Production method of wear-resistant steel plate with high surface hardness for engineering machinery

Abstract

The invention discloses a production method of a wear-resistant steel plate with high surface hardness for engineering machinery. The wear-resistant steel plate comprises the following chemical components in percentage by weight: 0.23 to 0.25 percent of C, 0.41 to 0.55 percent of Si, 0.95 to 0.99 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.008 percent of S, 1.15 to 1.25 percent of Cr, 0.40 to 0.50 percent of Ni, 0.30 to 0.40 percent of Mo, 0.0006 to 0.0016 percent of B, 0.011 to 0.018 percent of Ti, 0.015 to 0.020 percent of Nb, 0.015 to 0.030 percent of Als, 0.0006 to 0.0010 percent of Ce, less than or equal to 0.0045 percent of N and the balance of Fe and inevitable impurities. And other process parameters are optimized and controlled, the surface hardness of the obtained wear-resistant steel plate is larger than or equal to 465 HBW, and-40 impact KV2 is larger than or equal to 78 J.

Description

Technical Field

[0001] The present invention belongs to the technical field of wear-resistant steel, and specifically relates to a method for producing a wear-resistant steel plate for engineering machinery with high surface hardness, and in particular to a method for producing a wear-resistant steel plate for engineering machinery with both high surface hardness and excellent low-temperature toughness. Background Art

[0002] Wear-resistant steel is widely used in engineering machinery such as excavators, mine car carriages, and mining transportation equipment. The wear resistance can be effectively improved by increasing the hardness, but too high hardness will reduce the toughness of the steel. Therefore, it is of great significance to develop a method for producing wear-resistant steel plates for engineering machinery with high surface hardness and excellent low-temperature toughness. Summary of the invention

[0003] The present invention aims to provide a method for producing a wear-resistant steel plate for engineering machinery with a thickness of 50 to 60 mm and high surface hardness and excellent low-temperature toughness. The present invention obtains wear-resistant steel for engineering machinery with high surface hardness that can be used under -40°C environmental conditions through reasonable component design and corresponding process coordination, thereby ensuring that engineering machinery can work safely in a low-temperature environment. The specific technical scheme of the present invention is as follows.

[0004] One aspect of the present invention provides a method for producing a wear-resistant steel plate for engineering machinery with high surface hardness, the production method comprising the following process steps: smelting - continuous casting - heating and rolling - heat treatment, wherein:

[0005] In the smelting process, the chemical composition of the wear-resistant steel plate for engineering machinery is controlled to be C: 0.23-0.25%, Si: 0.41-0.55%, Mn: 0.95-0.99%, P≤0.015%, S≤0.008%, Cr: 1.15-1.25%, Ni: 0.40-0.50%, Mo: 0.30-0.40%, B: 0.0006-0.0016%, Ti: 0.011-0.018%, Nb: 0.015-0.020%, Als: 0.015-0.030%, Ce: 0.0006-0.0010%, N≤0.0045%, and the balance is Fe and unavoidable impurities;

[0006] In the heating and rolling process, the temperature of the cast billet out of the furnace is controlled to be 1215±15°C, the steel plate is rolled in a rough rolling and finishing rolling mode, the final rolling temperature is 840-855°C, and the steel plates are quickly stacked and slowly cooled after rolling;

[0007] The heat treatment process includes a quenching process and a tempering process, wherein in the quenching process, the insulation temperature is controlled at 900-910°C, the insulation time is 32±5 minutes, and the temperature of the steel plate after quenching is ≤50°C; in the tempering process, the insulation temperature is controlled at 175-185°C, and the steel plate is taken out of the furnace after insulation for 200-250 minutes. After taking out of the furnace, the steel plate is covered with an insulation cover and stacked for slow cooling.

[0008] In some embodiments, the wear-resistant steel plate for engineering machinery with high surface hardness has a thickness of 50-60 mm.

[0009] In some embodiments, the surface hardness of the wear-resistant steel plate for engineering machinery with high surface hardness is ≥465 HBW, -40 impact KV 2 ≥78J.

[0010] In some embodiments, the wear-resistant steel plate for engineering machinery with high surface hardness has a tensile strength of ≥1400 MPa and an elongation of A 50 ≥22%.

[0011] In some embodiments, in the smelting process, the molten iron for smelting is pre-treated with desulfurization to reduce the sulfur content of the molten iron, the scrap steel added is low-sulfur scrap steel, and the sulfur content of the molten steel is kept at a low level. The converter tapping temperature is maintained at 1630±15°C, the LF refining step ensures that the composition of the molten steel meets the requirements of the composition design, and the molten steel after vacuum treatment in the RH furnace reaches [N]≤45ppm.

[0012] In some embodiments, the microstructure of the wear-resistant steel plate for engineering machinery with high surface hardness after heat treatment is a tempered martensite microstructure plus a small amount of tempered bainite microstructure.

[0013] Another aspect of the present invention provides a wear-resistant steel plate for engineering machinery with high surface hardness, which is obtained by the above production method. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a metallographic photograph of the wear-resistant steel plate for engineering machinery with high surface hardness obtained in Example 1.

[0015] Figure 2 This is a metallographic structure photograph of the wear-resistant steel plate for engineering machinery with high surface hardness obtained in Example 2.

[0016] Figure 3 This is a metallographic photograph of the wear-resistant steel plate for engineering machinery with high surface hardness obtained in Example 3. DETAILED DESCRIPTION

[0017] The present invention is described in detail below through specific examples. The examples are intended to help understand the present invention but are not intended to limit the present invention.

[0018] The present invention aims to provide a method for producing a wear-resistant steel plate for engineering machinery with high surface hardness, which comprises the following steps:

[0019] 1. Smelting and casting

[0020] The hot metal for smelting needs to be pre-treated with desulfurization to reduce the sulfur content of the hot metal. The scrap steel added during the converter smelting process should be low-sulfur scrap steel to keep the sulfur content of the molten steel at a low level. The converter tapping temperature should be maintained at 1630±15℃. The LF refining step is to ensure that the composition of the molten steel meets the requirements of the composition design. The molten steel after vacuum treatment in the RH furnace reaches [N]≤45ppm. During smelting, the chemical composition is controlled by weight percentage as follows: C: 0.23-0.25%, Si: 0.41-0.55%, Mn: 0.95-0.99%, P≤0.015%, S≤0.008%, Cr: 1.15-1.25%, Ni: 0.40-0.50%, Mo: 0.30-0.40%, B: 0.0006-0.0016%, Ti: 0.011-0.018%, Nb: 0.015-0.020%, Als: 0.015-0.030%, Ce: 0.0006-0.0010%, N≤0.0045%, and the balance is Fe and unavoidable impurities.

[0021] The slab is casted by a continuous casting machine. To ensure the quality of the slab, a light reduction technique is used at the end of solidification. The continuous casting slab must be protected from wind and cooled slowly after it comes off the line.

[0022] 2. Heating and rolling

[0023] The temperature of the cast slab out of the furnace is 1215±15℃. The steel plate rolling adopts the rough rolling and finishing rolling mode, and the final rolling temperature is 840~855℃. After rolling, the steel plate is quickly stacked and slowly cooled.

[0024] 3. Heat treatment

[0025] Quenching process: control the holding temperature at 900-910°C, the holding time at 32±5 minutes, and the temperature of the steel plate after quenching is ≤50°C.

[0026] Tempering process: control the holding temperature at 175-185℃, keep it for 200-250 minutes before taking it out of the furnace. After taking it out of the furnace, cover the steel plates with a heat-insulating cover and stack them for slow cooling.

[0027] The microstructure of the steel plate after heat treatment is a tempered martensite structure plus a small amount of tempered bainite structure.

[0028] Example 1

[0029] The chemical composition of the steel plate is shown in Table 1. The temperature of the ingot out of the furnace is 1205℃. The steel plate rolling adopts the rough rolling and finishing rolling mode, the final rolling temperature is 848℃, and the steel plate is stacked and slowly cooled after rolling. Quenching process: the holding temperature is 903℃, and the steel plate is quenched after holding for 30min. Tempering process: the holding temperature is 182℃, and the steel plate is taken out of the furnace after holding for 210min. After the steel plate is taken out of the furnace, it is covered with an insulation cover and stacked and slowly cooled. The mechanical properties of the steel plate are shown in Table 2, and the metallographic structure of the steel plate is shown in Table 2. Figure 1 As shown, the structure is tempered martensite structure plus a small amount of tempered bainite structure.

[0030] Example 2

[0031] The chemical composition of the steel plate is shown in Table 1. The temperature of the ingot out of the furnace is 1215℃. The steel plate rolling adopts the rough rolling and finishing rolling mode, the final rolling temperature is 840℃, and the steel plate is stacked and slowly cooled after rolling. Quenching process: the holding temperature is 905℃, and the steel plate is quenched for 35min. Tempering process: the holding temperature is 185℃, and the steel plate is taken out of the furnace after 220min. After the steel plate is taken out of the furnace, it is covered with an insulation cover and stacked and slowly cooled. The mechanical properties of the steel plate are shown in Table 2, and the metallographic structure of the steel plate is shown in Table 2. Figure 1 As shown, the structure is tempered martensite structure plus a small amount of tempered bainite structure.

[0032] Example 3

[0033] The chemical composition of the steel plate is shown in Table 1. The temperature of the ingot out of the furnace is 1225℃. The steel plate rolling adopts the rough rolling and finishing rolling mode, the final rolling temperature is 850℃, and the steel plate is stacked and slowly cooled after rolling. Quenching process: quenching and holding temperature is 910℃, and the quenching is carried out by holding for 35min. Tempering process: tempering and holding temperature is 175℃, and the steel plate is slowly cooled after holding for 240min. After the steel plate is out of the furnace, it is covered with an insulation cover and stacked for slow cooling. The mechanical properties of the steel plate are shown in Table 2, and the metallographic structure of the steel plate is shown in Table 2. Figure 1 As shown, the structure is tempered martensite structure plus a small amount of tempered bainite structure.

[0034] Table 1: Chemical composition of steel plate (wt%)

[0035]

[0036] Table 2: Steel plate properties

[0037]

[0038] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for producing a wear-resistant steel plate for engineering machinery with high surface hardness, the production method comprising the following process steps: smelting - continuous casting - heating and rolling - heat treatment, wherein: In the smelting process, the chemical composition of the wear-resistant steel plate for engineering machinery is controlled to be C: 0.23-0.25%, Si: 0.41-0.55%, Mn: 0.95-0.99%, P≤0.015%, S≤0.008%, Cr: 1.15-1.25%, Ni: 0.40-0.50%, Mo: 0.30-0.40%, B: 0.0006-0.0016%, Ti: 0.011-0.018%, Nb: 0.015-0.020%, Als: 0.015-0.030%, Ce: 0.0006-0.0010%, N≤0.0045%, and the balance is Fe and unavoidable impurities; In the heating and rolling process, the temperature of the cast billet out of the furnace is controlled to be 1215±15°C, the steel plate is rolled in a rough rolling and finishing rolling mode, the final rolling temperature is 840-855°C, and the steel plates are quickly stacked and slowly cooled after rolling; The heat treatment process includes a quenching process and a tempering process, wherein in the quenching process, the insulation temperature is controlled at 900-910°C, the insulation time is 32±5 minutes, and the temperature of the steel plate after quenching is ≤50°C; in the tempering process, the insulation temperature is controlled at 175-185°C, and the steel plate is taken out of the furnace after insulation for 200-250 minutes. After taking out of the furnace, the steel plate is covered with an insulation cover and stacked for slow cooling.

2. The production method according to claim 1, wherein the wear-resistant steel plate for engineering machinery with high surface hardness has a thickness of 50-60 mm.

3. The production method according to claim 2, wherein the surface hardness of the wear-resistant steel plate for engineering machinery with high surface hardness is ≥465HBW, and -40 impact KV2 is ≥78J.

4. The production method according to claim 3, wherein the wear-resistant steel plate for engineering machinery with high surface hardness has a tensile strength of ≥1400MPa and an elongation of A 50 ≥22%.

5. The production method according to any one of claims 1-4, wherein in the smelting process, the molten iron for smelting is pre-treated with desulfurization to reduce the sulfur content of the molten iron, the scrap steel added is low-sulfur scrap steel to keep the sulfur content of the molten steel at a low level, the converter tapping temperature is maintained at 1630±15°C, the LF refining step ensures that the composition of the molten steel meets the requirements of the composition design, and the molten steel after vacuum treatment in the RH furnace reaches [N]≤45ppm.

6. The production method according to any one of claims 1 to 5, wherein the microstructure of the wear-resistant steel plate for engineering machinery with high surface hardness after heat treatment is a tempered martensite microstructure plus a small amount of tempered bainite microstructure.

7. A wear-resistant steel plate for engineering machinery with high surface hardness, obtained by the production method according to any one of claims 1 to 6.

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