Wear-resistant steel plate with high and low temperature impact toughness and production method thereof

Abstract

The invention provides a wear-resistant steel plate with high low-temperature impact toughness and a production method thereof, and belongs to the technical field of steel smelting. The production method of the wear-resistant steel plate with high and low temperature impact toughness comprises the steps of drying, smelting, refining, continuous casting, heating, rolling, heat treatment and the like. By reasonably controlling the chemical components of the steel plate and optimizing the production process, the non-uniform deformation of the steel plate in the rolling process is reduced; by reasonably controlling the slow cooling time and the cooling mode, the surface temperature difference is reduced, buckling caused by uneven cooling is avoided, and the prepared steel plate not only has high and low temperature impact toughness, but also belongs to a thin-specification wear-resistant steel plate, and is suitable for being used in a low-temperature environment.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and in particular to a wear-resistant steel plate with high and low temperature impact toughness and a production method thereof. Background Art

[0002] Wear-resistant steel is a special steel widely used in engineering machinery, mining machinery, coal mining machinery and other fields. Its performance requirements usually include high strength, high hardness and good impact toughness. Especially in low temperature environment, the low temperature impact toughness of wear-resistant steel is particularly important. In recent years, with the continuous advancement of technology, wear-resistant steel plates with high and low temperature impact toughness and their production methods have received extensive attention and research. The performance requirements of wear-resistant steel usually include hardness, tensile strength, yield strength, elongation and impact toughness. Hardness is an important indicator to measure the wear resistance of wear-resistant steel, and the hardness is usually required to be between 420-480HBW. Tensile strength and yield strength determine the bearing capacity of wear-resistant steel. The national standard recommends tensile strength ≥1250MPa and yield strength ≥1100MPa. Elongation reflects the plastic deformation ability of steel, and generally requires elongation ≥13%. Impact toughness refers to the ability of steel to resist impact loads without breaking at a certain temperature. For wear-resistant steel plates with high and low temperature impact toughness, the impact energy at -40℃ is usually required to be ≥40J.

[0003] At present, a variety of high and low temperature impact toughness wear-resistant steels have been developed and applied. For example, Hunan Valin Xiangtan Iron and Steel Co., Ltd. has developed a high and low temperature toughness NM450 wear-resistant steel plate, whose chemical composition and process parameters have been optimized, so that the steel plate has excellent low temperature impact toughness while maintaining high hardness and high strength. The hardness of the wear-resistant steel plate is 420-480HBW, the yield strength is ≥1100MPa, the tensile strength is ≥1350MPa, the elongation is ≥13%, and the impact energy at -40℃ is 40J. In addition, Laiwu Iron and Steel Group Yinshan Steel Co., Ltd. has also invented a wear-resistant steel plate with good low-temperature impact toughness and its preparation method. The chemical composition of the wear-resistant steel plate includes elements such as C, Si, Mn, Ni, Mo, Cr, and Ti. By controlling the content and proportion of each element, and adopting process measures such as slow cooling and heat treatment, the impact energy of the steel plate at -40°C reaches 50J, and the organizational morphology is residual austenite + tempered martensite, with excellent comprehensive performance. However, the above process still has some problems or defects. For example, special equipment is required during the preparation process, the tempering process is likely to cause the wear resistance and hardness of the steel plate to decrease, and micro-alloying affects the welding performance of the steel plate.

[0004] Therefore, how to develop a high and low temperature impact toughness wear-resistant steel with excellent comprehensive performance, which can significantly improve the low temperature impact toughness of wear-resistant steel and meet the needs of use in various harsh working conditions, is a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, the present invention provides a wear-resistant steel plate with high and low temperature impact toughness, wherein the steel plate is composed of the following raw materials in percentage by weight:

[0006] C: 0.15-0.25%, Si: 0.20-0.45%, Mn: 1.20-1.50%, Ni: 0.60-1.00%, Cr: 0.40-0.80%, Mo: 0.40-0.60%, Cu: ≤0.012%, Ti: 0.010-0.050%, Al: 0.030-0.050%, B: 0.001-0.003%, S: ≤0.005%, the balance is Fe and unavoidable impurities.

[0007] Preferably, the thickness of the steel plate is 2-7 mm.

[0008] Preferably, the method for producing the wear-resistant steel plate with high and low temperature impact toughness comprises the following steps:

[0009] (1) All raw materials are dried in a steelmaking raw material dryer;

[0010] (2) The dried raw materials are transferred to a steelmaking furnace for smelting and nitrogen blowing is performed throughout the process, and steel is tapped after smelting is completed;

[0011] (3) The molten steel is transferred to a refining furnace for refining. The refining process is carried out according to conventional processes, and then the molten steel is transferred to an RH furnace or a VD furnace for vacuum treatment;

[0012] (4) After the vacuum treatment is completed, continuous casting, heating and rolling are carried out in sequence;

[0013] (5) After the rolling process, heat treatment is performed to obtain a wear-resistant steel plate with high and low temperature impact toughness.

[0014] Preferably, the moisture content of the raw material after the drying treatment in step (1) is less than 0.5wt%.

[0015] Preferably, step (2) further comprises the step of adding ferrosilicon deoxidizer, the addition amount of the ferrosilicon deoxidizer is 1-3 kg / t, and the steel tapping temperature in step (2) is controlled between 1590-1620°C.

[0016] Preferably, the vacuum degree of the vacuum treatment in step (3) is 67-134 Pa, and the vacuum treatment time is 10-60 min.

[0017] Preferably, in the continuous casting process of step (4), dynamic light reduction technology is used to improve the internal quality of the continuous casting billet, the thickness and width of the continuous casting billet are adjusted according to specific needs, the cooling time of the insulation cover is controlled at 24-48h, and the light reduction speed is 0.84-0.90mm / min.

[0018] Preferably, the starting rolling temperature during the rolling process in step (4) is 1050°C-1160°C, and the final rolling temperature is 950-1000°C.

[0019] Preferably, the heat treatment in step (5) includes quenching and tempering.

[0020] Preferably, the heating temperature of the quenching is controlled between 850-900°C, the holding time is 1-5min, the quenching cooling method is oil cooling, the quenching final cooling temperature is 320°C, the heating temperature of the tempering is controlled between 180-230°C, the holding time is 1.0-1.5h, and the tempering cooling method is air cooling.

[0021] Compared with the prior art, the present invention has the following beneficial effects: the present invention reduces the uneven deformation of the steel plate during the rolling process by reasonably controlling the chemical composition of the steel plate and optimizing the production process; reduces the surface temperature difference by reasonably controlling the slow cooling time and the cooling method, and avoids the warping caused by uneven cooling. The prepared steel plate not only has high and low temperature impact toughness, but also is a thin-gauge wear-resistant steel plate, which is suitable for use in low temperature environments. DETAILED DESCRIPTION

[0022] A wear-resistant steel plate with high and low temperature impact toughness, the steel plate is composed of the following raw materials in percentage by weight:

[0023] C: 0.15-0.25%, Si: 0.20-0.45%, Mn: 1.20-1.50%, Ni: 0.60-1.00%, Cr: 0.40-0.80%, Mo: 0.40-0.60%, Cu: ≤0.012%, Ti: 0.010-0.050%, Al: 0.030-0.050%, B: 0.001-0.003%, S: ≤0.005%, the balance is Fe and unavoidable impurities.

[0024] In one embodiment, the thickness of the steel plate is 2-7 mm.

[0025] In one embodiment, the method for producing the wear-resistant steel plate with high and low temperature impact toughness comprises the following steps:

[0026] (1) All raw materials are dried in a steelmaking raw material dryer;

[0027] (2) The dried raw materials are transferred to a steelmaking furnace for smelting and nitrogen blowing is performed throughout the process, and steel is tapped after smelting is completed;

[0028] (3) The molten steel is transferred to a refining furnace for refining. The refining process is carried out according to conventional processes. The molten steel is then transferred to an RH furnace or a VD furnace for vacuum treatment to further reduce the gas and inclusion content in the molten steel and improve the purity and quality of the steel.

[0029] (4) After the vacuum treatment is completed, continuous casting, heating and rolling are carried out in sequence;

[0030] (5) After the rolling process, heat treatment is performed to obtain a wear-resistant steel plate with high and low temperature impact toughness.

[0031] In one embodiment, the moisture content of the raw material after the drying treatment in step (1) is less than 0.5 wt%.

[0032] In one embodiment, step (2) further comprises the step of adding ferrosilicon deoxidizer, the addition amount of the ferrosilicon deoxidizer is 1-3 kg / t, and the steel tapping temperature in step (2) is controlled between 1590-1620°C.

[0033] The main function of deoxidizer is to remove active oxygen in molten steel, reduce oxide inclusions in steel, and improve the purity and quality of steel. By adding deoxidizer, the flow properties of molten steel can be effectively improved and the negative impact of oxide inclusions on steel quality can be reduced.

[0034] In one embodiment, the vacuum degree of the vacuum treatment in step (3) is 67-134 Pa, and the vacuum treatment time is 10-60 min.

[0035] In one embodiment, in the continuous casting process of step (4), dynamic light reduction technology is used to improve the internal quality of the continuous casting billet. The thickness and width of the continuous casting billet are adjusted according to specific needs. The cooling time of the insulation cover is controlled at 24-48 hours to ensure the uniformity of the structure and the stability of the performance of the continuous casting billet. The light reduction speed is 0.84-0.90 mm / min.

[0036] In one embodiment, the starting rolling temperature in the rolling process of step (4) is 1050°C-1160°C, and the final rolling temperature is 950-1000°C. The rolling temperature is controlled to ensure that the ideal microstructure and mechanical properties are obtained.

[0037] In one embodiment, the heat treatment in step (5) includes quenching and tempering.

[0038] In one embodiment, the heating temperature of the quenching is controlled between 850-900°C, the holding time is 1-5min, the quenching cooling method is oil cooling, the quenching final cooling temperature is 320°C, the heating temperature of the tempering is controlled between 180-230°C, the holding time is 1.0-1.5h, and the tempering cooling method is air cooling to obtain the desired tempered martensite structure and good impact toughness.

[0039] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0040] The experimental methods or test methods described in the following examples are conventional methods unless otherwise specified; the raw materials and auxiliary agents are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0041] Example 1

[0042] A 2mm thick NM400 grade high and low temperature impact toughness wear-resistant steel plate, composed of the following raw materials in percentage by weight:

[0043] C: 0.17%, Si: 0.25%, Mn: 1.20%, Ni: 0.80%, Cr: 0.40%, Mo: 0.40%, P: 0.012%, Ti: 0.010%, Al: 0.020%, B: 0.001%, S: 0.005%, the balance is Fe and unavoidable impurities;

[0044] The production method of the wear-resistant steel plate consists of the following steps:

[0045] (1) placing the raw materials in a steelmaking raw material dryer for drying to ensure that the water content of the raw materials reaches 0.5wt%;

[0046] (2) transporting the dried raw materials to a steelmaking furnace for smelting, blowing nitrogen throughout the smelting process, and the nitrogen flow rate is 1.8N1 / min / ton of steel. After the smelting is completed, steel is tapped, and ferrosilicon deoxidizer is added during the tapping process. The amount of the ferrosilicon deoxidizer added is 1kg / t, and the tapping temperature is 1590° C.;

[0047] (3) The molten steel is transferred to the LF refining furnace for refining, and the basicity of the final slag is 2.2. It is then sent to the RH furnace for vacuum treatment, the vacuum degree is 67 Pa, and the vacuum treatment time is 60 min;

[0048] (4) After the vacuum treatment is completed, continuous casting, heating and rolling are carried out in sequence, wherein the continuous casting process is carried out under argon protection casting, and the dynamic soft reduction technology is used to improve the internal quality of the continuous casting billet. The soft reduction speed is 0.84 mm / min, the billet is heated to 1255°C for rolling, the starting rolling temperature is 1050°C, the final rolling temperature is 950°C, the insulation cover is used for cooling, the cooling time is controlled at 24h, and the cooling temperature is 550°C;

[0049] (5) After the rolling treatment, quenching and tempering treatment is carried out, wherein the quenching heating temperature is 850°C, the holding time is 1 min, the quenching cooling method is oil cooling, the quenching final cooling temperature is 320°C, the tempering heating temperature is 180°C, the holding time is 1.0 h, and the tempering cooling method is air cooling, thereby obtaining a 2 mm thick NM400 grade high and low temperature impact toughness wear-resistant steel plate.

[0050] According to the test, the surface Brinell hardness of the wear-resistant steel plate is 480HB, and the low-temperature impact energy of -40°C is 110J.

[0051] Example 2

[0052] A 4mm thick NM400 grade high and low temperature impact toughness wear-resistant steel plate, composed of the following raw materials in percentage by weight:

[0053] C: 0.18%, Si: 0.35%, Mn: 1.30%, Ni: 0.90%, Cr: 0.50%, Mo: 0.45%, P: 0.010%, Ti: 0.020%, Al: 0.030%, B: 0.001%, S: 0.003%, the balance is Fe and unavoidable impurities;

[0054] The production method of the wear-resistant steel plate consists of the following steps:

[0055] (1) placing the raw materials in a steelmaking raw material dryer for drying to ensure that the water content of the raw materials reaches 0.5wt%;

[0056] (2) transporting the dried raw materials to a steelmaking furnace for smelting, blowing nitrogen throughout the smelting process, and the nitrogen flow rate is 1.8N1 / min / ton of steel. After the smelting is completed, steel is tapped, and ferrosilicon deoxidizer is added during the tapping process. The amount of the ferrosilicon deoxidizer added is 2kg / t, and the tapping temperature is 1600°C;

[0057] (3) The molten steel is transferred to the LF refining furnace for refining, and the basicity of the final slag is 2.2. It is then sent to the VD furnace for vacuum treatment, the vacuum degree is 120 Pa, and the vacuum treatment time is 30 min;

[0058] (4) After the vacuum treatment is completed, continuous casting, heating and rolling are carried out in sequence, wherein the continuous casting process is carried out under argon protection casting, and the dynamic soft reduction technology is used to improve the internal quality of the continuous casting billet. The soft reduction speed is 0.88 mm / min, the billet is heated to 1255°C for rolling, the starting rolling temperature is 1120°C, the final rolling temperature is 980°C, the insulation cover is used for cooling, the cooling time is controlled at 36 hours, and the cooling temperature is 550°C;

[0059] (5) After the rolling treatment, quenching and tempering treatment is carried out, wherein the quenching heating temperature is 880°C, the holding time is 3 min, the quenching cooling method is oil cooling, the quenching final cooling temperature is 320°C, the tempering heating temperature is 200°C, the holding time is 1.3 h, and the tempering cooling method is air cooling, thereby obtaining a 4 mm thick NM400 grade high and low temperature impact toughness wear-resistant steel plate.

[0060] According to tests, the surface Brinell hardness of the wear-resistant steel plate is 450HB, and the low-temperature impact energy of -40°C is 90J.

[0061] Example 3

[0062] A 6mm thick NM400 grade high and low temperature impact toughness wear-resistant steel plate, composed of the following raw materials in percentage by weight:

[0063] C: 0.20%, Si: 0.45%, Mn: 1.40%, Ni: 1.00%, Cr: 0.60%, Mo: 0.50%, P: 0.002%, Ti: 0.030%, Al: 0.050%, B: 0.002%, S: 0.001%, the balance is Fe and unavoidable impurities;

[0064] The production method of the wear-resistant steel plate consists of the following steps:

[0065] (1) placing the raw materials in a steelmaking raw material dryer for drying to ensure that the water content of the raw materials reaches 0.5wt%;

[0066] (2) transporting the dried raw materials to a steelmaking furnace for smelting, blowing nitrogen throughout the smelting process, and the nitrogen flow rate is 1.8N1 / min / ton of steel. After the smelting is completed, steel is tapped, and ferrosilicon deoxidizer is added during the tapping process. The amount of the ferrosilicon deoxidizer added is 3kg / t, and the tapping temperature is 1620°C;

[0067] (3) The molten steel is transferred to the LF refining furnace for refining, and the basicity of the final slag is 2.2. Then, the molten steel is sent to the RH furnace for vacuum treatment, and the vacuum degree is 134 Pa. The vacuum treatment time is 10 min.

[0068] (4) After the vacuum treatment is completed, continuous casting, heating and rolling are carried out in sequence, wherein the continuous casting process is cast under argon protection throughout, and dynamic soft reduction technology is used to improve the internal quality of the continuous casting billet. The soft reduction speed is 0.90 mm / min, the billet is heated to 1255°C for rolling, the start rolling temperature is 1160°C, the final rolling temperature is 1000°C, the insulation cover is used for cooling, the cooling time is controlled at 48h, and the cooling temperature is 550°C;

[0069] (5) After the rolling treatment, quenching and tempering treatment is carried out, wherein the quenching heating temperature is 900°C, the holding time is 5 minutes, the quenching cooling method is oil cooling, the quenching final cooling temperature is 320°C, the tempering heating temperature is 230°C, the holding time is 1.5 hours, and the tempering cooling method is air cooling, thereby obtaining a 6 mm thick NM400 grade high and low temperature impact toughness wear-resistant steel plate.

[0070] According to the test, the surface Brinell hardness of the wear-resistant steel plate is 490HB, and the low-temperature impact energy of -40°C is 120J.

[0071] Comparative Example 1

[0072] The difference from Example 3 is that: the water content of the raw material after the drying treatment in step (1) is 0.7wt%;

[0073] According to the test, the surface Brinell hardness of the wear-resistant steel plate is 410HB, and the low-temperature impact energy of -40°C is 80J.

[0074] Comparative Example 2

[0075] The difference from Example 3 is that: the cooling time in step (4) is 20 hours;

[0076] According to tests, the surface Brinell hardness of the wear-resistant steel plate is 400HB, and the low-temperature impact energy of -40°C is 76J.

[0077] Comparative Example 3

[0078] The difference from Example 3 is that the heating temperature for quenching in step (5) is 950°C;

[0079] According to the test, the surface Brinell hardness of the wear-resistant steel plate is 390HB, and the low-temperature impact energy of -40°C is 70J.

[0080] Comparative Example 4

[0081] The difference from Example 3 is that the final quenching temperature in step (5) is 350°C;

[0082] According to the test, the surface Brinell hardness of the wear-resistant steel plate is 380HB, and the low-temperature impact energy of -40°C is 63J.

[0083] Comparative Example 5

[0084] The difference from Example 3 is that the heating temperature for tempering in step (5) is 250°C;

[0085] According to the test, the surface Brinell hardness of the wear-resistant steel plate is 390HB, and the low-temperature impact energy of -40°C is 60J.

[0086] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A wear-resistant steel plate with high and low temperature impact toughness, characterized in that: The steel plate is composed of the following raw materials in weight percentage: C: 0.15-0.25%, Si: 0.20-0.45%, Mn: 1.20-1.50%, Ni: 0.60-1.00%, Cr: 0.40-0.80%, Mo: 0.40-0.60%, Cu: ≤0.012%, Ti: 0.010-0.050%, Al: 0.030-0.050%, B: 0.001-0.003%, S: ≤0.005%, the balance is Fe and unavoidable impurities.

2. The wear-resistant steel plate with high and low temperature impact toughness according to claim 1, characterized in that: The thickness of the steel plate is 2-7 mm.

3. The method for producing a wear-resistant steel plate with high and low temperature impact toughness according to claim 1, characterized in that: The following steps are involved: (1) All raw materials are dried in a steelmaking raw material dryer; (2) The dried raw materials are transferred to a steelmaking furnace for smelting and nitrogen is blown throughout the process, and steel is tapped after smelting is completed; (3) The molten steel is transferred to a refining furnace for refining. The refining process is carried out according to conventional processes, and then the molten steel is transferred to an RH furnace or a VD furnace for vacuum treatment; (4) After the vacuum treatment is completed, continuous casting, heating and rolling are carried out in sequence; (5) After the rolling process, heat treatment is performed to obtain a wear-resistant steel plate with high and low temperature impact toughness.

4. The method for producing a wear-resistant steel plate with high and low temperature impact toughness according to claim 3, characterized in that: The moisture content of the raw material after the drying treatment in step (1) is less than 0.5wt%.

5. The method for producing a wear-resistant steel plate with high and low temperature impact toughness according to claim 3, characterized in that: Step (2) also includes the step of adding ferrosilicon deoxidizer, wherein the addition amount of the ferrosilicon deoxidizer is 1-3 kg / t, and the steel tapping temperature in step (2) is controlled between 1590-1620°C.

6. The method for producing a wear-resistant steel plate with high and low temperature impact toughness according to claim 3, characterized in that: The vacuum degree of the vacuum treatment in step (3) is 67-134 Pa, and the vacuum treatment time is 10-60 min.

7. The method for producing a wear-resistant steel plate with high and low temperature impact toughness according to claim 3, characterized in that: In step (4), dynamic soft reduction technology is used in the continuous casting process to improve the internal quality of the continuous casting billet. The thickness and width of the continuous casting billet are adjusted according to specific needs. The cooling time of the insulation cover is controlled at 24-48h, and the soft reduction speed is 0.84-0.90mm / min.

8. The method for producing a wear-resistant steel plate with high and low temperature impact toughness according to claim 3, characterized in that: The starting rolling temperature during the rolling process of step (4) is 1050°C-1160°C, and the final rolling temperature is 950-1000°C.

9. The method for producing a wear-resistant steel plate with high and low temperature impact toughness according to claim 3, characterized in that: The heat treatment in step (5) includes quenching and tempering.

10. The method for producing a wear-resistant steel plate with high and low temperature impact toughness according to claim 9, characterized in that: The heating temperature of the quenching is controlled between 850-900°C, the holding time is 1-5min, the quenching cooling method is oil cooling, the quenching final cooling temperature is 320°C, the heating temperature of the tempering is controlled between 180-230°C, the holding time is 1.0-1.5h, and the tempering cooling method is air cooling.