CN112080704B - High-toughness high-hardness cold and hot combined type die steel and preparation method thereof - Google Patents
High-toughness high-hardness cold and hot combined type die steel and preparation method thereof Download PDFInfo
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- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
Abstract
The invention provides high-toughness high-hardness cold and hot combined type die steel which comprises the following components in percentage by mass: C 0.75-0.85%, Si 0.8-1.2%, Mn 0.3-0.7%, Cr 5.0-6.0%, Mo 2.2-2.6%, V 0.4-0.7%, P<0.025％, S<0.003％ and the balance of Fe. The content of C is set between the components of the hot-work die steel and the cold-work die steel, so that the hardenability and hardenability of the material can be improved, alloy carbide can be formed, and the wear resistance is improved; the Si content is reduced to improve the toughness of the material; the content of V is reduced, the content of Mo is improved, the generation of V-containing eutectic carbide can be reduced, the influence on toughness is reduced, and the material is ensured to have better tempering softening resistance. The results of the examples show that the die steel has a hardness of 56 to 64HRC and an impact toughness of 80 to 140J.
Description
Technical Field
The invention relates to the technical field of die steel manufacturing, in particular to high-toughness high-hardness cold and hot combined die steel and a preparation method thereof.
Background
The die steel is used for manufacturing dies such as cold stamping dies, hot forging dies, die-casting dies and the like, is divided into three types of cold-work die steel, hot-work die steel and plastic die steel, and is used for forging, stamping, extruding, die-casting and the like. Since various dies are used in different applications and work conditions are complicated, die steels are required to have high hardness and high toughness to meet the use of different work conditions.
At present, the hardness and toughness of the die steel are generally improved by adjusting the component content of the die steel, for example, patent CN104561802A describes a high-hardness high-toughness cold-work die steel, which comprises the following chemical components in percentage by weight: c: 1.025 to 1.055%, Si: 0.85-0.90%, Mn: 0.20-0.40%, P < 0.02%, S < 0.02%, Cr: 8.30-8.50%, Mo: 1.95-2.05%, V: 0.20-0.40%, and the balance of Fe and inevitable impurities; and the above elements simultaneously need to satisfy the following relations: c ═ 0.1(Cr + Mo). Although the die steel with high toughness and high hardness is obtained by the process, the impact energy of the steel can only reach 76J, the higher the hardness of the die steel is, the poorer the impact toughness is, and the more complicated the working conditions of the die steel are, the higher the performance requirements on the die steel are, and the impact toughness of the die steel is difficult to meet the requirements. Therefore, it is necessary to further improve the toughness of the die steel while ensuring high hardness of the die steel.
Disclosure of Invention
The invention aims to provide high-toughness high-hardness cold and hot combined die steel and a preparation method thereof.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides high-toughness high-hardness cold and hot combined type die steel which comprises the following components in percentage by mass: 0.75-0.85% of C, 0.8-1.2% of Si, 0.3-0.7% of Mn, 5.0-6.0% of Cr5, 2.2-2.6% of Mo2, 0.4-0.7% of V, 0.025% of P, 0.003% of S and the balance of Fe.
Preferably, the method comprises the following steps of: 0.78-0.82% of C, 0.9-1.1% of Si, 0.4-0.6% of Mn, 5.3-5.7% of Cr, 2.3-2.5% of Mo, 0.5-0.6% of V, 0.020% of P, 0.002% of S and the balance of Fe.
Preferably, the method comprises the following steps of: 0.80% of C, 1.0% of Si, 0.5% of Mn0, 5.5% of Cr5, 2.4% of Mo2, 0.55% of V, less than 0.015% of P, less than 0.001% of S and the balance of Fe.
The invention provides a preparation method of cold and hot combined type die steel, which comprises the following steps:
(1) mixing alloy raw materials and smelting to obtain a steel ingot;
(2) forging the steel ingot obtained in the step (1) to obtain a forged alloy;
(3) and (3) carrying out heat treatment on the forged alloy obtained in the step (2) to obtain cold and hot combined die steel.
Preferably, the smelting in the step (1) sequentially comprises electric furnace smelting, LF furnace refining, VD degassing, pouring and electroslag remelting.
Preferably, the forging in the step (2) sequentially comprises forging cogging and forging forming.
Preferably, the heating temperature of the forging cogging is 1150-1250 ℃; the forging and cogging temperature is 1150-1230 ℃, and the finish forging temperature is more than 820 ℃.
Preferably, the forging forming starting temperature is 1150-1200 ℃.
Preferably, the forging forming is free forging forming.
Preferably, the heat treatment in the step (3) includes a fine grain heat treatment and a spheroidizing annealing which are sequentially performed.
The invention provides high-toughness high-hardness cold and hot combined type die steel which comprises the following components in percentage by mass: 0.75-0.85% of C, 0.8-1.2% of Si, 0.3-0.7% of Mn, 5.0-6.0% of Cr5, 2.2-2.6% of Mo2, 0.4-0.7% of V, 0.025% of P, 0.003% of S and the balance of Fe. The content of C is set between the components of the hot-work die steel and the cold-work die steel, so that the hardenability and hardenability of the material can be improved, alloy carbide can be formed, and the wear resistance is improved; the Si content is reduced to improve the toughness of the material; the Cr content is kept the same as that in the hot-work die steel H13, the V content is reduced, the Mo content is increased, the generation of V-containing eutectic carbide can be reduced, the influence on the toughness is reduced, and the material is ensured to have better tempering softening resistance. The example results show that the cold and hot combined type die steel provided by the invention has the hardness of 56-64 HRC, the wear resistance of the cold and hot combined type die steel is obviously improved compared with H13 steel (C0.36-0.40%), the impact toughness of 80-140J, and the toughness of the cold and hot combined type die steel is excellent compared with D2 (C1.45-1.7%), and the cold and hot combined type die steel has more excellent wear resistance and fracture resistance.
Drawings
FIG. 1 is a microstructure of a cold and hot combined type die steel prepared in example 1 of the present invention under an optical microscope of 100 times;
FIG. 2 is a microstructure of a 500-fold optical microscope of a cold and hot combined die steel prepared in example 1 of the present invention.
Detailed Description
The invention provides high-toughness high-hardness cold and hot combined type die steel which comprises the following components in percentage by mass: 0.75-0.85% of C, 0.8-1.2% of Si, 0.3-0.7% of Mn, 5.0-6.0% of Cr5, 2.2-2.6% of Mo2, 0.4-0.7% of V, 0.025% of P, 0.003% of S and the balance of Fe.
According to the mass percentage, the cold and hot combined type die steel provided by the invention comprises 0.75-0.85% of C, preferably 0.78-0.83%, and more preferably 0.80%. In the present invention, when the content of C is within the above range, hardenability and hardenability of the material can be improved, and alloy carbide can be formed to improve wear resistance, and when the content is beyond the above range, toughness of the material is reduced and cracking is likely to occur during heat treatment.
According to the mass percentage, the cold and hot combined type die steel provided by the invention comprises 0.8-1.2% of Si, preferably 0.9-1.1%, and more preferably 1.0%. In the present invention, when the Si content is within the above range, the Si can be dissolved in the matrix to perform a solid solution strengthening effect, and migration and precipitation of C atoms in the steel are controlled, so that the strength and the tempering stability of the steel are increased, and when the Si content exceeds the above range, a segregation phenomenon is caused, and the brittleness of the material is increased.
According to the mass percentage, the cold and hot combined type die steel provided by the invention comprises 0.3-0.7% of Mn0.4-0.6% preferably, and 0.5% more preferably. In the present invention, Mn is an austenite stabilizing element, and when the content is within the above range, hardenability of the steel can be improved, and exceeding the above range results in excessive retained austenite in the quenched structure, increases the tendency of grain growth of the material, reduces wear resistance, and increases the risk of cracking of the material.
According to the mass percentage, the cold and hot combined type die steel provided by the invention comprises 5.0-6.0% of Cr5.3-5.7%, preferably 5.5%. In the present invention, when the Cr content is within the above range, the hardenability of the alloy can be improved, and the wear resistance can be improved by forming carbide after the Cr content is combined with carbon; exceeding the above content range results in an increase in eutectic carbides and an increase in brittleness.
According to the mass percentage, the cold and hot combined type die steel provided by the invention comprises Mo2.2-2.6%, preferably 2.3-2.5%, and more preferably 2.4%. In the present invention, when the Mo content is within the above range, the tempering resistance of the steel can be improved, and fine carbides are formed in combination with carbon to improve wear resistance; exceeding the above content range results in a decrease in toughness of the material and an increase in cost.
According to the mass percentage, the cold and hot combined type die steel provided by the invention comprises V0.4-0.7%, preferably 0.5-0.6%, and more preferably 0.55%. In the invention, when the content of V is in the range, vanadium carbide can be formed, grain boundary can be pinned, crystal grains can be refined, and the vanadium carbide has stable property and plays a remarkable precipitation strengthening role; exceeding the above content range causes formation of eutectic vanadium carbide, and the hardness thereof is high, which easily causes occurrence of cracking phenomenon during forging or use.
According to the mass percentage, the cold and hot combined type die steel provided by the invention comprises P < 0.025%, preferably P < 0.020%, and more preferably P < 0.015%. In the present invention, P is a harmful element, which increases brittleness of steel, deteriorates weldability, and increases temper brittleness, so that the content thereof is controlled to 0.02% or less.
According to the mass percentage, the cold and hot combined type die steel provided by the invention comprises S < 0.003%, preferably S < 0.002%, and more preferably S < 0.001%. In the present invention, since S is a harmful element and causes a reduction in toughness of steel and anisotropy, the content thereof is controlled to 0.003% or less.
In the invention, the components of the cold and hot combined type die steel are preferably C0.78-0.82%, Si 0.9-1.1%, Mn 0.4-0.6%, Cr5.3-5.7%, Mo2.3-2.5%, V0.5-0.6%, P < 0.020%, S < 0.002% and the balance of Fe, and more preferably: 0.80% of C, 1.0% of Si, 0.5% of Mn0, 5.5% of Cr5, 2.4% of Mo2, 0.55% of V, less than 0.015% of P, less than 0.001% of S and the balance of Fe.
The content of C is set between the components of the hot-work die steel and the cold-work die steel, so that the hardenability and hardenability of the material can be improved, alloy carbide can be formed, and the wear resistance is improved; the Si content is reduced to improve the toughness of the material; the Cr content is kept the same as that in the hot die steel H13, the V content is reduced, the Mo content is increased, the generation of V-containing eutectic carbide can be reduced, the influence on toughness is reduced, the material is ensured to have better tempering softening resistance, and the hot and cold die steel material is a cold and hot die steel material.
The invention also provides a preparation method of the cold and hot combined type die steel, which comprises the following steps:
(1) mixing alloy raw materials and smelting to obtain a steel ingot;
(2) forging the steel ingot obtained in the step (1) to obtain a forged alloy;
(3) and (3) carrying out heat treatment on the forged alloy obtained in the step (2) to obtain cold and hot combined die steel.
The invention mixes the alloy raw materials and then smelts the alloy raw materials to obtain the steel ingot. The kind and source of the alloy raw materials are not particularly limited in the present invention, and raw materials capable of providing the above-mentioned alloy elements, which are well known to those skilled in the art, may be used. The operation of mixing the alloy raw materials is not particularly limited in the invention, and the technical scheme for preparing the mixed materials, which is well known to those skilled in the art, can be adopted.
In the invention, the smelting preferably sequentially comprises electric furnace smelting, LF furnace refining, VD degassing, pouring and electroslag remelting. The operation of the electric furnace smelting is not specially limited, and the P content during tapping is ensured to be less than 0.025 percent. The invention has no special limitation on the refining operation of the LF furnace, and the refining operation is only required to ensure that the S mass content in the steel is less than 0.003 percent after the refining is finished. The operation of VD degassing is not specially limited, as long as the mass content of oxygen in steel after degassing is less than or equal to 0.0025 percent and the mass content of H is less than or equal to 0.0002 percent.
In the present invention, the electroslag remelting is preferably performed in a protective atmosphere. The protective atmosphere in the present invention is not particularly limited, and a protective atmosphere known to those skilled in the art may be used. In the present invention, the protective atmosphere is preferably an argon atmosphere. The operation of the electroslag remelting is not specially limited, and the steel is ensured to have oxygen and sulfur contents of less than 0.003 percent by mass after the remelting is finished. In the invention, the electroslag remelting is carried out in a protective atmosphere, so that the purity of steel can be improved, and the solidification condition of the steel can be improved, thereby reducing the element segregation, reducing the defects of loosening and shrinkage cavity and the like, and improving the compactness of the steel ingot.
After the smelting is finished, the invention preferably pours the smelted molten steel to obtain a steel ingot. In the present invention, the pouring is preferably performed under the protection of argon. The operation of the casting is not particularly limited in the present invention, and may be performed by an operation known to those skilled in the art. In the invention, the argon protection pouring can prevent oxygen and water vapor dissolved in the steel into the atmosphere.
After the steel ingot is obtained, the steel ingot is forged to obtain a forged alloy. In the present invention, the forging preferably includes forging cogging and forging forming in this order. In the invention, the forging temperature of the forging cogging is preferably 1150-1230 ℃, and more preferably 1200-1220 ℃; the finish forging temperature is preferably more than 820 ℃, more preferably 850-1200 ℃, and most preferably 860-880 ℃. In the present invention, the forging cogging can process the steel ingot to the specification before forging forming. The invention has no special limit on the deformation amount of forging and cogging, and can process according to the actually required size.
In the invention, the forging temperature of the forging forming is preferably 1150-1200 ℃, and more preferably 1160-1180 ℃. The invention preferably heats the forging and cogging product to the forging forming initial forging temperature without cooling. The rate of heating to the forging initiation temperature is not particularly limited in the present invention, so long as the forging initiation temperature is ensured. In the present invention, the forging is preferably free forging, and more preferably hammer forging. The specific operation of the forging and forming is not particularly limited in the present invention, and the operation known to those skilled in the art may be adopted. The deformation amount of the forging forming is not specially limited, and the forging forming can be processed according to the actually required size. In the present invention, the forging molding enables the steel ingot to be processed into a desired size.
After the forging forming is completed, the invention preferably cools the forging formed product to obtain the forging alloy. In the present invention, the cooling is preferably air cooling, mist cooling or air cooling. The cooling rate is not particularly limited in the present invention, and may be a cooling rate well known to those skilled in the art.
After the forged alloy is obtained, the forged alloy is subjected to heat treatment to obtain the cold and hot combined type die steel. In the present invention, the heat treatment preferably includes a fine grain heat treatment and a spheroidizing annealing which are sequentially performed.
In the present invention, the fine grain heat treatment is preferably performed by heating the wrought alloy to a temperature for holding, and then cooling. In the invention, the fine grain heat treatment is carried out on the forged alloy, so that the forged alloy achieves the purposes of grain refinement and uniform structure after being cooled and heated.
The heating rate is not particularly limited in the present invention, and a heating rate well known to those skilled in the art may be used. In the invention, the temperature of the heat preservation is preferably 1000-1050 ℃, more preferably 1010-1040 ℃, and most preferably 1030 ℃; the heat preservation time is preferably 2.3-3 h of heat preservation according to the effective heating thickness of each 100mm, more preferably 2.5-2.8 h of heat preservation according to the effective heating thickness of each 100mm, and most preferably 2.6h of heat preservation according to the effective heating thickness of each 100 mm. In the present invention, the cooling is preferably at least one of water cooling, mist cooling and air cooling; the cooling end point temperature is preferably 250-400 ℃, more preferably 280-350 ℃, and even more preferably 300-320 ℃. The cooling rate is not particularly limited in the present invention, and may be a cooling rate well known to those skilled in the art.
In the present invention, the spheroidizing annealing is preferably isothermal spheroidizing annealing; the isothermal spheroidizing annealing preferably includes a first annealing and a second annealing in this order. According to the invention, through the spheroidizing annealing process, the secondary carbides of the steel grade are spherical and uniformly distributed in the ferrite matrix to form a pearlite structure, and the hardness is controlled to be 150-230 HB, so that the subsequent cutting processing is facilitated.
The heating rate of the first annealing is not particularly limited in the present invention, and a heating rate known to those skilled in the art may be used. In the invention, the heat preservation temperature of the first annealing is preferably 820-880 ℃, more preferably 840-860 ℃ and most preferably 850 ℃; the heat preservation time of the first annealing is preferably 10-20 h, more preferably 13-18 h, and most preferably 15 h. In the invention, the cooling rate of the first annealing is preferably less than 20 ℃/h, more preferably 15-17 ℃/h, and most preferably 16 ℃/h. In the present invention, the cooling end point temperature of the first annealing is preferably the soaking temperature of the second annealing.
In the invention, the heat preservation temperature of the second annealing is preferably 650-750 ℃, more preferably 720-740 ℃, and most preferably 730 ℃; the heat preservation time of the second annealing is preferably 10-20 hours, more preferably 12-18 hours, and most preferably 15-17 hours. In the invention, the cooling rate of the second annealing is preferably less than 20 ℃/h, more preferably 10-15 ℃/h, and most preferably 13 ℃/h. In the invention, the cooling end point temperature of the second annealing is preferably 400-500 ℃, more preferably 430-470 ℃, and most preferably 450 ℃.
The preparation method provided by the invention can further purify the matrix, and the secondary carbides are distributed in a fine and dispersed manner and have no large primary carbides, so that the hardness and toughness of the die steel are improved.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The cold and hot combined type die steel comprises the following components in percentage by mass: 0.80% of C, 1.0% of Si, 0.5% of Mn0, 5.5% of Cr5, 2.4% of Mo2, 0.55% of V, less than 0.025% of P, less than 0.001% of S and the balance of Fe;
the preparation method of the cold and hot combined type die steel comprises the following steps:
(1) mixing the materials according to the weight percentage, smelting in an electric furnace, controlling tapping P0.018wt%, refining in an LF furnace, and controlling S0.004wt%; degassing by a VD furnace, and controlling the oxygen content in the steel to be 0.0025 wt% and the H content to be 0.0002 wt%; then pouring under the protection of argon; then, carrying out electroslag remelting under the protection of atmosphere to reduce the oxygen content to 0.002 wt% and the sulfur content to 0.0008 wt% to obtain a steel ingot;
(2) forging the steel ingot obtained in the step (1), wherein forging and cogging are firstly carried out, the heating temperature for forging and cogging is 1230 ℃, the forging temperature is 1200 ℃, and the finish forging temperature is 850 ℃; forging and forming by adopting hammer forging, wherein the initial forging temperature of the forging and forming is 1180 ℃, and obtaining a forged alloy;
(3) and (3) cooling the wrought alloy obtained in the step (2) to 350 ℃ in air, then carrying out heat treatment, and firstly carrying out fine grain heat treatment: heating to 1030 ℃, preserving heat for 3 hours according to the effective heating thickness of each 100mm, and then cooling to 280 ℃ by adopting water cooling and air cooling; and then spheroidizing annealing: heating to 850 ℃ and preserving heat for 15h, cooling to 740 ℃ at the speed of 15 ℃/h and preserving heat for 15h, cooling to 500 ℃ at the speed of 15 ℃/h, and discharging to obtain the cold and hot mold steel.
Example 2
The cold and hot combined type die steel comprises the following components in percentage by mass: 0.85% of C, 1.1% of Si, 0.6% of Mn0, 5.3% of Cr5, 2.2% of Mo2, 0.55% of V, less than 0.025% of P, less than 0.002% of S and the balance of Fe;
the preparation method of the cold and hot combined type die steel comprises the following steps:
(1) mixing the materials according to the weight percentage, smelting in an electric furnace, controlling tapping P0.018wt%, refining in an LF furnace, and controlling S0.003wt%; degassing by a VD furnace, and controlling the oxygen content in the steel to be 0.0020 wt% and the H content to be 0.0002 wt%; then pouring under the protection of argon; then, carrying out electroslag remelting under the protection of atmosphere to reduce the oxygen content to 0.002 wt% and the sulfur content to 0.001 wt% so as to obtain a steel ingot;
(2) forging the steel ingot obtained in the step (1), wherein forging and cogging are firstly carried out, the heating temperature for forging and cogging is 1200 ℃, the forging temperature is 1180 ℃, and the finish forging temperature is 900 ℃; forging and forming by adopting hammer forging, wherein the initial forging temperature of the forging and forming is 1150 ℃, and obtaining a forged alloy;
(3) and (3) cooling the wrought alloy obtained in the step (2) to 350 ℃ in air, then carrying out heat treatment, and firstly carrying out fine grain heat treatment: heating to 1030 ℃, preserving heat for 3 hours according to the effective heating thickness of each 100mm, and then cooling to 300 ℃ by adopting water cooling and air cooling; and then spheroidizing annealing: heating to 850 ℃ and preserving heat for 15h, cooling to 740 ℃ at the speed of 15 ℃/h and preserving heat for 15h, cooling to 450 ℃ at the speed of 15 ℃/h, and discharging to obtain the cold and hot mold steel.
Example 3
The cold and hot combined type die steel comprises the following components in percentage by mass: 0.78% of C, 0.8% of Si, 0.7% of Mn0, 6.0% of Cr0%, 2.3% of Mo2, 0.60% of V, less than 0.025% of P, less than 0.002% of S and the balance of Fe;
the preparation method of the cold and hot combined type die steel comprises the following steps:
(1) mixing the materials according to the weight percentage, smelting in an electric furnace, controlling tapping P0.018wt%, refining in an LF furnace, and controlling S0.003wt%; degassing by a VD furnace, and controlling the oxygen content in the steel to be 0.0025 wt% and the H content to be 0.0002 wt%; then pouring under the protection of argon; then, carrying out electroslag remelting under the protection of atmosphere to reduce the oxygen content to 0.002 wt% and the sulfur content to 0.001 wt% so as to obtain a steel ingot;
(2) forging the steel ingot obtained in the step (1), wherein forging and cogging are firstly carried out, the heating temperature for forging and cogging is 1250 ℃, the forging temperature is 1230 ℃, and the finish forging temperature is 850 ℃; forging and forming by adopting hammer forging, wherein the initial forging temperature of the forging and forming is 1200 ℃, and obtaining a forged alloy;
(3) and (3) cooling the wrought alloy obtained in the step (2) to 350 ℃ in air, then carrying out heat treatment, and firstly carrying out fine grain heat treatment: heating to 1050 ℃, preserving heat for 3 hours according to the effective heating thickness of each 100mm, and then cooling to 280 ℃ by adopting water cooling and air cooling; and then spheroidizing annealing: heating to 850 ℃ and preserving heat for 15h, cooling to 750 ℃ at a speed of 17 ℃/h and preserving heat for 15h, cooling to 480 ℃ at a speed of 17 ℃/h and discharging to obtain the cold and hot die steel.
Example 4
The cold and hot combined type die steel comprises the following components in percentage by mass: 0.85% of C, 1.0% of Si, 0.7% of Mn0.5% of Cr5.5%, Mo2.4%, 0.65% of V, less than 0.025% of P, less than 0.003% of S and the balance of Fe;
the preparation method of the cold and hot combined type die steel comprises the following steps:
(1) mixing the materials according to the weight percentage, smelting in an electric furnace, controlling tapping P0.018wt%, refining in an LF furnace, and controlling S0.003wt%; degassing by a VD furnace, and controlling the oxygen content in the steel to be 0.0025 wt% and the H content to be 0.0002 wt%; then pouring under the protection of argon; then, carrying out electroslag remelting under the protection of atmosphere to reduce the oxygen content to 0.0025 wt% and the sulfur content to 0.0025 wt% so as to obtain a steel ingot;
(2) forging the steel ingot obtained in the step (1), wherein forging and cogging are firstly carried out, the heating temperature for forging and cogging is 1230 ℃, the forging temperature is 1200 ℃, and the finish forging temperature is 830 ℃; forging and forming by adopting hammer forging, wherein the initial forging temperature of the forging and forming is 1160 ℃, so as to obtain a forged alloy;
(3) and (3) cooling the wrought alloy obtained in the step (2) to 350 ℃ in air, then carrying out heat treatment, and firstly carrying out fine grain heat treatment: heating to 1030 ℃, preserving heat for 3 hours according to the effective heating thickness of each 100mm, and then cooling to 280 ℃ by adopting water cooling and air cooling; and then spheroidizing annealing: heating to 870 ℃, preserving heat for 18h, cooling to 740 ℃ at the speed of 13 ℃/h, preserving heat for 18h, cooling to 450 ℃ at the speed of 13 ℃/h, discharging to obtain the cold and hot mold steel.
Example 5
The cold and hot combined type die steel comprises the following components in percentage by mass: 0.80% of C, 1.0% of Si, 0.5% of Mn0, 5.5% of Cr5, 2.4% of Mo2, 0.55% of V, less than 0.025% of P, less than 0.001% of S and the balance of Fe;
the preparation method of the cold and hot combined type die steel comprises the following steps:
(1) mixing the materials according to the weight percentage, smelting in an electric furnace, controlling tapping P0.018wt%, refining in an LF furnace, and controlling S0.004wt%; degassing by a VD furnace, and controlling the oxygen content in the steel to be 0.0025 wt% and the H content to be 0.0002 wt%; then pouring under the protection of argon; then, carrying out electroslag remelting under the protection of atmosphere to reduce the oxygen content to 0.002 wt% and the sulfur content to 0.0008 wt% to obtain a steel ingot;
(2) forging the steel ingot obtained in the step (1), wherein forging and cogging are firstly carried out, the heating temperature for forging and cogging is 1230 ℃, the forging temperature is 1200 ℃, and the finish forging temperature is 850 ℃; forging and forming by adopting hammer forging, wherein the initial forging temperature of the forging and forming is 1180 ℃, and obtaining a forged alloy;
(3) and (3) cooling the wrought alloy obtained in the step (2) to 350 ℃ in air, then carrying out heat treatment, and firstly carrying out fine grain heat treatment: heating to 1030 ℃, preserving heat for 3 hours according to the effective heating thickness of each 100mm, and then cooling to 280 ℃ by adopting water cooling and air cooling; and then spheroidizing annealing: heating to 850 ℃ and preserving heat for 15h, cooling to 740 ℃ at the speed of 15 ℃/h and preserving heat for 15h, cooling to 430 ℃ at the speed of 15 ℃/h, and discharging to obtain the cold and hot mold steel.
As can be seen from fig. 1 and 2, the structure of the cold and hot combined die steel of the present invention was uniform, as shown in fig. 1, in which the structure of the cold and hot combined die steel prepared in example 1 was observed under an optical microscope of 100 × and as shown in fig. 2, in which the structure of the cold and hot combined die steel prepared in example 1 was observed under an optical microscope of 500 × respectively.
The cold and hot combined type die steel prepared in examples 1 to 5 was subjected to a performance test: the test results are shown in table 1:
TABLE 1 hardness and toughness test data for die steels prepared in examples 1-5
| Testing | Example 1 | Example 2 | Example 3 | Example 4 | Example 5 |
| Hardness (HRC) | 58 | 60 | 62 | 64 | 60 |
| 5X 10X 55 unnotched impact toughness (J) | 140 | 100 | 85 | 90 | 120 |
As can be seen from the above examples, the die steel provided by the present invention has high hardness and high toughness.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (8)
1. The high-toughness high-hardness cold and hot combined die steel comprises the following components in percentage by mass: 0.75-0.85% of C, 0.8-1.2% of Si, 0.3-0.7% of Mn, 5.0-6.0% of Cr, 2.2-2.6% of Mo, 0.4-0.7% of V, 0.025% of P, 0.003% of S and the balance of Fe;
the preparation method of the cold and hot combined type die steel comprises the following steps:
(1) mixing alloy raw materials and smelting to obtain a steel ingot;
(2) forging the steel ingot obtained in the step (1) to obtain a forged alloy;
(3) carrying out heat treatment on the forged alloy obtained in the step (2) to obtain cold and hot combined die steel;
the smelting in the step (1) sequentially comprises electric furnace smelting, LF furnace refining, VD degassing, pouring and electroslag remelting;
the heat treatment in the step (3) is fine grain heat treatment and spheroidizing annealing which are sequentially carried out;
the fine grain heat treatment is to heat the forged alloy to a heat preservation temperature for heat preservation and then cool the forged alloy; the temperature of the heat preservation is 1000-1050 ℃; the heat preservation time is 2.3-3 h according to the effective heating thickness of each 100 mm; the cooling end point temperature is 250-400 ℃;
the spheroidizing annealing is isothermal spheroidizing annealing; the isothermal spheroidizing annealing is sequentially a first annealing and a second annealing; the heat preservation temperature of the first annealing is 820-880 ℃, and the heat preservation time of the first annealing is 10-20 hours; the heat preservation temperature of the second annealing is 650-750 ℃, and the heat preservation time of the second annealing is 10-20 hours.
2. A cold-hot combined type die steel according to claim 1, which consists of the following components in percentage by mass: 0.78-0.82% of C, 0.9-1.1% of Si, 0.4-0.6% of Mn, 5.3-5.7% of Cr5, 2.3-2.5% of Mo, 0.5-0.6% of V, 0.020% of P, 0.002% of S and the balance of Fe.
3. A cold-hot combined type die steel according to claim 1, which consists of the following components in percentage by mass: 0.80% of C, 1.0% of Si, 0.5% of Mn, 5.5% of Cr, 2.4% of Mo, 0.55% of V, less than 0.015% of P, less than 0.001% of S and the balance of Fe.
4. The method for producing cold and hot combined type die steel according to any one of claims 1 to 3, comprising the steps of:
(1) mixing alloy raw materials and smelting to obtain a steel ingot;
(2) forging the steel ingot obtained in the step (1) to obtain a forged alloy;
(3) carrying out heat treatment on the forged alloy obtained in the step (2) to obtain cold and hot combined die steel;
the smelting in the step (1) sequentially comprises electric furnace smelting, LF furnace refining, VD degassing, pouring and electroslag remelting;
the heat treatment in the step (3) is fine grain heat treatment and spheroidizing annealing which are sequentially carried out;
the fine grain heat treatment is to heat the forged alloy to a heat preservation temperature for heat preservation and then cool the forged alloy; the temperature of the heat preservation is 1000-1050 ℃; the heat preservation time is 2.3-3 h according to the effective heating thickness of each 100 mm; the cooling end point temperature is 250-400 ℃;
the spheroidizing annealing is isothermal spheroidizing annealing; the isothermal spheroidizing annealing is sequentially a first annealing and a second annealing; the heat preservation temperature of the first annealing is 820-880 ℃, and the heat preservation time of the first annealing is 10-20 hours; the heat preservation temperature of the second annealing is 650-750 ℃, and the heat preservation time of the second annealing is 10-20 hours.
5. The production method according to claim 4, wherein the forging in the step (2) includes forging cogging and forging forming in this order.
6. The preparation method according to claim 5, wherein the heating temperature for forging and cogging is 1150-1250 ℃; the forging and cogging temperature is 1150-1230 ℃, and the finish forging temperature is more than 820 ℃.
7. The method according to claim 5, wherein the forging temperature is 1150-1200 ℃.
8. The method of manufacturing according to claim 5, wherein the forging forming is free forging forming.
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