Process for preparing gradient hardened metal plate through explosion hardening

Abstract

The invention relates to a process for preparing a gradient hardening metal plate through explosion hardening, and belongs to the technical field of explosion hardening and gradient hardening materials. In order to ensure the experiment safety, a test site is selected as a static explosion site, a rigid base, a metal plate to be subjected to gradient hardening and a poured high-detonation-velocity plate-shaped explosive are sequentially placed in the site from bottom to top, then the explosive is started by an electric detonator to carry out high-pressure and high-frequency impact hardening treatment on the metal plate, and finally the metal plate subjected to gradient hardening is obtained. The surface hardness is improved to 380-400 HV, and the depth of a hardened layer reaches 15 mm. The process is simple to operate, efficient, convenient and obvious in effect, and does not need large equipment and instruments.

Description

Technical Field

[0001] The invention relates to a process for preparing a gradient hardening metal plate by explosive hardening, and belongs to the technical field of explosive hardening and gradient hardening materials. Background Art

[0002] In the processing technology of modern metal materials, a hardened surface layer of a certain thickness is prepared on the surface of the material, that is, the surface hardening of the material is achieved, thereby optimizing the mechanical properties and service behavior of the material, meeting the use requirements of the specific environment for the material properties (such as strength, hardness, friction and wear, etc.), so as to be better applied to the development and application of the metal industry. Some of the processing technologies of modern metal materials are improved on the basis of many conventional metal pressure processing and mechanical processing technologies, and some use high-energy processing technologies. For example, high-energy metal explosion processing using explosives as energy is a widely used high-energy processing technology. Compared with traditional metal surface hardening methods such as heat treatment hardening, mechanical hardening, surface spraying, surface surfacing, laser shock hardening, etc., metal explosion hardening not only has the characteristics of simple equipment, rapidity, high efficiency, large hardening depth, high precision and low processing cost, but also can process parts that are difficult to process by conventional methods. Therefore, this method has huge development and application potential and practical value in industry.

[0003] Explosives are a high-density, cheap energy source. A series of physical and chemical reactions occur at the moment of the explosion, generating a certain impact load acting on the hardened metal plate, causing it to instantly hit the metal base at high speed. At the same time, the hardened plate undergoes strong plastic strain, generating a certain hardened structural layer on its metal surface and within a certain depth range, thereby improving the mechanical properties of the hardened structural layer. Therefore, this explosive hardening process is widely used in various industries. This high-strain, high-rate explosive hardening achieves surface hardening of metal plates. Literature has reported that the surfaces of high manganese steel, 45 steel, AISI304 stainless steel, low carbon steel and pure copper have achieved explosive hardening, and its application prospects are broad.

[0004] The metal explosion hardening method was first proposed by Norman et al. in the United States in 1955 in the hardening treatment of manganese steel, and the first patent for the explosion hardening process was obtained. Soon this hardening process was promoted and first used in foreign countries for the pre-hardening treatment of the surface of railway turnouts. After about 70 years of development, in-depth research has been conducted on the theory and technology of explosion hardening at home and abroad, and the application field has gradually expanded. The metal explosion hardening process has been put into use to varying degrees in the production of China, Russia, Australia, the United States, France, the United Kingdom and other countries, and has been applied to the construction, machinery, chemical industry, communications and other industries. Summary of the invention

[0005] The purpose of the present invention is to provide a process for preparing gradient hardened metal plates by explosive hardening. The process uses RDX-based (RDX) cast plate-shaped explosives to perform explosive hardening treatment on the metal plates, which will greatly improve their surface hardness and the hardening depth reaches 15mm.

[0006] A process for preparing a gradient hardened metal sheet by explosive hardening, the process steps comprising:

[0007] To ensure the safety of the experiment, the test site was selected in a static explosion field. A rigid base, a metal plate to be gradient hardened, and an RDX-based cast explosive were placed in the field from bottom to top. The RDX-based cast explosive was then detonated with an electric detonator, and the metal plate to be gradient hardened was subjected to high-pressure and high-frequency impact hardening treatment to finally obtain the gradient-hardened metal plate.

[0008] Furthermore, the metal plate to be gradient hardened is gun steel, and its chemical composition is (wt%): carbon C: 0.34~0.41; silicon Si: 0.17~0.37; manganese Mn: 0.25~0.50; sulfur S: allowable residual content ≤0.015; phosphorus P: allowable residual content ≤0.020; chromium Cr: 1.20~1.50; nickel Ni: 3.00~3.50; copper Cu: allowable residual content ≤0.020; molybdenum Mo: 0.35~0.45; vanadium V: 0.10~0.25, and the rest is iron; the size of the metal plate to be gradient hardened is 100mm×300mm×30mm.

[0009] Furthermore, the RDX-based cast explosive is composed of 35wt% RDX and 65wt% TNT, has a stable detonation velocity greater than or equal to 7200m / s, and has a size of 100mm×300mm×(2~4)mm.

[0010] Furthermore, the rigid base and the metal plate to be gradient hardened were both ground and polished before the experiment.

[0011] Furthermore, the contact surface between the metal plate to be gradient hardened and the rigid base is coated with high temperature resistant butter to avoid explosive welding.

[0012] Furthermore, the rigid base is made of No. 45 steel, and its dimensions are 120 mm×340 mm×100 mm.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The present invention provides a process for preparing gradient hardened metal plates by explosive hardening, wherein the rigid base and the metal plates to be gradient hardened are firstly ground and polished, and then plate-shaped explosives are placed for explosive hardening. Grinding can remove the micro-oxidation layer on the metal surface, so that the contact surface between the plate-shaped explosives and the metal plates to be gradient hardened is free of impurities; polishing can make the rigid base and the metal plates to be gradient hardened fit more tightly and firmly, thereby improving the hardening effect.

[0015] The process can process parts that are difficult to process by conventional methods, and has the characteristics of simple equipment, convenient operation, rapidity, high efficiency, large hardening depth, high precision and low processing cost. Therefore, the explosive hardening process is widely used in various industries and has important theoretical significance and practical value for the development and application of gradient hardening of harder metal materials.

[0016] After the explosion hardening treatment, the surface hardness of the metal plate reaches 380-400 HV, and the depth of the hardened layer reaches 15 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a comparison chart of the change in hardness of metal plates with depth before and after explosion hardening. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the drawings and embodiments, but the protection scope of the present invention is not limited to the scope of the embodiments. Based on the embodiments of the present invention, any non-creative replacement or change should be included in the protection scope of the present invention.

[0019] In the following examples and comparative examples:

[0020] Schematic diagram of hardness variation with depth: drawn using Origin 2021 software;

[0021] Hardness test: The model used is Shimadzu HMV-G21 DT micro Vickers hardness tester, and the test conditions are: load 980.7mN, holding time 15s.

[0022] The size of the metal plate is 100mm×300mm×30mm; the rigid base is 45# steel, and its size is 120mm×340mm×100mm; the high-explosive-velocity explosive is RDX-based cast explosive; and the butter is high-temperature-resistant butter.

[0023] Example 1

[0024] Step 1: Grind and polish the rigid base and the metal sheet to be gradient hardened;

[0025] Step 2: Evenly apply butter on the side of the rigid base that contacts the metal sheet to be gradient hardened;

[0026] Step 3: Place the 45# steel rigid base stably on the static explosion site;

[0027] Step 4: Place the metal plate to be gradient hardened in the center of the 45 steel rigid matrix;

[0028] Step 5: Place a 100mm×300mm×3mm RDX-based pouring explosive on the metal plate to be gradient hardened and make it fit tightly on the surface of the plate;

[0029] Step 6: Detonate the electric detonator and carry out explosion hardening treatment.

[0030] Step 7: Recover the hardened sample to obtain a gradient hardened metal sheet.

[0031] The surface of the sample obtained after explosion hardening is uniform and smooth. The hardness of the sample before and after hardening varies with depth as shown in the following figure: Figure 1 As shown by Figure 1 It can be seen that the hardness shows a gradient change with depth. The maximum hardness is 380HV, which is 35.8% higher than the initial hardness (280HV). The hardening depth reaches 15mm. The hardening effect is obvious and meets expectations.

[0032] Example 2

[0033] Step 1: Grind and polish the rigid base and the metal sheet to be gradient hardened;

[0034] Step 2: Evenly apply butter on the side of the rigid base that contacts the metal sheet to be gradient hardened;

[0035] Step 3: Place the 45# steel rigid base stably on the static explosion site;

[0036] Step 4: Place the metal plate to be gradient hardened in the center of the 45 steel rigid matrix;

[0037] Step 5: Place the RDX-based pouring explosive of size 100 mm × 300 mm × 2 mm on the metal plate to be gradient hardened and make it fit tightly on the surface of the plate;

[0038] Step 6: Detonate the electric detonator and carry out explosion hardening treatment.

[0039] Step 7: Recover the hardened sample to obtain a gradient hardened metal sheet.

[0040] The surface of the sample obtained after explosion hardening is uniform and smooth, and the change law of hardness after hardening with depth is consistent with that in Example 1. The surface hardness is improved to a certain extent, and the effect is more obvious.

[0041] Example 3

[0042] Step 1: Grind and polish the rigid base and the metal sheet to be gradient hardened;

[0043] Step 2: Evenly apply butter on the side of the rigid base that contacts the metal sheet to be gradient hardened;

[0044] Step 3: Place the 45# steel rigid base stably on the static explosion site;

[0045] Step 4: Place the metal plate to be gradient hardened in the center of the 45 steel rigid matrix;

[0046] Step 5: Place the RDX-based pouring explosive of size 100 mm × 300 mm × 4 mm on the metal plate to be gradient hardened and make it fit tightly on the surface of the plate;

[0047] Step 6: Detonate the electric detonator and carry out explosion hardening treatment.

[0048] Step 7: Recover the hardened sample to obtain a gradient hardened metal sheet.

[0049] The surface of the sample obtained after explosion hardening is uniform and smooth, and the change law of hardness after hardening with depth is consistent with that in Example 1. The surface hardness is improved to a certain extent, and the effect is more obvious.

[0050] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A process for preparing gradient hardened metal sheet by explosive hardening, characterized in that: The process steps include: In a static explosion field, a rigid base, a metal sheet to be gradient hardened and RDX-based cast explosives are placed in sequence from bottom to top, and then the RDX-based cast explosives are detonated with electric detonators to perform high-pressure and high-frequency impact hardening treatment on the metal sheet to be gradient hardened, and finally the gradient hardened metal sheet is obtained.

2. The process according to claim 1, characterized in that The metal plate to be gradient hardened is gun steel, and its chemical composition is calculated by mass percentage as follows: carbon C: 0.34~0.41; silicon Si: 0.17~0.37; manganese Mn: 0.25~0.50; sulfur S: allowable residual content ≤0.015; phosphorus P: allowable residual content ≤0.020; chromium Cr: 1.20~1.50; nickel Ni: 3.00~3.50; copper Cu: allowable residual content ≤0.020; molybdenum Mo: 0.35~0.45; vanadium V: 0.10~0.25, and the rest is iron.

3. The process according to claim 1, characterized in that The size of the metal sheet to be gradient hardened is 100mm×300mm×30mm.

4. The process according to claim 1, characterized in that The RDX-based cast explosive is composed of 35wt% RDX and 65wt% TNT, its stable detonation velocity is greater than or equal to 7200m / s, and its size is 100mm×300mm×(2~4)mm.

5. The process according to claim 1, characterized in that Both the rigid base and the metal sheet to be gradient hardened need to be ground and polished.

6. The process according to claim 1, characterized in that The contact surface between the metal plate to be gradient hardened and the rigid base is coated with high temperature resistant butter.

7. The process according to claim 1, characterized in that The rigid base is made of 45-gauge steel and its dimensions are 120 mm × 340 mm × 100 mm.

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