JP6765496B2 - Bainite steel wheels for high toughness railway transportation and their manufacturing methods - Google Patents

Description

The present invention relates to the fields of steel chemical composition design and wheel manufacturing, specifically, the design of bainite steel wheels for high toughness rail transport and its manufacturing method, and the design of steel for other parts and similar parts for rail transport. Regarding the manufacturing method.

"High speed, high load and low noise" are the major development directions of world rail transportation. Wheels are the "shoes" of rail transport, one of the most important traveling parts, and have a direct impact on operational safety. During normal operation of the train, the wheels bear the full load of the vehicle and are damaged by wear and rolling contact fatigue (RCF), which at the same time it has a very complex working relationship with railroad tracks, brake shoes, axles and surrounding media. And is in a dynamic, alternating stress state. In particular, wheels and railroad tracks, and wheels and brake shoes (excluding disc brakes) are two pairs of always-existing, non-negligible friction pairs. During emergencies or operation on special roads, the brakes are extremely severely damaged or scratched, causing thermal fatigue and affecting wheel safety and service life.

In rail transport, if the wheels meet basic strength, pay particular attention to the toughness index of the wheels to ensure safety and reliability. Freight transport wheels are heavily damaged by wear and rolling contact fatigue (RCF), and because of the tread brake, thermal fatigue damage is also large, causing defects such as peeling, peeling, and rim cracking. For passenger transport wheels, pay more attention to the toughness and low temperature toughness of the wheels. Since passenger transportation uses disc brakes, brake thermal fatigue is reduced.

Currently, steel wheels for railway transportation in China and abroad are based on, for example, Chinese wheel standards GB / T8601, TB / T2817, European wheel standards EN13262, Japanese wheel standards JRS and JIS B5402, and North American wheel standards AAR M107. It is a medium-high carbon steel or a medium-high carbon microalloyed steel, and its metal structure is a pearlite-ferrite structure.

CL60 steel wheels are rolled steel wheel steels that are mainly used in China's current rail transport vehicles (passenger transport and freight transport). BZ-L is a cast steel wheel steel mainly used in the current railway transportation vehicles (freight transportation) in China. Both metal structures are pearlite-ferrite structures.

The names of each part of the wheel are shown in FIG. Table 1 shows the requirements for the main technical indicators of CL60 steel.

During production, 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 wheels are hot, the treads of the rim are reinforced and cooled by a jet of water, improving the strength and hardness of the rim. The spoke plate portion and the wheel hub are equivalent to the normalizing heat treatment, the strength and toughness of the rim are highly consistent, and the spoke plate portion has high toughness. Ultimately, the wheels have excellent overall mechanical properties and service performance.

In pearlite-low volume ferrite wheel steel, ferrite is the soft phase of the material and has good toughness and low yield strength. Due to its softness, it has low resistance to rolling contact fatigue (RCF). In general, the higher the ferrite content, the better the impact toughness of the steel. Compared to ferrite, pearlite is inferior in impact performance due to its high strength and low toughness. The direction of development of railway transportation is high speed and high load, and the load on the wheels increases significantly during operation. Existing perlite-small amount ferrite material wheels present more and more problems during operation and service, with the following main drawbacks:
(1) The rim yield strength is low and generally does not exceed 600 MPa. Since the rolling contact stress between the wheel and the track is large during the running of the wheel and sometimes exceeds the yield strength of the wheel steel, plastic deformation occurs during the running process, causing plastic deformation of the secondary surface of the tread surface. In addition, since brittle phases such as inclusions and cementite are present in the steel, microcracks are likely to occur in the rim. These microcracks cause defects such as peeling and rim cracking due to rolling contact fatigue while the wheel is running.
(2) Steel has a high carbon content and low heat damage resistance. If scratches occur when the tread brakes are used or when the wheels slide, the wheels locally heat up to the austenitizing temperature of the steel and then quench to produce martensite. In this way, thermal fatigue is repeated, brake thermal cracks are formed, and defects such as peeling and large cracks occur.
(3) Poor hardenability of wheel steel. The wheel rim has a constant hardness gradient, and due to the non-uniform hardness, defects such as wear of the wheel edge and distortion of the circumference are likely to occur.

With the development and breakthrough of research on phase transformation of bainite steel, good matching of high strength and high toughness is achieved, especially by theoretical and applied research of carbide-free bainite steel. Carbide-free bainite steel has an ideal microstructure and excellent mechanical properties. Its microstructure is carbide free bainite, i.e., nanoscale lath-like supersaturated ferrite. In the middle is nanoscale thin-film carbon-rich retained austenite. As a result, the strength and toughness of the steel are improved, and in particular, the yield strength, impact toughness and fracture toughness of the steel are improved, and the notch sensitivity of the steel is reduced. Therefore, the bainite steel wheel effectively improves the resistance to rolling contact fatigue (RCF) of the wheel, reduces phenomena such as peeling and peeling of the wheel, and improves the safety and use performance of the wheel. Due to the low carbon content of baynite steel wheels, the thermal fatigue performance of the wheels is improved, heat cracks in the rim are prevented, the number of lathes and the amount of lathes are reduced, and the efficiency of rim metal use is improved. The service life of the wheel is extended.

The chemical composition range (wt%) of the steel disclosed in the Chinese patent "Baynite Steel for Railroad Vehicle Wheels" of CN1800247A (publication number) published on July 12, 2006 is carbon C: 0.08 to 0. .45%, Silicon Si: 0.60 to 2.10%, Manganese Mn: 0.60 to 2.10%, Molybdenum Mo: 0.08 to 0.60%, Nickel Ni: 0.00 to 2.10 %, Chromium Cr: <0.25%, Vanadium V: 0.00 to 0.20%, Copper Cu: 0.00 to 1.00%. The typical structure of the bainite steel is carbide-free bainite, which has excellent toughness, low notch sensitivity and good heat crack resistance. By adding the Mo element, the hardenability of steel can be improved, but in the case of a wheel having a large cross section, production control is difficult and the cost is high.

British Steel's patent CN1059239C discloses bainite steel and its production process. The chemical composition range (wt%) of the steel is carbon C: 0.05 to 0.50%, silicon Si and / or aluminum Al: 1.00 to 3.00%, manganese Mn: 0.50 to 2. 50%, chromium Cr: 0.25 to 2.50%. The typical structure of the bainite steel is carbide-free bainite, which has high wear resistance and rolling contact fatigue resistance. That type of steel has good toughness, but the cross section of the steel rail is relatively simple, the impact toughness at 20 ° C. is not high, and the cost of steel is high.

An object of the present invention is that the typical structure of the rim is carbide free bainite without the addition of alloying elements such as Mo, V, Cr and B, and features such as excellent strength and toughness and low notch sensitivity. The purpose of the present invention is to provide a C-Si-Mn-Ni-RE-based high toughness bainite steel wheel for railway transportation.

The present invention further provides a method for producing a toughness bainite steel wheel for rail transport, which provides the wheel with good overall mechanical properties and is easy to control production by means of a heat treatment process and technique.

The toughness rail transport bainite steel wheels according to the present invention are, by weight percent,
Carbon C: 0.10 to 0.40%, Silicon Si: 1.00 to 2.00%, Manganese Mn: 1.00 to 2.50%,
Nickel Ni: 0.25 to 1.00%, rare earth RE: 0.001 to 0.040%,
Containing phosphorus P ≤ 0.020% and sulfur S ≤ 0.020%
The rest is iron and unavoidable residual elements
Moreover, 1.50% ≦ Si + Ni ≦ 2.50% and 2.00% ≦ Si + Mn ≦ 4.00%.

Preferably, the toughness rail transport bainite steel wheels are in percent by weight.
Carbon C: 0.15-0.25%, Silicon Si: 1.20 to 1.80%, Manganese Mn: 1.60 to 2.10%,
Nickel Ni: 0.25 to 0.80%, rare earth RE: 0.010 to 0.040%, phosphorus P ≤ 0.020%, sulfur S ≤ 0.020%, the balance is iron and unavoidable residual elements And 1.50% ≦ Si + Ni ≦ 2.50%, 2.00% ≦ Si + Mn ≦ 4.00%.

Preferably, the toughness rail transport bainite steel wheels are in percent by weight.
Carbon C: 0.20%, Silicon Si: 1.45%, Manganese Mn: 1.92%,
It contains nickel Ni: 0.35%, rare earth RE: 0.018%, phosphorus P: 0.013%, sulfur S: 0.008%, and the balance is iron and unavoidable impurity elements.

When the total content of Si and Mn is less than 2%, the hardenability of the steel is lowered, carbides are easily formed, which is disadvantageous for obtaining a carbide-free bainite structure having excellent strength and toughness. If the total content of Si and Mn exceeds 4%, the hardenability of the steel is too high, and it becomes easy to form an undesired structure such as martensite, which makes production control difficult.

When the total content of Si and Ni is less than 1.5%, carbides are likely to be formed in the steel, which is disadvantageous for obtaining a carbide-free bainite structure having excellent strength and toughness. If the total content of Si and Ni exceeds 2.5%, the action of the element cannot be effectively exerted and the cost increases.

Regarding the obtained fine structure of the wheel, the metal structure within 40 mm from the bottom of the wheel rim tread is a carbide free bainite structure, that is, a nanoscale lath-shaped hypersaturated ferrite, and in the middle of the lath-shaped supersaturated ferrite. There are nanoscale thin carbon-rich retained austenite, with a volume percent of retained austenite ranging from 4% to 15%. The microstructure of the rim is a multiphase structure composed of supersaturated ferrite and carbon-rich retained austenite, the size of which is nanoscale, which means a length of 1 nm to 999 nm.

The wheels according to the invention can be applied to the production of freight car wheels and passenger car wheels, as well as other and similar parts of rail transport.

The method for producing a bainite steel wheel for high toughness railway transportation according to the present invention includes a smelting, refining, forming and heat treatment process. Conventional techniques are used in the smelting and molding process. In the heat treatment process
The molded wheel is heated to an austenitizing temperature, the rim tread is reinforced and cooled to 400 ° C. or lower by water injection, and tempered. Specifically, the heating to the austenitizing temperature is carried out at 860 to 930 ° C. and kept warm for 2.0 to 2.5 hours. In the tempering process, the wheels are tempered at a medium / low temperature of less than 400 ° C. for 30 minutes or more, and then air-cooled to room temperature, or the rim tread is reinforced and cooled to 400 ° C. or lower by water injection and air-cooled to room temperature. During that time, self-cooling is performed by the residual heat of the spoke plate and the wheel hub.

In the heat treatment process, the rim tread surface of the molded wheel can be reinforced and cooled to 400 ° C. or lower by direct water injection by the high temperature residual heat after molding, and can be treated by tempering. In the tempering process, the wheels are tempered at a medium / low temperature of less than 400 ° C. for 30 minutes or more, and then air-cooled to room temperature, or the rim tread is reinforced and cooled to 400 ° C. or lower by water injection and air-cooled to room temperature. During that time, self-cooling is performed by the residual heat of the spoke plate and the wheel hub.

In the heat treatment process, after the wheels are molded, the wheels can be air-cooled to 400 ° C. or lower and then tempered. In the tempering process, the wheels are tempered at a medium / low temperature of less than 400 ° C. for 30 minutes or more, and then air-cooled to room temperature after tempering, or air-cooled to 400 ° C. or lower and air-cooled to room temperature, during which the spoke plate portion, Self-burning is performed by the residual heat of the wheel hub.

Specifically, the heat treatment step is any of the following methods.
The wheels are heated to austenitizing temperature, the rim tread is reinforced and cooled to 400 ° C. or lower by water injection, air-cooled to room temperature, and self-tempering is performed by residual heat during that time.
Alternatively, the wheels are heated to an austenitizing temperature, the rim tread is reinforced and cooled to 400 ° C. or lower with a fountain, tempered at a medium or low temperature of less than 400 ° C. for 30 minutes or more, and then air-cooled to room temperature after tempering.

Specifically, the heating to the austenitizing temperature is carried out at 860 to 930 ° C. and kept warm for 2.0 to 2.5 hours.

Alternatively, using the high-temperature residual heat after wheel molding, the rim tread is reinforced and cooled to 400 ° C or lower by water injection, air-cooled to room temperature, and during that time, self-tempering is performed by the residual heat of the spoke plate and wheel hub. ..

Alternatively, using the high-temperature residual heat after wheel molding, the rim tread is reinforced and cooled to 400 ° C or lower by water injection, tempered at a medium or low temperature of less than 400 ° C for 30 minutes or more, and air-cooled to room temperature after tempering. ..
Alternatively, after molding the wheel, the wheel is air-cooled to 400 ° C. or lower, and during that time, self-tempering is performed by the residual heat of the spoke plate portion and the wheel hub.

Alternatively, after molding the wheel, the wheel is air-cooled to 400 ° C. or lower, then tempered at a medium / low temperature of less than 400 ° C. for 30 minutes or more, and after tempering, air-cooled to room temperature.

The action of each element in the present invention is as follows.
The C content is as follows. C is a basic element in steel and has a high effect of crevice solid solution hardening and precipitation strengthening. As the carbon content increases, the strength of the steel increases and the toughness decreases. Carbon is an effective austenite stabilizing element with a much higher solubility in austenite than ferrite. The volume fraction of carbides in steel is directly proportional to the carbon content. In order to obtain a carbide-free bainite structure, it is necessary to secure a constant C content dissolved in supercooled austenite and supersaturated ferrite so that the hardness of the material is further improved, and in particular, the yield strength of the material is improved. is there. If the C content exceeds 0.40%, cementite precipitation will occur and the toughness of the steel will decrease. If the C content is less than 0.10%, the supersaturation of ferrite will decrease and the strength of the steel will increase. The rational range of carbon content is preferably 0.10 to 0.40% because it decreases.

The Si content is as follows. Si is a basic alloy element in steel and is a commonly used deoxidizer. Its atomic radius is smaller than the radius of iron atom, and it has a high effect of solid solution strengthening on austenite and ferrite, and austenite shearing. Strength is improved. Si is a non-carbide forming element for preventing the precipitation of cementite, promoting the formation of a carbon-rich austenite thin film and (MA) island-like structure between bainite and ferrite, and obtaining a carbide-free bainite steel. It is a major element. Si can also prevent the precipitation of cementite and prevent the precipitation of carbides due to the decomposition of supercooled austenite. During tempering at 300 ° C to 400 ° C, the precipitation of cementite is completely suppressed, and the thermal stability and mechanical stability of austenite are improved. When the Si content in the steel exceeds 2.00%, the precipitation tendency of proeutectoid ferrite increases, the amount of retained austenite increases, the strength and toughness of the steel decrease, and the Si content is 1.00%. If it is less than, cementite is likely to be precipitated in the steel, and it is difficult to obtain a carbide-free bainite structure. Therefore, it is necessary to control the Si content to 1.00 to 2.00%.

The Ni content is as follows. Since Ni is a non-carbide forming element and can suppress the precipitation of carbides during bainite transformation, a stable austenite thin film is formed between bainite ferrite laths, which is advantageous for forming a carbide-free bainite structure. Ni is an alloying element that can improve the strength and toughness of steel and is indispensable for obtaining high impact toughness, and lowers the impact toughness transition temperature. If the Ni content is less than 0.20%, it is disadvantageous for the formation of carbide free bainite, and if the Ni content exceeds 1.00%, the contribution rate to the strength and toughness of the steel is greatly reduced, and the production cost is reduced. Therefore, it is necessary to control the Ni content to 0.25 to 1.00%.

The Mn content is as follows. 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 thin-film austenite structure having no carbide precipitation and distributed between bainite ferrite laths, that is, carbide-free bainite can be obtained. Mn can also increase the diffusion coefficient of P and increase the brittleness of steel. If the Mn content is less than 1.00%, the hardenability of the steel is poor, which is disadvantageous for obtaining carbide-free bainite. If the Mn content exceeds 2.50%, the hardenability of the steel is significantly improved. However, since the diffusion tendency of P is remarkably increased and the toughness of steel is lowered, it is necessary to control the Mn content to 1.00 to 2.50%.

The RE content is as follows. The addition of the RE element in the steel refines the austenite grains, has purifying and altering effects, reduces segregation of harmful impurities at the grain boundaries, improves and strengthens the grain boundaries, thereby strengthening the steel. And toughness can be improved. At the same time, RE can promote spheroidization of inclusions, further improve the toughness of the steel and reduce the notch sensitivity of the material. If the RE content is too high, its beneficial effects are diminished and at the same time the steel manufacturing cost is increased. If the RE content is less than 0.001%, the harmful elements cannot be completely removed to form toughness rare earth inclusions, and if the RE content exceeds 0.040%, the RE element is excessive. The RE content is controlled to 0.001 to 0.040% because the effect cannot be exhibited.

The P content is as follows. In medium- and high-carbon steels, P is likely to segregate at the grain boundaries, so that the grain boundaries are weakened and the strength and toughness of the steel are lowered. When P ≦ 0.020% as a harmful element, there is no significant adverse effect on performance.

The S content is as follows. S tends to segregate at grain boundaries, easily forms inclusions with other elements, and reduces the strength and toughness of steel. When S ≦ 0.020% as a harmful element, there is no significant adverse effect on performance.

In the elemental design of steel, the present invention adopts the C-Si-Mn-Ni-RE system, which is typical of rims by combining heat treatment processes without adding special alloying elements such as Mo, V, Cr and B. The structure is made into carbide free bainite, that is, nanoscale lath-like supersaturated ferrite. In the middle is nanoscale thin-film carbon-rich residual austenite. Residual austenite is 4% to 15%. Wheels have features such as excellent strength and toughness, and low notch sensitivity. This type of steel has moderate hardenability, is relatively easy to control production, and is low cost. Rare earth elements can spheroidize inclusions in steel and strengthen grain boundaries, so this type of steel has high impact toughness at 20 ° C. With the addition of Ni, the resulting bainite steel has higher 20 ° C impact toughness.

In the present invention, by designing the composition and manufacturing process, the objectives of achieving high strength and high toughness consistency of the wheel, providing the overall mechanical properties of the wheel, and improving the service performance of the wheel are achieved. It can also be used to manufacture other major parts of rail transport and similar parts.

The present invention mainly utilizes Si and Ni non-carbide forming elements to improve the activity of carbon in ferrite, delay and suppress the precipitation of carbides, and include an appropriate forming process (forging rolling or model casting, etc.). ), Especially by heat treatment process, depending on the steel formulation, the rim tread is reinforced and cooled by water injection to give the wheel rim a carbide-free bainite structure and self-tempered using residual heat or at medium and low temperatures. Tempered with to further improve the structural stability of the wheel and the overall mechanical properties of the wheel. At the same time, the excellent austenite stabilizing effect of the Mn element increases the hardenability of the steel and improves the strength of the steel. Rare earth elements have the function of adsorbing harmful gases such as hydrogen in steel, spheroidizing unavoidable inclusions in steel, and further improving the toughness of steel. By appropriately adjusting the contents of Si, Ni, Mn, and RE, the rim obtains a carbide-free bainite structure without carbide precipitation, and the strength and toughness of the wheel are further improved. Due to the excellent solid solution strengthening characteristics of the Ni element, the strength and toughness are further improved without lowering the toughness index. In addition, the corrosion resistance of the Ni element realizes resistance to atmospheric corrosion of the wheel, extends the service life of the wheel, realizes high toughness bainite steel wheel, and meets the strict requirements of railway transportation operating conditions.

Compared with the prior art, the bainite steel wheels manufactured according to the present invention have significantly improved rim strength and toughness consistency as compared to CL60 wheels. As a result, on the premise that safety is guaranteed, the yield strength, toughness and low temperature toughness of the wheel are effectively improved, the rolling contact fatigue (RCF) resistance of the wheel is improved, and the heat crack resistance of the wheel is improved. Improves wheel corrosion resistance, reduces wheel notch sensitivity, reduces the possibility of peeling and peeling during use of the wheel, achieves uniform wear of the wheel tread and less laminating, wheel rim metal Specification efficiency is improved, wheel life and overall benefits are improved, and there are certain economic and social benefits.

It is a figure which shows the name of each part of a wheel. 1 is a wheel hub hole, 2 is a rim outer surface, 3 is a rim, 4 is an inner surface of the rim, 5 is a spoke plate portion, 6 is a wheel hub, and 7 is a tread surface. It is a rim 100 × optical metal structure diagram of Example 1. FIG. It is a rim 500 × optical metal structure diagram of Example 1. FIG. It is a rim 100 × optical metal structure diagram of Example 2. FIG. It is a rim 500 × optical metal structure diagram of Example 2. FIG. It is a rim 500 × dyed metal structure diagram of Example 2. FIG. It is a transmission electron microscope structure diagram of the rim of Example 2. FIG. 3 is a rim 100 × optical metal structure diagram of Example 3. FIG. 5 is a rim 500 × optical metal structure diagram of Example 3. It is a continuous cooling transformation curve (CCT curve) of the steel of Example 2. It is a comparison of the relationship between the friction coefficient and the rotation speed in the friction and wear test of the wheel and the CL60 wheel of the second embodiment. It is the surface deformation structure of the sample after the frictional wear test of the wheel of Example 2 and the CL60 wheel.

Table 2 shows the weight percent of the chemical composition of the wheel steel in Examples 1, 2 and 3. In all of Examples 1, 2 and 3, electric furnace smelting is used, and after LF + RH refining vacuum degassing, a round billet having a diameter of 380 mm is continuously cast, and steel ingot cutting, heating and pressure rolling, heat treatment, and finishing are performed. After that, a wheel having a diameter of 915 mm was formed.

<Example 1>
Bainite steel wheels for high toughness rail transport contain the weight percent elements shown in Table 2 below.

A method for producing a tough rail transport baynite steel wheel includes the following steps: a molten steel having a chemical composition as shown in Example 1 of Table 2 is subjected to an electric furnace steelmaking process, an LF furnace refining process, an RH vacuum processing process, and the like. The wheels were formed through a round billet continuous casting process, a steel ingot cutting and rolling process, a heat treatment process, processing, and a finished product inspection process. In the heat treatment step, the mixture was heated to 860 to 930 ° C. and kept warm for 2.0 to 2.5 hours, the rim was cooled to 400 ° C. or lower with a fountain, and tempered at 280 ° C. for 4.5 to 5.0 hours.

As shown in FIGS. 2a and 2b, the metal structure of the wheel rim manufactured in this embodiment is mainly a carbide free bainite structure. Table 3 shows the mechanical performance of the wheels of this embodiment. The consistency between the strength and toughness of the actual wheel is superior to that of the CL60 wheel.

<Example 2>
Bainite steel wheels for high toughness rail transport contain the weight percent elements shown in Table 2 below.

A method for producing a tough rail transport baynite steel wheel includes the following steps: a molten steel having a chemical composition as shown in Example 2 of Table 2 is subjected to an electric furnace steelmaking process, an LF furnace refining process, an RH vacuum processing process, and the like. The wheels were formed through a round billet continuous casting process, a steel ingot cutting and rolling process, a heat treatment process, processing, and a finished product inspection process. In the heat treatment step, the mixture was heated to 860 to 930 ° C. and kept warm for 2.0 to 2.5 hours, the rim was cooled to 400 ° C. or lower with a fountain, and tempered at 240 ° C. for 4.5 to 5.0 hours.

As shown in FIGS. 3a, 3b, 3c and 3d, the metal structure of the wheel rim manufactured in this embodiment is mainly carbide free bainite. Table 3 shows the mechanical performance of the wheels of this embodiment. The consistency between the strength and toughness of the actual wheel is superior to that of the CL60 wheel.

<Example 3>
Bainite steel wheels for high toughness rail transport contain the weight percent elements shown in Table 2 below.

A method for producing a tough rail transport baynite steel wheel includes the following steps: a molten steel having a chemical composition as shown in Example 3 of Table 2 is subjected to an electric furnace steelmaking process, an LF furnace refining process, an RH vacuum processing process, and the like. The wheels were formed through a round billet continuous casting process, a steel ingot cutting and rolling process, a heat treatment process, processing, and a finished product inspection process. In the heat treatment step, the mixture was heated to 860 to 930 ° C. and kept warm for 2.0 to 2.5 hours, the rim was cooled to 400 ° C. or lower with a fountain, and tempered at 200 ° C. for 4.5 to 5.0 hours.

As shown in FIGS. 4a and 4b, the metal structure of the wheel rim manufactured in this example is mainly carbide free bainite. Table 3 shows the mechanical performance of the wheels of this embodiment. The consistency between the strength and toughness of the actual wheel is superior to that of the CL60 wheel.

Claims (8)

Bainite steel wheels for high toughness rail transport, by weight percent,
Carbon C: 0.10 to 0.40%, Silicon Si: 1.00 to 2.00%, Manganese Mn: 1.00 to 2.50%,
Nickel Ni: 0.25 to 1.00%, rare earth RE: 0.001 to 0.040%,
Containing phosphorus P ≤ 0.020% and sulfur S ≤ 0.020%
The rest is iron and unavoidable residual elements
A bainite steel wheel for rail transportation with high toughness, characterized in that 1.50% ≤ Si + Ni ≤ 2.50% and 2.00% ≤ Si + Mn ≤ 4.00%. The toughness rail transport bainite steel wheels are, by weight percent,
Carbon C: 0.15-0.25%, Silicon Si: 1.20 to 1.80%, Manganese Mn: 1.60 to 2.10%,
Nickel Ni: 0.25 to 0.80%, rare earth RE: 0.010 to 0.040%, phosphorus P ≤ 0.020%, sulfur S ≤ 0.020%.
The first aspect of claim 1, wherein the balance is iron and an unavoidable residual element, and 1.50% ≤ Si + Ni ≤ 2.50% and 2.00% ≤ Si + Mn ≤ 4.00%. Bainite steel wheels for high toughness rail transport. The toughness rail transport bainite steel wheels are, by weight percent,
Carbon C: 0.20%, Silicon Si: 1.45%, Manganese Mn: 1.92%, Nickel Ni: 0.35%, Rare Earth RE: 0.018%, Linn P: 0.013%, Sulfur S The bainite steel wheel for high toughness rail transport according to claim 1 or 2, wherein it contains 0.008% and the balance is iron and unavoidable residual elements. The metal structure within 40 mm from the bottom of the rim tread of the bainite steel wheel is a carbide-free bainite structure, that is, nanoscale lath-shaped hypersaturated ferrite, and the middle of the lath-shaped supersaturated ferrite is nanoscale thin carbon-rich. it is the residual austenite, percent by volume of residual austenite is 4% to 15%, high toughness rail transportation for bainitic steel wheel according to claim 1 or 2, characterized in that. A claim characterized in that the microstructure of the wheel rim is a multiphase structure composed of supersaturated ferrite and carbon-rich retained austenite, the size of which is nanoscale, and the nanoscale is 1 to 999 nm. The high toughness rail transport bainite steel wheel according to 1 or 2. It includes smelting, refining, molding and heat treatment processes, in which the molded wheels are heated to austenitizing temperature, the rim tread is reinforced and cooled to 400 ° C. or lower by water injection, and tempered. The method for manufacturing a bainite steel wheel for high toughness railway transportation according to any one of claims 1 to 5, which is characterized. The bainite for high toughness railway transportation according to claim 6, wherein the heating to the austenitizing temperature is specifically heated to 860 to 930 ° C. and kept warm for 2.0 to 2.5 hours. Manufacturing method of steel wheels. In the tempering process, the wheels are tempered at a medium / low temperature of less than 400 ° C. for 30 minutes or more and air-cooled to room temperature after tempering, or the rim tread is reinforced and cooled to 400 ° C. or lower by water injection and air-cooled to room temperature. The method for manufacturing a bainite steel wheel for high toughness railway transportation according to claim 6 or 7, wherein self-tempering is performed by residual heat during that period.