CN113528975B - Steel for shield, preparation method of steel, shield and preparation method of shield - Google Patents

Abstract

The invention provides steel for a shield, a preparation method thereof, the shield and a preparation method thereof, wherein the steel for the shield comprises the following chemical components in percentage by mass: c: 0.001-0.03%; p is less than or equal to 0.01 percent, S is less than or equal to 0.005 percent, Ni: 12-13.5%, Mo: 5.5-7%, Co: 7.5-9%, Ti: 1.25-1.45%, and the balance of Fe and inevitable impurities. The tensile strength of the shield provided by the invention is 2200-2390MPa, the strength is high, the bulletproof performance is better, and the cracking problem does not occur in the deformation process.

Description

Steel for shield and preparation method thereof, shield and preparation method thereof

Technical Field

The invention belongs to the technical field of shield preparation, and particularly relates to steel for a shield, a preparation method of the steel, the shield and the preparation method of the shield.

Background

Shields in the prior art are mainly divided into steel shields and non-steel shields, wherein the light shields are mainly made of non-steel materials, such as aramid fibers and PE, and have the defects of low protection level and poor multi-bullet continuous impact resistance. The steel shield is mainly used for producing a wheel type shield or a combined shield, and has thick thickness and poor maneuverability due to low strength level. The invention provides a steel shield, which adopts special component design and production process to improve the strength grade of a bulletproof material to over 2200MPa, so that the bulletproof performance is greatly improved; meanwhile, the steel shield product provided by the invention has the advantages of strong multi-bomb continuous impact resistance, strong environmental adaptability and long service cycle.

Disclosure of Invention

The invention provides steel for a shield, a preparation method of the steel, the shield and the preparation method of the shield, and aims to solve the technical problems of low shield strength and poor bulletproof performance in the technology.

On one hand, the invention provides steel for shields, which comprises the following chemical components in percentage by mass:

c: 0.001-0.03%; p is less than or equal to 0.01 percent, S is less than or equal to 0.005 percent, Ni: 12-13.5%, Mo: 5.5-7%, Co: 7.5-9%, Ti: 1.25-1.45%, and the balance of Fe and inevitable impurities.

Further, the thickness of the steel for the shield is 2.0-6.0 mm.

In still another aspect, the present invention provides a method for preparing steel for shields, the method comprising,

obtaining a plate blank; the slab comprises the following chemical components in percentage by mass: c: 0.001-0.03%; p is less than or equal to 0.01 percent, S is less than or equal to 0.005 percent, Ni: 12-13.5%, Mo: 5.5-7%, Co: 7.5-9%, Ti: 1.25-1.45%, and the balance of Fe and inevitable impurities;

heating, rough rolling, finish rolling and coiling the plate blank to obtain steel for a shield; the finish rolling starting temperature is 1100-1160 ℃, the finish rolling finishing temperature is 830-880 ℃, and the coiling temperature is 650-750 ℃.

Further, the heating temperature is 1220-.

In a third aspect, the present invention provides a method for preparing a shield, the method comprising,

carrying out first heating, pressing, first cooling, second heating and second cooling on the steel for the shield to obtain the shield; the pressing starting temperature is 650-840 ℃, the pressing ending temperature is 420-680 ℃, and the pressing time is 22-40 s.

Further, in the first heating, the heating temperature is 800-.

Further, the first cooling is air cooling, and the first cooling finishing temperature is 10-60 ℃.

Further, in the second heating, the heating temperature is 420-.

Further, the second cooling is air cooling, and the second cooling end temperature is 10-60 ℃.

In a fourth aspect, the invention also provides a shield made of steel for a shield of the kind described above.

One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

the invention provides steel for a shield, a preparation method thereof, the shield and the preparation method thereof, wherein the steel for the shield has the chemical composition characteristics of ultralow carbon, low phosphorus and low sulfur, elements with high nickel, high molybdenum, high cobalt and high titanium are added to improve the material strength, conventional solid solution strengthening elements such as manganese, silicon and the like are not added, and nickel, molybdenum, cobalt and titanium can be precipitated and strengthened in the subsequent shield manufacturing process of the steel for the shield, so that the strength of the shield is improved. The tensile strength of the shield provided by the invention is 2200-2390MPa, the strength is high, the bulletproof performance is better, and the cracking problem does not occur in the deformation process.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

FIG. 1 is a metallographic structure diagram of a shield according to an embodiment of the present invention.

Detailed Description

The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.

Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.

Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.

It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

In order to solve the technical problems, the embodiment of the invention provides the following general ideas:

on one hand, the embodiment of the invention provides steel for shields, which comprises the following chemical components in percentage by mass:

c: 0.001 to 0.03 percent; p is less than or equal to 0.01 percent, S is less than or equal to 0.005 percent, Ni: 12-13.5%, Mo: 5.5-7%, Co: 7.5-9%, Ti: 1.25-1.45%, and the balance of Fe and inevitable impurities.

In the present invention, the effects of the respective elements are as follows:

carbon: the invention adopts the design of an ultra-low carbon component system, avoids large-size cementite from reducing the toughness and the protective performance of the material, and controls the content of carbon element to be 0.001-0.03%.

Phosphorus and sulfur: phosphorus and sulfur are impurities in steel, and have adverse effects on the toughness and the shaping of the material, and the less the phosphorus and the sulfur, the better. In the invention, the content of phosphorus is limited to 0.004%, and the content of sulfur is limited to 0.01%.

Ni: the Ni element has the function of improving the strength and the corrosion resistance of the material, and the strength of the material is improved to 2200MPa by adding high Ni, so that high protection performance is obtained. However, since the Ni element alloy is expensive, the upper limit of the addition is controlled to reduce the alloy cost.

Mo: the invention improves the material strength by means of the solid solution strengthening, precipitation strengthening and phase change effects of Mo element. Meanwhile, the addition of high Mo plays an important role in refining the final martensite structure.

Co: the Co, Ni and Mo in the invention jointly play a role in precipitation strengthening, but because the alloy price is higher, the addition amount should be controlled.

Titanium: in the present invention, the titanium element acts as solid solution strengthening, and since there is not enough C element in the steel to combine with Ti to produce TiC, Ti exists mainly in a solid solution state in the steel, and has a solid solution strengthening effect. Because the alloy price of Ti element is low, the invention adds high titanium, and the element range is controlled to be 1.25-1.45%.

As an implementation mode of the embodiment of the invention, the thickness of the steel for the shield is 2.0-6.0 mm.

In another aspect, the embodiment of the invention also provides a preparation method of the steel for the shield, which comprises the following steps,

s1, obtaining a plate blank; the slab comprises the following chemical components in percentage by mass: c: 0.001-0.03%; p is less than or equal to 0.01 percent, S is less than or equal to 0.005 percent, Ni: 12-13.5%, Mo: 5.5-7%, Co: 7.5-9%, Ti: 1.25-1.45%, and the balance of Fe and inevitable impurities;

s2, heating, rough rolling, finish rolling and coiling the plate blank to obtain steel for a shield; the finish rolling starting temperature is 1220-1280 ℃, the finish rolling starting temperature is 1100-1160 ℃, the finish rolling finishing temperature is 830-880 ℃, and the coiling temperature is 650-750 ℃.

The finish rolling initial rolling temperature is too high, the structure is thick, and the smooth rolling process is not facilitated due to too low structure; the finish rolling finishing temperature is too high, so that the structure is thick, the finish rolling finishing temperature is too low, the rolling difficulty is high, and the strength is too high to be beneficial to subsequent uncoiling and straightening; and the coiled flat coil can be caused by overhigh coiling temperature, and the flat straightening can not be realized due to overhigh strip steel strength caused by overlow coiling temperature.

As an implementation manner of the embodiment of the present invention, the heating temperature is 1220-1280 ℃. The heating temperature is too high, the surface of the casting blank is seriously burnt, the original structure is thick, the heating temperature is too low, and the alloy can not be fully dissolved and homogenized.

In practice, the steel for shields can also be produced using hot continuous rolling, continuous casting and continuous rolling or cold rolling processes.

In a third aspect, embodiments of the present invention further provide a method for preparing a shield, the method including,

and carrying out first heating, pressing, first cooling, second heating and second cooling on the steel for the shield to obtain the steel for the shield.

Because the steel for the shield is stored in the form of hot rolled coils or cold rolled coils, before the first heating, the steel for the shield is straightened, flattened and transversely cut to obtain a flattened plate, and then the flattened plate is cut by plasma or laser according to the shape of the shield shell for blanking. And carrying out primary heating on the blanked steel plate. The first heating can be carried out in a heating furnace, the steel plate is discharged from the furnace after the first heating is finished to the conveying stage of the start of the pressing, and the steel plate is naturally cooled by air.

Wherein the pressing starting temperature is 650-840 ℃, the pressing ending temperature is 420-680 ℃, and the pressing time is 22-40 s. And the pressing is to put the heated steel plate into a shield pressing mould for pressing to form the target shield. Too low a press-forming start temperature makes it difficult to form the product and lowers the dimensional accuracy of the formed product; the pressing starting temperature is determined according to the heating temperature and the temperature reduction in the conveying process. Too high pressing finishing temperature can cause too short pressing time and difficult guarantee of the size precision of the shield; the pressing finishing temperature is too low, the pressing time is too long, and the production efficiency is reduced. Good dimensional accuracy can be guaranteed by controlling the pressing time, and the dimensional accuracy is difficult to guarantee due to the excessively short pressing time; the pressing time is too long, which affects the production efficiency.

As an implementation manner of the embodiment of the invention, in the first heating, the heating temperature is 800-. The heating temperature is too high, the heat preservation time is too long, crystal grains are easy to be large, and the strength of the shield is reduced; the heating temperature is too low, the heat preservation time is too short, and alloy elements cannot be fully dissolved, so that the strengthening effect is lost, and the strength of the shield is reduced.

In one embodiment of the present invention, the first cooling is air cooling, and the first cooling end temperature is 10 to 60 ℃.

As an implementation manner of the embodiment of the invention, in the second heating, the heating temperature is 420-. The precipitation of Ni, Mo, Co and Ti alloy elements is strengthened by long-time heating and heat preservation treatment, and the strength of the material beyond the temperature range and the heat preservation time range is greatly reduced. And discharging the shield subjected to the second heating, naturally cooling the shield by air, and cooling to room temperature to obtain a steel shield finished product.

In one embodiment of the present invention, the second cooling is air cooling, and the second cooling end temperature is 10 to 60 ℃.

The shield can be naturally cooled without air cooling or water cooling, so that the size precision and the industrial applicability of the shield are ensured

In a fourth aspect, based on the same inventive concept, embodiments of the present invention further provide a shield made of one of the above-mentioned steels for shields.

The steel for shield and the method for producing the same, the shield and the method for producing the same according to the present invention will be described in detail with reference to examples, comparative examples and experimental data.

Example 1

Embodiment 1 provides a shield preparation method, which comprises the following specific steps:

1. smelting in a converter to obtain qualified molten steel, wherein the molten steel comprises the following chemical components in percentage by mass: specifically, as shown in table 1, the balance is iron and inevitable impurities.

2. The production of the steel coil is carried out by adopting a hot continuous rolling process to obtain the steel hot coil for the shield, wherein the hot continuous rolling process comprises the following steps: the heating temperature, the finish rolling start temperature, the finish rolling end temperature, and the coiling temperature are shown in Table 2.

3. Straightening, flattening and transversely cutting the steel hot coil for the shield to obtain a flattening plate.

4. And (5) cutting and blanking by adopting plasma according to the shape of the shield shell through the opening plate.

5. And (3) heating the blanked steel plate for the first time, wherein the technological parameters of the first heating are shown in the table 2.

6. Putting the steel plate after the first heating into a shield press-forming die for press-forming to a target shield shell shape; the process parameters in the press forming are shown in table 2. Wherein, the steel plate is naturally cooled by air in the conveying stage from the discharging of the steel plate to the beginning of the pressing.

7. And naturally cooling the pressed shield to room temperature in the air.

8. And (4) carrying out secondary heating on the shield shell cooled to the room temperature in the step (7), wherein the technological parameters of the secondary heating are shown in the table 2.

9. And (4) discharging the shield subjected to the second heating, naturally cooling the air, and cooling to room temperature to obtain the shield.

Examples 2 to 6

Embodiments 2 to 6 provide a shield preparation method, comprising the following steps:

1. smelting by adopting an electric furnace to obtain qualified molten steel, wherein the molten steel comprises the following chemical components in percentage by mass: specifically, as shown in table 1, the balance is iron and inevitable impurities.

2. And producing the steel for the shield by adopting a continuous casting and rolling process.

3. And (3) straightening, flattening and transversely cutting the hot rolled coil prepared in the step (2) to obtain a flattened plate.

4. And cutting the flat plate into blanks by laser according to the shape of the shield shell.

5. And (3) heating the blanked steel plate for the first time, wherein the technological parameters of the first heating are shown in table 3.

6. Putting the steel plate after the first heating into a shield press-forming die for press-forming to a target shield shell shape; the process parameters in the profiling are shown in table 3. Wherein, the steel plate is naturally cooled by air in the conveying stage from the discharging of the steel plate to the beginning of the pressing.

7. And naturally cooling the pressed shield to room temperature in the air.

8. And (3) carrying out secondary heating on the shield shell cooled to the room temperature in the step (7), wherein the technological parameters of the secondary heating are shown in the table 3.

9. And (4) discharging the shield subjected to the second heating, naturally cooling the air, and cooling to room temperature to obtain the shield.

TABLE 1

Numbering	C/％	P/％	S/％	Ni/％	Mo/％	Co/％	Ti/％
								Example 1	0.003	0.09	0.002	13.5	5.8	7.5	1.25
Example 2	0.007	0.06	0.003	12.0	6.5	8.0	1.28
								Example 3	0.013	0.08	0.002	13.0	5.9	8.5	1.45
Example 4	0.018	0.07	0.002	13.2	7.0	7.5	1.38
								Example 5	0.022	0.10	0.002	12.5	6.5	8.2	1.33
Example 6	0.03	0.09	0.003	12.6	5.5	7.7	1.42

TABLE 2

Numbering	Heating temperature/. degree.C	Starting temperature of finish rolling/. degree.C	Finish rolling finishing temperature/. degree.C	Coiling temperature/. degree.C	Thickness/mm of hot coil
						Example 1	1230	1130	845	665	2
Example 2	1250	1140	856	670	4
						Example 3	1268	1155	865	685	6
Example 4	1275	1158	870	710	5
						Example 5	1245	1135	850	700	3
Example 6	1225	1122	833	655	2.5

TABLE 3

TABLE 4

Numbering	Tensile strength/MPa	Appearance of the product
			Example 1	2200	Is not cracked
Example 2	2250	Is not cracked
			Example 3	2360	Is not cracked
Example 4	2390	Is not cracked
			Example 5	2320	Is not cracked
Example 6	2260	Is not cracked

As can be seen from Table 4, the tensile strength of the shields prepared in examples 1-6 is 2200-2390MPa, the strength is high, the bulletproof performance is better, and the cracking problem does not occur in the deformation process.

As can be seen from the figure 1, the metallographic structure of the shield is a pure martensite structure, and the shield has good tensile strength and good bulletproof effect by combining precipitation of a large amount of alloy elements in the second heating process.

According to the invention, a shield is obtained by component design and adopting a two-step heating method in combination with air cooling and pressing, and the temperature interval and time of each production link are strictly limited, so that the target mechanical property and protective property are ensured to be obtained; compared with the traditional process of water quenching after hot forming, the method has higher strength and no cracking, and the production method has the characteristic of easy realization of industry. The shield provided by the invention has the tensile strength of 2200-2390MPa, high strength, better bulletproof performance and no cracking problem in the deformation process.

Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (3)

1. A shield, characterized in that the shield is prepared by a method comprising:

carrying out first heating, pressing, first cooling, second heating and second cooling on the steel for the shield to obtain the shield; the pressing starting temperature is 650-840 ℃, the pressing finishing temperature is 420-680 ℃, and the pressing time is 22-40 s;

in the first heating, the heating temperature is 800-;

the first cooling is air cooling, and the finishing temperature of the first cooling is 10-60 ℃;

in the second heating, the heating temperature is 420-;

the second cooling is air cooling, and the finishing temperature of the second cooling is 10-60 ℃;

the steel for the shield comprises the following chemical components in percentage by mass:

c: 0.001-0.03%; p is less than or equal to 0.01 percent, S is less than or equal to 0.005 percent, Ni: 12-13.5%, Mo: 5.5-7%, Co: 7.5-9%, Ti: 1.25-1.45%, and the balance of Fe and inevitable impurities;

the preparation method of the steel for the shield comprises the following steps:

obtaining a plate blank;

heating, rough rolling, finish rolling and coiling the plate blank to obtain steel for a shield; the finish rolling starting temperature is 1100-1160 ℃, the finish rolling finishing temperature is 830-880 ℃, and the coiling temperature is 650-750 ℃.

2. A shield according to claim 1, wherein the thickness of the steel for shields is 2.0-6.0 mm.

3. A shield according to claim 1, wherein the slab heating temperature is 1220-.

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