CN113106340A

CN113106340A - 450 HB-grade rare earth high-wear-resistance steel plate

Info

Publication number: CN113106340A
Application number: CN202110336136.XA
Authority: CN
Inventors: 袁晓鸣; 王栋; 屈文胜; 岳祎楠; 吴鹏飞; 乔建军; 朱秀光
Original assignee: Baotou Iron and Steel Group Co Ltd
Current assignee: Baotou Iron and Steel Group Co Ltd
Priority date: 2021-03-29
Filing date: 2021-03-29
Publication date: 2021-07-13

Abstract

The invention discloses a 450 HB-grade rare earth high-wear-resistance steel plate, which comprises the following chemical components in percentage by mass: c: 0.18 to 0.21%, Si: 0.20 to 0.50%, Mn: 1.10-1.40%, P: less than or equal to 0.012%, S: less than or equal to 0.002%, Cr: 0.40-0.90%, Ti: 0.008-0.018%, B: 0.0010-0.0020%, Mo: 0.15 to 0.50%, Ni: 0.15-0.30%, 0< Ce is less than or equal to 0.0035%, Als: 0.025 to 0.04%, CEV: 0.56-0.69%, and the balance of Fe and inevitable impurities. The steel plate provided by the invention has excellent wear resistance, and the wear loss under the same condition can reach less than 85% of that of the same-grade steel plate in the prior art.

Description

450 HB-grade rare earth high-wear-resistance steel plate

Technical Field

The invention belongs to the field of rare earth high-strength wear-resistant quenched and tempered steel plates, particularly relates to a 450 HB-grade rare earth high-wear-resistant steel plate, and particularly relates to a 450 HB-grade rare earth high-wear-resistant steel plate for a coal scraper conveyor.

Background

The working condition environment is extremely complex in the coal mining and transporting process, and the steel plate is subjected to the synergistic effect of multi-factor abrasion (or corrosion) such as coal, gangue, environment media (temperature, humidity and corrosive atmosphere), load stress and the like in the service process. The working conditions of different mines are greatly different: the content of gangue is about 10% under normal working conditions, and the gangue is normal temperature and humidity; under severe working conditions, the content of gangue can reach 50%, the underground temperature can reach 40 ℃, the humidity is more than 90%, and the abrasion mechanism and the failure behavior of the steel plate under different working conditions are greatly different. The coal mining and transportation typical wear-resistant part, namely the middle groove of the scraper conveyor, has the coal passing amount of about 800 ten thousand tons under the normal working condition, and has the coal passing amount of less than 500 ten thousand tons under the harsh working conditions of high gangue and high humidity and heat. With the continuous increase of high-yield and high-efficiency working faces of millions of tons of annual products in large mines, a novel high-wear-resistance steel plate material needs to be developed urgently to meet the urgent needs of the coal industry.

The low-alloy martensite wear-resistant steel is the wear-resistant steel which is most widely applied in the coal mining industry, has the obvious advantages of simple production process, low cost, excellent and stable comprehensive performance and the like compared with medium-high manganese austenite wear-resistant steel and bainite wear-resistant steel, and represents the development direction of the wear-resistant steel for coal mining. However, the conventional low-alloy martensitic steel improves the wear resistance by simply increasing the hardness, which leads to deterioration in the workability of the steel and a significant increase in the tendency of cracking of the wear-resistant member. How to improve the wear resistance without increasing the hardness and reducing the processability is a key technical problem in the development of high-wear-resistance steel for coal mining and transportation.

Patent document CN104451403A (hereinafter referred to as W1) discloses a low-temperature HB 450-grade wear-resistant steel with a complex phase structure, which adopts Cr-Ti-added trace V and a certain amount of silicon in the component design, and the component design is favorable for obtaining the complex phase structure, especially for obtaining a certain proportion of residual austenite and dispersed particles in a martensite + bainite matrix, so as to improve the comprehensive mechanical properties, especially the plasticity and toughness of the wear-resistant steel, and achieve good comprehensive mechanical properties under the premise of low cost, but the document W1 does not specifically represent the wear-resistant property, and also needs to use V element, which causes high cost and difficulty in smelting and continuous casting.

Patent document CN106244920A (hereinafter referred to as W2) discloses a brinell hardness 450-grade wear-resistant steel, which has excellent wear resistance and high toughness, and has uniform compressive stress on the surface thereof, and further enhances the wear resistance and fatigue resistance thereof, by controlling important chemical components C, Si, Mn, Cr, B, V, and the like, which have a large influence on residual stress, and by adopting reasonable processes such as quenching, tempering heat treatment, and the like; the wear-resistant steel has good residual stress uniformity, no cracking and deformation in the use process, wear resistance and long service life, however, the document W2 does not specifically represent the wear resistance, and V element is also needed, so that the cost is high, and the smelting and continuous casting are difficult.

Patent document CN108060362A (hereinafter referred to as W3) discloses an HB450 grade anti-crack wear-resistant steel with a complex phase structure, which takes bainite + martensite + retained austenite complex phase structure as a design main line, and adopts C-Si-Mn-Mo-Cr and Nb-Ti-B micro-alloying component design, which is beneficial to obtaining the complex phase structure, thereby improving the wear resistance, plasticity and toughness of the wear-resistant steel and having excellent anti-crack performance. However, the document W3 also does not specifically characterize its wear resistance.

Disclosure of Invention

Aiming at one or more problems in the prior art, the invention provides a 450 HB-grade rare earth high-wear-resistance steel plate which comprises the following chemical components in percentage by mass: c: 0.18 to 0.21%, Si: 0.20 to 0.50%, Mn: 1.10-1.40%, P: less than or equal to 0.012%, S: less than or equal to 0.002%, Cr: 0.40-0.90%, Ti: 0.008-0.018%, B: 0.0010-0.0020%, Mo: 0.15 to 0.50%, Ni: 0.15-0.30%, 0< Ce is less than or equal to 0.0031%, Als: 0.025 to 0.04%, CEV: 0.56-0.69%, and the balance of Fe and inevitable impurities;

the production method of the 450 HB-grade rare earth high-wear-resistance steel plate comprises the following process steps: smelting, continuous casting, rolling and heat treatment; wherein:

in the smelting process, molten iron for smelting is subjected to desulfurization pretreatment, scrap steel is added, and the components of the molten steel are ensured through LF refining heating, component fine adjustment and alloying; RH vacuum treatment time is 20min, and rare earth Ce-Fe alloy is added during vacuum treatment; soft blowing is carried out after the vacuum treatment is finished, the slag surface of the steel ladle is kept still during the soft blowing, and the liquid level of the molten steel cannot be exposed in the air;

in the continuous casting process, protective casting is adopted in the whole process, electromagnetic stirring and light reduction are carried out, the low-power detection of the plate blank requires that the center segregation is not more than class C3, and the center porosity is not more than class 2;

in the rolling process, the tapping temperature of a plate blank is 1200 +/-20 ℃, two-stage rolling is adopted, the initial rolling temperature of rough rolling is more than or equal to 1100 ℃, the finish rolling temperature is 820-870 ℃, and the plate blank is cooled to 630-680 ℃ after rolling;

in the heat treatment process, the quenching process comprises the following steps: quenching at 890-930 ℃ for 20-40 min by heat preservation; the tempering process comprises the following steps: and (3) keeping the temperature for 30-120 min at the temperature of 220 +/-10 ℃ and air cooling.

The 450 HB-grade rare earth high-wear-resistance steel plate comprises the following chemical components in percentage by mass: c: 0.19 to 0.20%, Si: 0.22-0.38%, Mn: 1.15-1.31%, P: less than or equal to 0.012%, S: less than or equal to 0.002%, Cr: 0.50-0.90%, Ti: 0.012-0.014%, B: 0.0014-0.0016%, Mo: 0.18 to 0.36%, Ni: 0.15-0.22%, 0.0015-0.0031% of Ce, and Als: 0.025 to 0.04 percent, and the balance of Fe and inevitable impurities.

The thickness of the 450 HB-level rare earth high-wear-resistance steel plate is 16-60 mm, and the thickness of the intermediate blank after the rolling process is 3 times that of the finished product.

According to the 450 HB-grade rare earth high-wear-resistance steel plate provided by the invention based on the technical scheme, from the chemical composition, the alloy components are mainly low carbon and low alloy, comprise a certain amount of Mn, Cr, Ti, Mo, Ni and the like, and are added with a trace amount of rare earth element Ce, but do not contain V with higher cost; from the production process, the rare earth cerium-iron alloy is added in the smelting process, the yield of rare earth is obviously improved, the stability of performance is ensured, meanwhile, the rolling process adopts the TMCP process for production, and the casting blank structure refinement and the hot rolling state structure refinement are realized by controlling the process parameters such as the thickness of the intermediate blank, the rolling deformation, the cooling speed and the like, the structure uniformity is improved, and then the steel plate with excellent mechanical property, wear resistance and the like is obtained. Therefore, the method can fully improve the beneficial effects of the casting blank in the aspects of dendritic crystal segregation, texture morphology, grain size, weldability, formability, high wear resistance and the like through reasonable component design and the addition and optimization process conditions of the rare earth elements. The wear-resisting property of the wear-resisting steel is obviously improved under the condition that the hardness of the thick-specification wear-resisting steel is not simply improved.

Tests prove that the rare earth high-strength high-wear-resistance steel plate provided by the invention has the advantages of high strength, high hardness, high low-temperature toughness (typical mechanical properties: the tensile strength is more than 1400MPa, the elongation is more than 10%, the surface Brinell hardness is more than 430HB, the core Brinell hardness is more than 400HB, the summer-specific V-type longitudinal impact energy at minus 40 ℃ is more than 60J) and the like, the microstructure is a fine martensite structure and residual austenite, the good matching of the wear resistance, the hardness and the toughness of the product is obviously improved, the service cycle can be obviously prolonged, the steel plate is not cracked and easy to weld, is suitable for manufacturing easily-worn parts in middle groove equipment of a coal scraper, the coal mining quantity of the equipment is obviously improved, and the steel plate has obvious economic benefits. The rare earth high-strength high-wear-resistance steel plate provided by the invention has very excellent wear resistance, and the wear loss is only less than 85% of that of the W1, W2 and W3 and the Hardox450 steel plate in Sweden under the same conditions.

Drawings

FIG. 1 is a transmission electron microscope photograph of metallographic structure of a 450 HB-grade rare earth high-wear-resistance steel plate according to an embodiment of the invention;

FIG. 2 is a transmission electron microscope photograph of metallographic structure of a 450 HB-grade rare earth high-wear-resistance steel plate according to an embodiment of the invention;

FIG. 3 is a transmission electron microscope photograph of the surface topography of 450HB grade rare earth high wear resistant steel plates BTNM450-2, NM450-2 and Swedish Hardox450 steel plates after abrasion, wherein the upper panel is magnified 200 times and the lower panel is magnified 500 times, according to one embodiment of the invention.

Detailed Description

The invention aims to provide a rare earth high-strength high-wear-resistance steel plate (450 HB-grade rare earth high-wear-resistance steel plate named as BTNM450) with good wear resistance and a production method thereof.

The 450 HB-grade rare earth high-wear-resistance steel plate comprises the following chemical components in percentage by mass: c: 0.18 to 0.21%, Si: 0.20 to 0.50%, Mn: 1.10-1.40%, P: less than or equal to 0.012%, S: less than or equal to 0.002%, Cr: 0.40-0.90%, Ti: 0.008-0.018%, B: 0.0010-0.0020%, Mo: 0.15 to 0.50%, Ni: 0.15-0.30%, 0< Ce is less than or equal to 0.0035%, Als: 0.025 to 0.04%, CEV: 0.56-0.69%, and the balance Fe and inevitable impurities.

Preferably, the 450 HB-grade rare earth high-wear-resistance steel plate comprises the following chemical components in percentage by mass: c: 0.19 to 0.20%, Si: 0.22-0.38%, Mn: 1.15-1.31%, P: less than or equal to 0.012%, S: less than or equal to 0.002%, Cr: 0.50-0.90%, Ti: 0.012-0.014%, B: 0.0014-0.0016%, Mo: 0.18 to 0.36%, Ni: 0.15-0.22%, 0.0015-0.0031% of Ce, and Als: 0.025 to 0.04 percent, and the balance of Fe and inevitable impurities.

The production method of the 450 HB-grade rare earth high-wear-resistance steel plate provided by the invention comprises the following process steps: smelting, continuous casting, rolling and heat treatment; the 450 HB-grade rare earth high-wear-resistance steel plate can be produced according to the existing production method for producing 450 HB-grade high-wear-resistance steel except the following process condition parameters:

in the smelting process, molten iron for smelting is subjected to desulfurization pretreatment, high-quality self-produced scrap steel is added, and the components and the temperature of the molten steel meet the requirements of subsequent processes through LF refining heating, component fine adjustment and alloying. And during RH vacuum treatment, the vacuum treatment time is 20min, rare earth Ce-Fe alloy (the yield of rare earth can reach more than 50 percent by adding the alloy) is added during vacuum treatment, and the temperature and the oxygen are measured before the alloy is added. Soft blowing is carried out after the vacuum treatment is finished, the slag surface of the steel ladle is kept still during the soft blowing, and the liquid level of the molten steel cannot be exposed in the air;

in the continuous casting process, protective casting is adopted in the whole continuous casting process, and a special anti-oxidation protective casting device made of rare earth steel is used in the casting process. The method ensures that the rare earth steel realizes the goals of no steel flocculation and continuous casting in the casting process. Meanwhile, electromagnetic stirring and soft reduction are carried out, the slab low-power detection requires that the center segregation is not more than class C3, and the center porosity is not more than class 2;

in the rolling process, the tapping temperature of a plate blank is 1200 +/-20 ℃, two-stage rolling is adopted, the initial rolling temperature of rough rolling is more than or equal to 1100 ℃, the finish rolling temperature is 820-870 ℃, and the plate blank is cooled to 630-680 ℃ after rolling; the thickness of the intermediate blank after the rolling process is 3 times that of the finished product, and the thickness of the finished product is 16-60 mm;

The present invention is described in more detail below with reference to examples. These examples are merely illustrative of the best mode of carrying out the invention and do not limit the scope of the invention in any way.

Example 1

The chemical composition weight percentages of the steel sheet are shown in table 1. The tapping temperature of the heating furnace of the plate blank is 1210 ℃, two-stage rolling is adopted, and the initial rolling temperature of rough rolling is 1160 ℃. The finish rolling temperature of the fine rolling is 835 ℃, the temperature is cooled to 680 ℃ after rolling, and the thickness of the intermediate billet is 3 times of that of the finished product. Quenching process: quenching at 890 ℃ for 20 min; and (3) tempering process: keeping the temperature at 230 ℃ for 30min and cooling in air. Finally, the steel plate BTNM450-1 can be obtained.

Example 2

The chemical composition weight percentages of the steel sheet are shown in table 1. The tapping temperature of the heating furnace of the plate blank is 1205 ℃, and the plate blank is rolled in time after being heated. Two-stage rolling is adopted, and the initial rolling temperature of rough rolling is 1150 ℃. The finish rolling temperature is 830 ℃, the temperature is cooled to 650 ℃ after rolling, and the thickness of the intermediate billet is 3 times that of the finished product. Quenching process: quenching at 905 deg.C for 25 min; and (3) tempering process: keeping the temperature at 220 ℃ for 50min and cooling in air. Finally, the steel plate BTNM450-2 can be obtained, and the transmission electron microscope photos of the metallographic structure are shown in figure 1 and figure 2.

Example 3

The chemical composition weight percentages of the steel sheet are shown in table 1. The tapping temperature of the heating furnace of the plate blank is 1200 ℃, and the plate blank is rolled in time after being heated. Two-stage rolling is adopted, and the initial rolling temperature of rough rolling is 1140 ℃. The finish rolling temperature is 840 ℃, the temperature is cooled to 630 ℃ after rolling, and the thickness of the intermediate billet is 3 times of that of the finished product. Quenching process: quenching at 920 ℃ for 30 min; and (3) tempering process: keeping the temperature at 220 ℃ for 70min and cooling in air. Finally, the steel plate BTNM450-3 can be obtained.

Example 4

The chemical composition weight percentages of the steel sheet are shown in table 1. The tapping temperature of the heating furnace of the plate blank is 1206 ℃, and the plate blank is rolled in time after being heated. Two-stage rolling is adopted, and the initial rolling temperature of rough rolling is 1130 ℃. And the finish rolling temperature of the finish rolling is 831 ℃, the finished product is cooled to 610 ℃ after rolling, and the thickness of the intermediate billet is 3 times that of the finished product. Quenching process: quenching at 930 ℃ for 40 min; and (3) tempering process: keeping the temperature at 210 ℃ for 120min and air cooling. Finally, the steel plate BTNM450-4 can be obtained.

Comparative example 1

The chemical composition weight percentages of the steel sheet are shown in table 1. The tapping temperature of the heating furnace of the plate blank is 1210 ℃, two-stage rolling is adopted, and the initial rolling temperature of rough rolling is 1160 ℃. The finish rolling temperature of the fine rolling is 835 ℃, the temperature is cooled to 680 ℃ after rolling, and the thickness of the intermediate billet is 3 times of that of the finished product. Quenching process: quenching at 890 ℃ for 20 min; and (3) tempering process: keeping the temperature at 230 ℃ for 30min and cooling in air. Finally, the steel plate NM450-1 is obtained.

Comparative example 2

The chemical composition weight percentages of the steel sheet are shown in table 1. The tapping temperature of the heating furnace of the plate blank is 1205 ℃, and the plate blank is rolled in time after being heated. Two-stage rolling is adopted, and the initial rolling temperature of rough rolling is 1150 ℃. The finish rolling temperature is 830 ℃, the temperature is cooled to 650 ℃ after rolling, and the thickness of the intermediate billet is 3 times that of the finished product. Quenching process: quenching at 905 deg.C for 25 min; and (3) tempering process: keeping the temperature at 220 ℃ for 50min and cooling in air. Finally, the steel plate M450-2 can be obtained.

Table 1: chemical composition of steel plate (wt%)

Element(s)	C	Si	Mn	P	S	Cr	Mo	Ni	B	Ti	Ce
												Example 1	0.20	0.38	1.30	0.009	0.001	0.50	0.18	0.15	0.0015	0.013	0.0015
Example 2	0.19	0.35	1.31	0.010	0.001	0.52	0.22	0.16	0.0016	0.012	0.0014
												Example 3	0.20	0.22	1.18	0.008	0.001	0.80	0.35	0.20	0.0015	0.014	0.0030
Example 4	0.20	0.24	1.15	0.012	0.001	0.90	0.36	0.22	0.0014	0.013	0.0031
												Comparative example 1	0.19	0.43	1.30	0.009	0.001	0.61	0.08	0.09	0.0015	0.014	0.0015
Comparative example 2	0.20	0.21	1.16	0.010	0.001	0.85	0.35	0.21	0.0013	0.013	--

The mechanical properties of the steel sheets obtained in the above examples 1 to 4 and comparative examples 1 and 2 were measured, and the results of the measurements are shown in table 2 below.

Table 2: mechanical properties of steel plate

From the detection results of the mechanical properties of the steel plate in table 2, it can be seen that the mechanical properties of the BTNM450 steel plate provided by the invention satisfy: the tensile strength is more than 1400MPa (more than or equal to 1444MPa), the elongation is more than 10 percent (more than or equal to 10.5 percent), the surface Brinell hardness is more than 430HB (more than or equal to 455HB), the core Brinell hardness is more than 400HB (more than or equal to 406HB), the Charpy V-shaped longitudinal impact energy at 40 ℃ is more than 60J (more than or equal to 62.1J), and the steel plate has the characteristics of high strength, high hardness, high elongation and the like and has excellent cold-bending forming performance, so the steel plate provided by the invention has good comprehensive mechanical properties.

The abrasion resistance tests were conducted by taking as examples the BTNM450-2, NM450-1 and NM450-2 steel sheets produced in the above example 2, comparative example 1 and comparative example 2, respectively, and the abrasion resistance tests were conducted on the above documents W1, W2, W3 and the sweden Hardox450 steel sheets (H1, H2, H3 in the following table 3). The abrasion resistance test is carried out on an MLS-225 type wet rubber wheel abrasive wear testing machine, a linear cutting device is adopted to cut and process samples with the size of 57.0mm multiplied by 25.5mm multiplied by 7.0mm from the surface in the thickness direction into sample pieces with the size of 57.0mm multiplied by 25.5mm multiplied by 7.0mm to carry out the abrasive wear test, the friction media are water and silt, the abrasion conditions adopted by all the samples are the same, the applied pressure is 100N, the rotating speed of a grinding wheel is 300r/min, the total rotating speed is 2000r, the testing time is 10 minutes, and each sample is repeated three times. The wear results for each sample are shown in table 3 below.

Table 3: wear results of BTNM450 and comparative materials

Table 3 above describes the results of comparative wear tests of the rare earth high strength wear resistant steel BTNM450 provided by the present invention and Hardox450 in Sweden, the high strength wear resistant steel NM450-2 without rare earth addition in comparative example 2, the rare earth added high strength wear resistant steel NM450-1 produced in comparative example 1, and the 450HB grade steel sheets disclosed in the above documents W1, W2 and W3 under the same wear cycle. It can be seen that the average wear amount of BTNM450, which is a rare earth high strength wear resistant steel, is 0.3900g, which is significantly lower than the wear amounts of steel sheets of hadox 450, NM450-1, NM450-2, and W1, W2, and W3 in sweden, and that it is possible to achieve a wear amount of only 85% or less of the wear amount of steel sheets of hadox 450, W1, W2, and W3 in sweden. Test results show that the rare earth high-strength wear-resistant steel BTNM450 provided by the invention has excellent wear resistance.

The surface appearances of the worn samples BTNM450-2, NM450-2 and Swedish Hardox450 are detected, and the results are shown in figure 3, which obviously shows that the wear resistance of the wear-resistant steel provided by the invention is obviously improved, and obvious pits are visible on the surfaces of the steel plates of the NM450-2 and Swedish Hardox 450.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The 450 HB-grade rare earth high-wear-resistance steel plate is characterized by comprising the following chemical components in percentage by mass: c: 0.18 to 0.21%, Si: 0.20 to 0.50%, Mn: 1.10-1.40%, P: less than or equal to 0.012%, S: less than or equal to 0.002%, Cr: 0.40-0.90%, Ti: 0.008-0.018%, B: 0.0010-0.0020%, Mo: 0.15 to 0.50%, Ni: 0.15-0.30%, 0< Ce is less than or equal to 0.0035%, Als: 0.025 to 0.04%, CEV: 0.56-0.69%, and the balance of Fe and inevitable impurities;

2. The 450HB grade rare earth high wear resistance steel plate of claim 1, wherein the chemical compositions of the 450HB grade rare earth high wear resistance steel plate comprise, by mass percent: c: 0.19 to 0.20%, Si: 0.22-0.38%, Mn: 1.15-1.31%, P: less than or equal to 0.012%, S: less than or equal to 0.002%, Cr: 0.50-0.90%, Ti: 0.012-0.014%, B: 0.0014-0.0016%, Mo: 0.18 to 0.36%, Ni: 0.15-0.22%, 0.0015-0.0031% of Ce, and Als: 0.025 to 0.04 percent, and the balance of Fe and inevitable impurities.

3. The 450 HB-grade rare earth high-wear-resistance steel plate according to claim 1, wherein the thickness of the 450 HB-grade rare earth high-wear-resistance steel plate is 16-60 mm, and the thickness of the intermediate blank after the rolling process is 3 times of the thickness of a finished product.