JP2019524994A - Bainitic steel wheels for high toughness railway transportation and manufacturing method thereof - Google Patents

Abstract

The present invention provides a high-toughness bainite steel wheel for rail transport and a method for manufacturing the same. The bainite steel wheels are, in 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: 0.00. 20 to 1.00%, rare earth RE: 0.001 to 0.040%, phosphorus P ≦ 0.020%, sulfur S ≦ 0.020%, the balance being iron and inevitable residual elements, and 1.50% ≦ Si + Ni ≦ 2.50%, 2.00% ≦ Si + Mn ≦ 4.00%. Compared to the prior art, the present invention provides the wheel rim with a carbide-free bainite structure by means of a steel chemical composition design and manufacturing process, in particular a heat treatment process and technique. The spoke plate portion and the wheel hub obtain a metallographic structure mainly composed of granular bainite and supersaturated ferrite. The wheel has comprehensive mechanical properties such as high yield strength, toughness, low temperature toughness, and good service performance. Costs are reduced, wheel service life and overall benefits are improved, and there are certain economic and social benefits.

Description

  The present invention relates to the field of steel chemical composition design and wheel manufacturing, specifically to high-toughness bainite steel wheels for rail transport and methods of manufacturing the same, as well as steel designs for other and similar parts of rail transport. It relates to a manufacturing method.

  “High speed, high load and low noise” is the main development direction of world rail transport. The wheel is a “shoe” for rail transport and is one of the most important traveling parts, directly affecting the safety of operation. During normal train operation, the wheels carry the full load of the vehicle and are damaged by wear and rolling contact fatigue (RCF), which at the same time is a very complex working relationship with the track, the control wheel, the axle and the surrounding medium. In a dynamically alternating stress state. In particular, wheels and tracks, and wheels and brakes (except for disc brakes) are two pairs of friction pairs that are always present and cannot be ignored. During emergency situations or on special roads, the brakes are severely damaged and scratched, causing thermal fatigue and affecting the safety and service life of the wheels.

  In rail transport, pay attention to the toughness index of the wheel to ensure safety and reliability when the wheel meets basic strength. Freight transport wheels are greatly damaged due to wear and rolling contact fatigue (RCF), and because of tread braking, thermal fatigue damage is also large, resulting in defects such as peeling, peeling, and rim cracking. For passenger transport wheels, pay more attention to wheel toughness and low temperature toughness. Passenger transport uses disc brakes, reducing brake thermal fatigue.

  Currently, rail transport wheel steel in China and abroad, for example, according to 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, Medium high carbon steel or medium high carbon microalloyed steel, the metal structure of which is a pearlite-ferrite structure.

  The CL60 steel wheel is a rolled steel wheel steel 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 China's current railway transportation vehicles (cargo transportation). Both metal structures are pearlite-ferrite structures.

The name of each part of a wheel is 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. In a state where the wheels are at a high temperature, the tread surface of the rim is strengthened and cooled by water jet, and the strength and hardness of the rim are improved. The spoke plate portion and the wheel hub are equivalent to the normalizing heat treatment, the consistency of the strength and toughness of the rim is high, and the spoke plate portion has high toughness. Ultimately, the wheels have excellent overall mechanical properties and service performance.

In pearlite-low volume ferritic 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 has high strength and low toughness, and therefore has poor impact performance. The development direction of rail transport is high speed and high load, and the load on the wheel increases greatly during operation. Existing pearlite-low ferritic material wheels present more and more problems during operation and service, mainly due to the following disadvantages:
(1) The rim yield strength is low and generally does not exceed 600 MPa. The rolling contact stress between the wheel and the track is large during traveling of the wheel, and sometimes exceeds the yield strength of the wheel steel, so that plastic deformation occurs during the traveling process, and plastic deformation of the sub surface of the tread surface occurs. In addition, since fragile phases such as inclusions and cementite are present in the steel, microcracks are easily generated in the rim. These micro cracks cause defects such as peeling and rim cracking due to rolling contact fatigue during running of the wheel.
(2) Steel has a high carbon content and low heat damage resistance. When scratches occur when tread brakes are used or when the wheels slide, the wheels are locally heated to the austenitizing temperature of the steel and then rapidly cooled to produce martensite. Thus, thermal fatigue is repeated, brake thermal cracks are formed, and defects such as peeling and large cracks occur.
(3) The hardenability of the wheel steel is poor. The wheel rim has a certain hardness gradient, and due to non-uniform hardness, defects such as ring edge wear and circumferential distortion are likely to occur.

  With the development and breakthrough of research on the phase transformation of bainite steel, a good match between high strength and high toughness is achieved especially by the theory and application research of carbide free bainite steel. Carbide-free bainite steel has an ideal microstructure and excellent mechanical properties. Its microstructure is carbide-free bainite, ie nanoscale lath-like supersaturated ferrite. In the middle is nanoscale thin film-like carbon-rich retained austenite. Thereby, 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 against 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. Since the carbon content of the bainite steel wheel is low, the thermal fatigue performance of the wheel is improved, the heat crack of the rim is prevented, the number of lathe processing and the amount of lathe processing of the wheel are reduced, the use efficiency of the rim metal is improved, The service life of the wheels is extended.

  The chemical composition range (wt%) of the steel disclosed in the Chinese patent “Bainite Steel for Rail Vehicle Wheels” of CN18000427A (public number) published on July 12, 2006 is carbon C: 0.08-0. .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. Although the hardenability of steel can be increased by adding Mo element, production control is difficult and cost is high in the case of a wheel with a large cross section.

  The British Steel 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 the steel is high.

  The object of the present invention is to provide carbide-free bainite with a typical structure of the rim without adding alloying elements such as Mo, V, Cr, and B, and has characteristics such as excellent strength and toughness and low notch sensitivity. It is to provide a bainite steel wheel for high-toughness railway transportation having a C-Si-Mn-Ni-RE system.

  The present invention further provides a method for producing high-toughness bainite steel wheels for rail transport that impart good overall mechanical properties to the wheels and that are easy to control production by heat treatment processes and techniques.

Bainite steel wheels for high toughness rail transport according to the present invention are in 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: 0.20 to 1.00%, rare earth RE: 0.001 to 0.040%,
Including phosphorus P ≦ 0.020%, sulfur S ≦ 0.020%,
The balance is iron and inevitable residual elements,
Further, 1.50% ≦ Si + Ni ≦ 2.50% and 2.00% ≦ Si + Mn ≦ 4.00%.

Preferably, the high toughness rail transport bainite steel wheels are in weight percent,
Carbon C: 0.15-0.25%, silicon Si: 1.20-1.80%, manganese Mn: 1.60-2.10%,
Nickel Ni: 0.20-0.80%, rare earth RE: 0.010-0.040%, phosphorus P ≦ 0.020%, sulfur S ≦ 0.020%, the balance being iron and inevitable residual elements And 1.50% ≦ Si + Ni ≦ 2.50% and 2.00% ≦ Si + Mn ≦ 4.00%.

Preferably, the high toughness rail transport bainite steel wheels are in weight percent,
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%, the balance being iron and inevitable impurity elements.

  When the total content of Si and Mn is less than 2%, the hardenability of the steel is lowered, carbides are easily generated, and this is disadvantageous for obtaining a carbide-free bainite structure excellent in 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 undesirable structure such as martensite, making production control difficult.

  When the total content of Si and Ni is less than 1.5%, carbide is easily generated in the steel, which is disadvantageous for obtaining a carbide-free bainite structure having excellent strength and toughness. When the total content of Si and Ni exceeds 2.5%, the effect of the element cannot be exhibited effectively, and the cost also increases.

  Regarding the microstructure of the obtained wheel, the metal structure within 40 mm from the tread surface of the wheel rim is a carbide-free bainite structure, that is, nanoscale lath-like supersaturated ferrite, in the middle of lath-like supersaturated ferrite. There is nanoscale thin film-like carbon-rich retained austenite, and the volume percent of retained austenite is between 4% and 15%. The microstructure of the rim is a multiphase structure composed of supersaturated ferrite and carbon-rich retained austenite, and its size 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 parts of rail transport and similar parts.

The method of manufacturing a bainite steel wheel for high toughness railway transportation according to the present invention includes smelting, refining, forming and heat treatment processes. Conventional processes are used in the smelting and forming processes. In the heat treatment process,
The formed wheel is heated to the austenitizing temperature, and the rim tread surface is tempered and cooled to 400 ° C. or less by water injection, and tempered. Specifically, the heating to the austenitizing temperature is performed by heating to 860 to 930 ° C. and keeping the temperature for 2.0 to 2.5 hours. In the tempering treatment, the wheel is tempered at a low and 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 tempered and cooled to 400 ° C. or less by water jet and air-cooled to room temperature. In the meantime, self-tempering is performed by the residual heat of the spoke plate portion and the wheel hub.

  In the heat treatment process, the rim tread surface of the molded wheel can be tempered and cooled to 400 ° C. or lower by direct water injection by the high-temperature residual heat after molding, and can also be processed by tempering. In the tempering treatment, the wheel is tempered at a low and 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 tempered and cooled to 400 ° C. or less by water jet and air-cooled to room temperature. In the meantime, self-tempering is performed by the residual heat of the spoke plate portion and the wheel hub.

  In the heat treatment process, after forming the wheel, the wheel may be air-cooled to 400 ° C. or lower and tempered. In the tempering process, the wheel is tempered at a low temperature of less than 400 ° C. for 30 minutes or more, and after tempering, it is air-cooled to room temperature, or air-cooled to 400 ° C. or less, and air-cooled to room temperature. Self-tempering is performed by the residual heat of the wheel hub.

Specifically, the heat treatment step is one of the following methods.
The wheel is heated to the austenitizing temperature, the rim tread surface is reinforced and cooled to 400 ° C. or lower by water injection, and air-cooled to room temperature, while self-tempering is performed by residual heat.
Alternatively, the wheel is heated to the austenitizing temperature, the rim tread surface is strengthened and cooled to 400 ° C. or lower with a fountain, tempered at a low temperature of less than 400 ° C. for 30 minutes or more, and air cooled to room temperature after tempering.

  Specifically, the heating to the austenitizing temperature is performed by heating to 860 to 930 ° C. and keeping the temperature for 2.0 to 2.5 hours.

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

Alternatively, using the high-temperature residual heat after wheel forming, the rim tread surface is tempered and cooled to 400 ° C. or less by water injection, tempered at a medium or low temperature below 400 ° C. for 30 minutes or more, and then air-cooled to room temperature after tempering. .
Or after shaping | molding a wheel, a wheel is air-cooled to 400 degrees C or less, and self-tempering is performed by the residual heat of a spoke board part and a wheel hub in the meantime.

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

The action of each element in the present invention is as follows.
About C content, it is as follows. C is a basic element in steel and has a high effect of solid solution hardening and precipitation strengthening. As the carbon content increases, the strength of the steel improves and the toughness decreases. Carbon has a much higher solubility in austenite than ferrite and is an effective austenite stabilizing element. 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 ensure a certain 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%, precipitation of cementite occurs and the toughness of the steel decreases. If the C content is less than 0.10%, the supersaturation degree of ferrite decreases and the strength of the steel decreases. Since it falls, it is preferable that the reasonable range of carbon content is 0.10 to 0.40%.

  About Si content, it is as follows. Si is a basic alloying element in steel and is a commonly used deoxidizing agent. Its atomic radius is smaller than that of iron atoms and has a high effect of solid solution strengthening on austenite and ferrite. Strength is improved. Si is a non-carbide forming element, prevents precipitation of cementite, promotes the formation of a carbon-rich austenite thin film and (MA) island-like structure between bainite and ferrite, and obtains a carbide-free bainite steel. It is a major element. Si can also prevent cementite precipitation and prevent carbide precipitation due to decomposition of supercooled austenite. During tempering at 300 ° C. to 400 ° C., precipitation of cementite is completely suppressed, and the thermal stability and mechanical stability of austenite are improved. If the Si content in the steel exceeds 2.00%, the precipitation tendency of pro-eutectoid 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 the range, cementite is likely to precipitate in the steel, and a carbide-free bainite structure is difficult to obtain. Therefore, it is necessary to control the Si content to 1.00 to 2.00%.

  About Ni content, it is as follows. Ni is a non-carbide-forming element and can suppress the precipitation of carbide during bainite transformation. Therefore, a stable austenite thin film is formed between laths of bainite ferrite, which is advantageous for the formation of a carbide-free bainite structure. Ni can improve the strength and toughness of steel, and is an indispensable alloy element for obtaining high impact toughness, and lowers the impact toughness transition temperature. When the Ni content is less than 0.20%, it is disadvantageous for the formation of carbide free bainite. When the Ni content exceeds 1.00%, the contribution 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 0.20 to 1.00%.

  About Mn content, it is as follows. Mn is an austenite stabilizing element in steel and increases the hardenability of the steel and improves the mechanical properties of the steel. By appropriately adjusting the alloy amount 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 the steel. When the Mn content is less than 1.00%, the hardenability of the steel is poor, which is disadvantageous for obtaining carbide-free bainite. When the Mn content exceeds 2.50%, the hardenability of the steel is remarkably improved. However, since the diffusion tendency of P is remarkably increased and the toughness of the 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 RE element in steel has the effect of refining austenite grains, purifying and altering, reducing segregation of harmful impurities at grain boundaries, improving and strengthening grain boundaries, thereby strengthening steel strength 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, the beneficial effect is weakened, and at the same time the production cost of steel increases. If the RE content is less than 0.001%, harmful elements cannot be completely removed to form tough rare earth inclusions. If the RE content exceeds 0.040%, the RE element is excessive. Since the effect cannot be exhibited, the RE content is controlled to 0.001 to 0.040%.

  About P content, it is as follows. In medium and high carbon steels, P tends to segregate at the grain boundaries, so the grain boundaries become weak, and the strength and toughness of the steel decrease. When P ≦ 0.020% as a harmful element, there is no significant adverse effect on performance.

  About S content, it is as follows. S tends to segregate at the grain boundaries, tends to form inclusions with other elements, and the strength and toughness of the steel decrease. As a harmful element, when S ≦ 0.020%, 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, and does not add special alloy elements such as Mo, V, Cr and B, and combines the heat treatment process, and the typical rim The typical structure is carbide free bainite, that is, nanoscale lath-like supersaturated ferrite. In the middle is nanoscale thin film carbon-rich residual austenite. The remaining austenite is 4% to 15%. The wheel has 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 in cost. Since rare earth elements can spheroidize inclusions in steel and strengthen grain boundaries, this type of steel has a high impact toughness of 20 ° C. With the addition of Ni, the resulting bainite steel has a higher 20 ° C. impact toughness.

  In the present invention, the composition and manufacturing process are designed to achieve the high strength and high toughness of the wheel, provide the overall mechanical properties of the wheel, and achieve the purpose of improving the service performance of the wheel However, 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, retard and suppress carbide precipitation, and include suitable forming processes (forging rolling or model casting, etc.) ), Especially by heat treatment process, depending on the steel composition, the rim tread surface is strengthened and cooled with water injection to give the wheel rim a carbide free bainite structure and use the residual heat for self-tempering or at low to medium temperature Tempering with to further improve the wheel's tissue stability 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. The rare earth element has a function of adsorbing harmful gases such as hydrogen in the steel, spheroidizes inevitable inclusions in the steel, and further improves the toughness of the steel. By appropriately adjusting the contents of Si, Ni, Mn, and RE, the rim obtains a carbide-free bainite structure with no carbide precipitation, and the strength and toughness of the wheel are further improved. Due to the excellent solid solution strengthening characteristics of Ni element, the strength and toughness are further improved without lowering the toughness index. Moreover, the corrosion resistance of Ni element realizes atmospheric corrosion resistance of the wheel, extends the service life of the wheel, realizes a high toughness bainitic steel wheel, and satisfies the severe requirements of railway transportation operation conditions.

  Compared to the prior art, the bainite steel wheels produced according to the present invention have a significantly improved consistency of rim strength and toughness compared to CL60 wheels. As a result, the yield strength, toughness, and low-temperature toughness of the wheel are effectively improved on the premise that safety is guaranteed, the resistance to rolling contact fatigue (RCF) of the wheel is improved, and the heat crack resistance of the wheel is improved. The corrosion resistance of the wheel is improved, the notch sensitivity of the wheel is reduced, the possibility of peeling and peeling off during use of the wheel is reduced, the wheel tread is evenly worn and less lathe processing is realized, and the wheel rim metal Specification efficiency is improved, wheel service 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 a rim inner surface, 5 is a spoke plate portion, 6 is a wheel hub, and 7 is a tread surface. It is a rim | limb 100x optical metal structure figure of Example 1. FIG. FIG. 3 is a diagram illustrating a rim 500 × optical metal structure of Example 1. It is a rim | limb 100x optical metal structure figure of Example 2. FIG. It is the rim | limb 500x optical metal structure figure of Example 2. FIG. It is the rim | limb 500x dyeing | staining metal structure figure of Example 2. FIG. FIG. 3 is a transmission electron microscope structure diagram of the rim of Example 2. FIG. 10 is a diagram illustrating a rim 100 × optical metal structure of Example 3. It is the rim | limb 500x optical metal structure figure of Example 3. FIG. 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 wear test of the wheel of Example 2, and a CL60 wheel. It is the surface deformation | transformation structure | tissue of the sample after the friction abrasion test of the wheel of Example 2, and a CL60 wheel.

  Table 2 shows the weight percentage of the chemical composition of the wheel steel in Examples 1, 2, and 3. In each of Examples 1, 2, and 3, electric furnace smelting was used, and after LF + RH refining vacuum degassing, a round billet with a diameter of 380 mm was directly continuously cast, and steel ingot cutting, heating and pressure rolling, heat treatment, and finishing were 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.

  The manufacturing method of a bainite steel wheel for high toughness railway transportation includes the following steps: an electric furnace steelmaking process, an LF furnace refining process, an RH vacuum treatment process, and a molten steel having a chemical composition as shown in Example 1 in Table 2; The wheel was formed through a round billet continuous casting process, a steel ingot cutting and rolling process, a heat treatment process, a 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 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 example is mainly a carbide-free bainite structure. Table 3 shows the mechanical performance of the wheel of this example. The consistency of the strength and toughness of the actual wheel is superior to the CL60 wheel.

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

  The manufacturing method of a bainite steel wheel for high toughness railway transportation includes the following steps: an electric furnace steelmaking process, an LF furnace refining process, an RH vacuum treatment process, and a molten steel having a chemical composition as shown in Example 2 in Table 2; The wheel was formed through a round billet continuous casting process, a steel ingot cutting and rolling process, a heat treatment process, a 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 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 example is mainly carbide-free bainite. Table 3 shows the mechanical performance of the wheel of this example. The consistency of the strength and toughness of the actual wheel is superior to the CL60 wheel.

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

  The manufacturing method of a bainite steel wheel for high toughness railway transportation includes the following steps: an electric furnace steelmaking process, an LF furnace refining process, an RH vacuum treatment process, and a molten steel having a chemical composition as shown in Example 3 in Table 2; The wheel was formed through a round billet continuous casting process, a steel ingot cutting and rolling process, a heat treatment process, a 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 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 wheel of this example. The consistency of the strength and toughness of the actual wheel is superior to the CL60 wheel.

Claims (10)

Bainitic steel wheels for high toughness railway transport, in 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: 0.20 to 1.00%, rare earth RE: 0.001 to 0.040%,
Including phosphorus P ≦ 0.020%, sulfur S ≦ 0.020%,
The balance is iron and inevitable residual elements,
A high-toughness bainite steel wheel for railway transportation, wherein 1.50% ≦ Si + Ni ≦ 2.50% and 2.00% ≦ Si + Mn ≦ 4.00%. The high toughness rail transport bainite steel wheels are in weight percent,
Carbon C: 0.15-0.25%, silicon Si: 1.20-1.80%, manganese Mn: 1.60-2.10%,
Nickel Ni: 0.20-0.80%, rare earth RE: 0.010-0.040%, phosphorus P ≦ 0.020%, sulfur S ≦ 0.020%,
The balance is iron and inevitable residual elements, and 1.50% ≦ Si + Ni ≦ 2.50% and 2.00% ≦ Si + Mn ≦ 4.00%. Bainite steel wheels for high toughness railway transportation. The high toughness rail transport bainite steel wheels are in weight percent,
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 The high-toughness bainite steel wheel for rail transport according to claim 1 or 2, wherein 0.008% is included and the balance is iron and inevitable residual elements.   The metal structure within 40 mm below the rim surface of the bainite steel wheel is a carbide-free bainite structure, that is, nanoscale lath-like supersaturated ferrite, and the middle of lath-like supersaturated ferrite is nanoscale thin film-like carbon-rich. The bainite steel wheel for high-toughness railway transportation according to claim 1 or 2, wherein the bainite steel wheel is a retained austenite, and a volume percentage of the retained austenite is 4% to 15%.   The microstructure of the wheel rim is a multiphase structure composed of supersaturated ferrite and carbon-rich retained austenite, the size thereof is nanoscale, and the nanoscale is 1 to 999 nm. A high-toughness bainite steel wheel for rail transport according to 1 or 2.   Including a smelting, refining, forming and heat treatment process, wherein the formed wheel is heated to an austenitizing temperature, the rim tread is tempered and cooled to 400 ° C. or less by water injection, and tempering is performed. The manufacturing method of the bainite steel wheel for high toughness railroad transportation as described in any one of Claims 1-5 characterized by the above-mentioned.   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. Steel wheel manufacturing method.   In the tempering treatment, the wheel is tempered at a low and 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 tempered and cooled to 400 ° C. or less by water jet and air-cooled to room temperature. In the meantime, self-tempering is performed by residual heat during the process, and the method for producing a bainite steel wheel for high-toughness railway transportation according to claim 6 or 7.   7. The heat treatment process according to claim 6, wherein the rim tread surface of the molded wheel is tempered and cooled to 400 ° C. or less by direct water injection by high-temperature residual heat after molding, and is tempered. A method of manufacturing high-toughness bainite steel wheels for rail transport.   The method for manufacturing a bainite steel wheel for high toughness railway transportation according to claim 6, wherein, in the heat treatment process, after the wheel is formed, the wheel is air-cooled to 400 ° C or lower and tempered.