High-tungsten steel and preparation method thereof

Abstract

The invention discloses high-tungsten steel and a preparation method thereof. The method comprises the steps that converter molten steel with the tapping temperature ranging from 1620 DEG C to 1670 DEG C is provided, argon blowing is carried out in the whole process of transferring the converter molten steel from a converter to an LF furnace through a steel ladle for tapping, 40 wt.%-80 wt.% of ferrotungsten alloy is added into the steel ladle in the tapping process, ferrotungsten alloying pretreatment is carried out on the converter molten steel, and first molten steel is obtained; the first molten steel is subjected to LF refining treatment, and 20 wt.%-60 wt.% of ferrotungsten alloy is added into the first molten steel for ferrotungsten alloying treatment; adding a nickel-iron alloy and a molybdenum-iron alloy in at least one process of transferring the converter molten steel from the converter to a steel ladle, transferring the converter molten steel from the steel ladle to an LF furnace and carrying out LF refining treatment on the first molten steel to obtain LF refined molten steel; the LF refined molten steel is subjected to RH vacuum treatment, and RH refined molten steel is obtained; and the RH refined molten steel is subjected to continuous casting, and the high-tungsten steel is obtained. According to the preparation method of the high-tungsten steel, tungsten and iron can be rapidly alloyed, and the tungsten content in the high-tungsten steel can be accurately controlled.

Description

Technical Field

[0001] The present application belongs to the technical field of high-tungsten steel smelting, and in particular relates to a high-tungsten steel and a preparation method thereof. Background Art

[0002] Metal tungsten plays a major role in solid solution strengthening, precipitation strengthening and dispersion strengthening in steel. It can effectively improve the strength, hardness, wear resistance and high temperature performance of alloy materials, and is used in various steels with special requirements. Common tungsten-containing steels include high-speed tool steel, alloy structural steel, spring steel, heat-resistant steel and stainless steel. Tungsten is an element with stable characteristics, with a high melting point and a high specific gravity (the melting point of pure tungsten is 3410±10℃, and the specific gravity is 19.3g / cm 3 ), common alloys are 70% ferrotungsten and 80% ferrotungsten. During the smelting process, ferrotungsten alloy is difficult to melt. There are usually two ways to alloy ferrotungsten: one is to add it together with other alloys in the middle and late stages of steelmaking in a converter or electric furnace. This process requires the steelmaking temperature to be increased by 20℃~30℃, which causes serious erosion of the furnace body refractory materials, and the ferrotungsten yield rate is unstable. It is difficult to accurately control the tungsten content of the finished tungsten steel product. Excessive addition of ferrotungsten alloy will also cause the ladle's air permeability to deteriorate. In severe cases, it is necessary to replace the ladle with good air permeability and reprocess it (i.e., invert the ladle), which will affect the time and efficiency of tungsten steel smelting and is not suitable for steels with high tungsten content. The other is to add ferrotungsten in small batches in the LF furnace. After each batch of ferrotungsten is added, argon stirring needs to be increased for a long time. This process increases the smelting time and increases power consumption. It is not conducive to the control of inclusions and causes serious erosion of the ladle refractory materials.

[0003] In order to solve the above technical problems, it is urgent to provide a new smelting method of high tungsten steel. Summary of the invention

[0004] The embodiment of the present application provides a method for preparing high-tungsten steel, which can quickly alloy tungsten iron and accurately control the tungsten content in the high-tungsten steel.

[0005] In a first aspect, the present application provides a method for preparing high-tungsten steel, comprising: providing molten steel from a converter, making the tapping temperature of the molten steel from the converter be 1620° C. to 1670° C., blowing argon throughout the process of transferring the molten steel from the converter to an LF furnace via a ladle for tapping, and adding 40wt.% to 80wt.% of tungsten-iron alloy to the ladle during the tapping process to perform tungsten-iron alloy pretreatment on the molten steel from the converter to obtain a first molten steel;

[0006] The first molten steel is subjected to LF refining treatment, and during the LF refining treatment, 20wt.% to 60wt.% of tungsten-iron alloy is added to the first molten steel to perform tungsten-iron alloying treatment on the first molten steel, and nickel-iron alloy and molybdenum-iron alloy are added during at least any one of the processes of transferring the molten steel from the converter to the ladle, transferring the molten steel from the ladle to the LF furnace, and refining treatment of the first molten steel in the LF furnace, and aluminum is added for deoxidation treatment to obtain LF refined molten steel;

[0007] Performing RH vacuum treatment on LF refined molten steel to obtain RH refined molten steel;

[0008] RH refined molten steel is continuously cast to obtain high tungsten steel. The chemical components of the high tungsten steel are as follows, by mass percentage: C: 0.07%-0.13%, Si: 0.2%-0.5%, Mn: 0.3%-0.6%, P≤0.02%, S≤0.01%, Alt≤0.02%, Cr: 8.5%-9.5%, W: 1.5%-2.0%, Mo: 0.3%-0.6%, V: 0.15%-0.25%, Ni: 0.1%-0.4%, Nb: 0.04%-0.09%, N: 0.03%-0.07%, B: 0.001%-0.006%, and the remainder is iron and other inevitable impurities.

[0009] According to an embodiment of the first aspect of the present application, providing converter steel comprises: providing molten iron; performing converter smelting on the molten iron to obtain converter steel, wherein the main components are, by mass percentage, C≤0.05%, Si: 0.02%-0.2%, Mn: 0.1%-0.2%, P: ≤0.015%, Alt: 0.02%-0.05%, W: 0.8%-1.3%, Mo: 0.2%-0.5%, Ni: 0.05%-0.15%, and the remainder is iron and other inevitable impurities.

[0010] According to the embodiment of the first aspect of the present application, argon is blown throughout the process of transferring the molten steel from the converter to the LF furnace via the ladle for tapping, and the flow rate of argon is 35Nm 3 / h~50Nm 3 / h.

[0011] According to the embodiment of the first aspect of the present application, the time for LF refining treatment of the first molten steel is 60 minutes to 140 minutes, and the temperature of the molten steel before tungsten-iron alloying is ≥1620°C.

[0012] According to the embodiment of the first aspect of the present application, during the LF refining process of the first molten steel, 20wt.% to 60wt.% of tungsten-iron alloy is added to perform tungsten-iron alloying treatment, and the first molten steel is heated to 45Nm 3 / h~60Nm3 / h of argon gas for strong stirring, and the stirring time is 10min to 50min.

[0013] According to an embodiment of the first aspect of the present application, the RH vacuum treatment of the LF refined steel liquid includes: performing the RH vacuum treatment on the LF refined steel liquid under the condition of blowing nitrogen, and the flow rate of the nitrogen is 150Nm 3 / h~230Nm 3 / h, and the RH vacuum treatment time is 25min~60min.

[0014] According to an embodiment of the first aspect of the present application, the tungsten-iron alloy satisfies the following chemical composition: W ≥ 70%, S ≤ 0.05%, P ≤ 0.06%, and C ≤ 0.8%.

[0015] According to an embodiment of the first aspect of the present application, the nickel-iron alloy satisfies the following chemical composition: Ni≥45%, Si≤14%, S≤0.6%, P≤0.1%, and C≤0.4%.

[0016] According to an embodiment of the first aspect of the present application, the molybdenum-iron alloy satisfies the following chemical composition: Mo ≥ 60%, Si ≤ 2.0%, S ≤ 0.15%, P ≤ 0.05%, C ≤ 0.15%, and Cu ≤ 1.0%.

[0017] In the second aspect, the present application provides a high tungsten steel, the chemical composition of the high tungsten steel is: in mass percentage, C: 0.07% ~ 0.13%, Si: 0.2% ~ 0.5%, Mn: 0.3% ~ 0.6%, P ≤ 0.02%, S ≤ 0.01%, Alt ≤ 0.02%, Cr: 8.5% ~ 9.5%, W: 1.5% ~ 2.0%, Mo: 0.3% ~ 0.6%, V: 0.15% ~ 0.25%, Ni: 0.1% ~ 0.4%, Nb: 0.04% ~ 0.09%, N: 0.03% ~ 0.07%, B: 0.001% ~ 0.006%, the remainder is iron and other inevitable impurities.

[0018] The preparation method of high-tungsten steel in the embodiment of the present application is to perform tungsten-iron alloying pretreatment by adding tungsten-iron alloy accounting for 40wt.% to 80wt.% of the total amount of tungsten-iron alloy added during the process of transferring the converter molten steel from the converter to the LF furnace via the ladle for steel tapping, and adding the remaining amount of tungsten-iron alloy to the obtained first molten steel during the LF refining treatment in the LF furnace for tungsten-iron alloying treatment, so that the tungsten content in the high-tungsten steel can be accurately and quickly controlled, and the tungsten iron yield rate can be high and stable; and nickel-iron alloy and molybdenum-iron alloy are added in at least any one of the processes of transferring the converter molten steel from the converter to the ladle, transferring the converter molten steel from the ladle to the LF furnace, and performing LF refining treatment on the first molten steel, and aluminum is added for deoxidation treatment to obtain LF refined molten steel; RH vacuum treatment is performed on the LF refined molten steel to obtain RH refined molten steel, and the RH refined molten steel is continuously cast to obtain high-tungsten steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 It is a schematic flow chart of a method for preparing high tungsten steel provided in one embodiment of the present application. DETAILED DESCRIPTION

[0021] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than to limit the present application. For those skilled in the art, the present application can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by illustrating the examples of the present application.

[0022] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0023] In order to solve the problems in the prior art, the present application provides a high-tungsten steel and a preparation method thereof. The preparation method of the high-tungsten steel provided in the present application is first introduced below.

[0024] Figure 1 The figure shows a schematic flow chart of a method for preparing high tungsten steel provided in one embodiment of the present application. Figure 1 As shown, the preparation method of high tungsten steel comprises:

[0025] S1, providing converter molten steel, making the tapping temperature of the converter molten steel be 1620° C. to 1670° C., transferring the converter molten steel from the converter to the LF furnace via the ladle for tapping with argon blowing throughout the process, and adding tungsten-iron alloy accounting for 40wt.% to 80wt.% of the total amount of tungsten-iron alloy into the ladle during the tapping process to perform tungsten-iron alloy pretreatment on the converter molten steel, to obtain the first molten steel;

[0026] S2, performing LF refining treatment on the first molten steel, adding 20wt.% to 60wt.% of tungsten-iron alloy to the first molten steel during the LF refining treatment to perform tungsten-iron alloying treatment on the first molten steel, and adding nickel-iron alloy and molybdenum-iron alloy in at least any one of the processes of transferring the molten steel from the converter to the ladle, transferring the molten steel from the ladle to the LF furnace, and performing LF refining treatment on the first molten steel, and adding aluminum for deoxidation treatment to obtain LF refined molten steel;

[0027] S3, performing RH vacuum treatment on the LF refined molten steel to obtain RH refined molten steel;

[0028] S4. RH refined molten steel is continuously cast to obtain high tungsten steel. The chemical components of the high tungsten steel are as follows: in percentage by mass, C: 0.07%-0.13%, Si: 0.2%-0.5%, Mn: 0.3%-0.6%, P≤0.02%, S≤0.01%, Alt≤0.02%, Cr: 8.5%-9.5%, W: 1.5%-2.0%, Mo: 0.3%-0.6%, V: 0.15%-0.25%, Ni: 0.1%-0.4%, Nb: 0.04%-0.09%, N: 0.03%-0.07%, B: 0.001%-0.006%, and the remainder is iron and other inevitable impurities.

[0029] The preparation method of high-tungsten steel in the embodiment of the present application is to perform tungsten-iron alloying pretreatment by adding tungsten-iron alloy accounting for 40wt.% to 80wt.% of the total amount of tungsten-iron alloy added during the process of transferring the converter molten steel from the converter to the LF furnace via the ladle for steel tapping, and adding the remaining amount of tungsten-iron alloy to the obtained first molten steel during the LF refining treatment in the LF furnace to perform tungsten-iron alloying treatment on the first molten steel, so that the tungsten content in the high-tungsten steel can be accurately and quickly controlled, and the tungsten iron yield rate can be high and stable; and nickel-iron alloy and molybdenum-iron alloy are added in at least any one of the processes of transferring the converter molten steel from the converter to the ladle, transferring the converter molten steel from the ladle to the LF furnace, and performing LF refining treatment on the first molten steel, and aluminum is added for deoxidation treatment to obtain LF refined molten steel; RH vacuum treatment is performed on the LF refined molten steel to obtain RH refined molten steel, and the RH refined molten steel is continuously cast to obtain high-tungsten steel.

[0030] In an embodiment of the present application, 40wt.% to 80wt.% of tungsten-ferroalloy can be added to the ladle during the process of transferring the molten steel from the converter to the middle ladle, or 40wt.% to 80wt.% of tungsten-ferroalloy can be added during the process of transferring the molten steel from the middle ladle to the LF furnace for refining treatment, so as to utilize the higher temperature of the molten steel in the converter to melt the tungsten-ferroalloy, and utilize the impact momentum during the transfer of the molten steel in the converter to fully disperse the tungsten-ferroalloy, and perform tungsten-ferroalloy pretreatment on the molten steel in the converter, and the remaining tungsten-ferroalloy is added to the LF furnace during the LF refining treatment, and the first molten steel is completely tungsten-ferroalloyed, so that the tungsten-ferroalloy is quickly alloyed in the molten steel, thereby increasing the tungsten content and hit rate of the molten steel. Illustratively, 45wt.%, 50wt.%, 54wt.%, 57wt.%, 60wt.%, 63wt.%, 66wt.%, 70wt.%, 72wt.%, 75wt.%, 78wt.% of tungsten-iron alloy may be added first.

[0031] In some embodiments, it is preferred to first add 40wt.% to 80wt.% of tungsten-iron alloy into the middle ladle during the process of transferring the molten steel from the converter to the middle ladle, so as to utilize the impact momentum of the molten steel in the converter with a higher temperature and the molten steel in the process, as well as the impact momentum of the molten steel in the process of transferring the molten steel from the middle ladle to the LF furnace to fully disperse the tungsten-iron alloy to pre-treat the molten steel in the converter with tungsten-iron alloy.

[0032] Optionally, in some embodiments, 40wt.% to 80wt.% of tungsten-iron alloy can be added to the middle ladle in the process of transferring the converter steel from the converter to the steel that accounts for 1 / 10 to 9 / 10 of the volume of the middle ladle, or 40wt.% to 80wt.% of tungsten-iron alloy can be added to the LF furnace in the process of transferring the converter steel from the middle ladle to the first steel LF furnace that accounts for 1 / 10 to 7 / 10 of the total amount of molten steel allowed by the LF furnace, so as to pre-treat the converter steel with tungsten-iron alloying, disperse the tungsten-iron alloy in the converter steel, and obtain the first molten steel with preliminary tungsten-iron alloying. Exemplarily, 40wt.% to 80wt.% of tungsten-iron alloy can be added to the process of transferring the converter steel that accounts for 1 / 10 to 3 / 10, 1 / 10 to 2 / 5, 1 / 10 to 3 / 5, 1 / 10 to 7 / 10 of the volume of the middle ladle to the middle ladle.

[0033] In the embodiments of the present application, in at least any one of the processes of transferring the molten steel from the converter to the ladle, transferring the molten steel from the ladle to the LF furnace, and performing LF refining on the first molten steel, adding nickel-iron alloy and ferromolybdenum alloy, and adding aluminum for deoxidation treatment, it means that the nickel-iron alloy and ferromolybdenum alloy can be added to the ladle during the process of transferring the molten steel from the converter to the middle ladle, and aluminum can be added for deoxidation treatment; the nickel-iron alloy and ferromolybdenum alloy can also be added during the process of transferring the molten steel from the middle ladle to the LF furnace, and aluminum can be added for deoxidation treatment; or the nickel-iron alloy and ferromolybdenum alloy can be added during the process of performing LF refining on the first molten steel, and aluminum can be added for deoxidation treatment. Or the nickel-iron alloy and ferromolybdenum alloy can be added in batches during any two or three of the three processes, and aluminum can be added for deoxidation treatment.

[0034] In some embodiments of the present application, providing converter steel comprises: providing molten iron; performing converter smelting on the molten iron to obtain converter steel, wherein the main components of the converter steel are, by mass percentage, C≤0.05%, Si: 0.02%-0.2%, Mn: 0.1%-0.2%, P: ≤0.015%, Alt: 0.02%-0.05%, W: 0.8%-1.3%, Mo: 0.2%-0.5%, Ni: 0.05%-0.15%, and the remainder is iron and other unavoidable impurities. It should be noted that the molten iron referred to in the present application refers to ordinary smelting molten iron, which is suitable for preparing steel of all types of steel before tungsten-iron alloying.

[0035] In the embodiments of the present application, the converter used for converter smelting is a basic oxygen furnace (BOF furnace), which is the English name of a basic oxygen steelmaking furnace.

[0036] The preparation method of high tungsten steel in the embodiment of the present application has the advantages of short smelting time and low power consumption through the process route of converter smelting, LF refining treatment, RH vacuum treatment, and conventional continuous casting. There is no need to increase the melting time of tungsten-iron alloy, so that the tungsten-iron yield reaches and stabilizes at 90% to 98%, solving the problems of difficult melting of tungsten-iron alloy, long smelting time, high refining power consumption, and unstable yield.

[0037] The preparation method of high-tungsten steel in the embodiment of the present application has a simple preparation process, does not require the addition of new smelting equipment, and does not require the increase of the steel-out temperature. The improvement of the smelting process can reduce the damage to the furnace body refractory material, and solve the problem of serious erosion of the converter body refractory material. At the same time, the tungsten iron alloy is added in two stages during the process of transferring the converter molten steel from the converter to the LF furnace via the ladle and during the LF refining treatment of the first molten steel, which can avoid the problem of poor ladle permeability and poor argon blowing caused by excessive addition of tungsten iron, and also avoid the technical problem of difficult control of inclusions caused by adding tungsten iron in small batches, resulting in poor cleanliness of the molten steel, and achieve stable control of the tungsten content of high-tungsten steel.

[0038] In some embodiments of the present application, argon is blown throughout the process of transferring the molten steel from the converter to the LF furnace via the ladle for tapping, and the argon flow rate is 35 Nm 3 / h~50Nm 3 / h. In the embodiment of the present application, the whole process of blowing argon can prevent other gases or impurities from entering the molten steel during the process of adding tungsten-iron alloy for tungsten-iron alloying pretreatment in the converter steel, so as to maintain the cleanliness of the molten steel. At the same time, the argon flow can drive the flow of the molten steel surface and promote the dispersion of tungsten-iron alloy.

[0039] In some embodiments of the present application, the first molten steel is subjected to LF refining treatment for 60 min to 140 min, and the temperature of the molten steel before tungsten-iron alloying is ≥1620° C. In the embodiments of the present application, the first molten steel is subjected to LF refining treatment for 60 min to 140 min while maintaining the temperature of the molten steel ≥1620° C. before complete tungsten-iron alloying, so that the excess tungsten-iron alloy can be fully dispersed.

[0040] In some embodiments of the present application, during the LF refining process of the first molten steel, 20 wt.% to 60 wt.% of tungsten-iron alloy is added to perform tungsten-iron alloying treatment, and the first molten steel is heated to 45 Nm 3 / h~60Nm 3 / h of argon gas for strong stirring, and the stirring time is 10min to 50min. In the embodiment of the present application, the remaining amount of ferrotungsten alloy can be added to the molten steel by overhead crane, and is subjected to strong stirring treatment with argon gas of limited flow rate, and the strong stirring treatment time is greater than 10 minutes, so that the ferrotungsten alloy is fully melted and dispersed, the tungsten content of the tungsten steel is increased, the chemical composition of the high tungsten steel is ensured to meet the requirements, and the yield of ferrotungsten is thereby increased.

[0041] In some embodiments of the present application, the ferrotungsten alloy satisfies the following chemical composition: W ≥ 70%, S ≤ 0.05%, P ≤ 0.06%, C ≤ 0.8%. In the embodiments of the present application, the ferrotungsten alloy is added to the converter molten steel or the first molten steel in the form of a mixture of blocks and particles, so the present application does not explicitly limit the size of the blocks or particles.

[0042] In some embodiments of the present application, the nickel-iron alloy satisfies the following chemical composition: Ni≥45%, Si≤14%, S≤0.6%, P≤0.1%, and C≤0.4%.

[0043] In some embodiments of the present application, the molybdenum-iron alloy satisfies the following chemical composition: Mo ≥ 60%, Si ≤ 2.0%, S ≤ 0.15%, P ≤ 0.05%, C ≤ 0.15%, and Cu ≤ 1.0%.

[0044] In the embodiments of the present application, the addition amounts of ferrotungsten alloy, ferronickel alloy and ferromolybdenum alloy can be calculated according to the composition and volume of the converter molten steel and the yield, so that the composition of the high tungsten steel meets the required content range.

[0045] In some embodiments of the present application, the RH vacuum treatment of the LF refined steel liquid includes: performing the RH vacuum treatment on the LF refined steel liquid under the condition of blowing nitrogen, and the flow rate of the nitrogen is 150Nm 3 / h~230Nm 3 / h, the RH vacuum treatment time is 25min~60min, and the vacuum degree of RH vacuum treatment is 500Pa~1500Pa.

[0046] The preparation method of high tungsten steel in the embodiment of the present application mainly uses BOF furnace, LF refining furnace, overhead crane, RH refining furnace, and conventional continuous casting machine, which respectively correspond to the converter smelting, LF refining treatment, RH refining treatment, and continuous casting steps, wherein the overhead crane is used to add tungsten iron alloy, nickel iron alloy, and molybdenum iron alloy, as well as the transfer of molten steel and the addition of other materials during the smelting process. After the RH refined molten steel is continuously cast to obtain a continuous casting slab, the slab is stored.

[0047] In an embodiment of the present application, nickel-iron alloy, molybdenum-iron alloy and aluminum are added for deoxidation treatment in at least any one of the processes of transferring molten steel from the converter to the ladle, transferring molten steel from the ladle to the LF furnace and subjecting the first molten steel to LF refining treatment in the LF furnace, so that the steel composition of the high-tungsten steel meets the required range, and the molten steel is deoxidized by adding metallic aluminum as a deoxidizer to reduce the oxygen content in the tungsten steel molten steel to the required range.

[0048] The preparation method of high-tungsten steel in the embodiment of the present application can achieve stable control of the material content of high-tungsten steel, provide technical guarantee for the research and development of high-tungsten steel, and also point out the direction for the optimization and cost reduction of high-tungsten steel.

[0049] The high tungsten steel prepared by the preparation method of the high tungsten steel of the embodiment of the present application has the following chemical components by mass percentage: C: 0.07% to 0.13%, Si: 0.2% to 0.5%, Mn: 0.3% to 0.6%, P≤0.02%, S≤0.01%, Alt≤0.02%, Cr: 8.5% to 9.5%, W: 1.5% to 2.0%, Mo: 0.3% to 0.6%, V: 0.15% to 0.25%, Ni: 0.1% to 0.4%, Nb: 0.04% to 0.09%, N: 0.03% to 0.07%, B: 0.001% to 0.006%, and the remainder is iron and other unavoidable impurities. Among them, high tungsten steel refers to tungsten steel with a tungsten content of more than 1.5%.

[0050] The technical solution of the present application is further described below through specific examples and comparative examples. The following are the composition requirements or available sources of the raw materials used in Examples 1-2 and Comparative Examples 1-3 of the present application.

[0051] Tungsten-iron alloy, with the composition satisfying: W ≥ 70%, S ≤ 0.05%, P ≤ 0.06%, C ≤ 0.8%, and the product model is: FeW70; purchased from Jiangxi Nanxin Tungsten-Molybdenum Technology Co., Ltd.; nickel-iron alloy, with the composition satisfying: Ni ≥ 45%, Si ≤ 14%, S ≤ 0.6%, P ≤ 0.1%, C ≤ 0.4%, and the product model is: FeNi45; purchased from Jiangsu Jiangnan Ferroalloy Co., Ltd.; molybdenum-iron alloy, with the composition satisfying: Mo ≥ 60%, Si ≤ 2.0%, S ≤ 0.15%, P ≤ 0.05%, C ≤ 0.15%, Cu ≤ 1.0%, and the product model is: FeMo60; purchased from Luoyang Luanchuan Molybdenum Industry Group Sales Co., Ltd.

[0052] Example 1

[0053] A high tungsten steel, steel grade: GC401 1A1, its chemical composition is: in mass percentage, C: 0.07% ~ 0.13%, Si: 0.2% ~ 0.5%, Mn: 0.3% ~ 0.6%, P ≤ 0.02%, S ≤ 0.01%, Alt ≤ 0.02%, Cr: 8.5% ~ 9.5%, W: 1.5% ~ 2.0%, Mo: 0.3% ~ 0.6%, V: 0.15% ~ 0.25%, Ni: 0.1% ~ 0.4%, Nb: 0.04% ~ 0.09%, N: 0.03% ~ 0.07%, B: 0.001% ~ 0.006%, the balance is iron and other inevitable impurities.

[0054] This embodiment provides a method for preparing the above-mentioned high-tungsten steel, including:

[0055] S1. Provide 206 tons of converter steel liquid, which meets the following composition: C: 0.037%, Si: 0.095%, Mn: 0.163%, P: 0.009%, Alt: 0.038%, W: 1.176%, Mo: 0.365%, Ni: 0.078%, and the balance is iron and other inevitable impurities; make the tapping temperature of the converter steel liquid 1624℃, and blow argon during the whole process of transferring the converter steel liquid from the converter to the LF furnace via the ladle for tapping, wherein the ladle capacity is 210 tons and the argon flow rate is 35Nm 3 / h, and in the process of tapping, 3050kg of ferro-tungsten alloy, 1200kg of ferro-molybdenum alloy, 100kg of ferro-nickel alloy and 306kg of aluminum block for deoxidation accounting for 60.04% of the total amount of ferro-tungsten alloy added are added into the ladle to perform ferro-tungsten alloy pretreatment on the converter molten steel to obtain the first molten steel;

[0056] S2, LF refining treatment is performed on the first molten steel. The total time of LF refining treatment is 122min. During the LF refining treatment of the first molten steel, 2030kg of tungsten-iron alloy accounting for 39.96% of the total amount of tungsten-iron alloy added is added to the first molten steel by overhead crane to perform tungsten-iron alloying treatment on the first molten steel. The flow rate of 53Nm2 is blown into the first molten steel. 3 / h argon gas was used for strong stirring for 12 minutes, the ladle was well blown with argon, the temperature of the first molten steel before tungsten-iron alloying treatment was 1628°C, and LF refined molten steel was obtained;

[0057] S3, LF refined steel liquid was subjected to RH vacuum treatment at a vacuum degree of 656Pa for 28min, and the nitrogen flow rate was 160Nm 3 / h, to obtain RH refined molten steel;

[0058] S4. RH refined molten steel is continuously cast to obtain high tungsten steel. The chemical composition of high tungsten steel is as follows: by mass percentage, C: 0.108%, Si: 0.273%, Mn: 0.432%, P: 0.018%, S: 0.005%, Alt: 0.018%, Cr: 8.985%, W: 1.641%, Mo: 0.361%, V: 0.212%, Ni: 0.138%, Nb: 0.059%, N: 0.037%, B: 0.002%, and the balance is iron and other inevitable impurities. The yield of tungsten iron in tungsten iron alloy in high tungsten steel is 96.1%.

[0059] Example 2

[0060] High tungsten steel grade: GC401 1A1, its chemical composition is the same as that of Example 1. The preparation method of high tungsten steel comprises:

[0061] S1. Provide 209 tons of converter steel liquid, which meets the following composition: C: 0.029%, Si: 0.129%, Mn: 0.146%, P: 0.012%, Alt: 0.043%, W: 1.035%, Mo: 0.383%, Ni: 0.082%, and the balance is iron and other inevitable impurities; make the tapping temperature of the converter steel liquid 1632℃, and blow argon during the whole process of transferring the converter steel liquid from the converter to the LF furnace via the ladle for tapping, wherein the ladle capacity is 210 tons, and the argon gas flow rate is 40Nm 3 / h, and in the process of tapping, 3102kg of ferro-tungsten alloy, 1210kg of ferro-molybdenum alloy, 108kg of ferro-nickel alloy, and 298kg of aluminum block for deoxidation accounting for 60.56% of the total amount of ferro-tungsten alloy added are added into the ladle to perform ferro-tungsten alloy pretreatment on the converter molten steel to obtain the first molten steel;

[0062] S2, LF refining treatment is performed on the first molten steel. The total time of LF refining treatment is 136min. During the LF refining treatment of the first molten steel, 2020kg of tungsten-iron alloy accounting for 39.44% of the total amount of tungsten-iron alloy added is added to the first molten steel by overhead crane to perform tungsten-iron alloying treatment on the first molten steel. The flow rate of blowing into the first molten steel is 58Nm 3 / h argon gas was used for strong stirring for 10 minutes, the ladle was well blown with argon, the temperature of the first molten steel before tungsten-iron alloying treatment was 1623°C, and LF refined molten steel was obtained;

[0063] S3, LF refined steel liquid was subjected to RH vacuum treatment at a vacuum degree of 631Pa for 26min, and the nitrogen flow rate was 180Nm 3 / h, to obtain RH refined molten steel;

[0064] S4. RH refined molten steel is continuously cast to obtain high tungsten steel. The chemical composition of high tungsten steel is as follows: by mass percentage, C: 0.112%, Si: 0.263%, Mn: 0.425%, P: 0.014%, S: 0.006%, Alt: 0.012%, Cr: 8.658%, W: 1.613%, Mo: 0.379%, V: 0.197%, Ni: 0.125%, Nb: 0.054%, N: 0.035%, B: 0.002%, and the balance is iron and other inevitable impurities. The yield of tungsten iron in tungsten iron alloy in high tungsten steel is 94.75%.

[0065] Example 3

[0066] High tungsten steel grade: GC4011A1, its chemical composition is the same as that of Example 1. The preparation method of high tungsten steel comprises:

[0067] S1. Provide 209 tons of converter steel liquid, which meets the following composition: C: 0.027%, Si: 0.119%, Mn: 0.136%, P: 0.010%, Alt: 0.035%, W: 1.125%, Mo: 0.380%, Ni: 0.071%, and the balance is iron and other inevitable impurities; make the tapping temperature of the converter steel liquid 1636℃, and blow argon during the whole process of transferring the converter steel liquid from the converter to the LF furnace via the ladle for tapping, wherein the ladle capacity is 210 tons and the argon flow rate is 42Nm 3 / h, and in the process of tapping, 3329.3kg of ferro-tungsten alloy, 1210kg of ferro-molybdenum alloy, 108kg of ferro-nickel alloy, and 298kg of aluminum block for deoxidation accounting for 65.00% of the total amount of ferro-tungsten alloy added are added into the ladle to perform ferro-tungsten alloying pretreatment on the converter molten steel to obtain the first molten steel;

[0068] S2, LF refining treatment is performed on the first molten steel. The total time of LF refining treatment is 134min. During the LF refining treatment of the first molten steel, 1792.7kg of tungsten-iron alloy accounting for 35% of the total amount of tungsten-iron alloy added is added to the first molten steel by overhead crane to perform tungsten-iron alloying treatment on the first molten steel. The flow rate of blowing into the first molten steel is 54Nm 3 / h argon gas was used for strong stirring for 10 minutes, the ladle was well blown with argon, the temperature of the first molten steel before tungsten-iron alloying treatment was 1628°C, and LF refined molten steel was obtained;

[0069] S3, LF refined steel liquid was subjected to RH vacuum treatment at a vacuum degree of 631Pa for 27min, and the nitrogen flow rate was 180Nm 3 / h, to obtain RH refined molten steel;

[0070] S4. RH refined molten steel is continuously cast to obtain high tungsten steel. The chemical composition of high tungsten steel is as follows: by mass percentage, C: 0.110%, Si: 0.235%, Mn: 0.452%, P: 0.012%, S: 0.007%, Alt: 0.011%, Cr: 8.578%, W: 1.643%, Mo: 0.396%, V: 0.187%, Ni: 0.151%, Nb: 0.055%, N: 0.035%, B: 0.002%, and the balance is iron and other inevitable impurities. The yield of tungsten iron in tungsten iron alloy in high tungsten steel is 97.72%.

[0071] Example 4

[0072] High tungsten steel grade: GC4011A1, its chemical composition is the same as that of Example 1. The preparation method of high tungsten steel comprises:

[0073] S1. Provide 207 tons of converter steel liquid, which meets the following composition: C: 0.027%, Si: 0.138%, Mn: 0.152%, P: 0.011%, Alt: 0.037%, W: 1.175%, Mo: 0.397%, Ni: 0.093%, and the balance is iron and other inevitable impurities; make the tapping temperature of the converter steel liquid 1640℃, and blow argon during the whole process of transferring the converter steel liquid from the converter to the LF furnace via the ladle for tapping, wherein the ladle capacity is 210 tons and the argon flow rate is 45Nm 3 / h, and in the process of tapping, 3585.4kg of ferro-tungsten alloy, 1210kg of ferro-molybdenum alloy, 108kg of ferro-nickel alloy, and 298kg of aluminum block for deoxidation accounting for 70% of the total amount of ferro-tungsten alloy added are added into the ladle to perform ferro-tungsten alloying pretreatment on the converter molten steel to obtain the first molten steel;

[0074] S2, LF refining treatment is performed on the first molten steel. The total time of LF refining treatment is 130min. During the LF refining treatment of the first molten steel, 1536.6kg of tungsten-iron alloy accounting for 30% of the total amount of tungsten-iron alloy added is added to the first molten steel by overhead crane to perform tungsten-iron alloying treatment on the first molten steel. The flow rate of blowing into the first molten steel is 59Nm 3 / h of argon gas for 10 minutes of strong stirring, the ladle argon blowing is good, the temperature of the first molten steel before tungsten-iron alloying treatment is 1630℃, and LF refined molten steel is obtained;

[0075] S3, LF refined steel liquid was subjected to RH vacuum treatment at a vacuum degree of 631Pa for 26min, and the nitrogen flow rate was 180Nm 3 / h, to obtain RH refined molten steel;

[0076] S4. RH refined molten steel is continuously cast to obtain high tungsten steel. The chemical composition of high tungsten steel is as follows: by mass percentage, C: 0.109%, Si: 0.292%, Mn: 0.375%, P: 0.016%, S: 0.005%, Alt: 0.015%, Cr: 8.674%, W: 1.649%, Mo: 0.368%, V: 0.201%, Ni: 0.131%, Nb: 0.062%, N: 0.038%, B: 0.003%, and the balance is iron and other inevitable impurities. The yield of tungsten iron in tungsten iron alloy in high tungsten steel is 97%.

[0077] Comparative Example 1

[0078] High tungsten steel grade: GC4011A1, its chemical composition is the same as that of Example 1, the ladle capacity is 210t, the molten steel weight is 207t, the smelting process is converter smelting → LF refining → RH vacuum treatment → conventional continuous casting, and the smelting method of tungsten iron alloying is:

[0079] (1) After the raw materials are smelted in the converter, the tapping temperature is 1678°C. Argon is blown throughout the tapping process, and the argon flow rate is 32Nm 3 / h, 5096kg of tungsten-iron alloy, 1200kg of molybdenum-iron alloy, 103kg of nickel-iron alloy and 302kg of aluminum block for deoxidation were added during alloying, and alloying of other elements was carried out in LF furnace;

[0080] (2) After the LF refined steel liquid entered the station, the argon blowing effect of the ladle bottom was not good, and the argon blowing of the ladle bottom was poor. After 35 minutes of smelting, the argon blowing of the ladle bottom gradually returned to normal. After sampling and testing, the W content in the steel was only 1.06wt%, which did not meet the high tungsten steel component requirements, and the tungsten iron alloy yield was only 62.22%. After repeated power supply, heating and stirring, the sample was taken again, and the W content was 1.51wt%, which met the product component requirements, and the tungsten iron alloy yield was 88.64%; the total smelting time of LF refining treatment was 196min, the tungsten iron melting time was relatively long, and the tungsten iron yield was low and unstable;

[0081] (3) Nitrogen is used throughout the RH vacuum treatment process, with a nitrogen flow rate of 175 Nm 3 / h, minimum vacuum degree 589Pa, processing time 29min;

[0082] (4) Continuous casting is performed by normal casting using a conventional slab continuous casting machine.

[0083] The smelting method of Comparative Example 1 was adopted. Although no additional smelting equipment was added, the tapping temperature of the converter increased by 43°C. The higher the temperature, the greater the erosion of the converter body and the ladle refractory. After the tungsten-iron alloy was added to the ladle, the ladle bottom blowing effect was not good, and the argon blowing of the LF station was poor, which seriously affected the smelting time of the LF furnace. The longer the molten steel was smelted in the LF furnace, the higher the power consumption and the higher the refining power consumption cost. Tungsten-iron alloy is difficult to melt quickly, the yield is low and fluctuates greatly, and the W component is difficult to control stably and accurately.

[0084] Comparative Example 2

[0085] High tungsten steel grade: GC401 1A1, composition is the same as in Example 1, ladle capacity is 210t, molten steel weight is 208t, smelting process is converter smelting → LF refining → RH vacuum treatment → conventional continuous casting, tungsten iron alloying smelting method is:

[0086] (1) After the raw materials are smelted in the converter, the tapping temperature is 1628°C. Argon is blown throughout the tapping process, and the argon flow rate is 36Nm 3 / h, 1185kg of ferromolybdenum alloy, 105kg of ferronickel alloy and 295kg of aluminum block for deoxidation were added during alloying, and alloying of other elements was carried out in LF furnace;

[0087] (2) After the LF refined steel was introduced into the station, the argon blowing at the bottom of the ladle was good. After the temperature of the steel was raised to 1625°C, tungsten-iron alloy was added in three batches (each batch took 10 min to 15 min) through an overhead crane. The total amount of tungsten-iron alloy was 5060 kg. After the steel was stirred for 20 min, the W content was sampled and tested to be 1.58 wt%. The total smelting time of the LF refining process was 175 min, and the yield of tungsten-iron alloy was 93.86%.

[0088] (3) Nitrogen is used throughout the RH vacuum treatment process, with a nitrogen flow rate of 165Nm3 / h, minimum vacuum degree 593Pa, processing time 26min;

[0089] (4) Continuous casting is performed by normal casting using a conventional slab continuous casting machine.

[0090] By adopting the smelting method of Comparative Example 2, although no additional smelting equipment is added and the steel-tapping temperature of the converter is not increased, all the tungsten-iron alloy is added in batches in the LF furnace, which increases the addition time of the tungsten-iron alloy and the strong stirring time, and prolongs the smelting time of the LF furnace. The power consumption of the LF furnace increases accordingly over a long time, and the power consumption cost increases accordingly; by comparison, the yield of tungsten-iron alloy by this smelting method is also low.

[0091] Comparative Example 3

[0092] High tungsten steel grade: GC401 1A1, its chemical composition is the same as that of Example 1, the ladle capacity is 210t, the molten steel weight is 203t, the smelting process is converter smelting → LF refining → RH vacuum treatment → conventional continuous casting, and the smelting method of tungsten iron alloying is:

[0093] (1) After the raw materials are smelted in the converter, the tapping temperature is 1628°C. Argon is blown throughout the tapping process, and the argon flow rate is 35Nm 3 / h, 302kg of aluminum block for deoxidation is added during alloying, and alloying of other elements is carried out in LF furnace;

[0094] (2) Before the LF refined molten steel enters the station, 4990 kg of ferro-tungsten alloy, 1180 kg of ferro-molybdenum alloy, and 100 kg of ferro-nickel alloy are baked in a ladle at a temperature of 850° C. for 2.5 h. After the molten steel enters the station, the temperature of the molten steel is raised to 1620° C. The baked alloy is added to the molten steel by an overhead crane. After stirring for 20 min, the temperature is measured and sampled. The composition of the molten steel meets the requirements of high-tungsten steel. The W content in the steel is 1.59 wt %, the ferro-tungsten alloy yield is 93.47%, and the total smelting time of the LF refining process is 142 min.

[0095] (3) Nitrogen is used throughout the RH vacuum treatment process, with a nitrogen flow rate of 175 Nm 3 / h, minimum vacuum degree 618Pa, processing time 26min;

[0096] (4) Continuous casting is performed by normal casting using a conventional slab continuous casting machine.

[0097] The smelting method of comparative example 3 does not increase the tapping temperature of the converter and has little effect on the smelting time of the LF furnace. The argon blowing effect of the ladle is good, but the alloy needs to be baked with an additional ladle, which increases the smelting equipment and gas consumption.

[0098] Some process parameters and test results of Examples 1-2 and Comparative Examples 1-3 are recorded in Table 1 for comparison:

[0099] Table 1

[0100]

[0101] It can be concluded from Table 1 that the preparation method of high tungsten steel of the embodiment of the present application can not only effectively shorten the time of tungsten iron alloying, but also make the tungsten content in the high tungsten steel reach the required content quickly and stably, and the tungsten content is above 1.5wt.%, and the yield of tungsten iron alloy is as high as 94.75% to 97.72%, that is, the yield of tungsten iron is stable at more than 94%. Compared with the comparative example 1, which uses high-temperature molten steel to melt tungsten iron alloy and its yield is unstable, the comparative example 2 uses a small amount of tungsten iron alloy added in batches to increase the LF furnace smelting time, and the comparative example 3 needs to use an additional ladle to bake the alloy to increase the smelting equipment and gas consumption, the preparation method of high tungsten steel in the present application, without increasing the smelting equipment and the smelting temperature, reduces the corrosion of the furnace body refractory material through process improvement, effectively overcomes the above-mentioned defects, saves smelting time, and enables the tungsten content of high tungsten steel to reach the required content quickly and stably.

[0102] The above is only a specific implementation method of the present application. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. It should be understood that the protection scope of the present application is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application.

Claims

1. A method for preparing high tungsten steel, characterized in that: include: Provide molten steel from a converter, so that the tapping temperature of the molten steel from the converter is 1620° C. to 1670° C., blow argon throughout the process of transferring the molten steel from the converter to an LF furnace via a ladle for tapping, and add 40wt.% to 80wt.% of tungsten-iron alloy to the ladle during the tapping process to perform tungsten-iron alloy pretreatment on the molten steel from the converter to obtain a first molten steel; The first molten steel is subjected to LF refining treatment, and during the LF refining treatment of the first molten steel, 20wt.% to 60wt.% of tungsten-iron alloy is added to the first molten steel to perform tungsten-iron alloying treatment on the first molten steel; and nickel-iron alloy and molybdenum-iron alloy are added during at least any one of the processes of transferring the molten steel from the converter to the ladle, transferring the molten steel from the ladle to the LF furnace, and performing LF refining treatment on the first molten steel, and aluminum is added for deoxidation treatment to obtain LF refined molten steel; Performing RH vacuum treatment on LF refined molten steel to obtain RH refined molten steel; RH refined molten steel is continuously cast to obtain high tungsten steel. The chemical components of the high tungsten steel are as follows, by mass percentage: C: 0.07%-0.13%, Si: 0.2%-0.5%, Mn: 0.3%-0.6%, P≤0.02%, S≤0.01%, Alt≤0.02%, Cr: 8.5%-9.5%, W: 1.5%-2.0%, Mo: 0.3%-0.6%, V: 0.15%-0.25%, Ni: 0.1%-0.4%, Nb: 0.04%-0.09%, N: 0.03%-0.07%, B: 0.001%-0.006%, and the remainder is iron and other inevitable impurities.

2. The preparation method according to claim 1, characterized in that: The providing of converter molten steel comprises: Provide molten iron; The molten iron is subjected to converter smelting to obtain converter molten steel, whose main components are, by mass percentage, C≤0.05%, Si: 0.02%-0.2%, Mn: 0.1%-0.2%, P: ≤0.015%, Alt: 0.02%-0.05%, W: 0.8%-1.3%, Mo: 0.2%-0.5%, Ni: 0.05%-0.15%, and the remainder is iron and other inevitable impurities.

3. The preparation method according to claim 1, characterized in that: During the whole process of transferring the converter steel liquid from the converter to the LF furnace via the ladle for tapping, argon was blown, and the flow rate of argon was 35Nm 3 / h~50Nm 3 / h.

4. The preparation method according to claim 1, characterized in that: The time for the LF refining treatment of the first molten steel is 60 minutes to 140 minutes, and the temperature of the molten steel before tungsten-iron alloying is ≥1620°C.

5. The preparation method according to claim 1, characterized in that: In the process of LF refining treatment of the first molten steel, 20wt.% to 60wt.% of tungsten-iron alloy is added to perform tungsten-iron alloying treatment, and the first molten steel is heated to 45Nm 3 / h~60Nm 3 / h of argon gas for strong stirring, and the stirring time is 10min to 50min.

6. The preparation method according to claim 1, characterized in that: The RH vacuum treatment of the LF refined steel liquid comprises: performing the RH vacuum treatment on the LF refined steel liquid under the condition of blowing nitrogen, the flow rate of the nitrogen being 150 Nm 3 / h~230Nm 3 / h, and the RH vacuum treatment time is 25min~60min.

7. The preparation method according to claim 1, characterized in that: The tungsten-iron alloy satisfies the following chemical composition: W≥70%, S≤0.05%, P≤0.06%, and C≤0.8%.

8. The preparation method according to claim 1, characterized in that: The nickel-iron alloy satisfies the following chemical composition: Ni≥45%, Si≤14%, S≤0.6%, P≤0.1%, and C≤0.4%.

9. The preparation method according to claim 1, characterized in that: The ferromolybdenum alloy satisfies the following chemical composition: Mo≥60%, Si≤2.0%, S≤0.15%, P≤0.05%, C≤0.15%, and Cu≤1.0%.

10. A high tungsten steel, characterized in that: According to the preparation method according to any one of claims 1 to 9, the chemical components of the high tungsten steel are: in mass percentage, C: 0.07% to 0.13%, Si: 0.2% to 0.5%, Mn: 0.3% to 0.6%, P≤0.02%, S≤0.01%, Alt≤0.02%, Cr: 8.5% to 9.5%, W: 1.5% to 2.0%, Mo: 0.3% to 0.6%, V: 0.15% to 0.25%, Ni: 0.1% to 0.4%, Nb: 0.04% to 0.09%, N: 0.03% to 0.07%, B: 0.001% to 0.006%, and the balance is iron and other inevitable impurities.

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