CN111334724A - Polymorphic high-degree deoxidation casting method for microalloyed rare earth cast steel - Google Patents
Polymorphic high-degree deoxidation casting method for microalloyed rare earth cast steel Download PDFInfo
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- C22C38/00—Ferrous alloys, e.g. steel alloys
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Abstract
The invention discloses a polymorphic high-degree deoxidation casting method of microalloyed rare earth cast steel, which belongs to the technical field of casting, and can realize that on one hand, the microstructure and the performance of a casting are improved by adding trace rare earth elements, so that the strength and the quality of a product are improved, on the other hand, a novel deoxidation component is introduced to carry out deoxidation treatment of various forms on molten steel in a ladle, including gaseous deoxidation, solid deoxidation and vibration deoxidation, and deoxidation is accompanied with the synchronous real-time release of deoxidation substances along with the rise of a liquid level, compared with the traditional aluminum block precipitation deoxidation, the polymorphic high-degree deoxidation casting method can ensure the uniformity and the comprehensiveness of deoxidation, further improve the deoxidation effect by using multi-element refining gas and mixed solid refining agents, quickly drive aluminum oxide inclusion to rise to float the liquid level for removal, and reduce the influence of deoxidation products on the microstructure and the performance of the product, the strength and quality of the final casting are improved.
Description
Technical Field
The invention relates to the technical field of casting, in particular to a polymorphic high-degree deoxidation casting method for microalloyed rare earth cast steel.
Background
Casting is a relatively early metal hot working process mastered by human beings, and has a history of about 6000 years. China has entered the full prosperity of bronze castings between about 1700 and the first 1000 b.c., and has achieved a fairly high level of technology. Casting is a method in which liquid metal is cast into a casting cavity that conforms to the shape of a part, and after it is cooled and solidified, a part or a blank is obtained. The casting material is mostly metal (such as copper, iron, aluminum, tin, lead, etc.) which is originally solid but is heated to liquid state, and the material of the casting mold can be sand, metal or even ceramic. The method used may be different according to different requirements
The large-scale steel casting has the characteristics of relatively easy forming, low production cost and the like, so the large-scale steel casting is widely applied to the fields of mines, cement, petroleum, ships and the like, but the large-scale steel casting is easy to have the defects of shrinkage porosity, shrinkage cavities, air holes, cracks and the like in the forming process, so the mechanical property and the service life of the large-scale steel casting are influenced, and great loss is caused to enterprises and national economy.
And (3) deoxidation: reactions that reduce the oxygen content of steel during steelmaking and casting. The method is an important process link for ensuring the quality of steel ingots (billets) and steel products, but in the prior art, a method for placing aluminum blocks in a steel ladle is mostly adopted in the steel making process, pure aluminum is melted and reacts with oxygen in molten steel for deoxidation when the molten steel impacts the bottom of the steel ladle, although the deoxidation reaction is fast, the time is short, the effect is obvious, the residual quantity of non-metallic inclusions formed in the molten steel is large, the influence on the strength and the quality of castings is certain, and simultaneously, because of the dissolution characteristic of the aluminum blocks, the deoxidation effect of the final molten steel, namely the liquid level part of the molten steel is shallow.
Disclosure of Invention
1. Technical problem to be solved
Aiming at the problems in the prior art, the invention aims to provide a polymorphic high-degree deoxidation casting method of microalloyed rare earth cast steel, which can realize that on one hand, the microstructure and the performance of a casting are improved by adding trace rare earth elements, so that the strength and the quality of a product are improved, on the other hand, a novel deoxidation component is introduced to carry out deoxidation treatment on molten steel in a ladle in various forms, including gaseous deoxidation, solid deoxidation and vibration deoxidation, and deoxidation is synchronously released in real time along with the rise of a liquid level, compared with the deoxidation method of a traditional aluminum block precipitation method, the homogeneity and the comprehensiveness of the deoxidation can be ensured, the deoxidation effect can be further improved by using multi-component refining gas and mixed solid refining agents, aluminum oxide inclusion is quickly driven to rise to the floating liquid level for removal, and the influence of the deoxidation product on the microstructure and the performance of the product is reduced, the strength and quality of the final casting are improved.
2. Technical scheme
In order to solve the above problems, the present invention adopts the following technical solutions.
A polymorphic high-degree deoxidation casting method of microalloyed rare earth cast steel comprises the following steps:
s1, preprocessing: before casting, drying scrap steel and alloy elements at 60-80 ℃, and simultaneously preheating a smelting furnace, a steel ladle and a casting mold;
s2, alloy batching: the main chemical components of the cast steel comprise C, Si, Mn, Nb, Ti, Re, B, Cr, La, Ce, P, S, iron and trace impurity elements;
s3, smelting scrap steel: sequentially putting the scrap steel into a smelting furnace in a descending order for high-temperature smelting;
s4, adding alloy: adding Nb, Ti, La, Ce, B and Cr alloy elements in advance after the scrap steel in the furnace is melted down, then adding ferromanganese, and adding ferrosilicon after the ferromanganese is completely melted down and the slag skimming is finished;
s5, tapping: controlling the tapping temperature at 1650-1680 ℃, mixing the modifier and the carburant with the molten steel and introducing into a steel ladle during tapping;
s6, polymorphic deoxidation: arranging a deoxidizing component at the center position in the ladle, pouring and spraying molten steel from the deoxidizing component and receiving the molten steel in the ladle, synchronously carrying out polymorphic deoxidizing along with the rising of the liquid level, standing for 15-30min after deoxidizing, and removing impurities such as oxides floating on the liquid level;
s7, casting and forming: pouring the molten steel in the ladle into a prepared casting mold, controlling the pouring temperature at 1550-1580 ℃, cooling, and removing the casting mold to obtain the formed alloy casting.
Furthermore, the mass percentages of C, Si, Mn, Nb, Ti, Re, B, Cr, La, Ce, P and S are respectively 0.30-0.40% of C, 0.60-0.80% of Si, 1.10-1.40% of Mn, 0.03-0.09% of Nb0.01-0.08% of Ti, 0.01-0.20% of Re0.01-0.028% of B, 0.01-0.024% of Cr0.01-0.10% of La0.01-0.15% of P, less than or equal to 0.035% of S and less than or equal to 0.010% of C, and after rare earth and other alloy elements are added, the structure and the performance of the cast steel are obviously improved, and the hardness is improved without reducing the elongation and the toughness.
Further, in the step S4, the alloy elements Nb, Ti, La, Ce, B, Cr, ferromanganese, and ferrosilicon should be subjected to impurity removal before being put in, and after being dried for 2-3 hours, the alloy elements, ferromanganese, and ferrosilicon are put into the ladle in the form of metal powder, so that the purities of the alloy elements, ferromanganese, and ferrosilicon are ensured, and impurities are not easily introduced to reduce the quality of the casting.
Furthermore, the modifier is SiC single substance micro powder particles, the carburant is pure carbon powder, and the particle sizes of the modifier and the carburant are smaller than 300nm, so that the structure and the performance can be improved, and the fatigue resistance and the wear resistance of the casting can be improved.
Further, the deoxidation subassembly in step S6 includes the stretching into deoxidation pole that the heliciform distributes, stretching into deoxidation pole lower extreme and being provided with a plurality of evenly distributed 'S double-purpose deoxidation ball, the elasticity that the stretching into deoxidation pole includes inside and outside distribution shakes pole and high temperature resistant protecting crust certainly, and high temperature resistant protecting crust parcel is shaken the pole surface certainly at elasticity, double-purpose deoxidation ball includes a plurality of crisscross distribution' S directly consumes deoxidation ball and harmless concise ball, realizes deoxidization 'S homogeneity and comprehensive along with the rising of molten steel liquid level in the space, utilizes elastic vibration' S characteristic both can enlarge the deoxidation scope simultaneously for deoxidation speed, the air that dissolves when can force simultaneously empting the molten steel spills over fast.
Furthermore, the elastic self-vibrating rod is made of high-elasticity high-temperature-resistant metal materials or plastic materials, the high-temperature-resistant protective shell is made of alumina fibers, the alumina fibers are one of the latest ultra-light high-temperature heat-insulating materials at home and abroad at present, the material is rich in elasticity, the thermal conductivity, the heating shrinkage rate and the thermal capacity of the alumina fibers are low, the thermal insulation performance is good, the thermal capacity is small, and the effect of protecting the elastic self-vibrating rod can be achieved.
Further, the direct-consuming deoxidizing ball is a hollow ball shell made of pure aluminum, a plurality of hemisphere clamping grooves matched with the direct-consuming deoxidizing ball are formed in the lower end of the stretching deoxidizing rod, the direct-consuming deoxidizing ball and the hemisphere clamping grooves are in interference fit, a ball-shaped cavity is formed between the nondestructive refining ball and the high-temperature-resistant protective shell in an integrated mode, a bent communication hole is communicated between the ball-shaped cavity and the hemisphere clamping grooves, a mixed solid refining agent is filled in the direct-consuming deoxidizing ball, multiple refining gases are filled in the nondestructive refining ball, the direct-consuming deoxidizing ball made of pure aluminum can be consumed and supplemented, the mixed solid refining agent is released to directly dissolve aluminum oxide inclusions in a short distance, and when the direct-consuming deoxidizing ball is consumed, the multiple refining gases in the nondestructive refining ball overflow to perform further refining.
Further, the mixed solid refining agent is composed of the following raw materials in percentage by mass: 20-30% of KCl, 20-30% of NaCl, 20-25% of NaF and 25-30% of Na3AlF 6. Wherein Na3AlF6, cryolite has good dissolving effect to alumina inclusion, and the gaseous phase aluminium trichloride that the reaction produced can be effective quick drive alumina slag come-up moreover, and is obvious to the effect of getting rid of oxide inclusion.
Further, the multi-element refining gas consists of the following gases in volume percent: 35% -42% of Ar, 22% -38% of He, 10% -20% of N2 and 8% -16% of Cl2, and the filling amount is 150% -180% of the volume of the spherical cavity. Good removal effect and little environmental pollution, has important significance for improving the compactness of the casting and fully improving the structural strength of the casting
Further, in the step S7, the casting is subjected to modified heat treatment in a multi-stage cooling mode, the temperature is cooled to 800-850 ℃ and kept for 2-5 hours, then the temperature is reduced to 180-300 ℃ at a constant speed of 20-50 ℃/h, then the temperature is heated to 600-800 ℃ and kept for 2-5 hours, and finally the casting is naturally cooled to the normal temperature, and then the die is removed to obtain a finished casting blank, so that the structure and the performance can be obviously improved, and the fatigue resistance and the wear resistance of the casting are improved.
3. Advantageous effects
Compared with the prior art, the invention has the advantages that:
(1) this scheme can realize improving the organizational structure and the performance of foundry goods through adding the trace rare earth element on the one hand, and then improve product strength and quality, on the other hand introduces neotype deoxidation subassembly and carries out the deoxidation processing of multiple form to the molten steel in the ladle, including gaseous state deoxidation, solid-state deoxidation and vibrations deoxidation, and the synchronous real-time release deoxidation material that rises along with the liquid level, compare in traditional aluminium pig precipitation method deoxidation, both can guarantee deoxidization's homogeneity and wholeness, can further improve deoxidation effect through many units refining gas and mixed solid refining agent simultaneously, and drive aluminium oxide inclusion matter fast and rise to float the well liquid level and detach, reduce the influence of deoxidation product to product organizational structure and performance, improve the intensity and the quality of final foundry goods.
(2) The weight percentage of C, Si, Mn, Nb, Ti, Re, B, Cr, La, Ce, P and S are respectively 0.30-0.40 percent of C, 0.60-0.80 percent of Si, 1.10-1.40 percent of Mn, 0.03-0.09 percent of Nb0.01-0.08 percent of Ti, 0.01-0.20 percent of Re0.01-0.028 percent of B, 0.01-0.024 percent of Cr0.01-0.10 percent of La0.01-0.15 percent of Ce, less than or equal to 0.035 percent of P and less than or equal to 0.010 percent of S.
(3) Nb, Ti, La, Ce, B, Cr alloy elements, ferromanganese alloy and ferrosilicon alloy are subjected to impurity removal treatment before being put in, and are put into a steel ladle in the form of metal powder after being dried for 2-3 hours, so that the purities of the alloy elements, the ferromanganese alloy and the ferrosilicon alloy are ensured, and impurities are not easy to introduce to reduce the quality of the casting.
(4) The modifier is SiC simple substance micro powder particles, the carburant is pure carbon powder, and the particle sizes of the modifier and the carburant are smaller than 300nm, so that the structure and the performance can be improved, and the fatigue resistance and the wear resistance of the casting can be improved.
(5) The deoxidation subassembly includes the stretching into deoxidation pole that the heliciform distributes, the stretching into formula deoxidation pole lower extreme is provided with a plurality of evenly distributed's double-purpose deoxidation ball, the elasticity that the formula of stretching into deoxidization pole includes inside and outside distribution shakes pole and high temperature resistant protecting crust, and high temperature resistant protecting crust parcel is shaken the pole surface at elasticity certainly, double-purpose deoxidation ball is including a plurality of crisscross distributions directly consume deoxidation ball and harmless concise ball, realize deoxidization homogeneity and comprehensive along with the rising of molten steel liquid level in the space, utilize elastic vibration's characteristic both can enlarge the deoxidation scope simultaneously, accelerate deoxidation speed, the air that dissolves when can force to empty the molten steel simultaneously spills over fast.
(6) The elastic self-vibrating rod is made of high-elasticity high-temperature-resistant metal materials or plastic materials, the high-temperature-resistant protective shell is made of alumina fibers, the alumina fibers are one of the latest ultra-light high-temperature heat-insulating materials at home and abroad at present, and are rich in elasticity, the thermal conductivity, the heating shrinkage rate and the thermal capacity of the alumina fibers are low, the thermal insulation property is good, the thermal capacity is small, and the effect of protecting the elastic self-vibrating rod can be achieved.
(7) The direct-consuming deoxidizing ball is a hollow ball shell made of pure aluminum, a plurality of hemisphere clamping grooves matched with the direct-consuming deoxidizing ball are formed in the lower end of the stretching-in type deoxidizing rod, the direct-consuming deoxidizing ball is in interference fit with the hemisphere clamping grooves, a spherical cavity is reserved between the nondestructive refining ball and the high-temperature-resistant protective shell in an integrated forming mode, a bent communication hole is communicated between the spherical cavity and the hemisphere clamping grooves, a mixed solid refining agent is filled in the direct-consuming deoxidizing ball, multiple refining gases are filled in the nondestructive refining ball, the direct-consuming deoxidizing ball made of pure aluminum can be consumed and supplemented, the direct-consuming deoxidizing ball is continuously consumed while being dissolved and deoxidized, the mixed solid refining agent is released to directly dissolve alumina inclusions in a short distance, and when the direct-consuming deoxidizing ball is consumed, the multiple refining gases in the nondestructive refining ball overflow for further refining.
(8) The mixed solid refining agent consists of the following raw materials in percentage by mass: 20-30% of KCl, 20-30% of NaCl, 20-25% of NaF and 25-30% of Na3AlF 6. Wherein Na3AlF6, cryolite has good dissolving effect to alumina inclusion, and the gaseous phase aluminium trichloride that the reaction produced can be effective quick drive alumina slag come-up moreover, and is obvious to the effect of getting rid of oxide inclusion.
(9) The multi-element refining gas consists of the following gases in volume percent: 35% -42% of Ar, 22% -38% of He, 10% -20% of N2 and 8% -16% of Cl2, and the filling amount is 150% -180% of the volume of the spherical cavity. Good removal effect and little environmental pollution, has important significance for improving the compactness of the casting and fully improving the structural strength of the casting
(10) And step S7, performing modified heat treatment on the casting by adopting a multi-stage cooling mode, firstly cooling to 800-850 ℃, preserving heat for 2-5h, then uniformly cooling to 180-300 ℃ at a constant speed of 20-50 ℃/h, then heating to 600-800 ℃, preserving heat for 2-5h, and finally naturally cooling to normal temperature to obtain a finished casting blank, wherein the finished casting blank can be obtained by removing the mold, the structure and the performance can be obviously improved, and the fatigue resistance and the wear resistance of the casting are improved.
Drawings
FIG. 1 is a schematic flow diagram of the present invention;
FIG. 2 is a schematic structural view of a deoxygenation assembly of the present invention;
FIG. 3 is a cross-sectional view of a portion of the deoxygenation assembly of the present invention;
FIG. 4 is a schematic diagram of the partially deoxygenated state of the deoxygenation assembly of the present invention;
FIG. 5 is a top view of a portion of the deoxygenation assembly of the present invention.
The reference numbers in the figures illustrate:
1 extending type deoxidizing rod, 101 elastic self-vibrating rod, 102 high temperature resistant protective shell, 2 double-purpose deoxidizing balls, 201 direct-consumption deoxidizing balls, 202 lossless refining balls, 3 zigzag communication holes and 4 mixed solid refining agent.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention; it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work are within the scope of the present invention.
In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top/bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise specifically stated or limited, the terms "mounted," "disposed," "sleeved/connected," "connected," and the like are used in a broad sense, and for example, "connected" may be a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection through an intermediate medium, and a communication between two elements.
Example 1:
referring to fig. 1, a polymorphic high-deoxidation casting method of microalloyed rare earth cast steel comprises the following steps:
s1, preprocessing: before casting, the scrap steel and the alloy elements are dried at 80 ℃, and a smelting furnace, a steel ladle and a casting mold are preheated simultaneously;
s2, alloy batching: the main chemical components of the cast steel comprise C, Si, Mn, Nb, Ti, Re, B, Cr, La, Ce, P, S, iron and trace impurity elements;
s3, smelting scrap steel: sequentially putting the scrap steel into a smelting furnace in a descending order for high-temperature smelting;
s4, adding alloy: adding Nb, Ti, La, Ce, B and Cr alloy elements in advance after the scrap steel in the furnace is melted down, then adding ferromanganese, and adding ferrosilicon after the ferromanganese is completely melted down and the slag skimming is finished;
s5, tapping: controlling the tapping temperature at 1650 ℃, mixing the modifier and the carburant with the molten steel and introducing into a steel ladle during tapping;
s6, polymorphic deoxidation: arranging a deoxidizing component at the center position in the ladle, pouring and spraying molten steel from the deoxidizing component and receiving the molten steel in the ladle, synchronously carrying out polymorphic deoxidizing along with the rising of the liquid level, and standing for 15min after the deoxidizing to remove impurities such as oxides floating on the liquid level;
s7, casting and forming: and pouring the molten steel in the ladle into a prepared casting mold, controlling the pouring temperature at 1550 ℃, cooling, and removing the casting mold to obtain the formed alloy casting.
C. The weight percentage of Si, Mn, Nb, Ti, Re, B, Cr, La, Ce, P and S are respectively 0.30 percent of C, 0.60 percent of Si, 1.10 percent of Mn, 0.03 percent of Nb0.03 percent of Ti, 0.01 percent of Re0.01 percent of B, 0.01 percent of Cr0.01 percent of C, 0.01 percent of La0.01 percent of C, less than or equal to 0.035 percent of P and less than or equal to 0.010 percent of S, after alloy elements such as rare earth and the like are added, the structure and the performance of the cast steel are obviously improved, the hardness is improved, and the elongation and the toughness are not reduced.
In the step S4, Nb, Ti, La, Ce, B, Cr alloy elements, ferromanganese alloy and ferrosilicon alloy are subjected to impurity removal treatment before being put in, and are put into a steel ladle in the form of metal powder after being dried for 2-3 hours, so that the purities of the alloy elements, the ferromanganese alloy and the ferrosilicon alloy are ensured, and impurities are not easy to introduce to reduce the quality of the casting.
The modifier is SiC simple substance micro powder particles, the carburant is pure carbon powder, and the particle sizes of the modifier and the carburant are smaller than 300nm, so that the structure and the performance can be improved, and the fatigue resistance and the wear resistance of the casting can be improved.
Referring to fig. 2-3, the deoxidizing component in step S6 includes a spirally-distributed telescopic deoxidizing rod 1, a plurality of uniformly-distributed dual-purpose deoxidizing balls 2 are disposed at a lower end of the telescopic deoxidizing rod 1, the telescopic deoxidizing rod 1 includes an elastic self-vibrating rod 101 and a high temperature resistant protective shell 102, the high temperature resistant protective shell 102 is wrapped on an outer surface of the elastic self-vibrating rod 101, the dual-purpose deoxidizing ball 2 includes a plurality of directly-consumed deoxidizing balls 201 and non-destructive refining balls 202 which are distributed in a staggered manner, the uniformity and the full-area performance of deoxidation are realized along with the rise of the liquid level of the molten steel in space, the deoxidizing range can be expanded and the deoxidizing speed can be increased by using the characteristic of elastic vibration, meanwhile, the dissolved air can be forced to overflow quickly when the molten steel is poured, the elastic self-vibrating rod 101 is made of a high-elasticity high temperature resistant metal material or a plastic material, and the high temperature resistant protective, the aluminum oxide fiber is one of the latest ultra-light high-temperature heat insulating materials at home and abroad at present, is rich in elasticity, has low thermal conductivity, heating shrinkage and heat capacity, good heat insulation and small heat capacity, and can play a role in protecting the elastic self-vibrating rod 101, the direct-consumption deoxidizing ball 201 is a hollow ball shell made of pure aluminum, a plurality of hemispherical clamping grooves matched with the direct-consumption deoxidizing ball 201 are formed at the lower end of the extension-type deoxidizing rod 1, the direct-consumption deoxidizing ball 201 is in interference fit with the hemispherical clamping grooves, a spherical cavity is integrally formed between the nondestructive refining ball 202 and the high-temperature-resistant protective shell 102 and reserved between the nondestructive refining ball 202 and the high-temperature-resistant protective shell, a zigzag communication hole 3 is communicated between the spherical cavity and the hemispherical clamping grooves, the direct-consumption deoxidizing ball 201 is filled with a mixed solid refining agent 4, the nondestructive refining ball 202 is filled with a plurality of refining gases, the direct-consumption deoxidizing ball 201 made of pure aluminum, the mixed solid refining agent 4 is released to directly dissolve alumina inclusions in a short distance, and when the directly consumed deoxidizing balls 201 are consumed, the multicomponent refining gas in the lossless refining balls 202 overflows to carry out further refining.
Referring to fig. 5, the molten steel is poured into the ladle from the right above the deoxidation component, which can ensure that the molten steel is blocked by the upper surface of the extension type deoxidation rod 1, and the direct consumption deoxidation ball 201 is not dissolved and consumed in advance, and after the liquid level gradually rises and contacts with the direct consumption deoxidation ball 201 after the molten steel enters the ladle, the direct consumption deoxidation ball 201 is rapidly dissolved and deoxidized, the mixed solid refining agent 4 in the aluminum oxide powder is released, then the aluminum oxide impurities which are deoxidized by the direct-consumption deoxidizing ball 201 are dissolved, and because of the filling amount, a large amount of gas is rushed out at first without damaging the multi-element refining gas in the refining ball 202, a large amount of bubbles are formed to swallow and ascend and dissipate the gas such as oxygen in the molten steel, meanwhile, the solid refining agent 4 can be impacted and mixed to enable a part of the solid refining agent to be rapidly diffused in the molten steel, and then the multielement refining gas in the refining ball 202 is not damaged and slowly released for refining, so that the effects of preliminary deoxidation refining and fine deoxidation refining on the molten steel can be achieved.
The mixed solid refining agent 4 comprises the following raw materials in percentage by mass: 20%% KCl, 30% NaCl, 20% NaF and 30% Na3AlF 6. Wherein, Na3AlF6, cryolite has good dissolving effect to alumina inclusion, and the gaseous phase aluminium trichloride that the reaction produced can be effectively rapid drives the alumina slag come-up moreover, and is obvious to the effect of getting rid of oxide inclusion, and the gas of multicomponent refining comprises the gas of following volume percent: 35% Ar, 30% He, 20% N2 and 15% Cl2, and the filling amount is 150% -180% of the volume of the spherical cavity. Good removal effect and little environmental pollution, has important significance for improving the compactness of the casting and fully improving the structural strength of the casting
And step S7, performing modified heat treatment on the casting by adopting a multi-stage cooling mode, cooling to 800 ℃ and preserving heat for 2h, then uniformly cooling to 180 ℃ at a speed of 20 ℃/h, heating to 600 ℃ and preserving heat for 2h, and finally naturally cooling to normal temperature to remove the mold and obtain a finished casting blank, so that the structure and performance can be obviously improved, and the fatigue resistance and wear resistance of the casting are improved.
Example 2:
referring to fig. 1, a polymorphic high-deoxidation casting method of microalloyed rare earth cast steel comprises the following steps:
s1, preprocessing: before casting, the scrap steel and the alloy elements are dried at 80 ℃, and a smelting furnace, a steel ladle and a casting mold are preheated simultaneously;
s2, alloy batching: the main chemical components of the cast steel comprise C, Si, Mn, Nb, Ti, Re, B, Cr, La, Ce, P, S, iron and trace impurity elements;
s3, smelting scrap steel: sequentially putting the scrap steel into a smelting furnace in a descending order for high-temperature smelting;
s4, adding alloy: adding Nb, Ti, La, Ce, B and Cr alloy elements in advance after the scrap steel in the furnace is melted down, then adding ferromanganese, and adding ferrosilicon after the ferromanganese is completely melted down and the slag skimming is finished;
s5, tapping: controlling the tapping temperature at 1660 ℃, mixing the modifier and the carburant with the molten steel and introducing into a steel ladle during tapping;
s6, polymorphic deoxidation: arranging a deoxidizing component at the center position in the ladle, pouring and spraying molten steel from the deoxidizing component and receiving the molten steel in the ladle, synchronously carrying out polymorphic deoxidizing along with the rising of the liquid level, and standing for 20min after the deoxidizing to remove impurities such as oxides floating on the liquid level;
s7, casting and forming: pouring the molten steel in the ladle into a prepared casting mold, controlling the pouring temperature at 1560 ℃, cooling, and removing the casting mold to obtain the formed alloy casting.
C. The weight percentage of Si, Mn, Nb, Ti, Re, B, Cr, La, Ce, P and S are respectively 0.35 percent of C, 0.70 percent of Si, 1.25 percent of Mn, 0.06 percent of Nb0.06 percent of Ti, 0.04 percent of Re0.1 percent of B, 0.019 percent of Cr, 0.018 percent of La0.05 percent of Ce, less than or equal to 0.035 percent of P and less than or equal to 0.010 percent of S, after alloy elements such as rare earth and the like are added, the structure and the performance of the cast steel are obviously improved, the hardness is improved, and the elongation and the toughness are not reduced.
And step S7, performing modified heat treatment on the casting by adopting a multi-stage cooling mode, cooling to 820 ℃ and preserving heat for 3h, then cooling to 240 ℃ at a constant speed of 35 ℃/h, heating to 700 ℃ and preserving heat for 3h, and finally naturally cooling to normal temperature to remove the mold and obtain a finished casting blank, so that the microstructure and the performance can be obviously improved, and the fatigue resistance and the wear resistance of the casting are improved.
The remainder was in accordance with example 1.
Example 3:
referring to fig. 1, a polymorphic high-deoxidation casting method of microalloyed rare earth cast steel comprises the following steps:
s1, preprocessing: before casting, the scrap steel and the alloy elements are dried at 80 ℃, and a smelting furnace, a steel ladle and a casting mold are preheated simultaneously;
s2, alloy batching: the main chemical components of the cast steel comprise C, Si, Mn, Nb, Ti, Re, B, Cr, La, Ce, P, S, iron and trace impurity elements;
s3, smelting scrap steel: sequentially putting the scrap steel into a smelting furnace in a descending order for high-temperature smelting;
s4, adding alloy: adding Nb, Ti, La, Ce, B and Cr alloy elements in advance after the scrap steel in the furnace is melted down, then adding ferromanganese, and adding ferrosilicon after the ferromanganese is completely melted down and the slag skimming is finished;
s5, tapping: controlling the tapping temperature at 1680 ℃, mixing the modifier and the carburant with the molten steel and introducing into a steel ladle during tapping;
s6, polymorphic deoxidation: arranging a deoxidizing component at the center position in the ladle, pouring and spraying molten steel from the deoxidizing component and receiving the molten steel in the ladle, synchronously carrying out polymorphic deoxidizing along with the rising of the liquid level, and standing for 30min after the deoxidizing to remove impurities such as oxides floating on the liquid level;
s7, casting and forming: and pouring the molten steel in the ladle into a prepared casting mold, controlling the pouring temperature at 1580 ℃, cooling, and removing the casting mold to obtain the formed alloy casting.
C. The mass percentage of Si, Mn, Nb, Ti, Re, B, Cr, La, Ce, P and S are respectively 0.40 percent of C, 0.80 percent of Si, 1.40 percent of Mn1, 0.09 percent of Nb0, 0.08 percent of Ti0, 0.20 percent of Re0, 0.028 percent of B, 0.024 percent of Cr0, 0.10 percent of La0, 0.15 percent of Ce0, less than or equal to 0.035 percent of P and less than or equal to 0.010 percent of S, and after alloy elements such as rare earth and the like are added, the structure and the performance of the cast steel are obviously improved, and the elongation and the toughness are not reduced while the hardness.
And step S7, performing modified heat treatment on the casting by adopting a multi-stage cooling mode, cooling to 850 ℃, preserving heat for 5h, uniformly cooling to 300 ℃ at a speed of 50 ℃/h, heating to 800 ℃, preserving heat for 5h, and naturally cooling to normal temperature to remove the mold to obtain a finished casting blank, so that the microstructure and the performance can be remarkably improved, and the fatigue resistance and the wear resistance of the casting are improved.
The remainder was in accordance with example 1.
According to the invention, on one hand, the microstructure and performance of the casting can be improved by adding trace rare earth elements, so that the strength and quality of the product are improved, on the other hand, a novel deoxidation component is introduced to perform deoxidation treatment of various forms on molten steel in a ladle, including gaseous deoxidation, solid deoxidation and vibration deoxidation, and deoxidation substances are synchronously released in real time along with the rise of the liquid level.
The above are merely preferred embodiments of the present invention; the scope of the invention is not limited thereto. Any person skilled in the art should be able to cover the technical scope of the present invention by equivalent or modified solutions and modifications within the technical scope of the present invention.
Claims (10)
1. A polymorphic high-degree deoxidation casting method of microalloyed rare earth cast steel is characterized in that: the method comprises the following steps:
s1, preprocessing: before casting, drying scrap steel and alloy elements at 60-80 ℃, and simultaneously preheating a smelting furnace, a steel ladle and a casting mold;
s2, alloy batching: the main chemical components of the cast steel comprise C, Si, Mn, Nb, Ti, Re, B, Cr, La, Ce, P, S, iron and trace impurity elements;
s3, smelting scrap steel: sequentially putting the scrap steel into a smelting furnace in a descending order for high-temperature smelting;
s4, adding alloy: adding Nb, Ti, La, Ce, B and Cr alloy elements in advance after the scrap steel in the furnace is melted down, then adding ferromanganese, and adding ferrosilicon after the ferromanganese is completely melted down and the slag skimming is finished;
s5, tapping: controlling the tapping temperature at 1650-1680 ℃, mixing the modifier and the carburant with the molten steel and introducing into a steel ladle during tapping;
s6, polymorphic deoxidation: arranging a deoxidizing component at the center position in the ladle, pouring and spraying molten steel from the deoxidizing component and receiving the molten steel in the ladle, synchronously carrying out polymorphic deoxidizing along with the rising of the liquid level, standing for 15-30min after deoxidizing, and removing impurities such as oxides floating on the liquid level;
s7, casting and forming: pouring the molten steel in the ladle into a prepared casting mold, controlling the pouring temperature at 1550-1580 ℃, cooling, and removing the casting mold to obtain the formed alloy casting.
2. The polymorphic high-deoxidation casting method of microalloyed rare earth cast steel according to claim 1, characterized in that: the mass percentages of C, Si, Mn, Nb, Ti, Re, B, Cr, La, Ce, P and S are respectively 0.30-0.40% of C, 0.60-0.80% of Si, 1.10-1.40% of Mn, 0.03-0.09% of Nb0.01-0.08% of Ti, 0.01-0.20% of Re0.01-0.028% of B, 0.01-0.024% of Cr0.01-0.10% of La0.01-0.15% of Ce, less than or equal to 0.035% of P and less than or equal to 0.010% of S.
3. The polymorphic high-deoxidation casting method of microalloyed rare earth cast steel according to claim 1, characterized in that: in the step S4, Nb, Ti, La, Ce, B, Cr alloy elements, ferromanganese and ferrosilicon alloy are subjected to impurity removal treatment before being put in, and are dried for 2-3 hours and then are put into a steel ladle in the form of metal powder.
4. The polymorphic high-deoxidation casting method of microalloyed rare earth cast steel according to claim 1, characterized in that: the modifier is SiC simple substance micro powder particles, the carburant is pure carbon powder, and the particle diameters of the modifier and the carburant are both smaller than 300 nm.
5. The polymorphic high-deoxidation casting method of microalloyed rare earth cast steel according to claim 1, characterized in that: the deoxidation component in the step S6 comprises a stretching-in deoxidation rod (1) which is distributed spirally, the lower end of the stretching-in deoxidation rod (1) is provided with a plurality of uniformly-distributed dual-purpose deoxidation balls (2), the stretching-in deoxidation rod (1) comprises an inner elastic self-vibration rod (101) and a high-temperature-resistant protective shell (102) which are distributed internally and externally, the high-temperature-resistant protective shell (102) is wrapped on the outer surface of the elastic self-vibration rod (101), and the dual-purpose deoxidation balls (2) comprise a plurality of directly-consumed deoxidation balls (201) which are distributed in a staggered mode and lossless refining balls (202).
6. The polymorphic high-deoxidation casting method of microalloyed rare earth cast steel as claimed in claim 5, characterized in that: the elastic self-vibration rod (101) is made of high-elasticity high-temperature-resistant metal materials or plastic materials, and the high-temperature-resistant protective shell (102) is made of alumina fibers.
7. The polymorphic high-deoxidation casting method of microalloyed rare earth cast steel as claimed in claim 5, characterized in that: the direct-consuming deoxidizing ball (201) is a hollow ball shell made of pure aluminum, a plurality of hemisphere clamping grooves matched with the direct-consuming deoxidizing ball (201) are formed in the lower end of the stretching deoxidizing rod (1), the direct-consuming deoxidizing ball (201) and the hemisphere clamping grooves are in interference fit, a spherical cavity is reserved between the nondestructive refining ball (202) and the high-temperature-resistant protective shell (102) in an integrated forming mode, a bent communication hole (3) is communicated between the spherical cavity and the hemisphere clamping grooves, a mixed solid refining agent (4) is filled in the direct-consuming deoxidizing ball (201), and multiple refining gases are filled in the nondestructive refining ball (202).
8. The polymorphic high-deoxidation casting process of microalloyed rare earth cast steel as claimed in claim 7, characterized in that: the mixed solid refining agent (4) is composed of the following raw materials in percentage by mass: 20-30% of KCl, 20-30% of NaCl, 20-25% of NaF and 25-30% of Na3AlF 6.
9. The polymorphic high-deoxidation casting process of microalloyed rare earth cast steel as claimed in claim 7, characterized in that: the multi-element refining gas consists of the following gases in volume percent: 35% -42% of Ar, 22% -38% of He, 10% -20% of N2 and 8% -16% of Cl2, and the filling amount is 150% -180% of the volume of the spherical cavity.
10. The polymorphic high-deoxidation casting method of microalloyed rare earth cast steel according to claim 1, characterized in that: and in the step S7, the casting is subjected to modified heat treatment in a multi-stage cooling mode, the temperature is firstly cooled to 800-850 ℃, the temperature is kept for 2-5h, then the temperature is uniformly reduced to 180-300 ℃ at the speed of 20-50 ℃/h, then the temperature is heated to 600-800 ℃, the temperature is kept for 2-5h, and finally the casting is naturally cooled to the normal temperature, so that the finished casting blank can be obtained after the mould is removed.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101748244A (en) * | 2008-12-19 | 2010-06-23 | 宋利军 | Deoxidizing ball for steelmaking production |
| CN103849818A (en) * | 2014-03-07 | 2014-06-11 | 湖北磊航铸业有限公司 | Wear-resisting cast steel and preparation method thereof |
| CN104818426A (en) * | 2015-05-19 | 2015-08-05 | 海安海太铸造有限公司 | High-strength microalloyed rare-earth cast steel and preparation method thereof |
| CN110527925A (en) * | 2019-09-18 | 2019-12-03 | 宁波市鄞州富春精密铸造有限公司 | A kind of cast steel adding rare earth element |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101748244A (en) * | 2008-12-19 | 2010-06-23 | 宋利军 | Deoxidizing ball for steelmaking production |
| CN103849818A (en) * | 2014-03-07 | 2014-06-11 | 湖北磊航铸业有限公司 | Wear-resisting cast steel and preparation method thereof |
| CN104818426A (en) * | 2015-05-19 | 2015-08-05 | 海安海太铸造有限公司 | High-strength microalloyed rare-earth cast steel and preparation method thereof |
| CN110527925A (en) * | 2019-09-18 | 2019-12-03 | 宁波市鄞州富春精密铸造有限公司 | A kind of cast steel adding rare earth element |
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