CN113584394A - Hot-forging die steel and preparation method thereof, and piston forging forming die and preparation method thereof - Google Patents
Hot-forging die steel and preparation method thereof, and piston forging forming die and preparation method thereof Download PDFInfo
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- CN113584394A CN113584394A CN202110894658.1A CN202110894658A CN113584394A CN 113584394 A CN113584394 A CN 113584394A CN 202110894658 A CN202110894658 A CN 202110894658A CN 113584394 A CN113584394 A CN 113584394A
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- C—CHEMISTRY; METALLURGY
- 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
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/32—Soft annealing, e.g. spheroidising
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- 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
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
Abstract
The invention provides a hot forging die steel and a preparation method thereof, and a piston forging forming die and a preparation method thereof. The hot forging die steel provided by the invention comprises the following chemical components in percentage by mass: 0.35-0.41% of C, 0.40-0.60% of Si, 0.40-0.50% of Mn, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 4.90-5.10% of Cr, 1.5-1.6% of Mo, 0.35-0.40% of V and the balance of Fe. The invention also provides a preparation method of the piston forging forming die, which comprises the following steps: sequentially carrying out rough machining, preheating treatment, quenching, high-temperature tempering and finish machining on the hot-forging die steel to obtain a die blank; and carrying out surface strengthening treatment on the die blank to obtain the piston forging forming die. Experimental results show that the service life of a die prepared from the hot forging die steel provided by the invention is 7000-10000.
Description
Technical Field
The invention relates to the technical field of forging dies, in particular to a hot forging die steel and a preparation method thereof, and a piston forging forming die and a preparation method thereof.
Background
With the development of science and technology, the automation technology represented by robots is gradually becoming the development trend of the forging industry. Among them, a forging die widely used in automated forging is a hot forging die.
At present, H13 die steel is widely used for preparing hot forging dies due to the advantages of high hardenability, high toughness, excellent hot cracking resistance and the like. However, when a forging with a complex structure, such as a steel piston, has the characteristics of deep cavity, small draft angle and thin wall thickness, a piston forging die made of H13 die steel has a short service life, and after 1000-2000 forgings, the die has serious defects of cracking, abrasion, collapse, ejector rod deformation and the like, so that the die is scrapped and cannot meet the requirement of automatic forging production.
Therefore, it is a problem to be solved to provide a hot forging die steel with long service life.
Disclosure of Invention
The invention aims to provide a hot forging die steel and a preparation method thereof, and a piston forging forming die and a preparation method thereof. The piston forging forming die prepared from the hot forging die steel has long service life.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a hot-forging die steel which comprises the following chemical components in percentage by mass: 0.35-0.41% of C, 0.40-0.60% of Si, 0.40-0.50% of Mn, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 4.90-5.10% of Cr, 1.5-1.6% of Mo, 0.35-0.40% of V and the balance of Fe.
Preferably, the chemical components comprise, in mass percent: 0.36-0.40% of C, 0.45-0.55% of Si, 0.42-0.48% of Mn, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 4.95-5.05% of Cr4, 1.55-1.6% of Mo, 0.36-0.39% of V and the balance of Fe.
Preferably, the chemical components comprise, in mass percent: 0.37-0.39% of C, 0.48-0.52% of Si, 0.45-0.47% of Mn, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 4.98-5.02% of Cr4, 1.58-1.6% of Mo, 0.36-0.39% of V and the balance of Fe.
The invention also provides a preparation method of the hot forging die steel in the technical scheme, which comprises the following steps:
(1) mixing alloy raw materials and smelting to obtain a steel ingot;
(2) carrying out hot forging on the steel ingot obtained in the step (1) to obtain a forged alloy;
(3) and (3) carrying out spheroidizing annealing on the forged alloy obtained in the step (2) to obtain the hot forging die steel.
Preferably, the spheroidizing annealing in the step (3) includes heating the wrought alloy, performing first heat preservation, performing second heat preservation after first cooling, and finally performing second cooling.
Preferably, the first heat preservation temperature is 850-870 ℃, and the first heat preservation time is 15-25 h.
Preferably, the temperature of the second heat preservation is 740-760 ℃, and the time of the second heat preservation is 15-20 hours.
The invention also provides a preparation method of the piston forging forming die, which comprises the following steps:
1) sequentially carrying out rough machining, preheating treatment, quenching, high-temperature tempering and finish machining on the hot-forging die steel or the hot-forging die steel prepared by the preparation method in the technical scheme to obtain a die blank;
2) carrying out surface strengthening treatment on the die blank obtained in the step 1) to obtain a piston forging forming die.
Preferably, the surface strengthening treatment in the step 2) includes nitriding treatment and physical vapor deposition treatment which are sequentially performed.
The invention also provides a piston forging forming die prepared by the preparation method in the technical scheme.
The invention provides a hot-forging die steel which comprises the following chemical components in percentage by mass: 0.35-0.41% of C, 0.40-0.60% of Si, 0.40-0.50% of Mn, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 4.90-5.10% of Cr4, 1.5-1.6% of Mo, 0.35-0.40% of V and the balance of Fe. The invention optimizes and improves the components on the basis of H13 die steel, and increases the carbide proportion formed by Mo in the die steel by increasing the content of Mo element, thereby increasing the hardness of the die steel; the hardness of the die steel is further improved by increasing the content of Mn element; the toughness of the die steel is improved by reducing the content of Si element; the generation of V-containing eutectic carbide can be reduced by reducing the content of the V element, and the adverse effect on the toughness is reduced, so that the service life of the die steel is prolonged by improving the strength and the toughness of the die steel. Experimental results show that the service life of a piston die prepared from the hot forging die steel provided by the invention reaches 7000-10000.
Drawings
FIG. 1 is a schematic sectional view showing a piston mold manufactured in application examples 1 to 3,
in the figure, 1 is an upper die sleeve, 2 is a base plate, 3 is an upper male die, 4 is a punch, 5 is a stress ring, 6 is a lower female die, 7 is a lower die core, and 8 is an ejector rod;
FIG. 2 is a schematic top view of a piston mold prepared in application examples 1 to 3;
in the figure, 5 is a stress ring, 6 is a lower concave die, 7 is a lower die core, and 8 is an ejector rod.
Detailed Description
The invention provides a hot-forging die steel which comprises the following chemical components in percentage by mass: 0.35-0.41% of C, 0.40-0.60% of Si, 0.40-0.50% of Mn, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 4.90-5.10% of Cr4, 1.5-1.6% of Mo, 0.35-0.40% of V and the balance of Fe.
According to the mass percentage, the hot forging die steel provided by the invention comprises 0.35-0.41% of C, preferably 0.36-0.40%, and more preferably 0.37-0.39%. The hardenability and hardenability of the die steel can be further improved by controlling the content of C in the hot forging die steel.
According to the mass percentage, the hot forging die steel provided by the invention also comprises 0.40-0.60% of Si, preferably 0.45-0.55%, further preferably 0.48-0.52%, and more preferably 0.50%. The invention can further improve the toughness of the die steel by controlling the Si content in the hot forging die steel.
The hot forging die steel provided by the invention also comprises 0.40-0.50% of Mn, preferably 0.42-0.48%, and more preferably 0.45-0.47% by mass. The invention can further improve the hardness of the die steel by controlling the Mn content in the hot forging die steel.
According to the mass percentage, the hot forging die steel provided by the invention also comprises 4.90-5.10% of Cr, preferably 4.95-5.05% of Cr, further preferably 4.98-5.02% of Cr, and more preferably 5.0%. The hardenability of the steel can be improved by controlling the Cr content in the hot forging die steel, so that the steel has better comprehensive mechanical properties after quenching and tempering treatment.
According to the mass percentage, the hot-forging die steel provided by the invention also comprises 1.5-1.6% of Mo, preferably 1.55-1.6%, and more preferably 1.58-1.6%. According to the invention, the proportion of carbide formed by Mo in the die steel can be increased by controlling the Mo content in the hot forging die steel, so that the hardness of the die steel is increased.
According to the mass percentage, the hot forging die steel provided by the invention also comprises V0.35-0.40%, preferably 0.36-0.39%, and more preferably 0.37-0.38%. According to the invention, the generation of V-containing eutectic carbide can be reduced by controlling the V content in the hot forging die steel, and the adverse effect on the toughness is reduced.
The hot-forging die steel provided by the invention also comprises P less than or equal to 0.025 percent, preferably less than or equal to 0.02 percent, and more preferably less than or equal to 0.015 percent in percentage by mass. The invention avoids the influence of excessive impurities on the steel performance by controlling the content of the impurity P in the hot forging die steel.
According to the mass percentage, the hot forging die steel provided by the invention also comprises S which is less than or equal to 0.015 percent, and is preferably less than or equal to 0.010 percent. The method avoids the influence of excessive impurities on the performance of the steel by controlling the content of the impurities S in the hot forging die steel.
According to the mass percentage, the hot forging die steel provided by the invention also comprises the balance of Fe.
The invention optimizes and improves the components on the basis of H13 die steel, and increases the carbide proportion formed by Mo in the die steel by increasing the content of Mo element, thereby increasing the hardness of the die steel; the hardness of the die steel is further improved by increasing the content of Mn element; the toughness of the die steel is improved by reducing the content of Si element; the generation of V-containing eutectic carbide can be reduced by reducing the content of the V element, and the adverse effect on the toughness is reduced, so that the service life of the die steel is prolonged by improving the strength and the toughness of the die steel.
The invention also provides a preparation method of the hot forging die steel in the technical scheme, which comprises the following steps:
(1) mixing alloy raw materials and smelting to obtain a steel ingot;
(2) carrying out hot forging on the steel ingot obtained in the step (1) to obtain a forged alloy;
(3) and (3) carrying out spheroidizing annealing on the forged alloy obtained in the step (2) to obtain the hot forging 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 present invention, the smelting preferably includes electric furnace smelting, external furnace refining, vacuum degassing, and electroslag remelting, which are performed in this order. The operations of electric furnace smelting, external furnace refining, vacuum degassing and electroslag remelting are not particularly limited, and smelting operations well known to those skilled in the art can be adopted.
After the steel ingot is obtained, the steel ingot is subjected to hot forging to obtain a forged alloy.
In the invention, the temperature of the hot forging is preferably 880-1000 ℃, and more preferably 900-950 ℃; the forging ratio of the hot forging is preferably not less than 4. The invention has no special limitation on other operations of the hot forging, and the defects of shrinkage cavity, bubble, crack, inclusion, peeling, white point, intergranular crack and the like which are visible to naked eyes can be ensured to be avoided in the forged alloy.
After obtaining the forging alloy, the invention carries out spheroidizing annealing on the forging alloy to obtain the hot forging die steel.
In the present invention, the spheroidizing annealing is preferably performed by heating the wrought alloy, performing a first heat preservation, performing a second heat preservation after the first cooling, and finally performing a second cooling. The invention adopts spheroidizing annealing to eliminate primary carbide, improve segregation, ensure that secondary carbide is uniformly distributed on a ferrite matrix in a globular shape, and obviously improve the transverse impact toughness of steel.
In the invention, the temperature of the first heat preservation is preferably 850-870 ℃, and more preferably 855-860 ℃; the first heat preservation time is preferably 15-25 h; when the diameter of the forged alloy is not more than 400mm but not less than 300mm, the first heat preservation time is preferably 18-22 h, and more preferably 20 h; when the diameter of the forged alloy is more than 400mm but not more than 550mm, the first heat preservation time is preferably 23-25 h, and more preferably 24 h. The invention can further improve the transverse impact toughness of the steel by controlling the temperature and the time of the first heat preservation.
In the invention, the heating rate is preferably less than or equal to 80 ℃/h, more preferably 50-75 ℃/h, and even more preferably 55-65 ℃/h.
In the invention, the first cooling rate is preferably less than or equal to 30 ℃/h, more preferably 10-25 ℃/h, and even more preferably 15-20 ℃/h.
In the invention, the temperature of the second heat preservation is preferably 740-760 ℃, more preferably 745-755 ℃, and more preferably 750 ℃; the second heat preservation time is preferably 15-20 h; when the diameter of the forged alloy is less than or equal to 400mm but not less than 300mm, the second heat preservation time is preferably 16-17 h; when the diameter of the forged alloy is larger than 400mm but not larger than 550mm, the time of the second heat preservation is preferably 18-19 h. The invention can further improve the transverse impact toughness of the steel by controlling the temperature and the time of the second heat preservation.
In the present invention, the spheroidizing annealing is preferably performed in a spheroidizing annealing furnace; preferably, the heat dissipation hole is not opened in the first heat preservation time and the second heat preservation time; preferably opening the furnace top and the heat dissipation holes at two sides of the spheroidizing annealing furnace during the first cooling; the furnace door of the spheroidizing annealing furnace is preferably not opened during the first cooling. The type of the spheroidizing annealing furnace is not particularly limited, and the spheroidizing annealing furnace known to those skilled in the art can be adopted.
In the present invention, the second cooling is preferably furnace cooling; the furnace cooling rate is preferably less than or equal to 30 ℃/h; preferably opening the furnace door of the spheroidizing annealing furnace when the furnace is cooled; the elevation height of the oven door preferably does not exceed 150 mm; the furnace cooling end point temperature is preferably 390-410 ℃, and more preferably 400 ℃.
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 invention also provides a preparation method of the piston forging forming die, which comprises the following steps:
1) sequentially carrying out rough machining, preheating treatment, quenching, high-temperature tempering and finish machining on the hot-forging die steel or the hot-forging die steel prepared by the preparation method in the technical scheme to obtain a die blank;
2) carrying out surface strengthening treatment on the die blank obtained in the step 1) to obtain a piston forging forming die.
The invention carries out rough machining, preheating treatment, quenching, tempering and finish machining on the hot forging die steel in sequence to obtain a die blank.
The rough machining operation is not particularly limited in the present invention, and conventional operations known to those skilled in the art may be employed. According to the invention, the hot forging die steel is subjected to rough machining, so that a large amount of redundant materials can be quickly removed, and a die blank can be obtained.
In the invention, the preheating treatment is preferably to heat the product obtained by the rough processing to a first preheating temperature for heat preservation, and then to a second preheating temperature for heat preservation; the first preheating temperature is preferably 350-450 ℃, and more preferably 400 ℃; the first preheating heat preservation time is preferably 0.5-1.5 h, and more preferably 1 h; the second preheating temperature is preferably 800-900 ℃, and more preferably 850 ℃; the second preheating heat preservation time is preferably 2.5-3.5 hours, and more preferably 3 hours. The heating rate of the first preheating temperature and the second preheating temperature is not limited in the present invention, and the heating rate known to those skilled in the art may be adopted. The preheating treatment in the present invention can further refine the texture.
In the present invention, the quenching is preferably oil quenching; the quenching temperature is preferably 1000-1050 ℃, and more preferably 1020 ℃; the heating coefficient of quenching is preferably 0.30-0.40 min/mm, and more preferably 0.35 min/mm. The quenching time is not particularly limited in the present invention, and the ordinary operation of those skilled in the art can be adopted. The invention adopts oil quenching to avoid the problem of cracking during water quenching.
In the invention, the high-temperature tempering temperature is preferably 620-650 ℃; the heat preservation time of the high-temperature tempering is preferably 2.5-3.5 hours, and more preferably 3 hours. The invention can eliminate residual stress by controlling the technological parameters of high-temperature tempering, thereby further improving the strength and toughness of the die.
In the invention, the finish machining is preferably formed by a precision machine tool, a high-strength alloy cutter or CNC cutting machining; the precision machine tool is preferably a five-axis machining center machine tool or a high-speed milling machine tool. The invention has no special limitation on the operation of the precision machine tool, the high-strength alloy cutter or CNC cutting and forming, adopts the operation known by the technicians in the field, and ensures that the profile tolerance of the die is controlled within the range of +/-0.05 mm, the geometric tolerance is controlled within the range of +/-0.05 mm and the surface roughness is controlled below Ra3.2 mu m.
In the invention, the hardness of the die blank is preferably 45.5-48.5 HRC. The invention can further improve the strength and toughness of the die by adopting preheating treatment, quenching and high-temperature tempering treatment so as to meet the comprehensive performance requirements of the complex forge piece on the high strength and the high toughness of the hot forging die.
After the die blank is obtained, the surface of the die blank is preferably strengthened to obtain the piston forging forming die.
According to the invention, the mold blank is preferably subjected to pretreatment before surface strengthening treatment; the pre-treatment preferably comprises high-speed sand blasting, fluid polishing and ultrasonic cleaning in sequence. The invention can further improve the effect of the mold blank surface strengthening treatment by adopting the pretreatment.
In the invention, the pressure of the high-speed sand blasting is preferably 0.6-0.7 MPa. The present invention is not limited to any particular process parameters for the high-speed blasting, and may be performed by procedures known to those skilled in the art. The invention adopts high-speed sand blasting to change the surface shape of the die by using the impact action of high-speed sand flow, and improves the mechanical property of the surface, thereby improving the fatigue resistance.
In the invention, the pressure of the fluid polishing is preferably 0.6-0.7 MPa; the fluid polishing medium is preferably high carbon cast steel grit; the hardness of the high-carbon cast steel sand grains is preferably 570-710 HV; the high carbon cast steel grit preferably has a sieve grade of G050. The invention adopts fluid polishing treatment to deeply clean the surface of the die, and can remove burrs, flash and round corners so as to reduce the waviness and roughness of the surface of the die cavity and improve the smoothness; and simultaneously, impurities such as residual oil stains on the surface can be removed, and the binding force of a subsequent coating is improved.
The operation of the ultrasonic cleaning is not particularly limited in the present invention, and an ultrasonic cleaning operation known to those skilled in the art may be used. The invention can further remove impurities on the surface of the die by adopting ultrasonic cleaning.
In the present invention, the surface strengthening treatment preferably includes nitriding treatment and physical vapor deposition treatment which are performed in this order.
In the present invention, the nitriding treatment is preferably performed in a nitriding furnace; the pressure of the nitriding treatment is preferably 250-350 Pa, and more preferably 300-320 Pa; the voltage of the nitriding treatment is preferably 650-800V, and more preferably 700-750V; the nitriding treatment temperature is preferably 470-520 ℃, and more preferably 500 ℃; the nitriding treatment time is preferably 8-9 h, and more preferably 8.5 h; the thickness of the nitriding layer obtained by nitriding treatment is preferably 0.15-0.2 mm; the hardness of the nitriding layer is preferably 1000-1200 HV. The invention can improve the forging wear resistance, high temperature diffusion wear resistance, fatigue resistance and high pressure resistance of the die by nitriding treatment, thereby further prolonging the service life of the die.
In the invention, the process parameters of the physical vapor deposition treatment comprise: the background vacuum degree is preferably 6X 10-3～8×10-4Pa, more preferably 8X 10-3～1×10-4Pa; the coating vacuum degree is preferably 0.5-1.5 Pa, and more preferably 1.0-1.2 Pa; the voltage is preferably 100-140V, and more preferably 120-130V; the current is preferably 20 to 25A, and more preferably 22 to 23A.
In the present invention, the material of the coating obtained by the physical vapor deposition treatment preferably includes TiN, AlN, CrN, ZrN, Al2O3And ZrO2Two or more of (1); the thickness of the plating layer is preferably 3-8 μm, and more preferably 5-7 μm; the bonding force between the plating layer and the substrate is preferably more than or equal to 150N; the hardness of the plating layer is preferably 2000-4000 HV. According to the invention, the high-temperature-resistant and wear-resistant nano coating can be formed on the surface of the die through physical vapor deposition treatment, so that the high-temperature diffusion wear resistance, the adhesion resistance and the corrosion resistance of the die are improved, and the service life of the die is further prolonged.
The invention adopts the composite strengthening treatment process of 'nitriding and PVD', so that the forging abrasion resistance and the high-temperature diffusion abrasion resistance of the die are improved, and the service life of the die is further prolonged.
Compared with the service life of the piston mold assembled by other existing parts, the piston forging forming mold prepared by the preparation method provided by the invention can be prolonged by more than 2 times, the mold cost of a unit product is reduced by more than 30%, the output on duty is increased by more than 20%, and the economic benefit is obvious.
The preparation method provided by the invention is simple to operate and suitable for industrial production.
The invention also provides a piston forging forming die prepared by the preparation method in the technical scheme. In the invention, the piston forging forming die is of a body structure of the piston. The operation of assembling the piston forging forming die into the piston die is not particularly limited, and the technical scheme of assembling the piston die, which is well known by the technical personnel in the field, can be adopted.
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 hot forging die steel comprises the following components in percentage by mass: 0.38% of C, 0.48% of Si, 0.45% of Mn0.020% of P, 0.010% of S, 5.0% of Cr, 1.58% of Mo, 0.36% of V and the balance of Fe;
the preparation method of the hot forging die steel comprises the following steps:
(1) the materials are mixed according to the weight percentage and then are sequentially smelted in an electric furnace, refined outside the furnace, degassed in vacuum and remelted in electroslag to obtain a steel ingot;
(2) carrying out hot forging on the steel ingot obtained in the step (1) at 900 ℃ to obtain a forged alloy; wherein the forging ratio is 5;
(3) heating the forged alloy obtained in the step (2), performing first heat preservation, performing second heat preservation after first cooling, and finally performing second cooling to obtain the hot forging die steel;
wherein the first heat preservation temperature is 850 ℃ and the time is 20 h; the heating rate of heating to the first heat preservation temperature is 50 ℃/h; the rate of the first cooling is 20 ℃/h; the temperature of the second heat preservation is 750 ℃, and the time is 20 hours; the second cooling is furnace cooling, the rate of the second cooling is 20 ℃/h, and the end point temperature is 390 ℃.
Application example 1
(1) The hot-forging die steel of example 1 is subjected to rough machining, then is heated to 350 ℃ and is kept warm for 1h, then is heated to 800 ℃ and is kept warm for 3h, then is subjected to oil quenching at 1020 ℃, and then is sequentially subjected to high-temperature tempering and finish machining to obtain a die blank;
wherein the heating coefficient of the oil quenching is 0.30 min/mm; the temperature of high-temperature tempering is 650 ℃, and the heat preservation time is 2.5 h; the fine machining is to adopt a precision machine tool to machine and form;
(2) sequentially performing nitriding treatment and physical vapor deposition treatment on the die blank obtained in the step (1) to obtain a piston forging forming die;
wherein the nitriding treatment is carried out in a nitriding furnace; nitriding treatment is carried out under the pressure of 300Pa, the voltage of 680V, the temperature of 500 ℃ and the time of 8 h; the thickness of the nitriding layer is 0.2mm, and the hardness is 1200 HV;
the process parameters of the physical vapor deposition treatment are as follows: background vacuum degree of 7X 10-3Pa, the vacuum degree of the coating is 1Pa, the coating voltage is 100V, and the current of the coating is 20A; the material of the plating layer is TiN and ZrN; the thickness of the plating layer was 5 μm.
Application example 2
(1) The hot-forging die steel of example 1 is subjected to rough machining, then is heated to 350 ℃ and is kept warm for 1h, then is heated to 800 ℃ and is kept warm for 2.5h, then is subjected to oil quenching at 1020 ℃, and then is sequentially subjected to high-temperature tempering and finish machining to obtain a die blank;
wherein the heating coefficient of the oil quenching is 0.30 min/mm; the temperature of high-temperature tempering is 650 ℃, and the heat preservation time is 2.5 h; the fine machining is to adopt a precision machine tool to machine and form;
(2) sequentially performing nitriding treatment and physical vapor deposition treatment on the die blank obtained in the step (1) to obtain a piston forging forming die;
wherein the nitriding treatment is carried out in a nitriding furnace; nitriding treatment is carried out under the pressure of 300Pa, the voltage of 680V, the temperature of 500 ℃ and the time of 8 h; the thickness of the nitriding layer is 0.2mm, and the hardness is 1200 HV;
the process parameters of the physical vapor deposition treatment are as follows: background of the inventionVacuum degree of 7X 10-3～8×10-4Pa, the vacuum degree of the coating is 1Pa, the coating voltage is 100V, and the current of the coating is 20A; the material of the coating is TiN, AlN, CrN, ZrN and ZrO2(ii) a The thickness of the plating layer was 5 μm.
Application example 3
(1) The hot-forging die steel of example 1 is subjected to rough machining, then is heated to 350 ℃ and is kept warm for 1h, then is heated to 800 ℃ and is kept warm for 2.5h, then is subjected to oil quenching at 1020 ℃, and then is sequentially subjected to high-temperature tempering and finish machining to obtain a die blank;
wherein the heating coefficient of the oil quenching is 0.30 min/mm; the temperature of high-temperature tempering is 650 ℃, and the heat preservation time is 2.5 h; the fine machining is to adopt a precision machine tool to machine and form;
(2) sequentially performing nitriding treatment and physical vapor deposition treatment on the die blank obtained in the step (1) to obtain a piston forging forming die;
wherein the nitriding treatment is carried out in a nitriding furnace; nitriding treatment is carried out under the pressure of 300Pa, the voltage of 750V, the temperature of 500 ℃ and the time of 8 h; the thickness of the nitriding layer is 0.2mm, and the hardness is 1200 HV;
the process parameters of the physical vapor deposition treatment are as follows: background vacuum degree of 7X 10-3～8×10-4Pa, the vacuum degree of the coating is 1Pa, the coating voltage is 120V, and the current of the coating is 20A; the material of the coating is TiN, AlN, CrN, ZrN and Al2O3And ZrO2(ii) a The thickness of the plating layer was 5 μm.
Assembling the piston forging forming die prepared in application examples 1-3 and other parts required by the piston die by adopting a conventional process to obtain the piston die; the piston forging forming die is split at the position with the maximum stress during preparation (the bottom of an inner cavity of the piston, namely the upper part comprises an upper die sleeve, a base plate, an upper male die and a punch, and the lower part comprises a stress ring, a lower groove and a lower die core) into two parts; and a gap is arranged at the matching part of the lower film core and the lower groove; the ejector rod is designed by a profiling structure; the ejector rod body is made of die steel H13, and then the side profile is machined by linear cutting; the end head of the ejector rod is made of conventional 45 steel; the ejector rod body and the ejector rod end adopt S7/h6 interference fit, the ejector rod end is preheated to 300 ℃ and assembled with the ejector rod body, and the ejector rod is obtained through natural cooling; the schematic structural diagram of the cross-sectional view of the piston mold is shown in fig. 1, wherein 1 is an upper mold sleeve, 2 is a base plate, 3 is an upper male mold, 4 is a punch, 5 is a stress ring, 6 is a lower female mold, 7 is a lower mold core, and 8 is an ejector rod; the schematic structural diagram of the piston mold in a top view is shown in FIG. 2; wherein, 5 is the stress circle, 6 is lower die, 7 is the lower mold core, 8 is the ejector pin.
The piston mold obtained by assembling a plurality of groups of piston forging forming molds prepared in application examples 1-3 is subjected to automatic hot die forging production line verification, and the service lives of the piston mold are 5000-5500 pieces, 6000-6500 pieces and 7000-8000 pieces respectively.
As can be seen from the above examples and application examples, the die made of the hot forging die steel provided by the invention has a long service life.
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 (10)
1. A hot forging die steel comprises the following chemical components in percentage by mass: 0.35-0.41% of C, 0.40-0.60% of Si, 0.40-0.50% of Mn, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 4.90-5.10% of Cr, 1.5-1.6% of Mo, 0.35-0.40% of V and the balance of Fe.
2. A hot die steel as claimed in claim 1, wherein the chemical composition comprises, in mass percent: 0.36-0.40% of C, 0.45-0.55% of Si, 0.42-0.48% of Mn, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 4.95-5.05% of Cr, 1.55-1.6% of Mo, 0.36-0.39% of V and the balance of Fe.
3. A hot die steel as claimed in claim 2, wherein the chemical composition comprises, in mass percent: 0.37-0.39% of C, 0.48-0.52% of Si, 0.45-0.47% of Mn, less than or equal to 0.025% of P, less than or equal to 0.015% of S, 4.98-5.02% of Cr, 1.58-1.6% of Mo, 0.36-0.39% of V and the balance of Fe.
4. A method of producing a hot-forging die steel as claimed in any one of claims 1 to 3, comprising the steps of:
(1) mixing alloy raw materials and smelting to obtain a steel ingot;
(2) carrying out hot forging on the steel ingot obtained in the step (1) to obtain a forged alloy;
(3) and (3) carrying out spheroidizing annealing on the forged alloy obtained in the step (2) to obtain the hot forging die steel.
5. The preparation method according to claim 4, wherein the spheroidizing annealing in the step (3) is performed by heating the wrought alloy, performing first heat preservation, performing first cooling, performing second heat preservation, and finally performing second cooling.
6. The preparation method according to claim 5, wherein the temperature of the first heat preservation is 850-870 ℃, and the time of the first heat preservation is 15-25 h.
7. The preparation method according to claim 5, wherein the temperature of the second heat preservation is 740 to 760 ℃, and the time of the second heat preservation is 15 to 20 hours.
8. The preparation method of the piston forging forming die is characterized by comprising the following steps:
1) sequentially carrying out rough machining, preheating treatment, quenching, high-temperature tempering and finish machining on the hot-forging die steel according to any one of claims 1 to 3 or the hot-forging die steel prepared by the preparation method according to any one of claims 4 to 7 to obtain a die blank;
2) carrying out surface strengthening treatment on the die blank obtained in the step 1) to obtain a piston forging forming die.
9. The manufacturing method according to claim 8, wherein the surface strengthening treatment in the step 2) includes nitriding treatment and physical vapor deposition treatment which are performed in this order.
10. A piston forging forming die produced by the production method according to claim 8 or 9.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
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| CN202110894658.1A CN113584394A (en) | 2021-08-05 | 2021-08-05 | Hot-forging die steel and preparation method thereof, and piston forging forming die and preparation method thereof |
| PCT/CN2022/108788 WO2023011330A1 (en) | 2021-08-05 | 2022-07-29 | Hot work die steel and preparation method therefor, and piston forging forming die and preparation method therefor |
| ZA2022/12794A ZA202212794B (en) | 2021-08-05 | 2022-11-24 | Hot-forging die steel and manufacturing method thereof as well as piston forging molding die and manufacturing method thereof |
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| CN202110894658.1A CN113584394A (en) | 2021-08-05 | 2021-08-05 | Hot-forging die steel and preparation method thereof, and piston forging forming die and preparation method thereof |
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| CN113584394A true CN113584394A (en) | 2021-11-02 |
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| CN (1) | CN113584394A (en) |
| WO (1) | WO2023011330A1 (en) |
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| WO2023011330A1 (en) * | 2021-08-05 | 2023-02-09 | 安徽安簧机械股份有限公司 | Hot work die steel and preparation method therefor, and piston forging forming die and preparation method therefor |
| WO2023109106A1 (en) * | 2021-12-15 | 2023-06-22 | 河北工业职业技术学院 | Short-process bainite hot-work die and preparation method therefor |
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| WO2023011330A1 (en) | 2023-02-09 |
| ZA202212794B (en) | 2023-05-31 |
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