than 15 minutes;

[0013] (5) Continuous casting: electromagnetic stirring and light pressure are used to ensure the quality of the casting;

[0014] (6) Heating process: The slab is cold loaded into the furnace, the furnace time is not less than 300 min, and the furnace temperature is 1250°C;

[0015] (7) Hot rolling process: The starting rolling temperature of the slab rough rolling is 1230±15℃. Considering the thinness of the steel plate, two-stage controlled rolling is not adopted. The final rolling temperature of the steel plate is set at 900±15℃. After rolling, the steel plate is not cooled under controlled conditions, but is cooled naturally in the air.

[0016] Furthermore, the chemical composition of the steel plate in mass percentage is: C: 0.24%, Si: 0.34%, Mn: 0.99%, P: 0.003%, S: 0.005%, Ni: 0.79%, Cr: 1.21%, Mo: 0.33%, Nb: 0.024%, Ti: 0.037%, B: 0.0013%, Al: 0.045%, Ce: 0.0030%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0017] Furthermore, the chemical composition of the steel plate in mass percentage is: C: 0.29%, Si: 0.34%, Mn: 0.99%, P: 0.003%, S: 0.005%, Ni: 0.78%, Cr: 1.21%, Mo: 0.33%, Nb: 0.027%, Ti: 0.033%, B: 0.0013%, Al: 0.045%, Ce: 0.0060%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0018] Furthermore, the chemical composition of the steel plate in mass percentage is: C: 0.25%, Si: 0.34%, Mn: 0.99%, P: 0.003%, S: 0.005%, Ni: 0.79%, Cr: 1.90%, Mo: 0.32%, Nb: 0.021%, Ti: 0.029%, B: 0.0011%, Al: 0.045%, Ce: 0.0090%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0019] Compared with the prior art, the beneficial technical effects of the present invention are:

[0020] The present invention improves the microstructure of steel materials by adding rare earth and other microalloying elements alone or in combination, achieving high strengthening, high toughness and low cost. In particular, the influence of rare earth elements on the hardness, cleanliness, organization and grain size of armor steel is explored. By utilizing the effect of rare earth element addition and the influence of rare earth elements on the hardness, cleanliness, organization and grain size of armor steel, the strength level of the armored bulletproof steel plate produced meets the requirements.

[0021] The performance of the steel plate meets the following technical requirements: yield strength R p0.2 Controlled at ≥900MPa, tensile strength Rm controlled at ≥1200MPa, elongation A controlled at ≥2%, Brinell hardness controlled at 400~450HBW. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below in conjunction with the accompanying drawings.

[0023] Figure 1The metallographic structure of Example 1;

[0024] Figure 2 The metallographic structure of Example 2;

[0025] Figure 3 This is the metallographic structure of Example 3. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below in conjunction with specific embodiments.

[0027] Embodiment 1:

[0028] (1) The embodiment includes the following chemical components in weight percentage: C: 0.29%, Si: 0.34%, Mn: 0.99%, P: 0.003%, S: 0.005%, Ni: 0.78%, Cr: 1.21%, Mo: 0.33%, Nb: 0.027%, Ti: 0.033%, B: 0.0013%, Al: 0.045%, Ce: 0.0060%, and the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

[0029] (2) Hot metal pretreatment: After hot metal desulfurization pretreatment, the S content is ≤0.003%.

[0030] (3) Converter steelmaking: The converter adopts the single slag process to ensure the success of carbon extraction in one go. The steel tapping process adopts bottom blowing argon operation. To ensure the effect, the bottom blowing mode of nitrogen and argon switching is adopted. The steel tapping temperature is less than 1670℃.

[0031] (4) LF refining: mainly for the addition of Si, Mn, Nb, V, Ti, Cr, Mo, and the addition of appropriate amount of alloy according to the requirements of internal control components. LF refining is carried out for no less than 40 minutes.

[0032] (5) RH refining: The vacuum treatment time in the RH stage is not less than 30 minutes. In the later stage of RH treatment, 50 kg of rare earth alloy is added for micro-alloying treatment. The molten steel after RH treatment must first be soft-blown with argon to ensure uniform composition and sufficient floating of inclusions for more than 15 minutes, and then allowed to stand and steel is added, with the standing time being not less than 15 minutes.

[0033] (6) Continuous casting: Electromagnetic stirring and light pressure are used to ensure the quality of the casting.

[0034] (7) Heating process: The slab is cold loaded into the furnace, the time in the furnace is not less than 300 min, and the furnace temperature is 1250°C.

[0035] (8) Hot rolling process: The starting rolling temperature of the slab rough rolling is 1230±15℃. Considering the thinness of the steel plate, two-stage controlled rolling is not adopted. The final rolling temperature of the steel plate is set to 900±15℃.

[0036] Embodiment 2:

[0037] (1) The embodiment includes the following chemical components in weight percentage: C: 0.29%, Si: 0.34%, Mn: 0.99%, P: 0.003%, S: 0.005%, Ni: 0.78%, Cr: 1.21%, Mo: 0.33%, Nb: 0.027%, Ti: 0.033%, B: 0.0013%, Al: 0.045%, Ce: 0.0060%, and the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

[0038] (2) Hot metal pretreatment: After hot metal desulfurization pretreatment, the S content is ≤0.003%.

[0039] (3) Converter steelmaking: The converter adopts the single slag process to ensure the success of carbon extraction in one go. The steel tapping process adopts bottom blowing argon operation. To ensure the effect, the bottom blowing mode of nitrogen and argon switching is adopted. The steel tapping temperature is less than 1670℃.

[0040] (4) LF refining: mainly for the addition of Si, Mn, Nb, V, Ti, Cr, Mo, and the addition of appropriate amount of alloy according to the requirements of internal control components. LF refining is carried out for no less than 40 minutes.

[0041] (5) RH refining: The vacuum treatment time in the RH stage is not less than 30 minutes. In the later stage of RH treatment, 50 kg of rare earth alloy is added for micro-alloying treatment. The molten steel after RH treatment must first be soft-blown with argon to ensure uniform composition and sufficient floating of inclusions for more than 15 minutes, and then allowed to stand and steel is added, with the standing time being not less than 15 minutes.

[0042] (6) Continuous casting: Electromagnetic stirring and light pressure are used to ensure the quality of the casting.

[0043] (7) Heating process: The slab is cold loaded into the furnace, the time in the furnace is not less than 300 min, and the furnace temperature is 1250°C.

[0044] (8) Hot rolling process: The starting rolling temperature of the slab rough rolling is 1230±15℃. Considering the thinness of the steel plate, two-stage controlled rolling is not adopted. The final rolling temperature of the steel plate is set to 900±15℃.

[0045] Embodiment 3:

[0046] (1) The embodiment includes the following chemical composition in weight percentage: C: 0.25%, Si: 0.34%, Mn: 0.99%, P: 0.003%, S: 0.005%, Ni: 0.79%, Cr: 1.90%, Mo: 0.32%, Nb: 0.021%, Ti: 0.029%, B: 0.0011%, Al: 0.045%, Ce: 0.0090%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0047] (2) Hot metal pretreatment: After hot metal desulfurization pretreatment, the S content is ≤0.003%.

[0048] (3) Converter steelmaking: The converter adopts the single slag process to ensure the success of carbon extraction in one go. The steel tapping process adopts bottom blowing argon operation. To ensure the effect, the bottom blowing mode of nitrogen and argon switching is adopted. The steel tapping temperature is less than 1670℃.

[0049] (4) LF refining: mainly for the addition of Si, Mn, Nb, V, Ti, Cr, Mo, and the addition of appropriate amount of alloy according to the requirements of internal control components. LF refining is carried out for no less than 40 minutes.

[0050] (5) RH refining: The vacuum treatment time in the RH stage is not less than 30 minutes. In the later stage of RH treatment, 50 kg of rare earth alloy is added for micro-alloying treatment. The molten steel after RH treatment must first be soft-blown with argon to ensure uniform composition and sufficient floating of inclusions for more than 15 minutes, and then allowed to stand and steel is added, with the standing time being not less than 15 minutes.

[0051] (6) Continuous casting: Electromagnetic stirring and light pressure are used to ensure the quality of the casting.

[0052] (7) Heating process: The slab is cold loaded into the furnace, the time in the furnace is not less than 300 min, and the furnace temperature is 1250°C.

[0053] (8) Hot rolling process: The starting rolling temperature of the slab rough rolling is 1230±15℃. Considering the thinness of the steel plate, two-stage controlled rolling is not adopted. The final rolling temperature of the steel plate is set to 900±15℃.

[0054] The mechanical properties of each embodiment are shown in Table 1.

[0055] Table 1 Mechanical properties of steel plates

[0056]

[0057] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a rare earth treated hot rolled armor steel plate, Features: The chemical composition of the steel plate by mass percentage is C: ≤0.50%, Si: ≤1.0%, Mn ≤1.85%, P: ≤0.020%, S: ≤0.015%, Ni ≤1.00%, Cr ≤1.5%, Mo ≤1.0%, Nb+V+Ti ≤0.1%, B ≤0.005%, Alt ≥0.015%, Ce: 0.0010-0.0100%, and the rest is Fe and unavoidable impurities; The total mass fraction is 100%; its preparation method includes: molten iron pretreatment - converter steelmaking - LF refining outside the furnace - RH vacuum degassing - continuous casting - heating - dephosphorization - rough rolling - finishing rolling - cooling; wherein, the heating temperature is 1250±15°C to reach the complete austenitization temperature, so that the slab structure is completely austenitized; the rough rolling adopts high temperature and large reduction rolling to ensure that the columnar crystals are fully crushed; the final rolling temperature is 900±15°C to ensure that the finishing rolling is rolled in the completely non-recrystallization temperature region.

2. The method for preparing the rare earth treated hot rolled armor steel plate according to claim 1, Features: The preparation method specifically comprises the following steps: (1) Hot metal pretreatment: After hot metal desulfurization pretreatment, the S content is ≤ 0.003%; (2) Converter steelmaking: The converter adopts single slag process to ensure the successful carbon extraction in one go; the steel tapping process adopts bottom blowing argon operation. To ensure the effect, the bottom blowing mode of nitrogen and argon switching is adopted; the steel tapping temperature is less than 1670℃; (3) LF refining: mainly for the addition of Si, Mn, Nb, Ni, Cr, and Mo, and adding appropriate amounts of alloys according to the requirements of internal control components; LF refining is carried out for no less than 40 minutes; (4) RH refining: vacuum treatment is performed for no less than 30 minutes in the RH stage; 50 kg of rare earth alloy is added for microalloying in the later stage of RH treatment; the molten steel after RH treatment is first subjected to soft argon blowing to ensure uniform composition and sufficient floating of inclusions for more than 15 minutes, and then allowed to stand and steel is added, wherein the standing time is no less than 15 minutes; (5) Continuous casting: electromagnetic stirring and light pressure are used to ensure the quality of the casting; (6) Heating process: The slab is cold loaded into the furnace, the furnace time is not less than 300 min, and the furnace temperature is 1250°C; (7) Hot rolling process: The starting rolling temperature of the slab rough rolling is 1230±15℃. Considering the thinness of the steel plate, two-stage controlled rolling is not adopted. The final rolling temperature of the steel plate is set at 900±15℃. After rolling, the steel plate is not cooled under controlled conditions, but is cooled naturally in the air.

3. The method for preparing the rare earth treated hot rolled armor steel plate according to claim 1, Features: The chemical composition of the steel plate in mass percentage is: C: 0.24%, Si: 0.34%, Mn: 0.99%, P: 0.003%, S: 0.005%, Ni: 0.79%, Cr: 1.21%, Mo: 0.33%, Nb: 0.024%, Ti: 0.037%, B: 0.0013%, Al: 0.045%, Ce: 0.0030%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

4. The method for preparing the rare earth treated hot rolled armor steel plate according to claim 1, Features: The chemical composition of the steel plate in mass percentage is: C: 0.29%, Si: 0.34%, Mn: 0.99%, P: 0.003%, S: 0.005%, Ni: 0.78%, Cr: 1.21%, Mo: 0.33%, Nb: 0.027%, Ti: 0.033%, B: 0.0013%, Al: 0.045%, Ce: 0.0060%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

5. The method for preparing the rare earth treated hot rolled armor steel plate according to claim 1, Features: The chemical composition of the steel plate in mass percentage is: C: 0.25%, Si: 0.34%, Mn: 0.99%, P: 0.003%, S: 0.005%, Ni: 0.79%, Cr: 1.90%, Mo: 0.32%, Nb: 0.021%, Ti: 0.029%, B: 0.0011%, Al: 0.045%, Ce: 0.0090%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

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