High-strength steel and casting process thereof

Abstract

The invention relates to the technical field of metal material processing, and provides high-strength steel and a casting process thereof, and the high-strength steel comprises the following components in percentage by weight: 0.26%-0.29% of C, 0.8%-1.0% of Si, 0.8%-1.0% of Mn, less than or equal to 0.02% of P, less than or equal to 0.02% of S, 0.9%-1.1% of Cr, 1.9%-2.2% of Ni, 0.35%-0.45% of Mo, 0.005%-0.015% of Al, 0.06%-0.08% of V, less than or equal to 3 * 10 <-4 >% of Ca + Zr, less than or equal to 0.86% of CE and the balance of Fe and other inevitable impurities. Through the technical scheme, the problems of low tensile strength and low elongation of high-strength steel in related technologies are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material processing, and in particular to high-strength steel and a casting process thereof. Background Art

[0002] High-strength steel is a type of steel with high yield strength and tensile strength. Compared with traditional ordinary carbon steel, high-strength steel has higher strength and hardness while still maintaining good plasticity and toughness. Therefore, high-strength steel has a wide range of applications and can be used in the fields of automobiles, aerospace, bridge construction and shipbuilding.

[0003] With the advancement of technology, all walks of life have put forward higher requirements on the performance of high-strength steel. In order to meet the requirements of modern industry for the performance of high-strength steel, it is necessary to develop a high-strength steel with high tensile strength and high elongation to improve the performance, safety and economic benefits of the product, etc., to meet the needs of modern industry for the performance of high-strength steel. Summary of the invention

[0004] The present invention provides a high-strength steel and a casting process thereof, which solves the problem of low tensile strength and elongation of high-strength steel in the related art.

[0005] The technical solution of the present invention is as follows: The present invention provides a high-strength steel, which is composed of the following components by weight percentage: C 0.26%~0.29%, Si 0.8%~1.0%, Mn 0.8%~1.0%, P≤0.02%, S≤0.02%, Cr 0.9%~1.1%, Ni 1.9%~2.2%, Mo 0.35%~0.45%, Al 0.005%~0.015%, V 0.06%~0.08%, Ca+Zr≤3×10 -4 %, CE≤0.86%, and the rest are Fe and other inevitable impurities.

[0006] As a further technical solution, 1≤Zr / Ca≤5.

[0007] As a further technical solution, the Zr / Ca=3.

[0008] As a further technical solution, the 1.4≤(Cr+Al+V+Ni) / (Mn+Si)≤2.1.

[0009] The present invention finds that the ratio of (Cr+Al+V+Ni) to (Mn+Si) affects the tensile strength and elongation of high-strength steel. When 1.4≤(Cr+Al+V+Ni) / (Mn+Si)≤2.1, it can help improve the tensile strength and elongation of high-strength steel.

[0010] As a further technical solution, the (Cr+Al+V+Ni) / (Mn+Si)=1.8.

[0011] As a further technical solution, the 1.8≤(Cr+Al) / (V+Ni)≤2.4.

[0012] The present invention finds that when 1.4≤(Cr+Al+V+Ni) / (Mn+Si)≤2.1 is further limited to 1.8≤(Cr+Al) / (V+Ni)≤2.4, the tensile strength and elongation of high-strength steel can be further improved.

[0013] As a further technical solution, the (Cr+Al) / (V+Ni)=2.1.

[0014] The present invention also provides a high-strength steel casting process, comprising the following steps: S1, after preparing the ingredients, smelting to obtain an ingot; S2, the ingot is subjected to rough rolling and finish rolling to obtain a billet; S3. After normalizing, quenching and tempering the blank, high-strength steel is obtained.

[0015] As a further technical solution, the normalizing in S3 is divided into two stages, the first stage normalizing is high temperature normalizing, and the second stage normalizing is conventional normalizing. The temperature of the high temperature normalizing is 950°C, and the temperature of the conventional normalizing is 900°C.

[0016] As a further technical solution, the heating rate of the blank to the first stage high temperature normalizing temperature is 20-40°C / s.

[0017] As a further technical solution, the heating rate of the blank to the first stage high temperature normalizing temperature is 30°C / s.

[0018] As a further technical solution, the cooling rate from the high temperature normalizing temperature to the conventional normalizing temperature is 3-6°C / s.

[0019] As a further technical solution, the cooling rate from the high temperature normalizing temperature to the conventional normalizing temperature is 5°C / s.

[0020] The present invention finds that the heating rate of the first-stage normalizing temperature and the cooling rate of the second-stage normalizing temperature have a great influence on the tensile strength and elongation of high-strength steel. When the heating rate of the first-stage normalizing temperature is 30°C / s and the cooling rate of the second-stage normalizing temperature is 5°C / s, they are combined with the components in the high-strength steel to better improve the tensile strength and elongation of the high-strength steel.

[0021] As a further technical solution, the quenching in S3 is oil quenching, and the temperature of the oil quenching is 900°C.

[0022] As a further technical solution, the tempering in S3 is divided into two stages, the tempering temperature in the first stage is 150°C, and the tempering temperature in the second stage is 150°C.

[0023] As a further technical solution, the time of the first stage high temperature normalizing in S3 is 1 to 4 hours, and the time of the second stage conventional normalizing is 1 to 4 hours.

[0024] As a further technical solution, the oil quenching time in S3 is 5 to 10 hours.

[0025] As a further technical solution, the time for the first stage tempering and the time for the second stage tempering in S3 are each independently 10 to 15 hours.

[0026] The present invention uses a high and a low normalizing treatment to lay a good foundation for the quenching structure transformation, effectively guarantee the quenching effect, improve the quality of the quenching structure, and limit the first stage normalizing treatment to 950°C and then to 900°C for the second stage normalizing treatment, which can further improve the tensile strength and elongation of the high-strength steel. Two temperings at 150°C are also carried out, which also further improves the tensile strength and elongation of the high-strength steel.

[0027] The working principle and beneficial effects of the present invention are: In the present invention, by reasonably limiting and optimizing the components in the high-strength steel and the proportion of each component, the elements such as C, Si, Mn, P, S, Ni, Al, Ca, Zr, etc. are coordinated with each other, so that the tensile strength and elongation of the high-strength steel can be further improved. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1 A high-strength steel consisting of the following components, measured by weight: C 0.26%, Si 0.8%, Mn 0.8%, P 0.01%, S 0.01%, Cr 0.9%, Ni 1.9%, Mo 0.35%, Al 0.005%, V 0.06%, Ca+Zr 2.2×10-4 %, CE 0.61%, the rest is Fe and other inevitable impurities; among which Zr / Ca=1, (Cr+Al+V+Ni) / (Mn+Si)=1.8, (Ni+V) / (Cr+Al)=2.2; The casting process of high-strength steel includes the following steps: S1, after preparing the ingredients, smelting to obtain an ingot; S2, the ingot is subjected to rough rolling and finish rolling to obtain a slab; S3. The slab is heated to 950°C at a heating rate of 30°C / s for the first stage of high temperature normalizing for 2 hours, then cooled to 900°C at a cooling rate of 5°C / s for the second stage of conventional normalizing for 3 hours, oil quenched at 900°C for 8 hours, then tempered at 150°C for the first time for 12 hours, and then tempered at 150°C for the second time for 12 hours to obtain high-strength steel.

[0030] Example 2 A high-strength steel consisting of the following components, measured by weight: C 0.28%, Si 0.9%, Mn 0.9%, P 0.015%, S 0.015%, Cr 1.0%, Ni 2%, Mo 0.4%, Al0.01%, V 0.07%, Ca+Zr 2.5×10 -4 %, CE 0.72%, and the rest are Fe and other inevitable impurities; among which Zr / Ca=1, (Cr+Al+V+Ni) / (Mn+Si)=1.8, (Ni+V) / (Cr+Al)=2.1.

[0031] The casting process of high-strength steel includes the following steps: S1, after preparing the ingredients, smelting to obtain an ingot; S2, the ingot is subjected to rough rolling and finish rolling to obtain a slab; S3. The slab is heated to 950°C at a heating rate of 20°C / s for the first stage of high temperature normalizing for 1 hour, then cooled to 900°C at a cooling rate of 3°C / s for the second stage of conventional normalizing for 4 hours, oil quenched at 900°C for 5 hours, then tempered at 150°C for the first time for 10 hours, and then tempered at 150°C for the second time for 10 hours to obtain high-strength steel.

[0032] Example 3 A high-strength steel consisting of the following components, measured by weight: C 0.29%, Si 1.0%, Mn 1.0%, P 0.02%, S 0.02%, Cr 1.1%, Ni 2.2%, Mo 0.45%, Al0.015%, V 0.08%, Ca+Zr 3×10-4 %, CE 0.86%, and the rest are Fe and other inevitable impurities; among which Zr / Ca=4, (Cr+Al+V+Ni) / (Mn+Si)=1.7, (Ni+V) / (Cr+Al)=2.0.

[0033] The casting process of high-strength steel includes the following steps: S1, after preparing the ingredients, smelting to obtain an ingot; S2, the ingot is subjected to rough rolling and finish rolling to obtain a slab; S3. The slab is heated to 950°C at a heating rate of 40°C / s for the first stage of high temperature normalizing for 4 hours, then cooled to 900°C at a cooling rate of 6°C / s for the second stage of conventional normalizing for 1 hour, oil quenched at 900°C for 5 hours, then tempered at 150°C for the first time for 10 hours, and then tempered at 150°C for the second time for 10 hours to obtain high-strength steel.

[0034] Example 4 The only difference between this embodiment and embodiment 2 is that Zr / Ca is 3.

[0035] Example 5 The only difference between this embodiment and embodiment 2 is that Zr / Ca is 5.

[0036] Example 6 A high-strength steel consisting of the following components, measured by weight: C 0.28%, Si 0.8%, Mn 0.8%, P 0.015%, S 0.015%, Cr 1.1%, Ni 2.2%, Mo 0.4%, Al0.015%, V 0.08%, Ca+Zr 2.5×10 -4 %, CE 0.72%, the rest is Fe and other inevitable impurities, among which Zr / Ca=1, (Cr+Al+V+Ni) / (Mn+Si)=2.1, (Ni+V) / (Cr+Al)=2.0; The casting process of high-strength steel is the same as that of Example 2.

[0037] Example 7 A high-strength steel consisting of the following components, measured by weight: C 0.28%, Si 1.0%, Mn 1.0%, P 0.015%, S 0.015%, Cr 0.9%, Ni 1.9%, Mo 0.4%, Al0.005%, V 0.06%, Ca+Zr 2.5×10 -4%, CE 0.72%, the rest is Fe and other inevitable impurities, among which Zr / Ca=1, (Cr+Al+V+Ni) / (Mn+Si)=1.4, (Ni+V) / (Cr+Al)=2.2; The casting process of high-strength steel is the same as that of Example 2.

[0038] Example 8 A high-strength steel consisting of the following components, measured by weight: C 0.28%, Si 0.9%, Mn 0.9%, P 0.015%, S 0.015%, Cr 1.1%, Ni 1.9%, Mo 0.4%, Al0.015%, V 0.065%, Ca+Zr 2.5×10 -4 %, CE 0.72%, and the rest are Fe and other inevitable impurities; among which Zr / Ca=3, (Cr+Al+V+Ni) / (Mn+Si)=1.8, (Ni+V) / (Cr+Al)=1.8.

[0039] The casting process of high-strength steel is the same as that of Example 2.

[0040] Example 9 A high-strength steel consisting of the following components, measured by weight: C 0.28%, Si 0.9%, Mn 0.9%, P 0.015%, S 0.015%, Cr 0.9%, Ni 2.1%, Mo 0.4%, Al0.005%, V 0.075%, Ca+Zr 2.5×10 -4 %, CE 0.72%, the rest is Fe and other inevitable impurities; among which Zr / Ca=3, (Cr+Al+V+Ni) / (Mn+Si)=1.8, (Ni+V) / (Cr+Al)=2.4; The casting process of high-strength steel is the same as that of Example 2.

[0041] Example 10 The only difference between this embodiment and embodiment 2 is that the heating rate of the slab to the first stage high temperature normalizing temperature is 30°C / s.

[0042] Embodiment 11 The only difference between this embodiment and embodiment 2 is that the heating rate of the slab to the first stage high temperature normalizing temperature is 40°C / s.

[0043] Example 12 The only difference between this embodiment and embodiment 2 is that the cooling rate from the high-temperature normalizing temperature in the first stage to the conventional normalizing temperature in the second stage is 5°C / s.

[0044] Embodiment 13 The only difference between this embodiment and embodiment 2 is that the cooling rate from the high-temperature normalizing temperature in the first stage to the conventional normalizing temperature in the second stage is 6°C / s.

[0045] Comparative Example 1 A high-strength steel consisting of the following components, measured by weight: C 0.28%, Si 0.9%, Mn 0.9%, P 0.015%, S 0.015%, Cr 1.0%, Ni 2%, Mo 0.4%, Al0.01%, V 0.07%, Ca+Zr 8×10 -4 %, CE 0.72%, the rest is Fe and other inevitable impurities; among which Zr / Ca=1, (Cr+Al+V+Ni) / (Mn+Si)=1.8, (Ni+V) / (Cr+Al)=2.1; The casting process of high-strength steel is the same as that of Example 2.

[0046] Comparative Example 2 A high-strength steel consisting of the following components, measured by weight: C 0.28%, Si 0.9%, Mn 0.9%, P 0.015%, S 0.015%, Cr 1.0%, Ni 2%, Mo 0.4%, Al0.01%, V 0.07%, CE 0.72%, the rest are Fe and other inevitable impurities; among which Zr / Ca=1, (Cr+Al+V+Ni) / (Mn+Si)=1.8, (Ni+V) / (Cr+Al)=2.1; The casting process of high-strength steel is the same as that of Example 2.

[0047] Comparative Example 3 A high-strength steel consisting of the following components, measured by weight: C 0.32%, Si 0.5%, Mn 0.6%, P 0.015%, S 0.015%, Cr 1.0%, Ni 2.8%, Mo 0.4%, Al0.01%, V 0.07%, CE 0.72%, the rest are Fe and other inevitable impurities; The casting process of high-strength steel is the same as that of Example 2.

[0048] Test example The high-strength steel in Examples 1 to 13 and Comparative Examples 1 to 3 were respectively made into specimens with a thickness of 50 mm, and the tensile strength and elongation of the specimens were measured according to the method in GB / T228.1-2021 "Tensile test of metallic materials Part 1: Room temperature test method", and the measurement results are shown in Table 1.

[0049] Table 1 Performance measurement results of high strength steel in Examples 1 to 13 and Comparative Examples 1 to 3

[0050] Compared with Comparative Example 3, Example 2 adds Zr and Ca, and Comparative Example 1 increases the addition amount of Zr and Ca. As a result, the tensile strength and elongation of the high-strength steel in Example 2 are higher than those in Comparative Example 1 and Comparative Example 3. Compared with Comparative Example 2, Example 2 changes the content of some components of the high-strength steel. As a result, the tensile strength and elongation of the high-strength steel in Example 2 are higher than those in Example Comparative Example 2, indicating that the components defined in the present invention can improve the tensile strength and elongation of high-strength steel.

[0051] Compared with Example 2, Examples 4 and 5 change the ratio of Zr to Ca. As a result, the tensile strength and elongation of the high-strength steel in Example 4 are higher than those in Example 1 and Example 5, indicating that when Zr / Ca is 3, the tensile strength and elongation of the high-strength steel can be further improved.

[0052] Compared with Example 2, Examples 6~7 changed the ratio of (Cr+Ti+V+Ni) to (Mn+Si), and Examples 8~9 changed the ratio of (Ni+V) to (Cr+Ti). As a result, the tensile strength and elongation of the high-strength steel in Example 2 were higher than those in Examples 6~9, indicating that when (Cr+Ti+V+Ni) / (Mn+Si)=1.8 and (Ni+V) / (Cr+Ti)=2.1 in the high-strength steel, the tensile strength and elongation of the high-strength steel can be further improved.

[0053] Compared with Example 2, Examples 10-11 change the heating rate of the first-stage high-temperature normalizing temperature, and Examples 12-13 change the cooling rate from the first-stage high-temperature normalizing temperature to the second-stage conventional normalizing temperature. As a result, the tensile strength and elongation of the high-strength steel in Example 10 are higher than those in Example 2 and Example 11, and the tensile strength and elongation of the high-strength steel in Example 12 are higher than those in Example 2 and Example 13, indicating that when the heating rate of the billet to the first-stage high-temperature normalizing temperature is 30°C / s, or the cooling rate from the first-stage high-temperature normalizing temperature to the second-stage conventional normalizing temperature is 5°C / s, it can better cooperate with the components in the high-strength steel to further improve the tensile strength and elongation of the high-strength steel.

[0054] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-strength steel, characterized in that: In terms of weight percentage, it is composed of the following components: C 0.26%~0.29%, Si 0.8%~1.0%, Mn 0.8%~1.0%, P≤0.02%, S≤0.02%, Cr 0.9%~1.1%, Ni 1.9%~2.2%, Mo 0.35%~0.45%, Al 0.005%~0.015%, V 0.06%~0.08%, Ca+Zr≤3×10 -4 %, CE≤0.86%, and the rest are Fe and other inevitable impurities.

2. The high-strength steel according to claim 1, characterized in that: The 1≤Zr / Ca≤5.

3. The high-strength steel according to claim 1, characterized in that: The 1.4≤(Cr+Al+V+Ni) / (Mn+Si)≤2.

1.

4. The high-strength steel according to claim 3, characterized in that: The 1.8≤(Cr+Al) / (V+Ni)≤2.

4.

5. A high-strength steel casting process according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, after preparing the ingredients, smelting to obtain an ingot; S2, the ingot is subjected to rough rolling and finish rolling to obtain a billet; S3. After normalizing, quenching and tempering the blank, high-strength steel is obtained.

6. A high-strength steel casting process according to claim 5, characterized in that: The normalizing in S3 is divided into two stages. The first stage normalizing is high temperature normalizing, and the second stage normalizing is conventional normalizing. The temperature of the high temperature normalizing is 950°C, and the temperature of the conventional normalizing is 900°C.

7. A high-strength steel casting process according to claim 6, characterized in that: The heating rate of the blank to the first stage high temperature normalizing temperature is 20-40°C / s.

8. A high-strength steel casting process according to claim 6, characterized in that: The cooling rate from the high temperature normalizing temperature to the conventional normalizing temperature is 3-6°C / s.

9. A high-strength steel casting process according to claim 5, characterized in that: The quenching in S3 is oil quenching, and the temperature of the oil quenching is 900°C.

10. A high-strength steel casting process according to claim 5, characterized in that: The tempering in S3 is divided into two stages, the tempering temperature in the first stage is 150°C, and the tempering temperature in the second stage is 150°C.

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