A heat treatment production method of a thin gauge series wear-resistant steel plate

Abstract

The present application relates to the technical field of metallurgy, and particularly relates to a heat treatment production method of a thin-gauge series wear-resistant steel plate, which comprises the following steps: steel plate preparation, stacking and fastening, heating and quenching, disassembly and separation, tempering treatment and straightening treatment, wherein the stacking and fastening step is to stack the thinner steel plates as interlayer thin plates, the thicker steel plates as top cover plates and bottom cover plates, place the top cover plate on the top of the several interlayer thin plates stacked on the bottom cover plate, and fasten the top cover plate and the bottom cover plate. The present application effectively reduces the quenching residual stress of the steel plate, improves the plate shape control ability and the plate shape quality, and realizes excellent control of the plate shape of the thin-gauge wear-resistant steel by heating and quenching the stacked and fastened multi-layer thin-gauge steel plate. Meanwhile, the present application realizes the production of wear-resistant steel plates with different hardness levels using the same component in combination with different quenching cooling speeds. After tempering, the steel plate is quickly straightened using the residual heat, and the produced thin-gauge series wear-resistant steel plate has high flatness.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, in particular to a heat treatment production method for a thin series of wear-resistant steel plates. Background Art

[0002] With the widespread application of wear-resistant steel in coal mines, mine cars, transport trailers and other equipment, the demand for ultra-thin high-strength wear-resistant steel plates with a yield strength ≥1000MPa is increasing. At the same time, for ease of use, users have increasingly stringent requirements on the flatness of the wear-resistant steel plates.

[0003] In the prior art, wear-resistant steel plates are generally produced through a quenching + low-temperature tempering heat treatment process. During the quenching process, the steel plate has a high temperature out of the furnace and a fast cooling speed. A large amount of residual stress is generated during the cooling process, which can easily cause the steel plate to have problems with poor plate shape, such as warping. Especially for thin-gauge steel plates with a thickness of ≤10mm, serious deformation is very likely to occur after quenching, and the severity of deformation becomes more serious with the increase in the width of the steel plate. The unevenness of some steel plates even exceeds 30mm / m, which cannot meet the use standard. At the same time, wear-resistant steel is an ultra-high-strength steel with a yield strength generally exceeding 1000Mpa. The high yield strength causes the steel to have poor plate shape problems and it is difficult to correct and save it after cooling and shaping. It cannot be put into use, causing huge losses.

[0004] Currently, thin-gauge wear-resistant steel plates (4-10mm) are subject to significant and difficult-to-correct deformation after quenching and cooling due to their thin thickness, making it difficult to maintain good plate quality. This is especially true for long-established quenching equipment, which makes it extremely difficult to produce thin-gauge wear-resistant steel plates with good plate shape, resulting in a high defective rate. Furthermore, traditional thin-gauge wear-resistant steel production methods primarily focus on mass-producing a single type of steel product, making it difficult to flexibly produce a range of steel products tailored to varying product needs. Summary of the Invention

[0005] In view of the problems in the prior art that thin-gauge wear-resistant steel plates produced are prone to severe deformation after quenching and cooling, resulting in poor plate shape that is difficult to correct and a high defective rate, and the existing production methods are difficult to produce series products according to different product requirements, the present invention provides a heat treatment production method for thin-gauge series wear-resistant steel plates. By stacking and tightening and then heating and quenching, the quenching residual stress of the steel plates is reduced, the plate shape control ability is improved, the plate shape quality is improved, and excellent plate shape control of thin-gauge wear-resistant steel is achieved; at the same time, different quenching and cooling speeds are combined to achieve the production of wear-resistant steel plates of different hardness levels using the same composition; after tempering, the residual heat is used to quickly straighten the steel plates, and the produced thin-gauge series wear-resistant steel plates have high flatness and a low defective rate.

[0006] In a first aspect, the present invention provides a method for heat treatment production of thin gauge series wear-resistant steel plates, comprising the following steps:

[0007] (1) Steel plate preparation: Prepare smooth steel plates of required specifications;

[0008] (2) Stacking and fastening: stacking the clean steel plates according to the specifications and fastening the stacked clean steel plates into a multi-layer steel plate group;

[0009] (3) Heating and quenching: The multi-layer steel plate group is subjected to a heating-quenching treatment in a furnace as a whole to obtain a quenched steel plate group;

[0010] (4) Disassembly and separation: disassembling the quenched steel plate group and separating it into single-layer quenched steel plates;

[0011] (5) Tempering treatment: Tempering the single-layer quenched steel plate to obtain a tempered steel plate;

[0012] (6) Straightening treatment: The tempered steel plate is straightened to obtain a thin series of steel plates.

[0013] Furthermore, the specific steps of preparing the steel plate in step (1) are:

[0014] (1.1) Process planning: Determine the raw material composition and process parameters of each link according to the hardness requirements of the wear-resistant steel produced;

[0015] (1.2) Steel plate production: The steel billet is subjected to smelting-continuous casting-steel plate rolling-cooling process to produce rolled steel plate;

[0016] (1.3) Shot blasting: Shot blasting is performed on the surface of the rolled steel plate to remove the surface iron oxide scale and produce a smooth steel plate.

[0017] Furthermore, the chemical composition and weight percentage of the steel plate raw material are C: 0.14%-0.20%, Si: 0.05%-0.35%, Mn: 0.4%-0.8%, P≤0.015%, S≤0.0040%, Nb: 0.020%-0.060%, Ti: 0.020%-0.040%, Als: 0.015%-0.050%, Cr+Ni+Mo: 0.40%-1.05%, B: 0.0080-0.0020%, and the balance is iron and other impurities.

[0018] The role and mechanism of the main alloying elements of the present invention:

[0019] Carbon (C): Carbon significantly increases the strength and hardenability of steel. However, excessive carbon content can significantly reduce the toughness of steel. Increased carbon content can also reduce the cold forming and welding properties of steel. The carbon content in this solution should be controlled between 0.14% and 0.20%.

[0020] Manganese (Mn): Manganese is the most effective element to improve strength and toughness, manganese is an austenite stabilizing element, a good desulfurizer and deoxidizer, and improves the hardenability of steel. Manganese can expand the austenite phase region, delay pearlite transformation, Mn can play a role in refining ferrite grains, and high manganese content is easy to cause segregation to form banded structure, and serious can be steel layering phenomenon. The manganese content of the present scheme is controlled at 0.4%-0.8%.

[0021] Silicon (Si): Silicon can dissolve in ferrite, play a role in solid solution strengthening, can significantly improve the strength and hardness of steel, but too high silicon content is easy to cause the surface oxide scale difficult to remove. The silicon content of the present scheme is controlled at 0.05%-0.35%.

[0022] Phosphorus (P): Phosphorus has a strong solid solution strengthening effect, which can significantly increase the strength and hardness of steel, but can significantly reduce the low temperature toughness of steel. At the same time, phosphorus has a certain segregation tendency, which affects the comprehensive performance of the steel. The phosphorus content of the present scheme is controlled at 0.015% or less.

[0023] Sulfur (S): Sulfur is a harmful element of steel, which affects the forming performance of steel plate, and sulfide inclusions significantly affect the impact toughness and fatigue performance of steel. Therefore, the content of sulfur element should be as low as possible, and the content of sulfur element in the present invention is controlled at 0.0040% or less.

[0024] Niobium (Nb): Niobium has a significant refining effect in steel, which can refine the size of primary austenite grains, improve the deformation resistance during hot rolling, and delay recrystallization, which is beneficial to the rolling of non-recrystallization zone. In steel, the formation of Nb(NC) as ferrite improves the favorable position, and pins the grain boundary to prevent grain boundary migration, further refining the grain structure after rolling. The strength and impact toughness of the steel plate can be effectively improved by Nb grain refinement. Therefore, the content of Nb is controlled at 0.020%-0.060%.

[0025] Titanium (Ti): Titanium is a strong carbide forming element, and titanium has strong affinity with carbon and nitrogen. Ti can form stable TiN during the solidification process of steel, which can strongly hinder the migration of austenite grain boundary, thereby refining the austenite grain. Ti combines with C to form TiC, which can play a role in precipitation strengthening. During the rolling process, Ti(CN) particles precipitated in the austenite high temperature zone can prevent the recrystallization process of austenite, and finally refine the transformed structure. Adding trace amounts of B in wear-resistant steel can also affect the precipitation of Ti(CN) and Ti(CN) particles. Trace B can be adsorbed on the austenite grain boundary, reducing the energy of the grain boundary and improving the hardenability of the steel. With the cooperation of Mn, air-cooled bainite steel can be obtained. The titanium content of the present scheme is controlled at 0.020%-0.040%.

[0026] Aluminum (Al): Aluminum acts as a deoxidizer for steel and also refines grains. To ensure the cleanliness of the molten steel, the Al content should not be too high. In this solution, the Al content is controlled at 0.020-0.050%.

[0027] Chromium (Cr): Cr is one of the basic elements of wear-resistant steel. Its main function is to improve the hardenability of steel, strengthen the matrix through solid solution, refine the structure, improve the high-temperature strength, hardness and wear resistance of steel, significantly improve the steel's antioxidant effect, and increase its corrosion resistance. Its reasonable combination with Mn and Si can greatly improve the hardenability, but it also increases the steel's tendency to temper brittleness.

[0028] Nickel (Ni): Nickel and carbon do not form carbides and are the main alloying elements for forming and stabilizing austenite. Adding a certain amount of Ni can improve the hardenability and retain a small amount of residual austenite in the structure at room temperature to improve its toughness.

[0029] Molybdenum (Mo): Molybdenum is added to wear-resistant steel in appropriate amounts to improve hardenability. Its effect on hardenability is stronger than that of Cr but less than that of Mn. Mo is a medium-strong carbide-forming element, primarily existing in steel as carbides, dispersed throughout the matrix to strengthen it. For thick-gauge, low-alloy wear-resistant steel, increasing the Mo content improves hardness uniformity through the thickness of the steel. Mo also effectively refines the ingot microstructure, enhances cross-sectional uniformity, and improves tempering stability. In this solution, the combined Cr, Ni, and Mo additions are controlled between 0.40% and 1.05%.

[0030] Boron (B): Boron is a key element in improving the permeability of wear-resistant steel. Adding even a very small amount of B (0.0005-0.0030%) to the steel significantly improves hardenability. Therefore, adding trace amounts to wear-resistant steel can effectively replace some expensive alloying elements. Boron atoms dissolved in austenite tend to segregate and adsorb on austenite grain boundaries, reducing the free energy of these boundaries and hindering the diffusion of carbon atoms, making the nucleation of new phases difficult. The B content in wear-resistant steel should not exceed 0.004%, otherwise it will easily form non-solubilized borides, causing boron embrittlement.

[0031] Furthermore, the rolled steel plate obtained in step (1.2) has a thickness of 4.0-16.0 mm and a width of 2000-3500 mm.

[0032] Furthermore, in step (2), a smooth steel plate with a thickness of 4-10 mm is selected as the sandwich thin plate, and a smooth steel plate with a thickness of 10-16 mm is selected as the top cover plate and the bottom cover plate; the bottom cover plate is fixed, and several flat sandwich thin plates are placed on the bottom cover plate, and after stacking, the top cover plate is placed on the top thin plate, and the top cover plate and the bottom cover plate are welded or bolted together with narrow steel plates.

[0033] Further, the total thickness of the multiple-layer steel plate group after fastening is 40-70mm.

[0034] Further, the heating temperature of the multiple-layer steel plate group in step (3) is 890-960℃, the heating and holding time is 1.4-1.8min / mm, and the quenched steel plate is discharged after heating and quenched.

[0035] Further, in step (5), the single-layer quenched steel plate is sent into a heat treatment furnace, and low-temperature tempering is performed at 180-300℃ according to the product performance requirements.

[0036] Further, in step (6), the tempered steel plate is straightened quickly by using the residual heat after tempering, so that the unevenness after straightening is less than or equal to 6mm / 2m.

[0037] Further, the surface hardness of the thin-gauge series steel plate prepared is 320-460HBW.

[0038] The beneficial effects of the present application are as follows:

[0039] (1) The present application provides a heat treatment production method of a thin-gauge series wear-resistant steel plate, which heats and quenches the multiple-layer thin-gauge steel plate after stacking and fastening, effectively reduces the quenched residual stress of the steel plate, improves the plate shape control ability and the plate shape quality, and realizes excellent control of the plate shape of the thin-gauge wear-resistant steel.

[0040] (2) The present application stacks and fastens the multiple-layer thin-gauge steel plates with different thicknesses, and then performs heat treatment, and combines different quenching and cooling speeds, so that the steel plates of each layer have different levels of surface hardness, and the technical goal of flexible production of a series of wear-resistant steel with the same composition is achieved.

[0041] (3) The present application straightens the quenched steel plate quickly by using the residual heat after tempering, so that the situation that the steel plate is difficult to straighten due to high yield strength after complete cooling is avoided, the thin-gauge series wear-resistant steel plate produced has high flatness, and the defective product rate is low.

[0042] (4) The raw material composition of the steel material of the present application adopts a low-cost design, the use amount of low-cost alloys such as C, Nb, Ti and B is increased, the organization is refined and the hardenability is improved, and then the use amount of valuable alloys such as Mn, Cr, Ni and Mo is reduced, and the production cost is reduced. DETAILED DESCRIPTION

[0043] In order for those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0044] Example 1

[0045] A heat treatment production method for a thin series of wear-resistant steel plates, comprising the following steps:

[0046] (1) Process planning: The chemical composition and weight percentage of the steel plate raw material are C: 0.18%, Si: 0.15%, Mn: 0.7%, P: 0.013%, S≤0.002%, Nb: 0.047%, Ti: 0.035%, Als: 0.034%, Cr+Ni+Mo: 0.75%, B: 0.0180%, and the balance is iron and other impurities.

[0047] (2) Steel plate production: The steel slab is subjected to the smelting-continuous casting-steel plate rolling-cooling process. In the hot rolling process of the steel plate, the slab starting rolling temperature is controlled at 950-1020℃, and the final rolling temperature is controlled at 800-860℃. The rolling thicknesses are 16mm, 12mm, 10mm, and 6mm respectively. After rolling, the steel plate is air-cooled to room temperature to produce four thicknesses of rolled steel plates.

[0048] (3) Shot blasting: Shot blasting is performed on the surface of each rolled steel plate to remove the surface iron oxide scale and produce a smooth steel plate.

[0049] (4) Stacking and tightening: The smooth steel plates are stacked according to the specifications. A 16mm thick smooth steel plate is placed on the bottom as the bottom cover plate. A 10mm thick, two 6mm thick, and a 10mm thick smooth steel plate are placed in sequence as the sandwich plates. They are stacked flatly together. A 12mm thick smooth steel plate is placed on the top layer of the sandwich plates as the top cover plate. The top cover plate and the bottom cover plate are 9300mm long and 2260mm wide. After stacking, the top cover plate and the bottom cover plate are welded and tightened with narrow steel strips of the same composition as the cover plates to form a multi-layer steel plate group. The overall thickness of the multi-layer steel plate group is 60mm to ensure through-hardening and tightening.

[0050] (5) Heating and quenching: The multi-layer steel plate group is put into a furnace for heating and quenching treatment as a whole. The heating temperature is 930°C, and the heating and holding time is controlled according to 1.5 min / mm. After the holding time requirement of ≥90 min is met, the multi-layer steel plate group is taken out of the furnace and quenched to obtain a quenched steel plate group.

[0051] (6) Disassembly and separation: disassemble the quenched steel plate group, remove the welded connection between the top cover plate and the bottom cover plate, and lift away the single-layer quenched steel plates one by one;

[0052] (7) Tempering treatment: The disassembled single-layer quenched steel plate is sent to a heat treatment furnace and subjected to low-temperature tempering treatment at 200-300°C for 30 minutes according to performance requirements to obtain a tempered steel plate;

[0053] (8) Straightening treatment: according to the plate shape, the tempered steel plate is quickly straightened by using the tempering residual temperature, the unevenness of the thin plate is not higher than 6mm / 2m, and the thin gauge series steel plate is obtained.

[0054] The hardness and flatness data of the thin gauge series wear-resistant steel plate prepared in Example 1 are shown in Table 1.

[0055] Table 1 Performance of the steel plate prepared in Example 1

[0056] Steel plate thickness Upper surface hardness / HBW Lower surface hardness / HBW Straightness after straightening mm / 2m 12mm 456 448 3 10mm 435 417 4 6mm 402 386 5 6mm 396 389 6 10mm 408 422 4 16mm 432 448 3

[0057] Example 2

[0058] A heat treatment production method of a thin gauge series wear-resistant steel plate, comprising the following steps:

[0059] (1) Process planning: the chemical composition and weight percentage of the steel plate raw material are C: 0.14%, Si: 0.28%, Mn: 0.5%, P: 0.011%, S≤0.018%, Nb: 0.024%, Ti: 0.022%, Als: 0.020%, Cr+Ni+Mo: 0.90%, B: 0.0100%, and the balance is iron and other impurities.

[0060] (2) Steel plate production: the steel billet is subjected to smelting-continuous casting-steel plate rolling-cooling process, in the hot rolling process of the steel plate rolling, the slab opening rolling temperature is controlled at 950-1020℃, the finish rolling temperature is controlled at 800-860℃, and the rolling thickness is 10mm, 8mm and 4mm respectively, and the rolled steel plate is cooled to room temperature after rolling.

[0061] (3) Shot blasting treatment: the surface of each rolled steel plate is subjected to shot blasting treatment to remove the surface iron oxide scale and obtain a smooth steel plate.

[0062] (4) Stacking and fastening: the smooth steel plates are stacked according to the size, a 10mm-thick smooth steel plate is placed as a bottom cover plate at the bottom, a 8mm-thick smooth steel plate, six 4mm-thick smooth steel plates and a 8mm-thick smooth steel plate are sequentially placed as interlayer thin plates, and are stacked together in a flat manner, and a 10mm-thick smooth steel plate is placed as a top cover plate on the top layer of the interlayer thin plates, the top cover plate and the bottom cover plate have a length of 9300mm and a width of 2260mm, and the top cover plate and the bottom cover plate are welded and fastened with narrow steel strips of the same composition as the cover plates to form a multi-layer steel plate group, the overall thickness of the multi-layer steel plate group is 60mm, and the quenching is fastened.

[0063] (5) Heating and quenching: the multi-layer steel plate group is subjected to overall heating and quenching in the furnace, the heating temperature is 950℃, the heating holding time is controlled according to 1.6min / mm, and the holding time is≥90min, and then the quenched steel plate group is obtained after quenching.

[0064] (6) disassembling and separating: disassembling the quenched steel plate group, removing the welding connection between the top cover plate and the bottom cover plate, and hoisting away the single-layer quenched steel plate;

[0065] (7) tempering treatment: sending the disassembled single-layer quenched steel plate into a heat treatment furnace, and performing 200-300℃, 30min low-temperature tempering treatment according to the performance requirement, to obtain a tempered steel plate;

[0066] (8) straightening treatment: according to the plate shape, using the tempering residual temperature to quickly straighten the tempered steel plate, and the unevenness of the thin plate is not higher than 6mm / 2m, to obtain a thin-gauge series steel plate.

[0067] The hardness and flatness data of the thin-gauge series wear-resistant steel plate prepared in Example 2 are shown in Table 2.

[0068] Table 2 Performance of the steel plate prepared in Example 2

[0069] Steel plate thickness Upper surface hardness / HBW Lower surface hardness / HBW Straightness after straightening mm / 2m 10mm 442 433 3 8mm 419 407 3 4mm 395 393 5 4mm 386 376 4 4mm 368 362 3 4mm 356 361 4 4mm 374 380 4 4mm 387 394 5 8mm 406 417 3 10mm 429 434 4

[0070] Although the present application has been described in detail by preferred embodiments, the present application is not limited to this. Various equivalent modifications or replacements can be made to the embodiments of the present application by those skilled in the art without departing from the spirit and essence of the present application, and these modifications or replacements shall be within the scope of the present application. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, and these changes or replacements shall be within the protection scope of the present application.

Claims

1. A heat treatment production method for thin gauge series wear-resistant steel plates, characterized in that: The following steps are involved: (1) Steel plate preparation: Prepare the smooth steel plate of the required specifications. The specific steps are as follows: (1.1) Process planning: The raw material composition and process parameters of each link are determined based on the hardness requirements of the wear-resistant steel to be produced. The chemical composition and weight percentage of the steel plate raw material are C: 0.14%-0.20%, Si: 0.05%-0.35%, Mn: 0.4%-0.8%, P≤0.015%, S≤0.0040%, Nb: 0.020%-0.060%, Ti: 0.020%-0.040%, Als: 0.015%-0.050%, Cr+Ni+Mo: 0.40%-1.05%, B: 0.0080-0.0020%, and the balance is iron and other impurities; (1.2) Steel plate production: The steel billet is subjected to smelting, continuous casting, steel plate rolling and cooling processes to produce rolled steel plates; (1.3) Shot blasting: Shot blasting is performed on the surface of the rolled steel plate to remove the surface iron oxide scale and produce a smooth steel plate; (2) Stacking and fastening: stack the smooth steel plates according to the specifications and fasten the stacked smooth steel plates into a multi-layer steel plate group, where: Select smooth steel plates with a thickness of 4-10mm as sandwich sheets, and select smooth steel plates with a thickness of 10-16mm as top and bottom covers; fix the bottom cover, place several sandwich sheets flush on the bottom cover, stack them, and place the top cover on the top sheet. Fasten the top and bottom covers with narrow steel plates by welding or bolting; (3) Heating and quenching: The multi-layer steel plate group is put into a furnace for heating and quenching to obtain a quenched steel plate group; (4) Disassembly and separation: disassemble the quenched steel plate group and separate it into single-layer quenched steel plates; (5) Tempering treatment: Tempering the single-layer quenched steel plate to obtain a tempered steel plate; (6) Straightening treatment: The tempered steel plate is straightened to obtain a thin series of steel plates.

2. The heat treatment production method of a thin gauge series wear-resistant steel plate according to claim 1, characterized in that: The rolled steel plate obtained in step (1.2) has a thickness of 4.0-16.0 mm and a width of 2000-3500 mm.

3. The heat treatment production method of a thin gauge series wear-resistant steel plate according to claim 1, characterized in that: The total thickness of the multi-layer steel plate group after tightening is 40-70mm.

4. The heat treatment production method of a thin gauge series wear-resistant steel plate according to claim 1, characterized in that: In step (3), the multi-layer steel plate group is heated to a temperature of 890-960° C., and the heating and holding time is 1.4-1.8 min / mm. After heating, the multi-layer steel plate group is taken out of the furnace for quenching.

5. The heat treatment production method of a thin gauge series wear-resistant steel plate according to claim 1, characterized in that: Step (5) The single-layer quenched steel plate is sent into a heat treatment furnace for low-temperature tempering at 180-300°C.

6. The heat treatment production method of a thin gauge series wear-resistant steel plate according to claim 1, characterized in that: Step (6) uses the residual heat after tempering to quickly straighten the tempered steel plate to ensure that the unevenness after correction is ≤6mm / 2m.

7. The heat treatment production method of a thin gauge series wear-resistant steel plate according to claim 1, characterized in that: The surface hardness of the produced thin gauge series steel plates is 320-460HBW.