CN115074641A - A kind of HB400 grade high wear-resistant cold-formable steel plate and production method thereof - Google Patents

Abstract

A HB400 grade high abrasion resistance cold-bending steel plate and its production method, the chemical composition in the steel is calculated according to the weight percent C0.14% -0.18%, Si 1.1% -1.50%, Mn0.7% -1.0%, Nb0.12% -0.20%, Cr0.15% -0.35%, Ni0.4% -0.6%; 0.03 percent or less of C and Nb, 2.0 percent or less of Si and Ni with the concentration of 1.5 percent or more, 0.040 to 0.060 percent of Al0, and the balance of Fe and inevitable impurities. Compared with the prior art, the invention has the beneficial effects that: continuous casting production can be carried out; the surface hardness is more than HB400, and the AKV is more than or equal to 40J at the temperature of minus 40 ℃; the wear resistance is more than 1.4 times of that of the low-alloy wear-resistant steel plate with the same hardness; the product has good cold forming performance and is qualified when the cold bending D of 180 degrees is 3 a.

Description

A kind of HB400 grade high wear-resistant cold-formable steel plate and production method thereof

technical field

The invention belongs to the field of metal materials, and in particular relates to an HB400 grade high wear-resistant cold-formable steel plate and a production method thereof, which can be used for the production of wear-resistant spare parts in the fields of construction machinery, mining, metallurgy, coal machinery and the like.

Background technique

General low-alloy wear-resistant steel is designed with martensitic matrix and low-hardness carbides such as Cr, Mo, V, Ti and other low-hardness carbides to enhance wear resistance, and is produced by heat treatment of quenching and low-temperature tempering. HB400 hardness level ordinary low-alloy Brinell The life of wear-resistant steel is generally about twice that of Q345B, and it is widely used in construction machinery, coal mining machinery and other fields, but its cold bending performance is relatively poor. Improving the wear resistance of wear-resistant steel can generally be achieved by increasing the carbon content and alloy content of the steel plate, which will lead to poorer processing performance and welding performance of steel, and worse cold-formed performance.

In recent years, in the production process of road construction machinery, heavy mining trucks, coal machines, power plants, cement and other industries, due to the hard materials and fast movement, the equipment wear is very serious, resulting in rapid wear of spare parts and short maintenance cycles. A kind of high wear resistance HB400 grade wear-resistant steel plate, which can prolong the service life of spare parts without increasing the hardness. At the same time, some wear-resistant spare parts with complex shapes need to be bent during the preparation process, and the cold bendability of ordinary low-alloy martensitic wear-resistant steel is difficult to meet its requirements.

In order to improve the wear resistance of low-alloy steel plates, in recent years, some steel mills at home and abroad have increased the content of Ti and V in low-alloy wear-resistant steel, and used the martensitic matrix to add high hardness TiC and VC to precipitate to enhance wear resistance. The properties are enhanced, but the plasticity and toughness are poor, so it cannot be cold-formed, and it is difficult to promote it in large quantities.

Tianjin Leigong Welding Materials Co., Ltd., Lei Wanjun; Chen Zerong; Xu Lixia; Grinding plate, including low-carbon steel plate or low-carbon alloy steel plate, said low-carbon steel plate or low-carbon alloy steel plate is welded with a wear-resistant alloy layer, characterized in that: in the percentage of the total mass of the wear-resistant alloy layer, the wear-resistant alloy layer The content of each component in the alloy layer is as follows: C: 0.35-0.55%; Si: 2-2.4%; Mn: 2.7-3.2%; Cr: 11-12.5%; Mo: 2.5-2.9%; V: 0.7-1.8%; W: 2.2-3.6%; B: 0.7-1.1%; the rest is iron. The advantage of the invention is that the surface of the wear-resistant plate can be guaranteed to be smooth and smooth, and the wear resistance is good. The invention is produced by the bimetal composite surfacing welding process, the process is complicated, and the cost is high. Due to the high hardness of the surfacing layer, the steel plate cannot be formed and processed.

Baoshan Iron and Steel Co., Ltd., Li Hongbin, Yao Liandeng, Miao Yuchuan, etc. Application Publication (Announcement) No.: CN103146997A The patent document "A low-alloy high-toughness wear-resistant steel plate and its manufacturing method" relates to a low-alloy high-toughness wear-resistant steel plate Steel plate and its manufacturing method, its chemical composition (wt%) is: C: 0.08-0.20%, Si: 0.10-0.60%, Mn: 1.00-2.00%, B: 0.0005-0.0040%, Cr≤1.50%, Mo≤ 0.80%, Ni≤1.50%, Nb≤0.080%, V≤0.080%, Ti≤0.060%, Al: 0.010-0.080%, Ca: 0.0010-0.0080%, N≤0.0080%, O≤0.0080%, H≤0.0004 %, P≤0.015%, S≤0.010%, and satisfy 0.20%≤(Cr/5+Mn/6+50B)≤0.55%, 0.02%≤(Mo/3+Ni/5+2Nb)≤0.45%, 0.01%≤(Al+Ti)≤0.13%, and the rest are Fe and inevitable impurities. The invention reduces the content of carbon and alloying elements, makes full use of the refinement and strengthening characteristics of microalloying elements such as Nb and Ti, and through the TMCP process, the wear-resistant steel plate has high strength, high hardness, good toughness, easy welding and excellent wear resistance, and is suitable for Wear parts in various mechanical equipment. Its mechanical properties: tensile strength greater than 1200MPa, elongation greater than 12%, Brinell hardness greater than 400HB, -40 ℃ Charpy V-shaped longitudinal impact energy greater than 60J. The invention has high strength, shaping, welding and other properties, but the wear resistance is comparable to that of ordinary martensitic wear-resistant steel of the same hardness.

Jiangyin Xingcheng Special Steel Co., Ltd., Liu Jun, Li Guozhong, Xu Xiaohong, etc. Publication (announcement) No.: CN111996441A Patent document "A TiC-reinforced martensitic wear-resistant steel plate with high toughness and good bending performance and its manufacturing method", The invention relates to a TiC-enhanced martensitic wear-resistant steel plate with high toughness and good bending performance and a manufacturing method thereof. ～0.40%, Al: 0.04～0.08%, Ni: ≤0.10%, Cu: ≤0.10%, Cr: 0.20～1.00%, Mo: 0.10～0.60%, B: 0.0010～0.0040%, Ca: 0.001～0.005% , P: ≤ 0.015%, S: ≤ 0.003%, O: ≤ 0.0015%, N: ≤ 0.0030%, H: ≤ 0.0002%, the remainder is Fe; and 0.13 ≤ C-Ti/4 ≤ 0.25, thus After the formation of TiC, the hardness of the martensite matrix reaches 400-480HB; the carbon equivalent CEV: ≤ 0.65%, and the machining and welding performance can meet the requirements of high wear resistance equipment manufacturing. The process flow is: converter or electric furnace steelmaking->LF refining->vacuum degassing->Ca treatment->continuous casting->heating->hot rolling->quenching->low temperature tempering. Elongation A50≥8%; low temperature impact toughness: -40℃Akv≥20J, cold bending performance of steel plate: d=5a cold bending 90° without cracking. The wear resistance reaches 1.4 times and above that of the low alloy martensitic wear-resistant steel NM450. The steel sheet prepared by this method has good machinability, and the hardness can reach HBW400-480. The invention has good forming performance, but the content of Ti is high, and smelting and continuous casting are difficult.

Jie Fuyi Steel Co., Ltd., Yusuke Terazawa; Naoki Takayama; Kenji Lin; Japanese Patent Documents of Kazubang Hase, Application Publication No. CN109072367A, "Abrasion Resistant Steel Plate and Manufacturing Method of Wear Resistant Steel Plate", discloses It has the following component composition and structure, and the component composition contains in mass %: C: 0.10 to 0.23%, Si: 0.01 to 1.0%, Mn: 0.30 to 3.00%, P: 0.025% or less, S: 0.02% or less , Cr: 0.01-2.00%, Al: 0.001-0.100%, and N: 0.01% or less, the remainder is composed of Fe and inevitable impurities, in the structure, the depth of 1 mm from the surface of the wear-resistant steel plate The volume fraction of martensite in the wear-resistant steel plate is 90% or more, the prior austenite grain size at the center of the plate thickness of the wear-resistant steel plate is 80 μm or less, and the hardness at a depth of 1 mm from the surface of the wear-resistant steel plate A wear-resistant steel plate with a Brinell hardness of 360 to 490HBW 10/3000 and a method for producing the wear-resistant steel plate. The steel plate has complex alloy composition, high cost, and only has ordinary wear resistance.

It can be seen that the existing HB400 wear-resistant steel plate has the following shortcomings:

1. The composition and process are complex, requiring heterogeneous compounding or surfacing;

2. Difficulty in smelting and continuous casting;

3. Can not be cold-formed;

4. Insufficient wear resistance.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a HB400 grade high wear-resistant cold-formable steel plate and a production method thereof. The present invention adopts a new wear-resistant concept on the basis of low-alloy wear-resistant steel, reasonably increases the Nb content in the steel, and utilizes dispersion precipitation. The high-hardness niobium carbide particles enhance the wear resistance, and the wear resistance is more than 1.4 times that of ordinary wear-resistant steel plates with the same hardness. Using a unique smelting, rolling and heat treatment production process, the surface of the steel plate is subjected to a crack arrest treatment to form a partial decarburization layer, coupled with reasonable residual austenite content control, to produce a Brinell hardness of 400HB grade with good plasticity and Toughness High wear resistance low alloy wear-resistant steel that can be cold-formed.

To achieve the above object, the present invention adopts the following technical solutions to realize:

An HB400 grade high wear-resistant cold-formable steel plate, the chemical composition of the steel is calculated by weight percentage as follows: C 0.14%-0.18%, Si 1.1%-1.50%, Mn 0.7%-1.0%, Nb 0.12%-0.20%, Cr 0.15%～0.35%, Ni0.4%～0.6%, Al 0.040%～0.060%, P≤0.012%, S≤0.002%, [N]≤0.0030%, [H]≤0.00015%, [O]≤ 0.0015%; the balance is Fe and inevitable impurities; and C*Nb≤0.0004%, 1.5%≤Si+Ni≤2.0%.

The chemical composition design of the steel plate of the invention is mainly characterized by microalloying of carbon, niobium and silicon, and the alloy content is relatively low, which is convenient for smelting and continuous casting. Through continuous casting, controlled rolling and controlled cooling, and then low temperature tempering heat treatment, HB400 grade steel plates with good plastic toughness and wear resistance are obtained.

The reasons for the design elements of the present invention are:

C: In order to ensure the high strength and hardness of the steel plate and stabilize the amount of retained austenite in the steel, a considerable carbon content is required to ensure it. At the same time, carbon can form carbide precipitation with Nb to increase wear resistance. If the carbon content is too high, the welding performance will decrease, and it will also affect the solid solution and precipitation of Nb in the steel. In order to ensure that the steel plate has high wear resistance and good welding performance, formability and wear resistance, the C content in the present invention is controlled at 0.14%～0.18%, and C*Nb≤0.03;

Si: The present invention focuses on adding elements. It is a non-carbide forming element. Its main function is to inhibit the precipitation of carbides and stabilize the residual austenite content in the steel, which is beneficial to improve the low temperature toughness and plasticity of the steel plate and ensure good cold bending ability. At the same time, it plays the role of stabilizing the thickness of the decarburized layer, but too much Si will reduce the welding performance, so the Si content in the present invention is controlled at 1.1% to 1.5%;

Mn: The main function is to improve the hardenability and at the same time promote the solid solution of Nb. It is beneficial to the improvement of strength and wear resistance, but when the content is too high, it is easy to form center segregation, which makes the center of the slab prone to cracks; it is not conducive to cold forming, so the Mn content in the present invention is controlled at 0.7% to 1.0%;

Nb: An important additive element in the present invention. Main function: increase wear resistance and plasticity. Nb is a strong carbon and nitrogen compound forming element. It can form compounds such as NbC and Nb(C, N) when combined with C and N in steel. It has the characteristics of high chemical stability and high hardness, which can form 1.4 times the wear resistance of ordinary wear-resistant steel. In addition, the addition of Nb element makes the low-temperature austenite structure induce a large amount of carbon and nitrogen during the rolling process. Nb dissolved in austenite inhibits recrystallization of austenite and refines austenite grains during the two-stage rolling process. It is beneficial to the cold bending performance of the steel plate. However, if the Nb content is too high, the mechanical properties of the steel sheet will be affected. Therefore, the added amount of Nb in the present invention is 0.12% to 0.20%.

Ni: a non-carbide forming element, the main function is to improve the toughness and plasticity of the steel. If the Ni content is less than 0.4%, the required effect cannot be achieved. If the Ni content is greater than 0.6%, the cost is too high, and austenite may remain during quenching. Too much body. The present invention controls Ni: 0.4% to 0.6%. Since both Si and Ni have the effect of promoting the content of retained austenite, the present invention controls the content of retained austenite to 5 to 10%, in order to prevent excessive or excessive amount of retained austenite. Since the total amount of Si+Ni is controlled, in the present invention, 1.5%≤Si+Ni≤2.0%.

Al: Effective element for deoxidation and nitrogen fixation. It can reduce the oxide inclusions in the steel and purify the steel, which is beneficial to improve the formability of the steel plate. If the content is too high, it will cause casting difficulties, and a large amount of Al ₂ O ₃ inclusions will be formed in the steel, resulting in poor ductility and nitrogen fixation. It is guaranteed that niobium is mainly combined with carbon. Therefore, in the present invention, Al: 0.04% to 0.06%%.

Cr: The effect of increasing the hardenability of steel. Chromium is a strong carbide forming element that increases strength and hardness. Adding too much Cr will affect the weldability, so the present invention controls Cr: 0.15% to 0.35%.

Impurity elements: In order to ensure that the steel plate has good plasticity and toughness, and to avoid fragmentation during wear and cracks during cold bending, the present invention controls P≤0.012%, S≤0.002%, [H]≤0.00015%, [O] ≤0.0015%.

The residual austenite content in the steel is 5% to 10%, and the thickness of the partial decarburization layer on the surface of the steel plate is 1 to 2 mm.

Under the same experimental conditions, the wear resistance of the steel plate is more than 1.4 times that of the NM400 steel plate with the same hardness, and the cold forming performance is 180° cold bending D=3a.

A production method of HB400 grade high wear-resistant cold-formable steel plate, the production process flow is: smelting→refining→slab continuous casting→cast slab heating and slow cooling→heating→controlled rolling→controlled cooling→tempering heat treatment, including the following method:

1) Smelting: RH degassing time control is carried out during refining in the present invention, RH vacuum cycle time ≥ 15min, through long-term vacuum treatment, molten steel can be controlled [N] ≤ 0.0030%, [O] ≤ 0.0015%, [H] ≤ 0.00015%. The characteristics of continuous casting are: appropriately increase the cooling rate of the secondary cooling zone of continuous casting, adopt the mode of medium cooling intensity, the water supply in the secondary cooling zone of continuous casting accounts for 60% to 80%, and control the casting speed of continuous casting to be 1.1 to 1.5m/ min; the purpose is to avoid excessive precipitation of coarse niobium carbides in the high temperature region. The slab thickness is 200-250mm, and electromagnetic stirring or light pressing is used during continuous casting to reduce center segregation. The present invention controls the center segregation ≤B0.5, and the intermediate crack ≤0.5 grade, the purpose is to ensure the lowest internal defect of the steel plate during cold bending. After continuous casting, the slab is heated to 550-650 ℃, and slowly cooled with the furnace for no less than 48 hours; it can effectively remove the hydrogen content in the billet, and at the same time, the slow cooling of about 600 ℃ is conducive to the full precipitation of fine niobium carbides.

2) Rolling: The temperature of the soaking section is heated by oxidizing atmosphere at 1250~1310℃, and the soaking time is not less than 2.5 hours; the purpose of higher heating temperature and longer holding time: 1) To ensure that the higher niobium can fully Solid solution; 2) Conducive to the homogenization of central segregation elements; 3) Conducive to the formation of a 1-2 mm partial decarburization layer on the surface after rolling, which can effectively improve the cold bending performance of the rolled steel plate.

During rolling, two-stage controlled rolling, rough rolling and finishing rolling, is used to fully refine and homogenize the hot-rolled microstructure. In the rough rolling stage, the rolling rolling temperature is ≥1100℃, the final rolling temperature is controlled at ≥1050℃, and the single-pass reduction rate of rough rolling is not less than 15%; it ensures the deep penetration of the rolling force and promotes the precipitation of niobium carbide; The rolling temperature is 970～1030℃, the deformation rate is not less than 70%, the purpose is to break the coarse niobium carbide and improve the core defect structure, and the finishing rolling temperature is 900～950℃.

Water cooling after rolling, using ultra-fast cooling + laminar cooling, ultra-fast cooling water temperature 870 ~ 920 ℃, ultra-fast cooling cooling rate ≥ 20 ℃/s, ultra-fast cooling final cooling temperature 600 ~ 650 ℃; laminar cooling rate 5 ～10℃/s, the temperature of returning to red is 200～250℃, air cooled to room temperature.

The front section adopts ultra-fast cooling, the inlet water temperature of ultra-fast cooling is 870-920°C, the cooling rate of ultra-fast cooling is ≥20°C/s, and the final cooling temperature of ultra-fast cooling is 600-650°C; it can reduce the crystallinity of niobium carbonitride during slow cooling. Aggregation of boundaries and refinement of the austenite grains are beneficial to plastic toughness and wear resistance. Laminar cooling is adopted in the rear section, the cooling rate is 5~10℃/s, the red temperature is 200~250℃, and the air is cooled to room temperature; the latter section is weakly cooled and controlled to be higher than 200℃, which can reduce the internal stress of the steel plate and retain a small amount of residual. The austenite content ensures that the flatness of the shape is below 5 mm/m and the cold bending performance.

3) Heat treatment: the tempering temperature is 200～250℃, and the tempering holding time is 8～12min/mm. The present invention adopts a tempering time higher than the conventional one (3-5 min/mm), and aims to fully remove the quenching internal stress, improve the plasticity of the steel plate, and ensure the cold forming performance of the steel plate.

Compared with the prior art, the beneficial effects of the present invention are:

The invention provides a 10-30 mm thick HB400 grade high wear-resistant cold-formable steel plate and a production method thereof.

1. Continuous casting production;

2. The surface hardness is greater than HB400, -40℃AKV≥40J;

3. The wear resistance is more than 1.4 times that of the same hardness and low alloy wear-resistant steel plate;

4. With good cold forming performance, 180° cold bending D=3a is qualified.

Detailed ways

Embodiments of the present invention are further described below in conjunction with specific examples:

According to chemical composition of the present invention and production technique, the actual chemical composition of smelting steel of the present invention is shown in Table 1, the smelting process is shown in Table 2, the actual rolling process parameters of the steel example of the present invention are shown in Table 3, and the controlled cooling process is shown in Table 4, The heat treatment process parameters are shown in Table 5, the physical performance test results of the present invention are shown in Table 6, and the wear resistance test results are shown in Table 7.

The smelting composition example of table 1 steel grade of the present invention, wt%

serial number C Si Mn Nb Cr Ni Al P S H 0 N Si+Ni C*Nb 1 0.14 1.5 1.0 0.12 0.35 0.40 0.040 0.009 0.0013 0.00012 0.0014 0.0030 1.90 0.00017 2 0.15 1.3 0.9 0.14 0.25 0.50 0.045 0.011 0.014 0.00014 0.0015 0.0022 1.82 0.00021 3 0.17 1.2 0.8 0.17 0.25 0.55 0.052 0.008 0.016 0.00015 0.0011 0.0025 1.75 0.00029 4 0.18 1.1 0.7 0.20 0.15 0.60 0.055 0.010 0.016 0.00008 0.0009 0.0020 1.72 0.00036

The smelting process of table 2 steel grade of the present invention

The actual rolling process parameter of table 3 steel example of the present invention

The actual controlled cooling process parameter of table 4 steel example of the present invention

The heat treatment process of table 5 steel example of the present invention

Table 6 Mechanical properties of steel examples of the present invention

The high wear-resistant steel plate of the present invention and the ordinary NM400 steel plate were compared with the MLS-225 type wet sand rubber wheel abrasion tester. minute. The experimental results are shown in Table 7.

Table 7 Comparison of wear resistance of embodiments of the present invention

Steel grade Wear AmountΔM/g Abrasion resistance comparison Ordinary NM400 0.06500 1.00 1-1 0.04452 1.46 1-2 0.04392 1.48 2-1 0.04483 1.45 2-2 0.04545 1.43 3-1 0.04610 1.41 3-2 0.04545 1.43 4-1 0.04483 1.45 4-2 0.04392 1.48

It can be seen that the wear resistance of the steel plate of the present invention is more than 1.4 times that of the ordinary wear-resistant steel plate NM400.

Claims (4)

1. An HB400 grade high wear-resistant cold-bending steel plate is characterized in that the steel comprises the following chemical components in percentage by weight: 0.14 to 0.18 percent of C, 1.1 to 1.50 percent of Si, 0.7 to 1.0 percent of Mn, 0.12 to 0.20 percent of Nb, 0.15 to 0.35 percent of Cr, 0.4 to 0.6 percent of Ni, 0.040 to 0.060 percent of Al, less than or equal to 0.012 percent of P, less than or equal to 0.002 percent of S, less than or equal to 0.0030 percent of N, less than or equal to 0.00015 percent of H and less than or equal to 0.0015 percent of O; the balance of Fe and inevitable impurities; and C is not more than 0.0004 percent of Nb, and not more than 1.5 percent of Si and Ni is not more than 2.0 percent.

2. The HB400 grade high wear resistance cold-bending steel plate according to claim 1, wherein the steel contains 5% -10% of residual austenite, and the decarburized layer on the surface of the steel plate is 1-2 mm thick.

3. The HB400 grade high wear resistant cold-bendable steel plate according to claim 1, characterized in that the wear resistance of the steel plate reaches more than 1.4 times of the same hardness NM400 steel plate under the same experimental conditions, and the cold formability is 180 ° cold bending D-3 a.

4. A method for producing a HB400 grade high wear resistant cold-bendable steel sheet as claimed in any one of claims 1 to 3, characterized by comprising the steps of:

1) smelting: the RH vacuum circulation time is more than or equal to 15min, and the casting speed of the continuous casting billet is controlled to be 1.1-1.5 m/min; the water supply amount of the continuous casting secondary cooling area accounts for 60-80%, the center segregation of the billet is less than or equal to B0.5, the center crack is less than or equal to 0.5 level, the casting blank is heated to 550-650 ℃ after continuous casting, and furnace slow cooling is carried out for not less than 48 hours;

2) rolling: heating the soaking section in oxidizing atmosphere at 1250-1310 ℃ for not less than 2.5 hours;

during rolling, controlled rolling is carried out in two stages of rough rolling and finish rolling, the rolling start temperature in the rough rolling stage is more than or equal to 1100 ℃, the finish rolling temperature is controlled to be more than or equal to 1050 ℃, and the single-pass reduction rate of the rough rolling is not lower than 15%; the finish rolling start temperature is 970-1030 ℃, the deformation rate is not lower than 70%, and the finish rolling temperature is 900-950 ℃;

after rolling, water cooling is carried out, and ultrafast cooling and laminar cooling are adopted, wherein the water inlet temperature of the ultrafast cooling is 870-920 ℃, the ultrafast cooling speed is more than or equal to 20 ℃/s, and the final cooling temperature of the ultrafast cooling is 600-650 ℃; laminar cooling speed is 5-10 ℃/s, the temperature of red return is 200-250 ℃, and air cooling is carried out to room temperature;

3) and (3) heat treatment: the tempering temperature is 200-250 ℃, and the tempering heat preservation time is 8-12 min/mm.