Low-temperature tempering method for improving performance of bulletproof steel

Abstract

The invention discloses a low-temperature tempering method for improving the performance of bulletproof steel, which comprises the following steps: heating at the temperature of 1250 + / -15 DEG C to reach a complete austenitizing temperature, so that the slab structure is completely austenitized; the finish rolling temperature of laboratory hot rolling is 900 + / -15 DEG C, it is guaranteed that finish rolling is conducted in a completely non-recrystallization temperature area, recrystallization growth of austenite is avoided, crystal grains are lengthened and fragmented, and then uniform and fine austenite crystal grains are obtained; and the heat treatment quenching temperature is 870 + / -10 DEG C, heat preservation is conducted for 20-40 min, the tempering temperature is 150-220 DEG C, heat preservation is conducted for 60-80 min, and finally the low-temperature tempered martensite structure is obtained. According to the low-temperature tempering method for improving the performance of the bulletproof steel, the quenching and low-temperature tempering heat treatment technology is adopted, so that the steel obtains a low-temperature tempered martensite structure and good obdurability cooperation, and it is guaranteed that the best bulletproof steel performance is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of bulletproof steel, and in particular relates to a low-temperature tempering method for improving the performance of bulletproof steel. Background Art

[0002] Patent 1, application number 201510539848.6, discloses a bulletproof steel plate with a tensile strength of 2000MPa and a Brinell hardness of 600, and also provides a method for manufacturing the bulletproof steel plate. The bulletproof steel plate described in the invention has a tensile strength of 2000MPa and a Brinell hardness of 600. Through alloy element design + reasonable manufacturing process, a bulletproof steel plate with ultra-high tensile strength and Brinell hardness is obtained, but its heat treatment process is not described in detail.

[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 method provided by the present invention is quenching + low-temperature tempering, the process is simpler, and the steel plate produced has excellent performance.

[0004] Reference 3 analyzes the effects of different heat treatment processes on the microstructure and mechanical properties of 40CrMnSi-MoV steel, and proposes a heat treatment process suitable for bulletproof helmets. By adjusting the process and appropriately reducing the strength, a higher impact toughness is obtained, thereby meeting the performance requirements of bulletproof helmets. However, this method is not suitable for high-strength bulletproof steel.

[0005] The control of microstructure has a significant impact on the anti-ballistic performance of armored steel plates. Under the same hardness, different heat treatment processes and thermal processing processes will produce different microstructures, which will affect the anti-ballistic performance of armored steel. Summary of the invention

[0006] The purpose of the present invention is to provide a low-temperature tempering method for improving the performance of bullet-proof steel. The heat treatment process of quenching + low-temperature tempering is adopted to make the steel obtain a low-temperature tempered martensite structure and a good combination of strength and toughness, thereby ensuring the best anti-ballistic performance.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The present invention provides a low temperature tempering method for improving the performance of bulletproof steel, comprising:

[0009] The heating temperature is 1250±15℃, reaching the complete austenitization temperature, so that the slab structure is completely austenitized;

[0010] The final rolling temperature of laboratory hot rolling is 900±15℃, which ensures that the finishing rolling is carried out in the completely non-recrystallization temperature region, so that the austenite will not recrystallize and grow, but the grains will be elongated and fragmented, thereby obtaining uniform and fine austenite grains;

[0011] The heat treatment quenching temperature is 870±10℃, and the heat preservation time is 20-40min. The tempering temperature is 150-220℃, and the heat preservation time is 60-80min. Finally, the low-temperature tempered martensite structure is obtained.

[0012] Furthermore, the chemical composition of the bulletproof steel in mass percentage is: C: ≤0.47%, Si: ≤0.70%, Mn ≤1.0%, P: ≤0.010%, S: ≤0.005%, Ni ≤3.0%, Cr ≤1.5%, Mo ≤0.7%, B ≤0.005%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0013] Furthermore, the chemical composition of the steel plate in mass percentage is: C: 0.40%, Si: 0.25%, Mn: 0.45%, P: 0.003%, S: 0.005%, Ni: 0.64%, Cr: 0.85%, Mo: 0.30%, Nb: 0.060%, Ti: 0.013%, B: 0.0014%, Al: 0.045%, Ce: 0.0030%, and the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

[0014] Furthermore, the chemical composition of the steel plate in mass percentage is: C: 0.40%, Si: 0.25%, Mn: 0.45%, P: 0.003%, S: 0.005%, Ni: 0.64%, Cr: 0.85%, Mo: 0.30%, Nb: 0.060%, Ti: 0.013%, B: 0.0014%, Al: 0.045%, Ce: 0.0060%, and the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

[0015] Furthermore, the chemical composition of the steel plate in mass percentage is: C: 0.40%, Si: 0.25%, Mn: 0.45%, P: 0.003%, S: 0.005%, Ni: 0.64%, Cr: 0.85%, Mo: 0.30%, Nb: 0.060%, Ti: 0.013%, B: 0.0014%, Al: 0.045%, Ce: 0.0090%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0016] Furthermore, a low temperature tempered martensite structure is finally obtained.

[0017] Furthermore, after treatment, the impact energy at -40°C is greater than 20J.

[0018] Compared with the prior art, the beneficial technical effects of the present invention are:

[0019] The present invention improves the microstructure of the steel material through a low-temperature tempering process, thereby achieving high strengthening, high toughness and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be further described below in conjunction with the accompanying drawings.

[0021] Figure 1 For example 1 organization;

[0022] Figure 2 For Example 2 organization;

[0023] Figure 3 Organized as in Example 3. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below in conjunction with specific embodiments.

[0025] Embodiment 1:

[0026] (1) The embodiment includes the following chemical compositions in weight percentage: C: 0.40%, Si: 0.25%, Mn: 0.45%, P: 0.003%, S: 0.005%, Ni: 0.64%, Cr: 0.85%, Mo: 0.30%, Nb: 0.060%, Ti: 0.013%, B: 0.0014%, Al: 0.045%, Ce: 0.0030%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%. (2) The high-strength and high-toughness steel plate is smelted and cast in a laboratory vacuum smelting furnace → hot rolled in a laboratory rolling mill → quenched in a laboratory → tempered at a low temperature in a laboratory.

[0027] (3) The heating temperature is 1250±15℃ to reach the complete austenitizing temperature, so that the slab structure is completely austenitized.

[0028] (4) The final rolling temperature of laboratory hot rolling is 900±15℃, which ensures that the finishing rolling is carried out in the completely non-recrystallization temperature region, so that the austenite will not recrystallize and grow, but the grains will be elongated and fragmented, thereby obtaining uniform and fine austenite grains.

[0029] (5) Heat treatment: quenching temperature is 870±10℃, holding temperature is 30min, tempering temperature is 150℃, holding temperature is 60min, and finally low-temperature tempered martensite structure is obtained.

[0030] Embodiment 2:

[0031] (1) The embodiment includes the following chemical components in weight percentage: C: 0.40%, Si: 0.25%, Mn: 0.45%, P: 0.003%, S: 0.005%, Ni: 0.64%, Cr: 0.85%, Mo: 0.30%, Nb: 0.060%, Ti: 0.013%, B: 0.0014%, Al: 0.045%, Ce: 0.0060%, and the rest are Fe and unavoidable impurities, with a total mass fraction of 100%.

[0032] (2) The high-strength and high-toughness steel plates are smelted and cast in a laboratory vacuum smelting furnace → hot rolled on a laboratory rolling mill → quenched in the laboratory → tempered at a low temperature in the laboratory.

[0033] (3) The heating temperature is 1250±15℃ to reach the complete austenitizing temperature, so that the slab structure is completely austenitized.

[0034] (4) The final rolling temperature of laboratory hot rolling is 900±15℃, which ensures that the finishing rolling is carried out in the completely non-recrystallization temperature region, so that the austenite will not recrystallize and grow, but the grains will be elongated and fragmented, thereby obtaining uniform and fine austenite grains.

[0035] (5) Heat treatment: quenching temperature is 870±10℃, holding temperature is 30min, tempering temperature is 180℃, holding temperature is 60min, and finally low-temperature tempered martensite structure is obtained.

[0036] Embodiment 3:

[0037] (1) The embodiment includes the following chemical components in weight percentage: C: 0.40%, Si: 0.25%, Mn: 0.45%, P: 0.003%, S: 0.005%, Ni: 0.64%, Cr: 0.85%, Mo: 0.30%, Nb: 0.060%, Ti: 0.013%, B: 0.0014%, Al: 0.045%, Ce: 0.0090%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

[0038] (2) The high-strength and high-toughness steel plates are smelted and cast in a laboratory vacuum smelting furnace → hot rolled on a laboratory rolling mill → quenched in the laboratory → tempered at a low temperature in the laboratory.

[0039] (3) The heating temperature is 1250±15℃ to reach the complete austenitizing temperature, so that the slab structure is completely austenitized.

[0040] (4) The final rolling temperature of laboratory hot rolling is 900±15℃, which ensures that the finishing rolling is carried out in the completely non-recrystallization temperature region, so that the austenite will not recrystallize and grow, but the grains will be elongated and fragmented, thereby obtaining uniform and fine austenite grains.

[0041] (5) Heat treatment: quenching temperature 870±10℃, holding temperature 30min, tempering temperature 220℃, holding temperature 60-80min, finally obtaining low temperature tempered martensite structure.

[0042] The mechanical properties of each embodiment are shown in Table 1, and the anti-ballistic properties are shown in Table 2.

[0043] Table 1 Mechanical properties of steel plates

[0044]

[0045] Table 2 Anti-ballistic properties of steel plates

[0046]

[0047]

[0048] 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 low temperature tempering method for improving the performance of bulletproof steel, characterized in that: include: The heating temperature is 1250±15℃, reaching the complete austenitization temperature, so that the slab structure is completely austenitized; The final rolling temperature of laboratory hot rolling is 900±15℃, which ensures that the finishing rolling is carried out in the completely non-recrystallization temperature region, so that the austenite will not recrystallize and grow, but the grains will be elongated and fragmented, thereby obtaining uniform and fine austenite grains; The heat treatment quenching temperature is 870±10℃, and the heat preservation time is 20-40min. The tempering temperature is 150-220℃, and the heat preservation time is 60-80min. Finally, the low-temperature tempered martensite structure is obtained.

2. The low temperature tempering method for improving the performance of bulletproof steel according to claim 1, characterized in that: The chemical composition of the bulletproof steel in mass percentage is: C: ≤0.47%, Si: ≤0.70%, Mn ≤1.0%, P: ≤0.010%, S: ≤0.005%, Ni ≤3.0%, Cr ≤1.5%, Mo ≤0.7%, B ≤0.005%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

3. The low temperature tempering method for improving the performance of bulletproof steel according to claim 2, characterized in that: The chemical composition of the steel plate in mass percentage is: C: 0.40%, Si: 0.25%, Mn: 0.45%, P: 0.003%, S: 0.005%, Ni: 0.64%, Cr: 0.85%, Mo: 0.30%, Nb: 0.060%, Ti: 0.013%, B: 0.0014%, Al: 0.045%, Ce: 0.0030%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

4. The low temperature tempering method for improving the performance of bulletproof steel according to claim 2, characterized in that: The chemical composition of the steel plate in mass percentage is: C: 0.40%, Si: 0.25%, Mn: 0.45%, P: 0.003%, S: 0.005%, Ni: 0.64%, Cr: 0.85%, Mo: 0.30%, Nb: 0.060%, Ti: 0.013%, B: 0.0014%, Al: 0.045%, Ce: 0.0060%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

5. The low temperature tempering method for improving the performance of bulletproof steel according to claim 2, characterized in that: The chemical composition of the steel plate in mass percentage is: C: 0.40%, Si: 0.25%, Mn: 0.45%, P: 0.003%, S: 0.005%, Ni: 0.64%, Cr: 0.85%, Mo: 0.30%, Nb: 0.060%, Ti: 0.013%, B: 0.0014%, Al: 0.045%, Ce: 0.0090%, and the rest is Fe and unavoidable impurities, with a total mass fraction of 100%.

6. The low temperature tempering method for improving the performance of bulletproof steel according to claim 1 or 2, characterized in that: Finally, a low temperature tempered martensite structure is obtained.

7. The low temperature tempering method for improving the performance of bulletproof steel according to claim 1, characterized in that: After treatment, the impact energy at -40℃ is greater than 20J.

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