WO2018006845A1

WO2018006845A1 - High toughness bainitic steel wheel for rail transit, and manufacturing method therefor

Info

Publication number: WO2018006845A1
Application number: PCT/CN2017/091930
Authority: WO
Inventors: 张明如; 赵海; 张峰; 方政; 浦红; 谢世红
Original assignee: 马钢(集团)控股有限公司; 马鞍山钢铁股份有限公司
Priority date: 2016-07-06
Filing date: 2017-07-06
Publication date: 2018-01-11
Also published as: JP6765496B2; EP3483298A4; EP3483298A1; CN106048430A; JP2019524994A; CN106048430B

Abstract

A high toughness bainitic steel wheel for rail transit, and a manufacturing method therefor. The wheel includes the following elements by weight percentage: carbon (C): 0.10-0.40%, silicon (Si): 1.00-2.00%, manganese (Mn): 1.00-2.50%, nickel (Ni): 0.20-1.00%, rare earth (RE): 0.001-0.040%, less than or equal to 0.020% of phosphorus (P), and less than or equal to 0.020% of sulphur (S), the remainder being iron and unavoidable residual elements, 1.50% ≤ Si+Ni ≤ 2.50%, 2.00% ≤ Si+Mn ≤ 4.00%. Via steel chemical composition design and manufacturing processes, the wheel rim has a carbide-free bainitic structure, the spokes and hub have a mainly granular bainitic and saturated ferritic microstructure, and the wheel has comprehensive mechanical properties such as high yield strength, toughness and low-temperature toughness, and good service usage properties. In addition, costs are reduced, and the service life and comprehensive benefits of the wheel are improved.

Description

Bainitic steel wheel for high-toughness rail transit and manufacturing method thereof

Technical field

The invention belongs to the field of chemical composition design and wheel manufacturing of steel, and particularly relates to a bainitic steel wheel for high-toughness rail transit and a manufacturing method thereof, and a steel type design and manufacturing method for other parts and the like of rail transit .

Background technique

"High speed, heavy load and low noise" is the main development direction of the world rail transit. The wheel is the "shoe" of rail transit and is one of the most important walking components, which directly affects the safety of operation. During normal train operation, the wheel is subjected to the full load of the vehicle, subject to wear and rolling contact fatigue (RCF) damage, and, more importantly, it is very complex with rails, brake shoes, axles, and surrounding media. The action relationship is in a dynamic, alternating stress state. In particular, the wheels and rails, the wheels and the brake shoes (except for the disc brakes) are two pairs of moments that cannot be ignored. In the case of emergency or special roads, the brakes are very hot and scratched. Significantly, thermal fatigue is generated, which also affects wheel safety and service life.

Rail transit, when the wheel meets the basic strength, pays special attention to the toughness index of the wheel to ensure safety and reliability. The wheel wear and rolling contact fatigue (RCF) damage of the freight is large, and it is the tread brake and the thermal fatigue damage. Large, resulting in defects such as peeling, flaking and splitting. The passengers use the wheel to pay more attention to the toughness and low temperature toughness of the wheel. Since the passenger transport adopts the disc brake, the brake thermal fatigue is alleviated.

At present, domestic and international rail steel for rail transportation, such as Chinese wheel standard GB/T8601, TB/T2817, European wheel standard EN13262, Japanese wheel standard JRS and JIS B5402, and North American wheel standard AAR M107, etc., are medium and high carbon carbon. Steel or medium-high carbon microalloyed steel, the metallographic structure is pearlite-ferrite structure.

CL60 steel wheel is the main steel wheel steel used in China's current rail transit vehicles (passenger and freight). BZ-L is the main cast steel wheel steel used in China's current rail transit vehicles (freight). Their metallographic structure is pearl light. Body-ferrite organization.

The schematic diagram of the names of the various parts of the wheel is shown in Figure 1. The main technical requirements of CL60 steel are shown in Table 1 below.

Table 1 Main technical requirements of CL60 wheels

During the manufacturing process, it is necessary to ensure that the wheel material is excellent and the content of harmful gases and harmful residual elements in the steel is low. When the wheel is at high temperature, the rim tread surface is cooled by water spray to further improve the strength and hardness of the rim; the web and the hub are equivalent to normalizing heat treatment, so that the rim has high strength and toughness matching, and the web has high toughness. In the end, the wheels have excellent comprehensive mechanical properties and service performance.

In pearlite-small ferritic wheel steel, ferrite is a soft phase in the material, has good toughness, low yield strength, and is resistant to rolling contact fatigue (RCF) due to its softness. Generally, the higher the ferrite content, the better the impact toughness of the steel; the higher the pearlite strength and the lower the toughness than the ferrite, the poorer the impact performance. The development direction of rail transit is high speed and heavy load. The load on the wheel will increase greatly. The existing pearlite-small ferritic wheel is exposed to more and more problems during operation and service. The main ones are as follows. Insufficient aspects:

(1) The rim yield strength is low, generally not exceeding 600 MPa. Because the rolling contact stress between the wheel and rail during the running of the wheel is large, sometimes exceeding the yield strength of the wheel steel, the wheel is plastically deformed during the running process, resulting in the tread surface. Plastic deformation occurs, and because there are brittle phases such as inclusions and cementite in the steel, it is easy to cause micro-cracks in the rim. These micro-cracks cause defects such as peeling and splitting under the action of rolling contact fatigue of the wheel.

(2) The steel has high carbon content and poor heat damage resistance. When the surface is braked or the wheel is slipped, the wheel locally heats up to the austenitizing temperature of the steel, and then chills to produce Markov. The body is repeatedly subjected to thermal fatigue to form a brake hot crack, which causes defects such as peeling and falling off.

(3) The wheel steel has poor hardenability, and the wheel rim has a certain hardness gradient, and the hardness is not uniform, which is easy to cause defects such as rim wear and roundness.

With the development and breakthrough of the research on the transformation of bainitic steel, especially the theoretical and applied research of the carbide-free bainitic steel, a good match of high strength and high toughness can be achieved. The carbide-free bainite steel has an ideal microstructure and excellent mechanical properties, and its fine microstructure is carbide-free bainite, that is, nano-scale lath-like supersaturated ferrite. In the middle, the nano-scale film-like carbon-rich retained austenite improves the strength and toughness of the steel, especially improves the yield strength, impact toughness and fracture toughness of the steel, and reduces the notch sensitivity of the steel. Therefore, the bainitic steel wheel effectively enhances the rolling contact fatigue resistance (RCF) performance of the wheel, reduces wheel peeling and peeling, and improves the safety performance and performance of the wheel. Because the carbon content of the bainitic steel wheel is low, the thermal fatigue performance of the wheel is improved, the hot crack of the rim is prevented, the number of repairs of the wheel and the repair amount are reduced, the use efficiency of the rim metal is improved, and the service life of the wheel is improved.

The chemical composition range (wt%) of the steel disclosed in the Chinese patent "Basitic Steel for Railway Vehicle Wheels" published on July 12, 2006, CN 1800427A is: carbon C: 0.08-0.45%, silicon Si: 0.60-2.10%, manganese Mn: 0.60-2.10%, molybdenum Mo: 0.08-0.60%, nickel Ni: 0.00-2.10%, chromium Cr: <0.25%, vanadium V: 0.00-0.20%, copper Cu: 0.00 -1.00%. The typical structure of the bainite steel is carbide-free bainite, which has excellent toughness, low notch sensitivity, and good thermal crack resistance. The addition of Mo element can increase the hardenability of steel, but for large-section wheels, production control is difficult and costly.

British Steel Co., Ltd. patent CN1059239C discloses a bainitic steel and a production process thereof, the chemical composition range (wt%) of the steel is: carbon C: 0.05-0.50%, silicon Si and/or aluminum Al: 1.00- 3.00%, manganese Mn: 0.50-2.50%, chromium Cr: 0.25-2.50%. The typical structure of the bainitic steel is carbide-free bainite, which has high wear resistance and rolling contact fatigue resistance. Although the steel has good toughness, the cross section of the rail is simple, the impact toughness at 20 ° C is not high, and the cost of the steel is high.

Summary of the invention

The object of the present invention is to provide a high-toughness rail transit bainite steel wheel, C-Si-Mn-Ni-RE system, without adding special alloy elements such as Mo, V, Cr and B, so that the rim is typically organized Carbide-free bainite, the wheel has excellent toughness and low notch sensitivity.

The invention also provides a method for manufacturing a bainitic steel wheel for high-toughness rail transit. The heat treatment process and technology are used to obtain good comprehensive mechanical properties of the wheel, and the production control is relatively easy.

The invention provides a high-toughness bainite steel wheel for rail transit, comprising the following weight percentage elements:

Carbon C: 0.10 to 0.40%, silicon Si: 1.00 to 2.00%, manganese Mn: 1.00 to 2.50%,

Nickel Ni: 0.20 to 1.00%, rare earth RE: 0.001 to 0.040%,

Phosphorus P≤0.020%, sulfur S≤0.020%, the rest being iron and inevitable residual elements;

And 1.50% ≤ Si + Ni ≤ 2.50%, 2.00% ≤ Si + Mn ≤ 4.00%.

Preferably, the high tenacity rail transit bainite steel wheel comprises the following weight percentage elements:

Carbon C: 0.15 to 0.25%, silicon Si: 1.20 to 1.80%, manganese Mn: 1.60 to 2.10%,

Nickel Ni: 0.20 to 0.80%, rare earth RE: 0.010 to 0.040%, phosphorus P ≤ 0.020%, sulfur S ≤ 0.020%, the balance being iron and unavoidable residual elements; and 1.50% ≤ Si + Ni ≤ 2.50%, 2.00 % ≤ Si + Mn ≤ 4.00%.

Carbon C: 0.20%, silicon Si: 1.45%, manganese Mn: 1.92%,

Nickel Ni: 0.35%, rare earth RE: 0.018%, phosphorus P: 0.013%, sulfur S: 0.008%, and the balance is iron and inevitable impurity elements.

When the total content of Si and Mn is less than 2%, the hardenability of steel is lowered, and carbides are easily formed, which is disadvantageous for obtaining a carbide-free bainite structure with good toughness; when the total content of Si and Mn is more than 4% The hardenability of steel is too high, and it is easy to form bad structures such as martensite, and production control is difficult.

When the total content of Si and Ni is less than 1.5%, carbides are easily formed in the steel, which is not conducive to obtaining a carbide-free bainite structure with good toughness; when the total content of Si and Ni is higher than 2.5%, the element cannot be effectively exerted. And will increase costs.

The obtained wheel microstructure is: the metallographic structure within 40 mm under the wheel rim tread is a carbide-free bainite structure, which is a nano-scale lath-like super-saturated ferrite, lath-like supersaturated ferrite In the middle is a nano-scale film-like carbon-rich retained austenite, wherein the residual austenite volume percentage is 4% to 15%; the complex phase composed of the rim microstructure super-saturated ferrite and the carbon-rich retained austenite The structure, whose size is on the nanometer scale, and the nanoscale refers to the length from 1 nm to 999 nm.

The wheels provided by the present invention can be used in the production of truck wheels and passenger car wheels, as well as other components of rail transit and the like.

The invention provides a method for manufacturing a high-toughness rail transit bainite steel wheel, which comprises a smelting, refining, forming and heat treatment process; the smelting and forming process utilizes the prior art, and the heat treatment process is:

The formed wheel is heated to the austenitizing temperature, and the rim tread surface is sprayed with water to strengthen the cooling to below 400 ° C, and tempered. The heating to austenitizing temperature is specifically: heating to 860-930 ° C for 2.0-2.5 hours. The tempering treatment is as follows: the wheel is less than 400 ° C in low temperature tempering, the tempering time is more than 30 minutes, and the air is cooled to room temperature after tempering; or the rim tread surface is sprayed to strengthen the cooling to below 400 ° C, and air cooled to room temperature, during which the web is used The residual heat of the wheel is tempered.

The heat treatment process may also be: using the high-temperature residual heat after molding, directly cooling the formed wheel wheel tread surface to 400 ° C or less, and tempering. The tempering treatment is as follows: the wheel is less than 400 ° C in low temperature tempering, the tempering time is more than 30 minutes, and the air is cooled to room temperature after tempering; or the rim tread surface is sprayed to strengthen the cooling to below 400 ° C, and air cooled to room temperature, during which the web is used The residual heat of the wheel is tempered.

The heat treatment process can also be: after the wheel is formed, the wheel is air cooled to below 400 ° C and tempered. Back The fire treatment is as follows: the wheel is less than 400 ° C in low temperature tempering, the tempering time is more than 30 minutes, and the air is cooled to room temperature after tempering; or air cooled to below 400 ° C, air cooled to room temperature, during which the residual heat of the web and the hub is self-tempered.

Specifically, the heat treatment process is any one of the following methods:

The wheel is heated to the austenitizing temperature, and the rim tread surface is sprayed with water to strengthen the cooling to below 400 ° C, and air cooled to room temperature, during which time the residual heat is self-tempered;

Or, the wheel is heated to the austenitizing temperature, the rim tread surface is sprayed with water to enhance cooling to below 400 ° C, less than 400 ° C low temperature tempering, tempering time of more than 30 minutes, tempering, air cooling to room temperature.

The heating to austenitizing temperature is specifically: heating to 860-930 ° C for 2.0-2.5 hours.

Or, using the high temperature residual heat after the wheel is formed, the rim tread surface is sprayed with water to strengthen the cooling to below 400 ° C, and air cooled to room temperature, during which the residual heat of the web and the hub is self-tempered.

Or, using the high temperature residual heat after the wheel is formed, the rim tread surface is sprayed with water to enhance cooling to below 400 ° C, less than 400 ° C low temperature tempering, tempering time of more than 30 minutes, tempering and then air cooling to room temperature;

Or, after the wheel is formed, the wheel is air-cooled to below 400 ° C, during which the residual heat of the web and the hub is self-tempered.

Or, after the wheel is formed, the wheel is air cooled to below 400 ° C, and then tempered at a low temperature of less than 400 ° C, the tempering time is more than 30 minutes, and tempered to cool to room temperature.

The functions of the elements in the present invention are as follows:

C content: the basic element in steel, with strong interstitial solid solution hardening and precipitation strengthening. With the increase of carbon content, the strength of steel increases and the toughness decreases; the solubility of carbon in austenite is better than that in ferrite. It is much larger and is an effective austenite stabilizing element; the volume fraction of carbides in steel is proportional to the carbon content. In order to obtain a carbide-free bainite structure, it is necessary to ensure that a certain C content is dissolved in the supercooled austenite, and in the supersaturated ferrite, the material hardness is further effectively improved, in particular, the yield strength of the material is improved. When the C content is higher than 0.40%, the precipitation of cementite will be caused, and the toughness of the steel will be lowered. When the C content is less than 0.10%, the supersaturation of the ferrite is lowered and the strength of the steel is decreased. Therefore, the reasonable range of the carbon content is preferably 0.10. -0.40%.

Si content: the basic alloying element in steel, the commonly used deoxidizer, its atomic radius is smaller than the radius of iron atom, has a strong solid solution strengthening effect on austenite and ferrite, and increases the shear strength of austenite; Si is non- Carbide forming elements, prevent the precipitation of cementite, promote the formation of bainite-ferrite carbon-rich austenite film and (MA) island structure, and are the main elements for obtaining carbide-free bainitic steel; Si can also prevent the precipitation of cementite, prevent the precipitation of carbides from the supercooled austenite, and the cementite precipitation during tempering at 300 °C ~ 400 °C. It is completely suppressed, improving the thermal stability and mechanical stability of austenite. The content of Si in steel is higher than 2.00%, the tendency of pre-eutectoid ferrite increases, the amount of retained austenite increases, the toughness of steel decreases, and when the content of Si is less than 1.00%, cementite is easily precipitated in steel, which is difficult to obtain. There is no carbide bainite structure, so the Si content should be controlled at 1.00-2.00%.

Ni content: Ni is a non-carbide forming element, which inhibits the precipitation of carbides during the bainite transformation, thereby forming a stable austenite film between the bainitic ferrite laths, which is beneficial to the carbide-free shell. Formation of clastic tissue. Ni can improve the strength and toughness of steel, is an essential alloying element for obtaining high impact toughness, and reduces the impact toughness transition temperature. The Ni content is less than 0.20%, which is not conducive to the formation of carbide-free bainite. The Ni content is higher than 1.00%. The contribution rate of steel toughness will decrease greatly and the production cost will increase. Therefore, the Ni content should be controlled at 0.20. -1.00%.

Mn content: Mn is an austenite stabilizing element in steel, which increases the hardenability of steel and improves the mechanical properties of steel. By appropriately adjusting the amount of alloy of Si and Mn, a film-like austenite structure free from carbide precipitation and distributed between the bainitic ferrite slabs, that is, carbide-free bainite can be obtained; Mn can also Increase the diffusion coefficient of P and increase the brittleness of steel. The Mn content is less than 1.00%, the hardenability of steel is poor, which is not conducive to obtaining carbide-free bainite. The Mn content is higher than 2.50%, the hardenability of steel is significantly increased, and the diffusion tendency of P is greatly increased, and the steel is lowered. Toughness, so the Mn content should be controlled at 1.00-2.50%.

RE content: RE element is added to steel to refine austenite grains, and it has purification and metamorphism. It can reduce the segregation of harmful impurity elements at grain boundaries, improve and strengthen grain boundaries, and thus improve the strength and toughness of steel. . At the same time, RE can promote the spheroidization of inclusions, further improve the toughness of steel and reduce the notch sensitivity of materials. When the RE content is too high, its beneficial effect will be weakened, and at the same time, the production cost of steel will increase. When the RE content is less than 0.001%, it is impossible to completely remove harmful elements to form tough rare earth inclusions. When the RE content is higher than 0.040%, the RE element is surplus and cannot effectively exert its effect. Considering the RE content, the RE content is controlled at 0.001-0.040%. .

P content: P in the medium and high carbon steel, easy to segregate at the grain boundary, thereby weakening the grain boundary and reducing the strength and toughness of the steel. As a harmful element, when P ≤ 0.020%, there is no significant adverse effect on performance.

S content: S tends to be segregated at the grain boundary, and easily forms inclusions with other elements, reducing the strength and toughness of the steel. As a harmful element, when S ≤ 0.020%, there is no significant adverse effect on performance.

In the element design of steel, the invention adopts C-Si-Mn-Ni-RE system, and does not particularly add alloying elements such as Mo, V, Cr and B, and combines heat treatment process to make the rim typical structure into carbide-free bainite. ,and also That is, the nano-scale lath-like super-saturated ferrite with nano-scale film-like carbon-rich retained austenite in the middle, wherein the retained austenite is 4% to 15%, and the wheel has excellent toughness and low gap. Sensitivity and other characteristics. The steel has moderate hardenability, is easy to control production, and has low cost. The rare earth element can spheroidize the inclusions in the steel and strengthen the grain boundary, so that the steel has a high impact toughness performance of 20 °C. The addition of Ni gives the obtained bainitic steel a higher 20 ° C impact toughness performance.

In the invention, the design of the component and the manufacturing process realize the cooperation of the high strength and the high toughness of the wheel, provide the comprehensive mechanical properties of the wheel, achieve the purpose of improving the service performance of the wheel, and can also be used for other key components and the like of the rail transit. Manufacturing.

The invention mainly utilizes Si and Ni non-carbide forming elements, improves the activity of carbon in ferrite, delays and inhibits carbide precipitation, and adopts a suitable molding process (including forging rolling or model casting, etc.). It is a heat treatment process. According to the formula of steel, the rim tread water spray is used to strengthen the cooling to make the wheel rim obtain the carbide-free bainite structure, and the residual heat is used for self-tempering or low-temperature tempering to further improve the structural stability of the wheel and the integration of the wheel. Mechanical properties. At the same time, the Mn element has excellent austenite stabilization, increases the hardenability of the steel, and increases the strength of the steel. The rare earth element has the function of adsorbing harmful gases such as hydrogen in the steel, and the inevitable inclusions in the spheroidized steel further improve the toughness of the steel. By appropriately adjusting the contents of Si, Ni and Mn, and RE, the rim obtains a carbide-free bainite structure free from carbide precipitation, further improving the strength and toughness of the wheel, and utilizing the characteristics of Ni solid-solution strengthening. Further improve the strength and toughness without lowering the toughness index; also use the Ni element to have corrosion resistance, achieve the atmospheric corrosion resistance of the wheel, improve the service life of the wheel, realize the high toughness bainite steel wheel, and meet the harsh operating conditions of the rail transit. Requirements.

Compared with the prior art, the bainite steel wheel prepared by the invention has significantly improved rim toughness matching compared with the CL60 wheel, thereby effectively improving the yield strength, toughness and low temperature toughness of the wheel under the premise of ensuring safety. Improve the anti-rolling contact fatigue (RCF) performance of the wheel, improve the thermal crack resistance of the wheel, improve the corrosion resistance of the wheel, reduce the wheel notch sensitivity, reduce the probability of the wheel peeling and peeling during use, and realize the wheel tread Uniform wear and less repair, improve the use efficiency of wheel rim metal, improve the service life and comprehensive benefits of the wheel, have certain economic and social benefits.

DRAWINGS

Figure 1 is a schematic view of the names of various parts of the wheel;

1 is the hub hole, 2 is the outer side of the rim, 3 is the rim, 4 is the inner side of the rim, 5 is the web, 6 is Wheel hub, 7 is the tread;

2a is a 100× optical metallographic structure diagram of the rim of the embodiment 1;

2b is a ferrule 500× optical metallographic structure diagram of Embodiment 1;

Figure 3a is a ferrule 100 x optical metallographic structure of the embodiment 2;

Figure 3b is a ferrule 500 x optical metallographic structure diagram of Embodiment 2;

Figure 3c is a diagram showing the structure of the rim 500×stained metallurgy of Example 2;

Figure 3d is a structural diagram of the rim transmission electron microscope of Embodiment 2;

Figure 4a is a ferrule 100 x optical metallographic structure diagram of Example 3;

4b is a ferrule 500× optical metallographic structure diagram of Embodiment 3;

Figure 5 is a continuous cooling transition curve (CCT curve) of the steel of Example 2;

6 is a comparison of the relationship between the friction coefficient and the number of revolutions in the friction and wear test of the wheel of the embodiment 2 and the CL60 wheel;

Figure 7 is a diagram showing the surface deformation layer structure of the sample after the friction and wear test of the wheel of Example 2 and the CL60 wheel.

detailed description

The chemical composition weight percentages of the wheel steels in Examples 1, 2, and 3 are as shown in Table 2. Examples 1, 2, and 3 were directly cast into electric furnace smelting by LF+RH refining vacuum degassing.

The round billet is formed into a wheel having a diameter of 915 mm by ingot cutting, heating and rolling, heat treatment and finishing.

Example 1

A bainitic steel wheel for high-toughness rail transit, which has the following weight percentage elements as shown in Table 2 below.

A method for manufacturing a bainitic steel wheel for high-toughness rail transit, comprising the following steps:

The molten steel of the first embodiment shown in Table 2 was formed by an electric furnace steelmaking process, an LF furnace refining process, an RH vacuum process, a round billet continuous casting process, an ingot rolling process, a heat treatment process, a processing, and a finished product inspection process. The heat treatment step is: heating to 860-930 ° C for 2.0-2.5 hours, rim spray cooling, cooling to below 400 ° C, and then tempering at 280 ° C for 4.5-5.0 hours.

As shown in FIG. 2a and FIG. 2b, the metallographic structure of the wheel rim prepared in this embodiment is mainly a carbide-free bainite structure. The mechanical properties of the wheel of this embodiment are shown in Table 3. The physical toughness of the wheel is better than that of the CL60 wheel.

Example 2

The molten steel of the second embodiment of the chemical composition is formed by an electric furnace steelmaking process, an LF furnace refining process, an RH vacuum process, a round billet continuous casting process, an ingot rolling process, a heat treatment process, a processing, and a finished product inspection process. The heat treatment step is: heating to 860-930 ° C for 2.0-2.5 hours, rim spray cooling, cooling to below 400 ° C, and then tempering at 240 ° C for 4.5-5.0 hours.

As shown in Figures 3a, 3b, 3c, and 3d, the metallographic structure of the wheel rim prepared in this embodiment is mainly carbide-free bainite. The mechanical properties of the wheel of this embodiment are shown in Table 3. The physical toughness of the wheel is better than that of the CL60 wheel.

Example 3

The molten steel of the third embodiment of the chemical composition is formed by an electric furnace steelmaking process, an LF furnace refining process, an RH vacuum process, a round billet continuous casting process, an ingot rolling process, a heat treatment process, a processing, and a finished product inspection process. The heat treatment step is: heating to 860-930 ° C for 2.0-2.5 hours, rim spray cooling, cooling to below 400 ° C, and then tempering at 200 ° C for 4.5-5.0 hours. .

As shown in Figures 4a and 4b, the metallographic structure of the wheel rim prepared in this embodiment is mainly carbide-free bainite. The mechanical properties of the wheel of this embodiment are shown in Table 3. The physical toughness of the wheel is better than that of the CL60 wheel.

Table 2 Chemical compositions (wt%) of the wheels of Examples 1, 2, 3 and Comparative Examples

Table 3 Example 1, 2, 3 and comparative examples of wheel rim mechanical properties

Claims

A bainitic steel wheel for high-toughness rail transit, characterized in that the bainitic steel wheel for high-toughness rail transit comprises the following weight percentage elements:

Carbon C: 0.10 to 0.40%, silicon Si: 1.00 to 2.00%, manganese Mn: 1.00 to 2.50%,

Nickel Ni: 0.20 to 1.00%, rare earth RE: 0.001 to 0.040%,

Phosphorus P≤0.020%, sulfur S≤0.020%, the rest being iron and inevitable residual elements;

And 1.50% ≤ Si + Ni ≤ 2.50%, 2.00% ≤ Si + Mn ≤ 4.00%.
The high-toughness rail transit bainite steel wheel according to claim 1, wherein the high-toughness rail transit bainite steel wheel comprises the following weight percentage elements:

Carbon C: 0.15 to 0.25%, silicon Si: 1.20 to 1.80%, manganese Mn: 1.60 to 2.10%,

Nickel Ni: 0.20 to 0.80%, rare earth RE: 0.010 to 0.040%, phosphorus P ≤ 0.020%, sulfur S ≤ 0.020%, the balance being iron and unavoidable residual elements; and 1.50% ≤ Si + Ni ≤ 2.50%, 2.00 % ≤ Si + Mn ≤ 4.00%.
The high-toughness rail transit bainite steel wheel according to claim 1 or 2, wherein the high-toughness rail transit bainite steel wheel comprises the following weight percentage elements:

Carbon C: 0.20%, silicon Si: 1.45%, manganese Mn: 1.92%, nickel Ni: 0.35%, rare earth RE: 0.018%, phosphorus P: 0.013%, sulfur S: 0.008%, and the balance is iron and inevitable impurities element.
The bainitic steel wheel for high-toughness rail transit according to claim 1 or 2, wherein the metallographic structure within 40 mm of the bain surface of the bainitic steel wheel is a carbide-free bainite structure, that is, For the nano-scale lath-like super-saturated ferrite, the middle of the lath-like super-saturated ferrite is a nano-scale film-like carbon-rich retained austenite, wherein the residual austenite volume percentage is 4% to 15%.
The high-toughness rail transit bainite steel wheel according to claim 1 or 2, wherein the wheel rim microstructure is a multiphase structure composed of supersaturated ferrite and carbon-rich retained austenite, Its size is on the nanometer scale, and the nanoscale is 1-999 nm.
A method for manufacturing a high-toughness rail transit bainite steel wheel according to any one of claims 1 to 5, comprising a smelting, refining, forming and heat treatment process, characterized in that the heat treatment process is: forming a wheel It is heated to the austenitizing temperature, and the rim tread is sprayed with water to strengthen the cooling to below 400 °C, and tempered.
The method for manufacturing a high-toughness rail transit bainite steel wheel according to claim 6, wherein the heating to the austenitizing temperature is specifically: heating to 860-930 ° C for 2.0-2.5 hours.
The method for manufacturing a high-toughness rail transit bainite steel wheel according to claim 6 or 7, wherein the tempering treatment is: low-temperature tempering in a wheel of less than 400 ° C, and tempering time of 30 minutes or more, After tempering, air cool to room temperature; or rim tread water spray enhanced cooling to below 400 ° C, air cooled to room temperature, during the use of residual heat self-tempering.
The method for manufacturing a high-toughness rail transit bainite steel wheel according to claim 6, wherein the heat treatment process further comprises: directly cooling the formed wheel wheel tread surface by using high-temperature residual heat after molding to 400 ° C. Following, tempering.
The method for manufacturing a high-toughness rail transit bainite steel wheel according to claim 6, wherein the heat treatment process may further be: after the wheel is formed, the wheel is air-cooled to 400 ° C or less and tempered.