CN101691640A - High strength low alloy wear resistance steel plate and preparation method thereof - Google Patents

Abstract

A high-strength low-alloy wear-resistant steel plate and its manufacturing method. The chemical composition of the steel is: C 0.18-0.22%, Si 0.2-0.5%, Mn 1.0-1.6%, P≤0.010%, S≤0.005% , Al 0.02~0.03%, Ti 0.016~0.022%, Cr 0.16~0.20%, B 0.0005~0.0015%, and the rest are Fe and unavoidable impurities. And the carbon equivalent Ceq(%)≤0.5, and satisfy at the same time: Ceq(%)=C+Mn/6+Si/24+Ni/40+Cr/5+Mo/4+V/14. The manufacturing method includes ultra-pure steel process steps, and is characterized in that the specific parameters are controlled as follows: the slab is heated to 1180-1200 ° C, the heating time is ≥ 150 minutes; the reduction rate of each rolling pass is 15-30%, and the cumulative reduction rate is ≥ 70%, the starting temperature of hot rolling is 1050-1100°C, and the ending temperature is above 950°C; heat treatment (quenching + low-temperature tempering) is carried out after steel plate rolling; the quenching system is: heating to 910-950°C, holding time 3min/mm; The fire system is: heating to 250°C, holding time 2.5min/mm. The invention improves the wear resistance, welding performance, strength and hardness of the steel plate, simplifies the production process and reduces the cost of the steel plate.

Description

A kind of high-strength low-alloy wear-resistant steel plate and its manufacturing method

technical field

The invention relates to a wear-resistant steel plate for mechanical engineering, in particular to a low-alloy wear-resistant steel plate with high strength, high hardness and reasonable matching of strength and toughness and a manufacturing process thereof.

Background technique

At present, the wear-resistant steels used in China mainly include high-manganese steels and medium- and low-alloy wear-resistant steels. The wear resistance of high manganese steel is conditional. Only when the impact is large, the stress is high, and the abrasive is hard, the high manganese steel is wear-resistant, and its yield strength is low and easy to deform. The medium and low alloy wear-resistant steel has excellent strength, toughness, wear resistance and corrosion resistance, and its cost is relatively low compared with other wear-resistant steels, so it is suitable for manufacturing various wear-resistant parts.

Domestically produced medium and low-alloy wear-resistant steels generally have high alloy content and many types of alloys. However, wear-resistant parts used in mining machinery and construction machinery often need to be welded. Excessive alloy content will damage the welding performance of the steel plate. . At the same time, there are also problems such as high cost, poor hardenability of thicker plates, insufficient hardness and toughness, and poor wear resistance.

For example, domestically produced low-alloy wear-resistant steels usually add higher levels of Mo and Ni. The content of Mo is usually between 0.25 and 0.60%, and the content of Ni is between 0.25 and 0.50%. These two elements are more expensive and the cost is higher. , the content of these two elements should be reduced as much as possible or Mo and Ni elements should not be added, which will greatly reduce the cost. At the same time, some elements such as Cr and V are also added more in the previous wear-resistant steel. For example, the Cr content is usually between 0.3 and 0.8%, which will increase the carbon equivalent of the steel and have a great impact on the welding performance of the steel plate.

Contents of the invention

The purpose of the present invention is to provide a high-strength low-alloy wear-resistant steel plate and its manufacturing method, which can improve the wear resistance, welding performance, strength and hardness of the steel plate, simplify the production process, and reduce the cost of the steel plate.

A high-strength low-alloy wear-resistant steel according to the present invention, the chemical composition of the steel is: C0.18-0.22%, Si 0.2-0.5%, Mn 1.0-1.6%, P≤0.010%, S≤ 0.005%, Al 0.02~0.03%, Ti 0.016~0.022%, Cr 0.16~0.20%, B 0.0005~0.0015%, and the rest are Fe and unavoidable impurities. And the carbon equivalent Ceq(%)≤0.5, and satisfy at the same time: Ceq(%)=C+Mn/6+Si/24+Ni/40+Cr/5+Mo/4+V/14.

铁水脱硫-真空处理-浇注成板坯-板坯加热-轧制-空冷-钢板热处理，其特征在于具体参数控制为：The manufacturing method of the high-strength low-alloy wear-resistant steel plate includes the following steps: smelting by ultra-pure steel technology

Hot metal desulfurization-vacuum treatment-casting into slab-slab heating-rolling-air cooling-steel plate heat treatment, characterized in that the specific parameters are controlled as follows:

The slab is heated to 1180～1200℃, and the heating time is ≥150min;

The reduction rate of each rolling pass is 15-30%, the cumulative reduction rate is ≥70%, the hot rolling start temperature is 1050-1100°C, and the end temperature is above 950°C;

Heat treatment (quenching + low temperature tempering) after steel plate rolling; quenching system: heating to 910-950°C, holding time 3min/mm; tempering system: heating to 250°C, holding time 2.5min/mm.

Main chemical composition content and main effect of the present invention are:

The content of carbon (C) in the present invention is 0.18-0.22%. Carbon is a crucial element affecting the strength, hardness, toughness, hardenability and wear resistance of wear-resistant steel. If the carbon content is too high, the high-carbon martensite formed after heat treatment has high hardness, but low toughness, and cracks are easy to form during heat treatment; if the carbon content is too low, the hardness is low and the wear resistance is not good.

The silicon (Si) content of the present invention is 0.2~0.5%. Silicon is used as a reducing agent and a deoxidizer in the steelmaking process, and combined with chromium, it has the effect of improving corrosion resistance and oxidation resistance. When it exceeds 0.5%, it will cause steel The toughness of the steel decreases, and the high silicon content will deteriorate the weldability of the steel.

The content of manganese (Mn) in the present invention is 1.0-1.6%. Manganese has low cost, is a good deoxidizer and desulfurizer, and significantly improves hardenability. Manganese has a great influence on the hardness and impact toughness of steel. The hardness increases with the increase of manganese content, while the impact toughness decreases. Excessive manganese content will reduce weldability.

Phosphorus (P) content≤0.010% and sulfur (S) content≤0.005% in the present invention: Phosphorus and sulfur are usually harmful elements in steel, increasing the brittleness of steel. Phosphorus will destroy the weldability and plasticity of steel; sulfur is easy to combine with manganese to produce inclusions, and it can also reduce the toughness of steel. Therefore, the content of phosphorus and sulfur in steel should be reduced as much as possible.

The content of aluminum (Al) in the present invention is 0.02-0.03%: the main function of Al is deoxidation. Adding a small amount of aluminum to steel can refine grains and improve impact toughness. Excessive aluminum content will increase the inclusion of Al oxides and reduce the purity of the steel.

The content of titanium (Ti) in the present invention is 0.016-0.022%: Ti can form fine carbon and nitride, prevent the growth of austenite grains and refine the grains. At the same time, it can also improve the welding performance of steel.

The content of chromium (Cr) in the present invention is 0.16-0.20%. The main function of chromium is to improve the hardenability of steel, and at the same time solid solution strengthen the matrix, refine the structure, significantly improve the anti-oxidation effect of steel, and increase its anti-corrosion ability.

The content of boron (B) in the present invention is 0.0005-0.0015%: a trace amount of boron can improve the compactness and hot-rolling performance of steel, improve the hardenability and strength of the steel plate.

The present invention has the following advantages

1. The surface Brinell hardness of the steel plate of the present invention is HB400~HB440, the tensile strength is 1350MPa~1450MPa, and the elongation is >11%. The steel of the invention has extremely high surface hardness, so it has good wear resistance, high tensile strength, good elongation, suitable strength and toughness matching, and excellent comprehensive performance.

2. The chemical composition design adopted by the steel plate of the present invention has fewer types of alloy elements, no precious metal elements or less content, low cost; low carbon equivalent, excellent welding performance; reasonable composition design makes the steel plate have good Hardenability.

3. The rolling of the present invention adopts rolling in the austenite recrystallization zone, and adopts a large amount of secondary deformation to increase the recrystallization amount of austenite, refine the grains, and save the intermediate waiting time, thereby shortening the rolling cycle. The manufacturing process is simple, and the production cost can be reduced.

Description of drawings

Fig. 1 is the photograph of the composite structure obtained after the heat treatment of the high-strength wear-resistant steel plate in Example 1;

Fig. 2 is the photograph of the composite structure obtained after the heat treatment of the high-strength wear-resistant steel plate in Example 2;

Detailed ways

The technical scheme of the present invention is illustrated with the following two specific examples:

Example 1

The specific chemical composition of the 12mm thick high-strength wear-resistant steel plate in Example 1 is shown in Table 1:

Table 1 is the chemical composition (mass percentage, %) of steel of embodiment 1

Carry out vacuum smelting according to the above chemical composition ratio, and cast into blanks.

The slab is heated to 1180~1200°C, and the heating time is ≥150min.

The reduction rate of each hot rolling pass is 15~30%, the cumulative reduction rate is ≥70%, the starting temperature of hot rolling is 1050~1100°C, and the ending temperature is ≥950°C.

Heat treatment (quenching + low temperature tempering) is carried out after the steel plate is rolled.

Quenching system: heating to 950°C, holding time 36min, water cooling; tempering system: heating to 250°C, holding time 30min, air cooling.

After heat treatment, a composite structure of martensite with high hardness, a small amount of retained austenite with good toughness and fine carbides dispersed and precipitated is obtained, as shown in Figure 1.

The concrete mechanical performance detection result of embodiment 1 steel is shown in Table 2:

Table 2 is the mechanical property of embodiment 1 steel

Example 2

The specific chemical composition of the 12mm thick high-strength wear-resistant steel plate in Example 2 is shown in Table 3:

Table 3 is the chemical composition (mass percentage, %) of embodiment 2 steel

Carry out vacuum smelting according to the above chemical composition ratio, and cast into blanks.

The slab is heated to 1180～1200℃, and the heating time is at least ≥150min;

The reduction rate of each pass of hot rolling is 15-30%, the cumulative reduction rate is ≥70%, the hot-rolling start temperature is 1050-1100°C, and the end temperature is ≥950°C. The steel plate is heat-treated after rolling, and tempered at low temperature after quenching.

Quenching system: heating to 950°C, holding time 36min, water cooling; tempering system: heating to 250°C, holding time 30min, air cooling.

After heat treatment, a composite structure of martensite with high hardness, a small amount of retained austenite with good toughness and fine carbides dispersed and precipitated is obtained, as shown in Figure 2.

The concrete mechanical performance detection result of embodiment 2 steel is shown in Table 4:

Table 4 is the mechanical property of embodiment 2 steel

Claims (6)

1. A high-strength low-alloy wear-resistant steel plate, characterized in that the chemical composition of the steel is: C0.18-0.22%, Si 0.2-0.5%, Mn 1.0-1.6%, P≤0.010%, S≤ 0.005%, Al 0.02～0.03%, Ti0.016～0.022%, Cr 0.16～0.20%, B 0.0005～0.0015%, the rest is Fe and unavoidable impurities. And the carbon equivalent Ceq(%)≤0.5, and satisfy at the same time: Ceq(%)=C+Mn/6+Si/24+Ni/40+Cr/5+Mo/4+V/14. 2. Another high-strength low-alloy wear-resistant steel plate as claimed in claim 1, characterized in that the chemical composition of the steel can also be: C 0.16-0.20%, Si 0.2-0.4%, Mn 1.0- 1.6%, P≤0.010%, S≤0.005%, Ni 0.18～0.22%, Al 0.02～0.03%, Ti 0.016～0.022%, Mo 0.18～0.22%, Cr 0.16～0.20%, B 0.0008～0.0015%, the rest It is Fe and unavoidable impurities, and the carbon equivalent Ceq(%)≤0.6, and at the same time satisfy: Ceq(%)=C+Mn/6+Si/24+Ni/40+Cr/5+Mo/4+V /14. 3. The high-strength low-alloy wear-resistant steel plate according to claim 1 or 2, characterized in that the Brinell hardness value of the steel plate is between HB400-HB440, the tensile strength is 1350MPa-1450MPa, and the elongation is >11% ; Steel plate impact toughness -20 ℃ and -40 ℃, more than 24J/cm2. 4. A method for manufacturing a high-strength low-alloy wear-resistant steel plate as claimed in claim 3, comprising the steps of: smelting by an ultra-pure steel process

- hot metal desulfurization - vacuum treatment - pouring into slab - slab heating - rolling - air cooling - steel plate heat treatment, characterized in that the parameters of the following steps are controlled as follows: 1) Carry out vacuum smelting according to the chemical composition of the ratio and cast it into billets; 2) The slab is heated to 1180-1200°C, and the heating time is ≥150min; 3) Rolling is carried out at 950-1100°C, the reduction in each pass is 15-30%, and the cumulative reduction rate is not less than 70%; 4) Carry out quenching treatment, heat to 910-950°C and keep warm for 3min/mm, then water-cool; 5) Tempering treatment at 250°C, holding time 2.5min/mm, air cooling. 5. The manufacturing method according to claim 4, characterized in that 3) the starting temperature of hot rolling is 1050-1100°C, and the finishing temperature is 950°C or higher. 6. The manufacturing method according to claim 4, characterized in that 4) the heat treatment of the steel plate after rolling includes quenching and low-temperature tempering treatment, the quenching system is: heating to 910-950°C, holding time 3min/mm; tempering system For: heating to 250 ℃, holding time 2.5min/mm.

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