WO2018001346A1

WO2018001346A1 - Low alloy cast steel, and smelting method and heat treatment thereof, and railway locomotive part of same

Info

Publication number: WO2018001346A1
Application number: PCT/CN2017/091007
Authority: WO
Inventors: 张俊新; 文超
Original assignee: 中车戚墅堰机车车辆工艺研究所有限公司
Priority date: 2016-06-30
Filing date: 2017-06-30
Publication date: 2018-01-04
Also published as: CN105908081A; CN105908081B

Abstract

A low alloy cast steel, and a smelting method and heat treatment thereof, and a railway locomotive part of same. The low alloy cast steel comprises the following components in the respective weight percentages: 0.19-0.25% of carbon, 0.30-0.50% of silicon, 0.90-1.15% of manganese, ≤ 0.030% of phosphorus, ≤ 0.030% of sulfur, 0.19-0.29% of chromium, 0.13-0.19% of molybdenum, 0.02-0.06% of aluminum, 0.02-0.10% of tungsten, and 0.01-0.05% of niobium, wherein 0.04% ≤ tungsten + niobium ≤ 0.12%; and a remainder of iron and other unavoidable elements. After heat treatment, the steel can be used as a Grade B+ steel.

Description

Low alloy cast steel and its smelting method, heat treatment method and railway locomotive parts

Technical field

The invention belongs to the technical field of alloy steel, and relates to a low alloy cast steel, in particular to a low alloy cast steel containing tungsten ruthenium, a smelting method and a heat treatment method of the low alloy cast steel, a B+ grade steel obtained after heat treatment, and Mainly applied to the railway locomotive parts prepared by the B+ grade steel.

Background technique

The American Railway Association (AAR) revised and released the M-201-05 standard in 2005 to meet the material requirements of cast parts such as the railway industry. The alloy cast steel was graded and classified as A grade steel. Grade B steel, B+ grade steel, C grade steel and E grade steel, and define their main chemical composition range and mechanical properties.

The American Railway Association (AAR) M-201-05 standard specifies B+ grade steel, which cannot be applied to the B+ grade performance by quenching and tempering heat treatment. At present, in the widely used B+ grade steel, in order to meet the mechanical performance requirements of B+ grade steel and not use quenching and tempering treatment, it is necessary to use chromium-nickel-molybdenum and chromium-nickel alloys and design blending alloy components, such as Chinese patent disclosure. No. B+ grade steel disclosed in the related patents of CN1995429A and CN101701325A. Therefore, in the current B+ grade steel, it is necessary to compound and add the more expensive alloying element nickel.

However, with the widespread use of nickel in the fields of stainless steel and heat-resistant steel, nickel resources are becoming increasingly scarce, and the cost of B+ grade steel is also increasing.

Summary of the invention

It is an object of the present invention to reduce the cost of low alloy cast steel and to enable it to at least meet the mechanical performance requirements of B+ grade steel.

To achieve the above object or other objects, the present invention provides the following technical solutions.

According to a first aspect of the invention, there is provided a low alloy cast steel, the components thereof and their weight percentage relative to the total weight of the low alloy cast steel are:

Carbon 0.19% to 0.25%, silicon 0.30% to 0.50%, manganese 0.90% to 1.15%, phosphorus ≤0.030%, sulfur ≤0.030%, chromium 0.19% to 0.29%, molybdenum 0.13% to 0.19%, aluminum 0.02% to 0.06 %, and 0.02% to 0.10% of tungsten, 铌0.01% to 0.05%, and must satisfy 0.04% ≤ tungsten + 铌 ≤ 0.12%; and the balance is iron and other unavoidable elements.

According to a second aspect of the present invention, there is provided a heat treatment method for the above low alloy cast steel, comprising the steps of:

Providing a steel casting of the low alloy cast steel;

The steel casting is subjected to normalizing treatment, wherein the normalizing treatment is: heating the steel casting to 900 ° C to 940 ° C for 3 to 6 hours, and then cooling the air to room temperature.

According to a third aspect of the present invention, there is provided a B+ grade steel obtained by treating the above low alloy cast steel by the above heat treatment method.

According to a fourth aspect of the present invention, there is provided a smelting method for the above low alloy cast steel, wherein the smelting is carried out by an electric arc furnace oxidation method, comprising the steps of:

Loading step: based on the component requirements, the corresponding charge is put into the electric arc furnace, wherein the furnace charge comprises ferromolybdenum and tungsten iron;

a melting step of melting the charge;

Oxidation period step: when the bath temperature is greater than or equal to 1560 ° C, iron ore is added to the electric arc furnace to decarburize, and dephosphorization operation is performed;

a reduction period step of: adding a ferrochrome alloy to the electric arc furnace, and comparing the result with a weight percentage of each chemical component of the low alloy cast steel according to the detection result of the sampling analysis chemical composition, to the electric arc furnace At least iron-iron alloy is added to the inside;

The tapping water step and the pouring step.

According to a fifth aspect of the invention, there is provided a railway locomotive component which is formed using the B+ grade steel described above.

In order to avoid or save the use of nickel, the low alloy cast steel of the invention adds the alloying elements tungsten and niobium, and selects the appropriate ratio, thereby effectively suppressing austenite grain growth during the casting process, and refining the crystal. Granules, while strengthening the matrix.

Moreover, after the low-alloy cast steel of the present invention is subjected to the normalizing heat treatment process of the present invention, the metallographic structure of the obtained low-alloy cast steel is mainly pearlite + ferrite, and the mechanical properties of the M-201 are AAR- The requirements of B+ grade steel in the 05 standard, the cost of B+ grade steel is greatly reduced. In addition, in terms of hardness (for example, it can fall within the range of 150 HBW to 180 HBW from the hardness index), it is particularly good; from the viewpoint of carbon equivalent, the carbon equivalent of the low alloy cast steel is lowered, and the weldability is improved; the tensile strength is improved. Performance indicators such as yield strength can also reflect the strengthening of the matrix of low alloy cast steel.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a photograph showing a metallographic structure of a low alloy cast steel obtained by a normalizing treatment in accordance with an embodiment of the present invention.

2 is a picture of a metallographic structure obtained by magnifying 500 times of a low alloy cast steel after normalizing treatment according to an embodiment of the present invention.

detailed description

The following is a description of some of the various possible embodiments of the invention, which are intended to provide a basic understanding of the invention and are not intended to identify key or critical elements of the invention or the scope of the invention. It is to be understood that, in accordance with the technical aspects of the present invention, those skilled in the art can suggest other alternatives that are interchangeable without departing from the spirit of the invention. Therefore, the following detailed description and the accompanying drawings are merely illustrative of the embodiments of the invention, and are not intended to

In the present application, "low alloy cast steel" refers to alloy steel with a alloying element content of less than 5% by weight in cast steel. B+ grade steel was revised and released in 2005 according to the American Railroad Association (AAR). The steel grade defined by the 201-05 standard for alloy steel classification.

The inventors of the present application have found that with the increase in the cost of raw materials required for the production of B+ grade steel, the industry has put forward higher requirements for controlling the cost of B+ grade steel, and is working to reduce the cost of B+ grade steel, but simply saves it. Or the use of expensive nickel components can not be obtained to meet the mechanical performance requirements of B+ grade steel (in the case where quenching and tempering is not required); the inventors of the present application also noted that the introduction of tungsten can be used for low alloy cast steel. The pearlite and bainite transformation have a great influence, which is beneficial to reduce the overheat sensitivity and strength of the cast steel.

In one embodiment of the present invention, the measurement of mechanical properties is carried out in accordance with the relevant provisions of the M-201-05 standard of AAR, and the sample used for the measurement of mechanical properties is a Kiel test block. The calculation formula of carbon equivalent CE is: CE=C+(Mn+Si)/6+(Cr+Mo+V)/5+(Ni+Cu)/15, among which some alloy elements in the above formula have May be an inevitable margin element.

The application provides the following technical solutions:

Technical Solution 1, a low alloy cast steel, wherein each component and its weight percentage relative to the total weight of the low alloy cast steel are:

Carbon 0.19% to 0.25%, silicon 0.30% to 0.50%, manganese 0.90% to 1.15%, phosphorus ≤0.030%, sulfur ≤0.030%, chromium 0.19% to 0.29%, molybdenum 0.13% to 0.19%, aluminum 0.02% 0.06%, and 0.02% to 0.10% of tungsten, 铌0.01% to 0.05%, and must satisfy 0.04% ≤ tungsten + 铌 ≤ 0.12%; and the balance is iron and other unavoidable elements.

The low-alloy cast steel according to claim 1, wherein the weight percentage of carbon is 0.20% to 0.24%, 0.21% to 0.24%, or 0.20% by weight relative to the total weight of the low alloy cast steel. 0.25%.

The low alloy cast steel according to any one of claims 1-2, wherein the weight percentage of silicon is 0.33% to 0.39%, or 0.36% to 0.47%, relative to the total weight of the low alloy cast steel. , or 0.33% to 0.45%, or 0.36% to 0.42%.

The low-alloy cast steel according to any one of claims 1 to 3, wherein the weight percentage of manganese is 0.91% to 1.14%, or 0.98% to 1.15%, relative to the total weight of the low alloy cast steel. , or 0.98% to 1.13%.

The low alloy cast steel according to any one of claims 1 to 4, wherein the weight percentage of phosphorus is ≤0.025% or ≤0.020% with respect to the total weight of the low alloy cast steel.

The low-alloy cast steel according to any one of claims 1 to 5, wherein the weight percentage of sulfur is ≤0.025%, or ≤0.020%, or ≤0.015%, relative to the total weight of the low alloy cast steel. .

The low alloy cast steel according to any one of claims 1 to 6, wherein the weight percentage of chromium is 0.20% to 0.29%, or 0.23% to 0.29%, relative to the total weight of the low alloy cast steel. , or 0.24% to 0.28%, or 0.24% to 0.29%.

The low-alloy cast steel according to any one of claims 1 to 7, wherein the weight percentage of molybdenum is 0.13% to 0.18%, or 0.14% to 0.18%, relative to the total weight of the low alloy cast steel. , or 0.15% to 0.18%.

The low alloy cast steel according to any one of claims 1 to 8, wherein the weight percentage of aluminum is 0.02% to 0.04%, or 0.03% to 0.05%, based on the total weight of the low alloy cast steel. .

The low-alloy cast steel according to any one of claims 1-9, wherein the weight percentage of bismuth is 0.02% to 0.04%, or 0.03% to 0.05%, relative to the total weight of the low alloy cast steel. .

The low-alloy cast steel according to any one of claims 1 to 10, wherein the weight percentage of tungsten is 0.02% to 0.09%, or 0.05% to 0.09%, relative to the total weight of the low alloy cast steel. .

The low-alloy cast steel according to any one of claims 1 to 11, wherein The carbon equivalent CE of the low alloy cast steel is between 0.45% and 0.62%, and the carbon equivalent CE is calculated according to the following formula:

CE=C+(Mn+Si)/6+(Cr+Mo+V)/5+(Ni+Cu)/15

Wherein C represents the weight percentage of carbon, Mn represents the weight percentage of manganese, Si represents the weight percentage of silicon, Cr represents the weight percentage of chromium, Mo represents the weight percentage of molybdenum, V represents the weight percentage of vanadium, and Ni represents the weight percentage of nickel. , Cu represents the weight percentage of copper.

The low alloy cast steel according to any one of claims 1 to 12, wherein the low alloy cast steel is a B+ grade steel obtained by normalizing.

The low-alloy cast steel according to claim 13, wherein the normalizing treatment is: heating the steel casting to 900 ° C to 940 ° C for 3 to 6 hours, and then cooling the air to room temperature.

The low-alloy cast steel according to claim 14, wherein the hardness ranges from 150 HBW to 180 HBW.

The method of heat treatment of a low alloy cast steel according to any one of claims 1 to 15, wherein the method comprises the steps of:

Providing a steel casting of the low alloy cast steel;

The heat treatment method according to claim 16, wherein after the heat treatment, the metallographic structure of the low alloy cast steel is mainly pearlite and ferrite.

The heat treatment method according to claim 16, wherein in the normalizing treatment step, the steel casting is heated to 920 ° C to 930 ° C for 4 to 5 hours, and then air-cooled to room temperature.

The invention provides a B+ grade steel obtained by treating the low alloy cast steel according to any one of claims 16 to 18 by the heat treatment method according to any one of claims 16 to 18.

The smelting method of the low-alloy cast steel according to any one of claims 1 to 12, wherein the smelting is performed by an electric arc furnace oxidation method, wherein the following steps are included:

a melting step of melting the charge;

a reduction period step of: adding a ferrochrome alloy to the electric arc furnace, and comparing the result to a weight percentage of a chemical composition of the low alloy cast steel according to a result of sampling and analyzing chemical composition, and following the low alloy The weight percentage of each chemical component of the cast steel is required to add at least the charge containing at least the strontium iron alloy to the electric arc furnace;

The tapping water step and the pouring step.

The smelting method according to claim 20, wherein in the charging step, the tungsten iron is of a grade of FeW75, wherein the weight percentage of W is 75%.

The smelting method according to claim 20, wherein in the melting step, the furnace material is melted and the slag is dephosphorized in advance, wherein when the charge is melted by 25% to 45%, the blowing is performed. Oxygen assists to accelerate the melting of the charge.

The smelting method according to claim 20 or 22, wherein, in the oxidizing period, after the decarburization, a large slag amount slag dephosphorization operation is performed.

The smelting method according to claim 23, wherein in the reducing step, the ferrochrome alloy is added after the formation of the thin slag, and then carbon powder or silicon carbide is added to the slag surface to form a reducing slag. After the reducing slag turns white, the sampling and analysis chemical composition operations are performed by stirring.

The smelting method according to claim 24, wherein in the reducing period step, based on the sampling analysis result and the comparison result, an aluminum block, a ferrosilicon alloy, a ferromanganese alloy, and the like are sequentially added as needed. Ferroalloy, including at least strontium iron alloy; of course, if it is not required, that is, if the sampling analysis indicates that a chemical component has satisfied the weight percentage requirement of the chemical composition of the low alloy cast steel, then it is not necessary to add The corresponding material containing the chemical composition.

The smelting method according to claim 20, wherein in the tapping step, when the bath temperature is in the range of 1620 to 1650 ° C, the chemical components are further sampled and analyzed, and after the components are qualified, the tapping water is performed. , steel slag mixed desulfurization operation.

Technical Solution 27, a railway locomotive component, wherein the B+ grade steel according to any one of claims 1-5 and 19 is prepared.

The railway locomotive component according to claim 27, wherein the railway locomotive component is a bolster or a side frame of the bogie, or has the same mechanical performance requirement. Other parts.

In the following examples, the component contents are all based on their weight percentage.

Example 1

In the tungsten-rhenium-containing low alloy cast steel of Example 1, the components and their weight percentages are as follows: carbon 0.24%, silicon 0.42%, manganese 1.13%, phosphorus 0.026%, sulfur 0.019%, chromium 0.26%, molybdenum 0.14%, aluminum 0.02%, tungsten 0.07%, 铌0.03%, of which tungsten + bismuth is 0.10%, the balance is iron and other unavoidable elements. Among them, the calculation formula of carbon equivalent CE is: CE=C+(Mn+Si)/6+(Cr+Mo+V)/5+(Ni+Cu)/15, in which some alloying elements in the formula are possible It is an inevitable margin element.

Based on the calculation formula of the above carbon equivalent, it is determined that the carbon equivalent in the low alloy cast steel of the embodiment 1 is specifically 0.58, which satisfies the carbon equivalent requirement of the B-grade steel of the M-201-05 standard of AAR, and therefore the weldability is good. .

The tungsten-rhenium-containing low alloy cast steel of Example 1 can be, but is not limited to, prepared by the smelting method exemplified below.

In an example, the smelting is performed by an electric arc furnace large slag oxidation method, which specifically includes the following steps:

I Charge: The base component is required to be put into the corresponding charge. Among them, a suitable amount of ferromolybdenum and tungsten iron is added to the furnace charge. The tungsten iron is specifically made of tungsten iron of the grade of FeW75, which represents the weight percentage of W. About 75%. The furnace charge generally includes, for example, scrap steel, high quality pig iron, iron alloy, recycled material, and the like.

II Melting period: The furnace material melting and slag dephosphorization treatment can be carried out at the maximum power matched by the electric arc furnace. When the charge is melted by 25% to 45%, the oxygen can be blown and the furnace charge can be accelerated.

III oxidation period: When the temperature of the molten pool is greater than or equal to 1560 ° C, the iron ore is decarburized. Under this temperature condition, the iron ore is relatively easy to decarburize; and the large slag slag dephosphorization operation is carried out.

IV reduction period: after the formation of the thin slag, adding the ferrochrome alloy, then adding carbon powder or adding silicon carbide on the surface of the slag to form the reducing slag; when the reducing slag is substantially turned into white, stirring, sampling and analyzing the chemical composition operation, and According to the results of the test report, in comparison with the chemical composition weight percentage requirement of the low alloy cast steel of the above Example 1, the pure aluminum block, the silicon, the ferromanganese alloy and the neodymium iron alloy are added in a controlled manner, at least including the neodymium iron alloy; If necessary, that is, if the sampling analysis indicates that a chemical component has satisfied the weight percentage requirement of each chemical component of the low alloy cast steel, it is not necessary to add a corresponding material containing the chemical component. In this embodiment, the addition of the strontium iron alloy in the reduction period step is avoided, the oxidation reaction of the bismuth in the molten steel is avoided earlier, the enthalpy loss is reduced, and the percentage content of the lanthanum element in the low alloy cast steel after formation is ensured. Corresponding effect.

V tapping: When the temperature of the molten pool is in the range of 1620～1650°C, the chemical composition operation is carried out by sampling and analyzing; after the composition is qualified, when the temperature reaches the tapping water temperature, the molten steel and steel slag are mixed and desulfurized.

VI casting: After the molten steel has completed the specified sedation time in the ladle, the casting is cast and cast.

After the smelting and casting of the low-alloy cast steel of the above Example 1 is obtained by the smelting method of the above example, the steel can be heat-treated to obtain a B+ grade steel having better performance. In this embodiment, the heat treatment process is normalized, and Avoid quenching and tempering after normalizing. Specifically, the normalizing treatment process is heated to 920 ° C for 4 hours, and then discharged to air cooling.

After the normalized fire treatment of the low alloy cast steel of the above embodiment 1, the metallographic structure obtained is mainly ferrite + pearlite, and the specific metallographic structure is shown in FIG. 1 and FIG. And Figure 2 shows a typical ferritic + pearlite metallographic morphology (where the dark gray black part is pearlite and the light gray part is ferrite), which avoids the appearance of bainite; and, the grain size Significantly refined, the uniformity of the structure is very good, because the tungsten and niobium in the low alloy cast steel can be combined to increase the austenite grain growth during the casting process, which is beneficial to refining the cast steel. The grain, the pearlite grains of the low alloy cast steel obtained after the normalizing treatment are also relatively fine. Moreover, the addition of tungsten and niobium in a certain weight percentage is beneficial to strengthening the matrix.

The mechanical properties of the low alloy cast steel of the above Example 1 (after the above normalizing heat treatment) were measured, and the following test results were obtained: tensile strength 597 MPa, yield strength 386 MPa, elongation 33%, and section shrinkage 49.5%, - Charpy V-type impact energy at 7 ° C (average value) 38 J, hardness 169 HBW.

It can be seen from the AAR-based M-201-05 standard that the low alloy cast steel based on the above Example 1 can obtain the mechanical performance requirements of the B+ grade steel meeting the American Railway Association standard M-201-05, and is particularly manifested in terms of hardness and strength. good.

Therefore, the low alloy cast steel of the above Example 1 is subjected to the normalizing heat treatment of the above example After that, it can be used as a B+ grade steel, and it performs well in terms of hardness, strength, and weldability; and, depending on the addition of nickel, the cost is greatly reduced.

Examples 2 to 10

Basically, in the same manner as in the first embodiment, the specific components and contents and carbon equivalents in the low-alloy cast steels of Examples 2 to 10 are shown in Table 1. The corresponding mechanical properties are shown in Table 2 below:

Table 1 Composition (% by weight) and carbon equivalent of the low alloy cast steel of Examples 2 to 10

Among them, the role of the alloying element aluminum is mainly used for deoxidation, and at the same time can achieve a certain degree of grain refining effect.

The low-alloy cast steel containing tungsten ruthenium of Examples 2 to 10 can be, but is not limited to, prepared by the smelting method exemplified above to obtain a corresponding steel casting.

After obtaining the steel castings by the smelting and casting of the low alloy cast steels of the above embodiments 2 to 10, the heat treatment can be performed to obtain the B+ grade steel with better performance. In this embodiment, the heat treatment process is normalized; in particular, positive In the fire treatment, the steel castings are usually heated to 900 ° C ~ 940 ° C for 3 to 6 hours, and then air cooled to room temperature. Further optimization of normalizing treatment, the steel castings can be heated to 920 ° C ~ 930 ° C for 4 to 5 hours.

After the normalizing treatment of the low alloy cast steels of the above Examples 2 to 10, the metallographic structure obtained is mainly pearlite + ferrite, and the specific metallographic structure is similar to that shown in Figs. 1 and 2.

The low alloy cast steel of the above Examples 2 to 10 (after the above heat treatment) was machined The mechanical properties were measured and the test results shown in Table 2 below were obtained:

Table 2 Mechanical properties of low alloy cast steel of Examples 2 to 10

It can be seen from the mechanical performance data of Table 2 above that the following mechanical performance indexes can be achieved: tensile strength ≥ 552 MPa, yield strength ≥ 345 MPa, elongation ≥ 24%, reduction in area ≥ 36%, and Charpy to -7 °C. The V-type impact energy is ≥21J, and the hardness ranges from 137HBW to 228HBW; in particular, the hardness ranges from 150HBW to 180HBW.

Therefore, the low alloy cast steel based on the above Examples 2 to 10 can obtain B+ grade steel satisfying the mechanical performance requirements of the B+ grade cast steel of the American Railway Association Standard M-201-05; and in terms of hardness (for example, from the hardness index) It can fall well in the range of 150HBW to 180HBW), especially in terms of carbon equivalent, the carbon equivalent of low alloy cast steel decreases, weldability is improved; performance indexes such as tensile strength and yield strength can also reflect low alloy casting. The matrix of the steel is strengthened.

Therefore, the low-alloy cast steels of the above Examples 1 to 10 can be used as B+ grade steel after the normalizing heat treatment of the above examples, and have superior weldability, good hardness and strength, and in particular, cost is large. reduce.

It should be noted that the low alloy cast steels of the above embodiments 1 to 10 can be used without being used. Nickel is used as an alloying element to obtain good mechanical properties. The main reason is that the alloying elements tungsten and rhenium are compounded and a suitable ratio (tungsten 0.02% to 0.10%, 铌0.01% to 0.05%, and must be satisfied) 0.04% ≤ tungsten + 铌 ≤ 0.12%), can effectively inhibit austenite grain growth during casting, refine grains, and strengthen the matrix; therefore, the low alloy cast steel in the embodiment of the present application After the normalized heat treatment process, the hardness of the low alloy cast steel is obviously improved compared with the traditional B+ grade steel, and the strength is high and the weldability is superior, and the overall mechanical performance requirements of the B+ grade steel are satisfied.

The low alloy cast steels of the above embodiments 1 to 10 can be used to prepare corresponding parts on a railway locomotive after normalizing, for example, key components in a bogie such as a bolster, a side frame, and the like. It should be understood that the specific application of the low alloy cast steel of the above embodiment is not limited to the above embodiment, and those skilled in the art can also use it for components on railway machines or other equipment having substantially the same mechanical performance requirements, such as wheels. core.

The above examples mainly illustrate the low alloy cast steel of the present invention, various smelting methods and heat treatment methods, B+ grade steel obtained after heat treatment, and applications thereof. Although only a few of the embodiments of the present invention have been described, it will be understood by those skilled in the art that the invention may be practiced in many other forms without departing from the spirit and scope of the invention. Accordingly, the present invention is to be construed as illustrative and not restrictive, and the invention may cover various modifications without departing from the spirit and scope of the invention as defined by the appended claims With replacement.

Claims

A low alloy cast steel characterized in that the weight percentage of each component and its total weight relative to the low alloy cast steel is:

Carbon 0.19% to 0.25%, silicon 0.30% to 0.50%, manganese 0.90% to 1.15%, phosphorus ≤0.030%, sulfur ≤0.030%, chromium 0.19% to 0.29%, molybdenum 0.13% to 0.19%, aluminum 0.02% to 0.06 %, and 0.02% to 0.10% of tungsten, 铌0.01% to 0.05%, and must satisfy 0.04% ≤ tungsten + 铌 ≤ 0.12%; and the balance is iron and other unavoidable elements.
The low alloy cast steel according to claim 1, wherein the weight percentage of carbon is from 0.21% to 0.24% based on the total weight of the low alloy cast steel.
The low alloy cast steel according to claim 1, wherein the weight percentage of silicon is from 0.33% to 0.39% with respect to the total weight of the low alloy cast steel.
The low alloy cast steel according to claim 1, wherein the weight percentage of manganese is from 0.91% to 1.14% with respect to the total weight of the low alloy cast steel.
The low alloy cast steel according to claim 1, wherein the weight percentage of chromium is from 0.23% to 0.29% with respect to the total weight of the low alloy cast steel.
The low alloy cast steel according to claim 1, wherein the weight percentage of molybdenum is from 0.14% to 0.18% with respect to the total weight of the low alloy cast steel.
The low alloy cast steel according to claim 1, wherein the weight percentage of aluminum is from 0.03% to 0.05% with respect to the total weight of the low alloy cast steel.
The low alloy cast steel according to claim 1, wherein the weight percentage of niobium is from 0.02% to 0.04% based on the total weight of the low alloy cast steel.
The low alloy cast steel according to claim 1, wherein the weight percentage of tungsten is 0.05% to 0.09% with respect to the total weight of the low alloy cast steel.
The low alloy cast steel according to claim 1, wherein said low alloy cast steel has a carbon equivalent CE of between 0.45% and 0.62%, and said carbon equivalent CE is calculated according to the following formula:

CE=C+(Mn+Si)/6+(Cr+Mo+V)/5+(Ni+Cu)/15

Wherein C represents the weight percentage of carbon, Mn represents the weight percentage of manganese, Si represents the weight percentage of silicon, Cr represents the weight percentage of chromium, Mo represents the weight percentage of molybdenum, V represents the weight percentage of vanadium, and Ni represents the weight percentage of nickel. , Cu represents the weight percentage of copper.
The low-alloy cast steel according to claim 1, wherein the low-alloy cast steel is a B+ grade steel obtained by normalizing.
The low-alloy cast steel according to claim 11, wherein the normalizing treatment is: heating the steel casting to 900 ° C to 940 ° C for 3 to 6 hours, and then cooling to room temperature.
The low alloy cast steel according to claim 12, which has at least one of the following mechanical properties: tensile strength ≥ 552 MPa, yield strength ≥ 345 MPa, and hardness ranging from 137 HBW to 228 HBW.
The low-alloy cast steel according to claim 13, which further has at least one of the following mechanical properties: elongation ≥ 24%, reduction in area ≥ 36%, and Charpy V-type impact at -7 ° C. Power ≥ 21J,
The low alloy cast steel according to claim 12, which has the following mechanical properties: a hardness ranging from 150 HBW to 180 HBW.
A method of heat-treating a low-alloy cast steel according to any one of claims 1 to 15, comprising the steps of:

Providing a steel casting of the low alloy cast steel;

The steel casting is subjected to normalizing treatment, wherein the normalizing treatment is: heating the steel casting to 900 ° C to 940 ° C for 3 to 6 hours, and then cooling the air to room temperature.
The heat treatment method according to claim 16, wherein after said heat treatment, said metallographic structure of said low alloy cast steel is mainly pearlite and ferrite.
The heat treatment method according to claim 16, wherein in the normalizing treatment step, the steel casting member is heated to 920 ° C to 930 ° C for 4 to 5 hours, and then air-cooled to room temperature.
A B+ grade steel obtained by treating the low alloy cast steel according to any one of claims 1 to 10 by the heat treatment method according to any one of claims 16 to 18.
A smelting method for a low-alloy cast steel according to any one of claims 1 to 10, wherein the smelting is carried out by an electric arc furnace oxidation method, characterized in that it comprises the following steps:

Loading step: based on the component requirements, the corresponding charge is put into the electric arc furnace, wherein the furnace charge comprises ferromolybdenum and tungsten iron;

a melting step of melting the charge;

Oxidation period step: when the bath temperature is greater than or equal to 1560 ° C, iron ore is added to the electric arc furnace to decarburize, and dephosphorization operation is performed;

a reduction period step of: adding a ferrochrome alloy to the electric arc furnace, and comparing the result with a weight percentage of each chemical component of the low alloy cast steel based on a result of sampling analysis according to a result of sampling analysis chemical composition operation, And adding a charge comprising at least a neodymium iron alloy to the electric arc furnace according to the weight percentage requirement of each chemical component of the low alloy cast steel;

The tapping water step and the pouring step.
A railway locomotive component, characterized in that it is formed by using B+ grade steel according to claim 19.
A railway locomotive component according to claim 21, wherein said railway locomotive component is a bolster or side frame of a bogie or other component having equivalent mechanical performance requirements.