Armor Plate With 2000 MPA-Graded Tensile Strength, and Manufacturing Method Therefor

Abstract

A bulletproof steel plate with a tensile strength of 2000 MPa grade and a Brinell Hardness of 600 grade and a manufacturing method thereof, characterized by that the chemical elements in mass percentage thereof being: 0.35-0.45% of C, 0.80-1.60% of Si, 0.3-1.0% of Mn, 0.02-0.06% of Al, 0.3-1.2% of Ni, 0.30-1.00% of Cr, 0.20-0.80% of Mo, 0.20-0.60% of Cu, 0.01-0.05% of Ti, 0.001-0.003% of B, and the balance being Fe and inevitable impurities. The tensile strength of the steel plate can reach a grade of 2000 MPa and its Brinell Hardness can reach a grade of 600.

Claims

1. A bulletproof steel plate with a tensile strength of 2000 MPa grade and a Brinell Hardness of 600 grade, characterized by that the chemical elements in mass percentage thereof being: 0.35-0.45% of C, 0.80-1.60% of Si, 0.3-1.0% of Mn, 0.02-0.06% of Al, 0.3-1.2% of Ni, 0.30-1.00% of Cr, 0.20-0.80% of Mo, 0.20-0.60% of Cu, 0.01-0.05% of Ti, 0.001-0.003% of B, and the balance being Fe and inevitable impurities.

2. The bulletproof steel plate according to claim 1, characterized in that the microstructure of the bulletproof steel plate is tempered martensite+a very small amount of residual austenite.

3. The bulletproof steel plate according to claim 2, characterized in that the structural proportion of said residual austenite is less than 1%.

4. The bulletproof steel plate according to claim 1, characterized in that among said inevitable impurities, P0.010% and S0.005%.

5. The bulletproof steel plate according to claim 1, characterized in that the thickness of the bulletproof steel plate is 6-22 mm.

6. The bulletproof steel plate according to claim 1, characterized in that the microstructure is tempered martensite+a very small amount of residual austenite, wherein the structural proportion of the residual austenite is lower than 1%, and the thickness of said bulletproof steel plate is 6-22 mm.

7. A method for manufacturing the bulletproof steel plate of claim 1, comprising the following steps in sequence: (1) smelting and casting; (2) heating; (3) rolling; (4) cooling; (5) quenching; and (6) low temperature tempering.

8. The manufacturing method of claim 7, characterized in that in said step (2), the heating temperature is 1130-1250 C. and the heating time is 120-180 min.

9. The manufacturing method of claim 8, characterized in that in said step (3), the finish rolling temperature is controlled at 950-1050 C.

10. The manufacturing method of claim 7, characterized in that in said step (4), the cooling method is air cooling.

11. The manufacturing method of claim 7, characterized in that in said step (5), the quenching temperature is 880-930 C. and the temperature holding time is plate thickness(2-3) min/mm.

12. The manufacturing method of claim 11, characterized in that in said step (6), the tempering temperature is 180-220 C. and the temperature holding time is plate thickness(3-5) min/mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] FIG. 1 shows the metallographic structure of a bulletproof steel plate of Example 4 with a 500-fold magnification under an optical microscope.

[0047] FIG. 2 shows the metallographic structure of a bulletproof steel plate of Example 4 with a 5000-fold magnification under a scanning electron microscope.

DETAILED DESCRIPTION OF EMBODIMENTS

[0048] The bulletproof steel plate and the manufacturing method for the bulletproof steel plate according to the present invention will be further explained and illustrated in conjunction with the accompanying drawings and specific examples below; however, the explanation and illustration do not unduly limit the technical solution of the present invention.

Examples 1-6

[0049] Table 1 lists the mass percentages of the chemical elements in the bulletproof steel plates of Examples 1-6.

TABLE-US-00001 TABLE 1 (wt. %, the balance being Fe and inevitable impurity elements) Number C Si Mn Al Ni Cr Mo Cu Ti B Plate thickness (mm) 1 0.36 1.55 0.41 0.034 0.40 0.39 0.30 0.40 0.023 0.0015 6 2 0.38 0.95 0.64 0.047 0.55 0.94 0.55 0.26 0.034 0.0022 8 3 0.40 1.36 0.80 0.038 0.46 0.46 0.28 0.55 0.034 0.0026 10 4 0.42 1.45 0.95 0.042 0.33 0.76 0.34 0.48 0.015 0.0016 15 5 0.42 0.85 0.50 0.045 0.97 0.95 0.67 0.39 0.045 0.0019 18 6 0.44 1.50 0.65 0.040 1.17 0.70 0.75 0.25 0.028 0.0020 22

[0050] The bulletproof steel plates in Examples 1-6 mentioned above are manufactured by the following steps in sequence:

[0051] (1) smelting and casting;

[0052] (2) heating: the heating temperature is 1130-1250 C. and the heating time is 120-180 min;

[0053] (3) rolling: the finish rolling temperature is controlled at 950-1050 C.;

[0054] (4) cooling: the cooling method is air cooling;

[0055] (5) quenching: the quenching temperature is 880-930 C. and the temperature holding time is plate thickness(2-3) min/mm; and

[0056] (6) low temperature tempering: the tempering temperature is 180-220 C. and the temperature holding time is plate thickness(3-5) min/mm.

[0057] Table 2 lists the specific process parameters of the method for manufacturing the bulletproof steel plates in Examples 1-6.

TABLE-US-00002 TABLE 2 Step (3) Step (2) Finish Step (5) Step (6) Heating Heating rolling Quenching Temperature Quenching Temperature temperature time temperature temperature holding time* temperature holding time* Number ( C.) (min) ( C.) ( C.) (min) ( C.) (min) 1 1250 120 980 900 12 200 20 2 1250 180 1000 890 18 190 30 3 1200 120 1010 880 30 180 40 4 1200 150 980 920 30 210 60 5 1180 180 980 930 40 220 70 6 1130 120 975 900 50 210 80 Note: the temperature holding time in step (5) is plate thickness (2-3) min/mm, and the temperature holding time in step (6) is plate thickness (3-5) min/mm.

[0058] After sampling the bulletproof steel plates of Examples 1-6, the samples are subjected to a steel plate shooting test according to the requirements of FB5 grade in EU standard EN.1063, with the test conditions and results both being listed in Table 3.

[0059] Table 3 lists the results of the bulletproof steel plates of Examples 1-6 after a shooting test.

TABLE-US-00003 TABLE 3 Number Shooting distance/m Shooting speed/m/s Result 1 10 982/984/981 Not punctured 2 10 983/984/981 Not punctured 3 10 983/982/981 Not punctured 4 10 985/983/984 Not punctured 5 10 980/982/981 Not punctured 6 10 983/985/984 Not punctured

[0060] It can be seen from Table 3 that none of the bulletproof steel plates of Examples 1-6 is punctured in the shooting test, so the bulletproof steel plates of the above-mentioned examples all satisfy the requirements of FB5 grade in EU standard EN.1063.

[0061] After sampling the bulletproof steel plates of Examples 1-6, the samples are subjected to tensile strength and Brinell hardness tests, and the test results are all listed in Table 4.

[0062] Table 4 Tensile strength and Brinell hardness of the bulletproof steel plates of Examples 1-6.

TABLE-US-00004 TABLE 4 Number Brinell hardness (MPa) Tensile strength (MPa) 1 590 2030 2 587 2020 3 594 2120 4 600 2140 5 592 2038 6 598 2136

[0063] It can be seen from Table 4 that the Brinell hardnesses of the bulletproof steel plates of Examples 1-6 all reach a grade of 600 and the tensile strengths are all greater than 2000 MPa.

[0064] FIGS. 1 and 2 respectively show the metallographic structure of the bulletproof steel plate of Example 4 with a 500-fold magnification under an optical microscope and the metallographic structure of the bulletproof steel plate with a 5000-fold magnification under a scanning electron microscope; and it can be seen from FIGS. 1 and 2 that the microstructure of the bulletproof steel plate is mainly tempered martensite, with the content of residual austenite being very low.

[0065] It can be seen therefrom that the technical solution of the present invention gives a bulletproof steel plate with an ultrahigh tensile strength and an ultrahigh Brinell hardness by means of an alloying element design+a rational manufacturing process.

[0066] It should be noted that the examples listed above are only the specific examples of the present invention, and obviously the present invention is not limited to the above examples and can have many similar changes. All variations which can be directly derived from or associated with the disclosure of the invention by those skilled in the art should be within the scope of protection of the present invention.