CN112575146A - Smelting process and application of 42CrMo4 steel - Google Patents
Smelting process and application of 42CrMo4 steel Download PDFInfo
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- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0025—Adding carbon material
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
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- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
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- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
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- C22C33/04—Making ferrous alloys by melting
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Abstract
The invention relates to a smelting process and application of 42CrMo4 steel for large-scale shaft forgings, wherein the process comprises the following steps: (1) the bottom of the furnace is primed by lime, the target value of the end point carbon is controlled to be more than or equal to 0.03 percent, the target value of the phosphorus is controlled to be less than or equal to 0.008 percent, the tapping temperature is controlled to be more than or equal to 1630 percent, and C is more than or equal to 0.20 percent in the first sample in the refining stage; tapping in the smelting stage is strictly forbidden to discharge slag, and the tapping materials are added in the following sequence: carburant, deoxidizer, ferroalloy and slag charge; (2) transferring the molten steel to a refining furnace, and adding Si and C powder; the white slag retention time is not less than 30 minutes; adjusting slag before ladle discharge, and feeding Al and Ca-Si wires into molten steel; (3) and transferring the molten steel to a vacuum refining furnace, blowing protective gas after the vacuum is broken, and finally pouring under the protective atmosphere. The invention adopts the step-by-step refining process of the smelting stage, the refining stage and the vacuum refining stage, improves the purity of the 42CrMo4 steel, and provides an important basis for developing high-quality steel.
Description
Technical Field
The invention relates to the field of Cr-Mo alloy smelting methods, in particular to a smelting process and application of 42CrMo4 steel for large-scale shaft forgings.
Background
The following in the background art merely refers to information that is understood by the inventor to be relevant to the present invention and is intended to augment understanding of the present invention through a description of some basic technical knowledge related to the present invention, which information does not necessarily have to constitute knowledge that is well known by those of ordinary skill in the art.
With the development of science and technology and the progress of society, the development of clean non-fossil energy becomes the key research field of the 21 st century. In particular, wind energy is a renewable energy with huge reserves, is safe, clean and abundant, and can provide an energy source with unstable source. The method has the advantages of greatly developing wind energy resources, and playing an important role in improving the energy structure of China, protecting the ecological environment and realizing the sustainable development of economy.
The 42CrMo4 steel is used as ultrahigh-strength steel with high strength, high toughness and excellent hardenability, and is widely applied to the field of materials for main shafts of fans. In recent years, with the continuous development of metal smelting process, the refining process of 42CrMo steel is deeply developed along with the increase of demand, and the prior art discloses some process methods for smelting 42CrMo steel, for example, Chinese patent document with publication number CN111321273A proposes a method for accurately controlling the alkalinity of 42CrMo steel refining slag, wherein aluminum particles are added for diffusion deoxidation after a ladle is operated to an LF furnace, lime premelting refining slag is added, and iron, ferromolybdenum, ferrosilicon, ferromanganese and the like are added after white slag is formed to control the alkalinity of the 42CrMo steel refining slag. For another example, chinese patent publication No. CN106244899A proposes an energy-saving 42CrMo smelting process, which improves the heat utilization rate of the furnace by simplifying the process steps, thereby achieving the effects of energy saving, environmental protection, and energy saving.
It can be seen that the prior art improves the smelting process of the steel for the main shaft of the blower mainly from the aspects of reducing the slag content in the 42CrMo smelting process, reducing the energy consumption in the smelting process and the like. However, the inventors believe that: impurity components in molten steel, including S, P and various oxide inclusions, are easy to generate serious segregation in the solidification process of the molten steel, and cause serious influence on the comprehensive mechanical properties of steel, such as welding performance, impact toughness, cold and hot brittleness and the like, and the content of harmful elements in the molten steel needs to be strictly controlled within the requirement range of high-quality steel.
In particular, the difficulty in smelting 42CrMo4 steel is that the S content is high, and a water gap is easily blocked in the casting process, so that the method for improving the purity of the steel is a fundamental solution.
Disclosure of Invention
Aiming at the problems, the invention provides a smelting process of 42CrMo4 steel and application thereof, and the process adopts a step-by-step refining process of a smelting stage, a refining stage and a vacuum refining stage, successfully improves the purity of the 42CrMo4 steel and provides an important basis for developing high-quality steel. In order to realize the purpose, the invention discloses the following technical scheme:
in a first aspect of the invention, a 42CrMo4 steel smelting process is provided, which comprises the following steps:
(1) a smelting stage: the bottom of the furnace is bottomed by lime, the target value of the end point carbon is controlled to be more than or equal to 0.03 percent, the target value of the phosphorus is controlled to be less than or equal to 0.008 percent, the tapping temperature is controlled to be more than or equal to 1630 ℃, and the C of the first sample entering the next refining stage is more than or equal to 0.20 percent so as to ensure that the later stage does not carry out large recarburization; tapping in the smelting stage is strictly forbidden to discharge slag, and the tapping materials are added in the following sequence: the alloy steel comprises a recarburizing agent, a deoxidizing agent, an iron alloy and slag charge, wherein the deoxidizing agent is Al powder.
(2) And (3) refining: transferring the molten steel in the step (1) to a refining furnace, and adding Si and C powder; the white slag retention time is not less than 30 minutes; and (3) adjusting the slag before tapping to ensure that the molten steel has proper alkalinity and good fluidity, and feeding Al wires and Ca-Si wires into the molten steel before entering the next VD vacuum refining stage.
(3) And (3) vacuum refining: and (3) transferring the molten steel obtained in the step (2) to a vacuum refining furnace, blowing protective gas after the vacuum is broken, and finally pouring in the protective gas atmosphere to obtain the steel.
Further, in the step (1), the recarburizer comprises at least one of wood carbons, coal carbons, coke carbons, graphite and the like, the recarburizer is added after graphitization, carbon atom arrangement is in a graphite microscopic form under the high-temperature condition, graphitization can reduce the content of impurities in the recarburizer, the carbon content of the recarburizer is improved, and the sulfur content is reduced, so that a better recarburization effect is achieved.
Further, in the step (1), the iron alloy comprises at least one of silicon-carbon alloy, silicon-calcium-manganese alloy and the like, and the iron alloy has the functions of removing oxygen in molten steel in the smelting process, and adding alloy elements into the steel according to the component requirements of the steel to improve the performance of the steel, such as manganese content and silicon content.
Further, in the step (1), the slag includes lime (CaO) and fluorite (CaF)2) Etc., the main functions of the slag are dephosphorization and desulfurization: after lime with large porosity and small volume density is added into the converter, slag in the converter can rapidly permeate into the converter along the pores and cracks of the lime, so that the contact area between the slag and the lime is remarkably increased; fluorite (CaF)2) Added into the furnace to react with lime (CaO)The melting of lime is directly promoted, and 2CaO & SiO can be remarkably reduced2Melting point of (C) so that the slag has a lower melting temperature at high basicity, fluorite (CaF)2) And simultaneously, the viscosity of the alkaline slag can be reduced. Preferably, the addition proportion of the slag charge is 14-16 kg/ton.
Further, in the step (1), the deoxidizer comprises at least one of silicon-aluminum-barium-calcium-iron, silicon-calcium core-spun yarn, aluminum wire and the like, and mainly has the main function of reacting with oxygen dissolved in molten steel to mainly generate a non-metallic compound, and the formed precipitate floats to a slag layer so as to remove slag. Preferably, the addition ratio of the deoxidizer is 0.8 to 1.2 kg/ton.
Further, in the step (2), the adding proportion of the Si powder is 1-5 kg/ton, and the adding proportion of the C powder is 1-5 kg/ton.
Further, in the step (2), the addition ratio of the Al wire and the Ca-Si wire is 3 m/ton.
Further, in step (2), the slag is adjusted at least 5 minutes from the ladle.
Further, in the step (3), the vacuum degree in the vacuum refining furnace is less than or equal to 66.7Pa, and the holding time is more than or equal to 18 minutes; and soft blowing Ar gas for 10-25 minutes after the air is broken.
Further, in the step (3), the casting temperature is 1545-1555 ℃, and the casting is carried out under the protection of Ar gas to prevent molten steel from being oxidized.
In a second aspect of the invention, the application of the 42CrMo4 steel smelting process in the preparation of products such as wind power main shafts, large gears for locomotive traction, transmission gears of superchargers, deep well drill rod joints and the like is disclosed.
Compared with the prior art, the invention has the beneficial effects that:
(1) in the refining stage, the invention finds that when the white slag is kept for not less than thirty minutes, the mass transfer process of nonmetallic inclusions can be remarkably promoted, more inclusions are promoted to be adsorbed, the white slag can have good deoxidation and desulfurization effects after being formed, oxygen in molten steel under the white slag is diffused to slag, and the white slag is easy to separate from the molten steel to float upwards, so that the molten steel purification effect is achieved.
(2) Compared with the traditional smelting process of 42CrMo4 steel, the invention adds Si powder and C powder in the refining stage, and can convert free oxygen in the steel into oxides as early as possible by the measure, thereby providing more time for floating removal of the inclusion and removing the inclusion as much as possible.
(3) Compared with the traditional smelting process of 42CrMo4 steel, the method adopts the process of feeding Ca-Si wires and Al wires in the refining stage, and by the measures, on one hand, S in the molten steel is converted into CaS inclusions to carry out molten steel, on the other hand, the generated aluminum oxide can effectively reduce the oxygen content in the molten steel, and the purity of the molten steel is further improved under the dual effects of the two deoxidizers.
(4) In the vacuum refining stage, the measures of keeping the soft blowing protective gas in the vacuum state can effectively promote the full gathering and floating of the inclusions in the steel, and further improve the purity of the molten steel.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 is a flow chart of a smelting process of 42CrMo4 steel in an embodiment of the invention.
FIG. 2 is a diagram showing the effect of the first embodiment of the invention on the blank of the fan spindle after the 42CrMo4 steel is cast.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed.
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out according to conventional conditions or according to conditions recommended by the manufacturers.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The reagents or starting materials used in the present invention can be purchased from conventional sources, and unless otherwise specified, the reagents or starting materials used in the present invention can be used in a conventional manner in the art or in accordance with the product specifications.
In addition, any methods and materials similar or equivalent to those described herein can be used in the methods of the present invention. The preferred methods and materials described herein are exemplary only, and the invention will now be further described with reference to specific embodiments.
The present invention relates to terms in heat treatment of iron-carbon alloys, and the terms are explained for the convenience of the skilled person to understand the present invention, but the contents of the explanations do not necessarily constitute the common general knowledge in the field, and specifically include:
the term "EBT electric arc furnace": the steel tapping groove of the traditional electric furnace is changed into a steel tapping box, and a steel tapping hole is vertically downward at the bottom of the steel tapping box. The lower part of the steel-tapping hole is provided with a steel-tapping hole opening and closing mechanism for opening and closing the steel-tapping hole, and the center of the top of the steel-tapping box is provided with an operating hole for facilitating the filling operation and maintenance of the steel-tapping hole
The term "LF ladle refining furnace: the method is used for refining molten steel melted in a primary smelting furnace, can adjust the temperature of the molten steel, performs process buffering, and is important metallurgical equipment meeting the requirements of continuous casting and continuous rolling.
The term "VD ladle refining furnace": the refining furnace utilizes the five-stage steam jet pump to work, so that the working vacuum degree of a vacuum chamber reaches below 67Pa, and the refining purpose is achieved through the action of negative pressure.
The term "white slag": the term "white slag" refers to slag formed during diffusion deoxidation in the reduction phase of electric arc furnace steelmaking.
The term "basicity": the mark of the free oxygen ion concentration in the slag is an index for representing the chemical property of the slag and is one of important bases for determining the slagging system of the blast furnace.
The term "purity": the quantity, the form and the distribution of non-metallic inclusions in molten steel are important factors influencing the quality of steel.
The chemical composition of 42CrMo4 steel for the following examples is designed as shown in table 1:
TABLE 1
First embodiment
A smelting process of 42CrMo4 steel for large shaft forgings comprises the following steps:
(1) the smelting process of the EBT electric arc furnace comprises the following steps: high-quality scrap steel is selected as a material; 1000kg of furnace bottom lime; the target value of the end point carbon is controlled to be 0.03 percent, and the target value of the phosphorus is controlled to be 0.008 percent; controlling the tapping temperature at 1630 ℃; the content of C in the first sample in the LF furnace is more than or equal to 0.20 percent so as to ensure that a large amount of recarburization is not generated in the later period; the EBT steel tapping is strictly forbidden to carry out slag tapping; the steel ladle is well baked, and the air permeability is normal; adding tapping materials in sequence: carburant (graphite powder added with the proportion of 1Kg \ T), deoxidizer (Al added with the proportion of 1 Kg/T), iron alloy (silicon-calcium-manganese added with the proportion of 1.1 Kg/T) and slag charge (lime added with the proportion of 15 Kg/T).
(2) The LF ladle refining furnace smelting process comprises the following steps: driving a ladle car carrying the ladle obtained in the step (1) to a heating station of an LF furnace, measuring the temperature of molten steel to be 1560 ℃, and adding Si and C powder (the adding proportion is 1.5Kg/T respectively) to strengthen deoxidation; the white slag retention time is 30 minutes; slag is adjusted 5 minutes before ladle discharging, so that the molten steel has certain alkalinity and good fluidity; before the ladle enters a VD furnace, an Al wire (the adding proportion is 3 m/T) and a Ca-Si wire (the adding proportion is 3 m/T) are fed into the molten steel, S in the molten steel is converted into CaS inclusion to carry out molten steel, and meanwhile, the oxygen content in the molten steel is effectively reduced.
(3) The VD ladle refining furnace smelting process comprises the following steps: transferring the molten steel obtained in the step (2) to a VD furnace, setting the vacuum degree to be 66.7Pa, and keeping the vacuum degree for 18 minutes; soft blowing Ar gas for 15 minutes after air breaking;
(4) the casting process comprises the following steps: and after refining in the VD furnace is finished, adjusting the pouring temperature of the molten steel to 1545 ℃, adopting Ar gas for protection pouring, and cooling to obtain a 42CrMo4 steel ingot, wherein the obtained effect diagram of the fan main shaft blank is shown in figure 1.
The chemical composition of the 42CrMo4 steel obtained in the first example is shown in Table 2:
TABLE 2
First comparative example
A smelting process of 42CrMo4 steel for large shaft forgings comprises the following steps:
(1) the smelting process of the EBT electric arc furnace comprises the following steps: high-quality scrap steel is selected as a material; 1000kg of furnace bottom lime; the target value of the end point carbon is controlled to be 0.03 percent, and the target value of the phosphorus is controlled to be 0.008 percent; controlling the tapping temperature at 1630 ℃; the content of C in the first sample in the LF furnace is more than or equal to 0.20 percent so as to ensure that a large amount of recarburization is not generated in the later period; the EBT steel tapping is strictly forbidden to carry out slag tapping; the steel ladle is well baked, and the air permeability is normal; adding tapping materials in sequence: carburant (graphite powder added with the proportion of 1 Kg/T), deoxidizer (Al added with the proportion of 1 Kg/T), iron alloy (silicon-calcium-manganese added with the proportion of 1.1 Kg/T) and slag charge (lime added with the proportion of 15 Kg/T).
(2) The LF ladle refining furnace smelting process comprises the following steps: driving a ladle car carrying the ladle obtained in the step (1) to an LF furnace heating station, measuring the temperature of molten steel to be 1560 ℃, and adding Si and C powder (the adding proportion is 1.5Kg \ T respectively) to strengthen deoxidation; the white slag retention time is reduced by 5 minutes to 25 minutes compared with the first embodiment; slag is adjusted 5 minutes before ladle discharging, so that the molten steel has certain alkalinity and good fluidity; before the ladle enters a VD furnace, an Al wire (the adding proportion is 3 m/T) and a Ca-Si wire (the adding proportion is 3 m/T) are fed into the molten steel, S in the molten steel is converted into CaS inclusion to carry out molten steel, and meanwhile, the oxygen content in the molten steel is effectively reduced.
(3) The VD ladle refining furnace smelting process comprises the following steps: transferring the molten steel obtained in the step (2) to a VD furnace, setting the vacuum degree to be 66.7Pa, and keeping the vacuum degree for 18 minutes; soft blowing Ar gas for 15 minutes after air breaking;
(4) the casting process comprises the following steps: and after refining in the VD furnace is finished, adjusting the pouring temperature of the molten steel to 1545 ℃, adopting Ar gas for protection pouring, and cooling to obtain a 42CrMo4 steel ingot.
The chemical composition of the 42CrMo4 steel obtained in the first comparative example is shown in Table 3:
TABLE 3
Second embodiment
A smelting process of 42CrMo4 steel for large shaft forgings comprises the following steps:
(1) the smelting process of the EBT electric arc furnace comprises the following steps: high-quality scrap steel is selected as a material; 1000kg of furnace bottom lime; the target value of the end point carbon is controlled to be 0.04 percent, and the target value of the phosphorus is controlled to be 0.007 percent; controlling the tapping temperature at 1635 ℃; the content of C in the first sample in the LF furnace is more than or equal to 0.20 percent so as to ensure that a large amount of recarburization is not generated in the later period; the EBT steel tapping is strictly forbidden to carry out slag tapping; the steel ladle is well baked, and the air permeability is normal; adding tapping materials in sequence: carburant (graphite powder added with the proportion of 1 Kg/T), deoxidizer (Al added with the proportion of 1 Kg/T), iron alloy (calcium silicon manganese added with the proportion of 1.1 Kg/T) and slag charge (lime added with the proportion of 14 Kg/T).
(2) The LF ladle refining furnace smelting process comprises the following steps: the ladle car carrying the ladle obtained in the step (1) is driven to a heating station of an LF furnace, Si powder and C powder (the adding proportion is 1.5Kg/T respectively) are added for enhancing deoxidation when the temperature of molten steel is measured to be 1563 ℃; the white slag retention time is increased by 35 minutes compared with the first embodiment; slag is adjusted 5 minutes before ladle discharging, so that the molten steel has certain alkalinity and good fluidity; before the ladle enters a VD furnace, an Al wire (the adding proportion is 3 m/T) and a Ca-Si wire (the adding proportion is 3 m/T) are fed into the molten steel, S in the molten steel is converted into CaS inclusion to carry out molten steel, and meanwhile, the oxygen content in the molten steel is effectively reduced.
(3) The VD ladle refining furnace smelting process comprises the following steps: transferring the molten steel obtained finally in the step (2) into a VD furnace, setting the vacuum degree to be reduced by 0.2Pa to 66.5Pa compared with the first embodiment, and setting the holding time to be increased by 2 minutes to 20 minutes compared with the first embodiment; the soft Ar gas blowing time after the air breaking is increased by 20 minutes compared with that of the first embodiment;
(4) the casting process comprises the following steps: after refining in the VD furnace is finished, the pouring temperature of the molten steel is adjusted to be 1550 ℃ higher than that in the first embodiment, Ar gas is adopted for protection pouring, and a 42CrMo4 steel ingot is obtained after cooling.
The chemical composition of the 42CrMo4 steel obtained in the second example is shown in Table 4:
TABLE 4
Second comparative example
A smelting process of 42CrMo4 steel for large shaft forgings comprises the following steps:
(1) the smelting process of the EBT electric arc furnace comprises the following steps: high-quality scrap steel is selected as a material; 1000kg of furnace bottom lime; the target value of the end point carbon is controlled to be 0.04 percent, and the target value of the phosphorus is controlled to be 0.007 percent; controlling the tapping temperature at 1635 ℃; the content of C in the first sample in the LF furnace is more than or equal to 0.20 percent so as to ensure that a large amount of recarburization is not generated in the later period; the EBT steel tapping is strictly forbidden to carry out slag tapping; the steel ladle is well baked, and the air permeability is normal; adding tapping materials in sequence: carburant (graphite powder added with the proportion of 1 Kg/T), deoxidizer (Al added with the proportion of 1 Kg/T), iron alloy (silicon-calcium-manganese added with the proportion of 1.1 Kg/T) and slag charge (lime added with the proportion of 14 Kg/T).
(2) The LF ladle refining furnace smelting process comprises the following steps: driving a ladle car carrying the ladle obtained in the step (1) to an LF furnace heating station, and adding Si and C powder (the adding proportion is 1.0Kg \ T respectively) to strengthen deoxidation when the temperature of molten steel is measured to be 1563 ℃; the white slag retention time is 20 minutes; slag is adjusted 5 minutes before ladle discharging, so that the molten steel has certain alkalinity and good fluidity; before the ladle enters a VD furnace, an Al wire (the adding proportion is 3 m/T) and a Ca-Si wire (the adding proportion is 3 m/T) are fed into the molten steel, S in the molten steel is converted into CaS inclusion to carry out molten steel, and meanwhile, the oxygen content in the molten steel is effectively reduced.
(3) The VD ladle refining furnace smelting process comprises the following steps: transferring the molten steel obtained in the step (2) into a VD furnace, setting the vacuum degree to be 66.5Pa, and keeping the vacuum degree for 20 minutes; soft blowing Ar gas for 20 minutes after air breaking;
(4) the casting process comprises the following steps: and after refining in the VD furnace is finished, adjusting the pouring temperature of the molten steel to 1550 ℃, adopting Ar gas for protection pouring, and cooling to obtain a 42CrMo4 steel ingot.
The chemical composition of the 42CrMo4 steel obtained in the second comparative example is shown in table 5:
TABLE 5
Third comparative example
A smelting process of 42CrMo4 steel for large shaft forgings comprises the following steps:
(1) the smelting process of the EBT electric arc furnace comprises the following steps: high-quality scrap steel is selected as a material; 1000kg of furnace bottom lime; the target value of the end point carbon is controlled to be 0.04 percent, and the target value of the phosphorus is controlled to be 0.007 percent; controlling the tapping temperature at 1635 ℃; the content of C in the first sample in the LF furnace is more than or equal to 0.20 percent so as to ensure that a large amount of recarburization is not generated in the later period; the EBT steel tapping is strictly forbidden to carry out slag tapping; the steel ladle is well baked, and the air permeability is normal; adding tapping materials in sequence: carburant (graphite powder added with the proportion of 1 Kg/T), deoxidizer (Al added with the proportion of 1 Kg/T), iron alloy (silicon-calcium-manganese added with the proportion of 1.1 Kg/T) and slag (fluorite added with the proportion of 15.5 Kg/T).
(2) The LF ladle refining furnace smelting process comprises the following steps: and (2) driving the ladle car carrying the ladle obtained in the step (1) to an LF furnace heating station, pouring the ladle car into the LF furnace when the temperature of molten steel is measured to be 1563 ℃, feeding Al wires (the addition ratio is 3 m/T) and Ca-Si wires (the addition ratio is 3 m/T) to the molten steel before hoisting the ladle into the VD furnace, converting S in the molten steel into CaS inclusion and taking out the molten steel, and effectively reducing the oxygen content in the molten steel.
(3) The VD ladle refining furnace smelting process comprises the following steps: transferring the molten steel obtained in the step (2) into a VD furnace, setting the vacuum degree to be 66.5Pa, and keeping the vacuum degree for 20 minutes; soft blowing Ar gas for 20 minutes after air breaking;
(4) the casting process comprises the following steps: and after refining in the VD furnace is finished, adjusting the pouring temperature of the molten steel to 1550 ℃, adopting Ar gas for protection pouring, and cooling to obtain a 42CrMo4 steel ingot.
The chemical composition of the 42CrMo4 steel obtained in the third comparative example is shown in table 6:
TABLE 6
Third embodiment
A smelting process of 42CrMo4 steel for large shaft forgings comprises the following steps:
(1) the smelting process of the EBT electric arc furnace comprises the following steps: high-quality scrap steel is selected as a material; 1000kg of furnace bottom lime; the target end point carbon value is controlled to be 0.05 percent, and the target phosphorus value is controlled to be 0.006 percent; controlling the tapping temperature to be 1640 ℃; the content of C in the first sample in the LF furnace is more than or equal to 0.20 percent so as to ensure that a large amount of recarburization is not generated in the later period; the EBT steel tapping is strictly forbidden to carry out slag tapping; the steel ladle is well baked, and the air permeability is normal; adding tapping materials in sequence: carburant (charcoal powder added with 1 Kg/T), deoxidizer (Al added with 1 Kg/T), iron alloy (silicon-calcium-manganese added with 1 Kg/T), and slag (fluorite added with 15.5 Kg/T).
(2) The LF ladle refining furnace smelting process comprises the following steps: the ladle car carrying the ladle obtained in the step (1) is driven to a heating station of an LF furnace, Si and C powder (the adding proportion is increased by 0.1Kg/T to 1.6Kg/T respectively compared with the second embodiment) are added for strengthening deoxidation when the temperature of molten steel is measured to be 1565 ℃; the white slag retention time is increased by 38 minutes compared with the second embodiment; slag is adjusted 5 minutes before ladle discharging, so that the molten steel has certain alkalinity and good fluidity; before the ladle enters a VD furnace, an Al wire (the adding proportion is 3 m/T) and a Ca-Si wire (the adding proportion is 3 m/T) are fed into the molten steel, S in the molten steel is converted into CaS inclusion to carry out molten steel, and meanwhile, the oxygen content in the molten steel is effectively reduced.
(3) The VD ladle refining furnace smelting process comprises the following steps: transferring the molten steel obtained finally in the step (2) into a VD furnace, setting the vacuum degree to be reduced by 0.2Pa to 66.3Pa compared with the second embodiment, and setting the holding time to be increased by 3 minutes to 23 minutes compared with the second embodiment; the soft Ar gas blowing time after the air breaking is increased by 25 minutes compared with the second embodiment;
(4) the casting process comprises the following steps: and after refining in the VD furnace is finished, adjusting the pouring temperature of the molten steel to 1555 minutes compared with that in the second embodiment, adopting Ar gas for protection pouring, and cooling to obtain a 42CrMo4 steel ingot.
The chemical composition of the 42CrMo4 steel obtained in the third example is shown in Table 7:
TABLE 7
Fourth comparative example
A smelting process of 42CrMo4 steel for large shaft forgings comprises the following steps:
(1) the smelting process of the EBT electric arc furnace comprises the following steps: high-quality scrap steel is selected as a material; 1000kg of furnace bottom lime; the target end point carbon value is controlled to be 0.05 percent, and the target phosphorus value is controlled to be 0.006 percent; controlling the tapping temperature to be 1640 ℃; the content of C in the first sample in the LF furnace is more than or equal to 0.20 percent so as to ensure that a large amount of recarburization is not generated in the later period; the EBT steel tapping is strictly forbidden to carry out slag tapping; the steel ladle is well baked, and the air permeability is normal; adding tapping materials in sequence: carburant (charcoal powder added with 1Kg \ T), deoxidizer (Al added with 1 Kg/T), ferroalloy (silicon-calcium-manganese added with 1Kg \ T), slag charge (lime added with 16 Kg/T).
(2) The LF ladle refining furnace smelting process comprises the following steps: driving a ladle car carrying the ladle obtained in the step (1) to an LF furnace heating station, and adding Si and C powder (the addition ratio is 5Kg \ T respectively) to strengthen deoxidation when the temperature of molten steel is measured to be 1565 ℃; the white slag retention time is increased by 38 minutes compared with the second embodiment; and the slag is adjusted 5 minutes before tapping, so that the molten steel has certain alkalinity and good fluidity.
(3) The VD ladle refining furnace smelting process comprises the following steps: transferring the molten steel obtained finally in the step (2) into a VD furnace, and setting the vacuum degree to be reduced by 0.2Pa to 66.3Pa compared with the second embodiment, and setting the holding time to be reduced by 3 minutes to 23 minutes compared with the second embodiment; the soft Ar gas blowing time after the air breaking is increased by 25 minutes compared with the second embodiment;
(4) the casting process comprises the following steps: after refining in the VD furnace is finished, the pouring temperature of the molten steel is adjusted to be increased by 5 ℃ to 1555 ℃ compared with that in the second embodiment, Ar gas is adopted for protection pouring, and a 42CrMo4 steel ingot is obtained after cooling.
The chemical composition of the 42CrMo4 steel obtained in the fourth comparative example is shown in table 8:
TABLE 8
Fourth embodiment
A smelting process of 42CrMo4 steel for large shaft forgings comprises the following steps:
(1) the smelting process of the EBT electric arc furnace comprises the following steps: high-quality scrap steel is selected as a material; 1000kg of furnace bottom lime; the target value of the end point carbon is controlled to be 0.04 percent, and the target value of the phosphorus is controlled to be 0.005 percent; controlling the tapping temperature at 1645 ℃; the content of C in the first sample in the LF furnace is more than or equal to 0.20 percent so as to ensure that a large amount of recarburization is not generated in the later period; the EBT steel tapping is strictly forbidden to carry out slag tapping; the steel ladle is well baked, and the air permeability is normal; adding tapping materials in sequence: carburant (charcoal powder added with 1 Kg/T), deoxidizer (Al added with 1 Kg/T), iron alloy (silicon-calcium-manganese added with 1 Kg/T) and slag (fluorite added with 15 Kg/T).
(2) The LF ladle refining furnace smelting process comprises the following steps: the ladle car carrying the ladle obtained in the step (1) is driven to a heating station of an LF furnace, Si powder and C powder (the adding proportion is 1.6Kg/T respectively) are added for enhancing deoxidation when the temperature of molten steel is measured to be 1565 ℃; the white slag retention time is 38 minutes; slag is adjusted 5 minutes before ladle discharging, so that the molten steel has certain alkalinity and good fluidity; before the ladle enters a VD furnace, an Al wire (the adding proportion is 3 m/T) and a Ca-Si wire (the adding proportion is 3 m/T) are fed into the molten steel, S in the molten steel is converted into CaS inclusion to carry out molten steel, and meanwhile, the oxygen content in the molten steel is effectively reduced.
(3) The VD ladle refining furnace smelting process comprises the following steps: transferring the molten steel obtained in the step (2) into a VD furnace, setting the vacuum degree to be 66.7Pa, and keeping for 25 minutes; the soft Ar gas blowing time after the air break is reduced by 10 minutes compared with the third embodiment;
(4) the casting process comprises the following steps: and after refining in the VD furnace is finished, adjusting the pouring temperature of the molten steel to 1545 ℃, adopting Ar gas for protection pouring, and cooling to obtain a 42CrMo4 steel ingot.
The chemical composition of the 42CrMo4 steel obtained in the fourth example is shown in Table 9:
TABLE 9
Fifth comparative example
A smelting process of 42CrMo4 steel for large shaft forgings comprises the following steps:
(1) the smelting process of the EBT electric arc furnace comprises the following steps: high-quality scrap steel is selected as a material; 1000kg of furnace bottom lime; the target value of the end point carbon is controlled to be 0.04 percent, and the target value of the phosphorus is controlled to be 0.005 percent; controlling the tapping temperature at 1645 ℃; the content of C in the first sample in the LF furnace is more than or equal to 0.20 percent so as to ensure that a large amount of recarburization is not generated in the later period; the EBT steel tapping is strictly forbidden to carry out slag tapping; the steel ladle is well baked, and the air permeability is normal; adding tapping materials in sequence: carburant (charcoal powder added with 1 Kg/T), deoxidizer (Al added with 1 Kg/T), iron alloy (silicon-calcium-manganese added with 1 Kg/T) and slag (fluorite added with 15 Kg/T).
(2) The LF ladle refining furnace smelting process comprises the following steps: the ladle car carrying the ladle obtained in the step (1) is driven to an LF furnace heating station, Si and C powder (the adding proportion is 1.6Kg \ T respectively) are added for strengthening deoxidation when the temperature of molten steel is measured to be 1565 ℃; the white slag retention time is 38 minutes; slag is adjusted 5 minutes before ladle discharging, so that the molten steel has certain alkalinity and good fluidity; before the ladle enters the VD furnace, an Al wire (the adding proportion is 3 m/T) and a Ca-Si wire (the adding proportion is 3 m/T) are fed into the molten steel, S in the molten steel is converted into CaS inclusion to carry out molten steel, and meanwhile, the oxygen content in the molten steel is effectively reduced, compared with the fourth embodiment, the VD ladle refining furnace is not adopted for smelting.
(3) The casting process comprises the following steps: and adjusting the pouring temperature of the molten steel to 1545 ℃, adopting Ar gas for protection pouring, and cooling to obtain a 42CrMo4 steel ingot.
The chemical composition of the 42CrMo4 steel obtained in the fifth comparative example is shown in Table 10:
watch 10
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A smelting process of 42CrMo4 steel is characterized by comprising the following steps: the method comprises the following steps:
(1) a smelting stage: the bottom of the furnace is primed by lime, the target value of the end point carbon is controlled to be more than or equal to 0.03 percent, the target value of the phosphorus is controlled to be less than or equal to 0.008 percent, the tapping temperature is controlled to be more than or equal to 1630 ℃, and C of the first sample entering the next refining stage is more than or equal to 0.20 percent; tapping in the smelting stage is strictly forbidden to discharge slag, and the tapping materials are added in the following sequence: the alloy steel comprises a carburant, a deoxidizer, an iron alloy and slag charge, wherein the deoxidizer is Al powder;
(2) and (3) refining: transferring the molten steel in the step (1) to a refining furnace, and adding Si and C powder; the white slag retention time is not less than 30 minutes; before the ladle is taken out, the furnace slag is adjusted, and before the next VD vacuum refining stage, Al wires and Ca-Si wires are fed into the molten steel;
(3) and (3) vacuum refining: and (3) transferring the molten steel obtained in the step (2) to a vacuum refining furnace, blowing protective gas after the vacuum is broken, and finally pouring in the protective gas atmosphere to obtain the steel.
2. The smelting process of 42CrMo4 steel according to claim 1, characterized in that: in the step (1), the carburant comprises at least one of wood carbons, coal carbons, coke and graphite.
3. The smelting process of 42CrMo4 steel according to claim 1, characterized in that: in the step (1), the iron alloy comprises at least one of silicon-carbon alloy and silicon-calcium-manganese alloy.
4. The smelting process of 42CrMo4 steel according to claim 1, characterized in that: in the step (1), the slag comprises at least one of lime and fluorite; preferably, the addition proportion of the slag charge is 14-16 kg/ton.
5. The smelting process of 42CrMo4 steel according to claim 1, characterized in that: in the step (1), the deoxidizer comprises at least one of silicon-aluminum-barium-calcium-iron, silicon-calcium core-spun yarn and aluminum wire; preferably, the addition ratio of the deoxidizer is 0.8 to 1.2 kg/ton.
6. The smelting process of 42CrMo4 steel according to claim 1, characterized in that: in the step (2), the adding proportion of the Si powder is 1-5 kg/ton, and the adding proportion of the C powder is 1-5 kg/ton.
7. The smelting process of 42CrMo4 steel according to claim 1, characterized in that: in the step (2), the adding proportion of the Al wire is 3 m/ton; or the addition proportion of the Ca-Si wires is 3 m/ton;
alternatively, in step (2), the slag is adjusted at least 5 minutes from the ladle.
8. A process for smelting 42CrMo4 steel according to any one of claims 1 to 7, wherein: in the step (3), the vacuum degree in the vacuum refining furnace is less than or equal to 66.7Pa, and the holding time is more than or equal to 18 minutes; and blowing Ar gas for 10-25 minutes after breaking the air.
9. A process for smelting 42CrMo4 steel according to any one of claims 1 to 7, wherein: in the step (3), the casting temperature is 1545-1555 ℃, and the casting is performed under the protection of Ar gas to prevent the molten steel from being oxidized.
10. Use of the 42CrMo4 steel smelting process according to any one of claims 1 to 9 in the production of wind power main shafts, large gears for locomotive traction, transmission gears of superchargers or deep well drill pipe joint products.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114908219A (en) * | 2022-05-31 | 2022-08-16 | 联峰钢铁（张家港）有限公司 | Smelting method for reducing silicon-manganese impurities in aluminum killed steel |
| CN115386787A (en) * | 2022-08-26 | 2022-11-25 | 东北特殊钢集团股份有限公司 | Smelting and electroslag remelting production process for shield machine bearing ring 42CrMo4 |
| CN116574965A (en) * | 2023-07-11 | 2023-08-11 | 江苏永钢集团有限公司 | Method for improving inclusion level of wind power steel |
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2020
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114908219A (en) * | 2022-05-31 | 2022-08-16 | 联峰钢铁（张家港）有限公司 | Smelting method for reducing silicon-manganese impurities in aluminum killed steel |
| CN114908219B (en) * | 2022-05-31 | 2024-04-26 | 联峰钢铁（张家港）有限公司 | Smelting method for reducing silicomanganese inclusion in aluminum killed steel |
| CN115386787A (en) * | 2022-08-26 | 2022-11-25 | 东北特殊钢集团股份有限公司 | Smelting and electroslag remelting production process for shield machine bearing ring 42CrMo4 |
| CN115386787B (en) * | 2022-08-26 | 2023-08-29 | 东北特殊钢集团股份有限公司 | Smelting and electroslag remelting production process for shield machine bearing ring 42CrMo4 |
| CN116574965A (en) * | 2023-07-11 | 2023-08-11 | 江苏永钢集团有限公司 | Method for improving inclusion level of wind power steel |
| CN116574965B (en) * | 2023-07-11 | 2023-09-15 | 江苏永钢集团有限公司 | Method for improving inclusion level of wind power steel |
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