CN113174541B - High-strength die forged steel base material, sandwich layer forging die and preparation method thereof - Google Patents
High-strength die forged steel base material, sandwich layer forging die and preparation method thereof Download PDFInfo
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- CN113174541B CN113174541B CN202110465785.XA CN202110465785A CN113174541B CN 113174541 B CN113174541 B CN 113174541B CN 202110465785 A CN202110465785 A CN 202110465785A CN 113174541 B CN113174541 B CN 113174541B
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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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J13/00—Details of machines for forging, pressing, or hammering
- B21J13/02—Dies or mountings therefor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
- B21J5/002—Hybrid process, e.g. forging following casting
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
- B23P15/24—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass dies
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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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
Abstract
The invention discloses a high-strength die forged steel base material, a sandwich layer forging die and a preparation method thereof. The high-strength die forged steel base material comprises the following components in percentage by mass: 0.5 to 0.7 percent of C, 0.3 to 0.4 percent of Si, 0.7 to 0.9 percent of Mn, 0.8 to 1.0 percent of Cr, 1.5 to 1.8 percent of Ni, 0.1 to 0.3 percent of Mo, 0.1 to 0.2 percent of Cu and the balance of iron; wherein the total amount of impurities is less than 0.12%, wherein P is less than or equal to 0.01%, and S is less than or equal to 0.01%. The invention solves the technical problems that the hardness and the strength of the existing die matrix are rapidly reduced, and the existing die matrix is easy to deform and crack under the conditions that the temperature is more than 350 ℃ and the local instantaneous stress is more than 650MPa in use working condition; the bonding strength between the die forged steel base material and the multi-gradient functional layer manufactured by additive manufacturing is improved, the one-time service life of the large hot forging die is effectively prolonged, the number of times of repairable remanufacturing is increased, 7 batches of high-strength steel forgings are produced on an 8-ten-thousand-ton press, the die base does not deform or crack, and the one-time service life of the large hot forging die is prolonged by more than 10 times.
Description
Technical Field
The invention belongs to the technical field of die forged steel manufacturing, and particularly relates to a die forged steel base material, a die forged steel base, a sandwich layer forging die and a preparation method thereof, wherein the die forged steel base material is used for preparing a large hot forging die high-strength die under a high-temperature heavy-load condition.
Background
With the development of the national heavy equipment manufacturing industry, the equipment manufacturing industry such as aircraft and ship manufacturing needs to be rapidly improved. The largest large die forging hydraulic machine (8 ten thousand ton press) in the world is produced, and the large hot forging dies (the weight of a single set of the dies reaches 60-100 tons) used by the large die forging hydraulic machine are widely applied to the production and the manufacture of large die forgings in the fields of aviation, aerospace, nuclear power, petrochemical industry and the like, such as a large aircraft fuselage frame, an undercarriage, an engine turbine disc, a large cylinder body, a pump body and the like, wherein the forging materials of the forgings mainly comprise aluminum alloy, high-temperature alloy, titanium alloy and the like. However, the initial forging temperature of large forgings made of materials difficult to deform (such as high-temperature alloy, titanium alloy, ultrahigh-strength steel and the like) is high, the strength and hardness of the die are rapidly reduced due to the fact that the contact time of the forgings and the die is long in the forging forming process, the bearing pressure of the die is high, and the temperature is rapidly increased to be more than 350-700 ℃, so that the problems that the dies made of conventional 5CrNiMo and 5CrMnMo materials are severely plastically deformed and cracked and the like are caused, the service life of the dies is extremely short, the deformation of the dies is up to more than 10mm after 1-2 forgings are forged, and the dies are severely failed and cannot be reused and the like are caused.
Also having now chooseing for use behind the H13 steel as the mould material, the deformation degree of mould alleviates to some extent, but new problem also appears quietly, and the mould often takes place preheating and the condemned condition of whole fracture when placing. Analysis suggests that this is associated with metallurgical defects and insufficient stress relief for the machining. When the weight of the H13 material die exceeds 15 tons, the H13 material die is influenced by low casting metallurgical quality of large steel ingots, poor free forging penetration of the steel ingots and low heat treatment quenching hardness, the flaw detection qualification rate is extremely low, the qualification rate is only about 50 percent, the service life of the die cannot be ensured, and the production efficiency and the production cost of the die are seriously influenced.
In order to solve the technical problems, the applicant (inventor) has designed a sandwich layer forging die and a process method for overlaying a sandwich layer of the forging die, and applied for patent ZL201510171656.4; according to the invention, gradient functional layer additive manufacturing is carried out on a large forging die matrix, and then a final die is obtained through tempering stress removal, machining forming and the like, so that the obtained large forging die can basically meet the performance requirements of the forging die under extreme working conditions, the service life of the forging die is effectively prolonged, the production cost is reduced, and the manufacturing and using dies with low cost, short time and high utilization rate are realized.
However, in the process of implementing the method, the applicant finds that when the large hot-forging die for performing multi-gradient functional layer additive manufacturing on the die base forms a material difficult to deform on an 8-million ton press, the requirement of the base material on the plasticity/toughness performance under the condition of meeting the heavy load (local instantaneous stress at high temperature is more than 650 MPa) at high temperature (more than 350 ℃) needs to be further improved, and how to avoid the problems of severe plastic deformation, cracking and the like of the base of the hot-forging die under extreme conditions is a technical problem to be solved by a person skilled in the art; further, how to combine well and transition smoothly the matrix material with the multi-gradient functional layer manufactured by additive manufacturing in the background art, how to ensure that the performance of the matrix material meets the use requirements of multiple repair and remanufacture (multiple use, reduction of single-piece amortization cost) of a large hot forging die on an 8 ten thousand ton press, is also a technical problem which needs to be solved urgently by technical personnel in the field.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to solve the problems that: how to provide a high-strength die forged steel base material for a hot forging die, which is used for preparing a high-strength die forged steel base and solves the technical problems that the hardness and the strength of the existing die base are rapidly reduced, the performance cannot meet the requirements and the like under the conditions that the temperature is more than 350 ℃ and the local instantaneous stress is more than 650 MPa.
The invention also provides application of the high-strength forged steel base material in hot forging of a die, a prepared high-strength forged steel base and a preparation method for obtaining the high-strength sandwich layer forging die.
In order to solve the technical problems, the invention adopts the following technical scheme:
a high-strength die forged steel base material comprises the following components in percentage by mass: 0.5 to 0.7 percent of C, 0.3 to 0.4 percent of Si, 0.7 to 0.9 percent of Mn, 0.8 to 1.0 percent of Cr, 1.5 to 1.8 percent of Ni, 0.1 to 0.3 percent of Mo, 0.1 to 0.2 percent of Cu and the balance of iron; wherein the total amount of impurities is less than 0.12wt.%, wherein P is less than or equal to 0.01%, and S is less than or equal to 0.01%.
In the invention, because the alloy elements have a decisive effect on the performance of the forged steel, the forged steel material is required to have a good alloy element proportion. Wherein: the carbon content is 0.5-0.7% by mass, because the carbon element can increase the pearlite content in the carbon steel, thereby increasing the strength of the carbon steel; the carbon steel strength is good when the carbon content is in the interval, and the defects of hot blast and cold cracking are not easy to occur through analysis. The silicon content is 0.3-0.4%, because the silicon element can obviously improve the elastic limit and yield limit of the steel, and when the carbon steel containing silicon is heated in an oxidizing atmosphere, a layer of silicon dioxide film is also formed on the surface of the carbon steel, thereby improving the oxidation resistance of the steel at high temperature; analysis shows that the silicon content in the interval can form better solid solution strengthening effect in ferrite, and simultaneously a layer of silicon dioxide film is formed on the surface; effectively improves the strength and the hardness of the forged steel without obviously reducing the plasticity and the toughness of the forged steel. The manganese content is 0.7-0.9% by mass, because the manganese can eliminate the influence of sulfur and oxygen on the hot brittleness of the steel to a certain extent, the hot workability of the steel is improved, the cold brittleness tendency of the steel is improved, the strength of the steel is effectively improved, and the plasticity and the impact toughness of the steel are not remarkably reduced. The mass percent of the chromium is 0.8-1.0 percent, because the chromium element is a carbide forming element, and the proper increase of the chromium element has the functions of strengthening the matrix, refining grains and improving the hardenability, but the content of the chromium is not too high, otherwise the nonuniformity and the temper brittleness of the carbide can be increased. The mass percent of nickel is 1.5-1.8%, because nickel is a non-carbide forming element, and a proper amount of nickel can be dissolved into alpha-Fe to form a solid solution, strengthen a matrix, reduce the overheating sensitivity, play a role in precipitation strengthening, and keep good toughness while improving the strength and hardness of steel. The mass percentage of the molybdenum is 0.1-0.3 percent, because a proper amount of molybdenum element can form stable carbide in the steel to cause secondary hardening, so that the cast steel has high red hardness, and the wear resistance of the steel can be improved and the crystal grains can be prevented from growing. The mass percent of copper is 0.1-0.2%, because the proper amount of copper element can improve the strength and toughness of steel and improve the corrosion performance of steel under the atmosphere. The impurities are substances which have no influence on the performance of the high-strength die forged steel base material prepared by the method and cannot be removed and need to be controlled within 0.12%; wherein the mass percent of the phosphorus and the sulfur is respectively less than or equal to 0.01 percent, and the P element can form brittle Fe3The P compound causes the plasticity and toughness of the forged steel to be sharply reduced, and causes the brittle transition temperature of the forged steel to be increased to form cold brittleness defects; therefore, the condition that the strength of the steel is weakened and the cold cracking tendency of the steel is increased can be effectively avoided by controlling the content of the phosphorus. Because the S element is easy to form FeS low-melting-point substances at the grain boundary, when the S element is stressed at a high temperature, the material can form cracks along the grain boundary to form hot brittleness defects; the method avoids the condition that sulfides are solidified at the peripheral position of the crystal grains of the steel when the solidification process of the steel is finished, obviously reduces the high-temperature strength of the steel and forms hot cracks.
The invention also provides application of the high-strength die forged steel base material.
The invention also provides a high-strength die forged steel matrix prepared from the high-strength die forged steel matrix material.
The high-strength die forged steel matrix provided by the invention is prepared from the high-strength die forged steel matrix material.
The mechanical properties of the high-strength die forged steel matrix are as follows: the yield strength sigma s is more than or equal to 900MPa, the tensile strength sigma b is more than or equal to 1100MPa, the hardness after heat treatment is more than or equal to 35HRC, the elongation delta is more than or equal to 18%, the shrinkage psi is more than or equal to 30%, and the impact energy AKv is more than or equal to 32J.
Specifically, the preparation method comprises the following steps: the high-strength die forging steel base material is adopted as a die base material, the die base material is smelted in an induction furnace, after the die base material is cast into a steel ingot, the steel ingot is heated to the temperature of 1200 +/-10 ℃, the temperature is kept for 6-8 hours, forging processing is carried out, the initial forging temperature is 1050 +/-10 ℃, the final forging temperature is not less than 900 ℃, and then the high-strength die forging steel base is prepared through heat treatment after forging.
The invention also provides a high-strength sandwich layer forging die and a preparation method thereof.
A preparation method of a high-strength sandwich layer forging die comprises the following steps:
1) Preparing the high-strength die forged steel base body by adopting the high-strength die forged steel base body material; obtaining a cavity part through machining and reserving a surfacing allowance;
2) Overlaying a sandwich layer welding material with good plasticity and low yield strength on the high-strength die forged steel substrate obtained in the step 1) along the shape of a reserved overlaying part; the sandwich layer is overlaid by 40 to 60 percent of the radian of the substrate layer;
3) On the high-strength die forged steel base body welded with the sandwich layer in the step 2), overlaying a transition layer welding material with higher strength and hardness along the shape of the reserved overlaying part allowance and the shape of the sandwich layer, completely covering and wrapping the sandwich layer material, and continuously welding the sandwich layer welding material to 8-11 mm below the contour line of the die cavity;
4) Overlaying a high-temperature wear-resistant layer welding material on the high-strength die forged steel base welded with the transition layer in the step 3), covering a main wear-resistant working area or a whole wear-resistant area of the die, and welding the high-temperature wear-resistant layer welding material to the contour line of the die cavity by 4-6 mm;
5) Repeatedly carrying out a tempering and slow cooling process twice on the die after three times of surfacing, and then placing the die after the second slow cooling in air for air cooling to room temperature; wherein the tempering temperature is 530-570 ℃, and the slow cooling temperature is 160-180 ℃;
6) And (5) machining the die after air cooling in the step 5) to enable the sizes of all parts of the die to be in place, and obtaining the high-strength sandwich layer forging die.
Further, the step of forging the steel matrix by the high-strength die in the step 1) comprises the following steps: smelting the high-strength die base material in an induction furnace, casting the high-strength die base material into a steel ingot, heating the steel ingot to the temperature of 1200 +/-10 ℃, preserving the heat for 6-8 hours for forging, performing initial forging at the temperature of 1050 +/-10 ℃, and performing final forging at the temperature of more than or equal to 900 ℃, and performing heat treatment after forging to obtain the high-strength die forged steel base.
Preferably, the thickness of the reserved surfacing allowance in the step 1) is 40-90 mm.
Specifically, the good surfacing plasticity and the low yield strength in the step 1) mean that the mechanical property index can reach the following standard: the sigma s yield strength is more than or equal to 550MPa, the sigma b tensile strength is more than or equal to 760MPa, the delta elongation is more than or equal to 14.7 percent, the psi shrinkage is more than or equal to 31.2 percent, and the hardness is 30-35 HRC.
Preferably, the sandwich layer in the step 2) is welded to the position 14-16 mm below the contour line of the mold cavity.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention provides a novel high-strength die forged steel base material, which replaces the existing method that integral homogeneous forged steel is adopted to manufacture a die; through testing the die base body, the mechanical property indexes can reach: the yield strength sigma s is more than or equal to 900MPa, the tensile strength sigma b is more than or equal to 1100MPa, the hardness after heat treatment is more than or equal to 35HRC, the elongation delta is more than or equal to 18%, the shrinkage rate psi is more than or equal to 30%, and the impact energy AKv is more than or equal to 32J; the die matrix obtained by the invention can meet the performance requirements of good strength and hardness under extreme working conditions of more than 350 ℃ and more than 650MPa of local instantaneous stress, fundamentally solves the problem that the existing large-scale hot forging die is easy to deform and crack under the condition of high temperature and heavy load, and solves the problem that the deformation of more than 10mm occurs after the existing large-scale hot forging die is used for 1-2 times.
2. By designing the alloy element proportion in the high-strength die forged steel base material, the large-scale hot forging die base meets the performance requirements of strength, hardness, toughness, plasticity and the like under extreme working conditions of more than 350 ℃ and more than 650MPa of local instantaneous stress; still make the welding performance of large-scale hot forging mould base member better, make the welding effect of mould base member and multi-gradient functional layer better, test the die base member and the splice of multi-gradient functional layer, the joint strength of splice exceeds 1250MPa, guarantee that joint strength is greater than the intensity of die base member and multi-gradient functional layer self, make under extreme operating condition, the condition that can not appear droing takes place between die base member and the multi-gradient functional layer, make the life of large-scale hot forging mould improved once more.
3. According to the invention, the high-strength sandwich layer forging die is prepared by designing the alloy element proportion in the high-strength die forged steel base material, and is applied to actual forging production by combining forging equipment, so that a new thought is provided for a large-scale hot forging process.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
It should be noted that these examples are only for illustrating the present invention, and not for limiting the present invention, and the simple modification of the method based on the idea of the present invention is within the protection scope of the present invention.
A high-strength die forged steel base material comprises the following components in percentage by mass: 0.5 to 0.7 percent of C, 0.3 to 0.4 percent of Si, 0.7 to 0.9 percent of Mn, 0.8 to 1.0 percent of Cr, 1.5 to 1.8 percent of Ni, 0.1 to 0.3 percent of Mo, 0.1 to 0.2 percent of Cu and the balance of iron; wherein the total amount of impurities is less than 0.12wt.%, wherein P is less than or equal to 0.01%, and S is less than or equal to 0.01%.
The specific embodiment is as follows:
a preparation method of a high-strength die forged steel matrix comprises the following steps.
The high-strength die forging steel base material is adopted as a die base material, the die base material is smelted in an induction furnace, after being cast into a steel ingot, the steel ingot is heated to the temperature of 1200 +/-10 ℃, the temperature is kept for 5-6 hours, forging processing is carried out, the initial forging temperature is 1050 +/-10 ℃, the final forging temperature is more than or equal to 900 ℃, and then the high-strength die forging steel base material is prepared through post-forging heat treatment.
Through tests, the mechanical property indexes of the high-strength die forged steel base material are as follows: the yield strength sigma s is more than or equal to 900MPa, the tensile strength sigma b is more than or equal to 1100MPa, the hardness after heat treatment is more than or equal to 35HRC, the elongation delta is more than or equal to 18%, the shrinkage psi is more than or equal to 30%, and the impact energy AKv is more than or equal to 32J.
A preparation method of a high-strength sandwich layer forging die comprises the following steps:
1) Preparing the high-strength die forged steel base by adopting the high-strength die forged steel base material as a forged steel base material; obtaining a cavity part through machining and reserving a surfacing allowance;
2) Overlaying a sandwich layer welding material with good plasticity and low yield strength on the high-strength die forged steel substrate obtained in the step 1) along the shape of a reserved overlaying part; the sandwich layer is overlaid and covers 40 to 60 percent of the radian of the substrate layer;
3) On the high-strength die forged steel base body welded with the sandwich layer in the step 2), completely covering and wrapping the sandwich layer material along the shape of the allowance of the reserved surfacing part and the shape of the sandwich layer with the transition layer welding material with higher surfacing strength and hardness, and continuously welding the sandwich layer material to 8-11 mm below the contour line of the die cavity;
4) Overlaying a high-temperature wear-resistant layer welding material on the high-strength die forged steel base welded with the transition layer in the step 3), covering a main wear-resistant working area or a whole wear-resistant area of the die, and welding the high-temperature wear-resistant layer welding material to the contour line of the die cavity by 4-6 mm;
5) Repeatedly carrying out the tempering and slow cooling process twice on the mold after three times of surfacing, and then placing the mold after the second slow cooling in air for air cooling to room temperature; wherein the tempering temperature is 530-570 ℃, and the slow cooling temperature is 160-180 ℃;
6) And (5) machining the die after air cooling in the step 5) to enable the sizes of all parts of the die to be in place, and obtaining the high-strength sandwich layer forging die.
Further, the step of forging the steel matrix by the high-strength die in the step 1) comprises the following steps: smelting the high-strength die base material in an induction furnace, casting the high-strength die base material into a steel ingot, heating the steel ingot to the temperature of 1200 +/-10 ℃, preserving the heat for 5-6 hours for forging, performing initial forging at the temperature of 1050 +/-10 ℃, and performing final forging at the temperature of more than or equal to 900 ℃, and performing post-forging heat treatment to obtain the high-strength die forged steel base.
Preferably, the thickness of the reserved surfacing allowance in the step 1) is 40-90 mm.
Specifically, the good surfacing plasticity and the low yield strength in the step 1) mean that the mechanical property index can reach the following standard: the sigma s yield strength is more than or equal to 550MPa, the sigma b tensile strength is more than or equal to 760MPa, the delta elongation is more than or equal to 14.7 percent, the psi shrinkage is more than or equal to 31.2 percent, and the hardness is 30-35 HRC.
Preferably, the sandwich layer in the step 2) is welded to the position 14-16 mm below the contour line of the mold cavity.
Experiments prove that 7 batches of high-strength steel forgings are produced by the large hot-forging die prepared from the forged steel base material on an 8-million-ton press, and the die base does not deform or crack, so that the service life of the large hot-forging die is prolonged by more than 10 times; the large hot-forging die after being used for many times cannot be integrally scrapped, so that the problem of serious failure of the large hot-forging die is avoided, the large hot-forging die can be repaired and remanufactured, the large hot-forging die can be reused, and the scrappage of the large hot-forging die is obviously reduced; the production cost of the large hot forging die is reduced, and the manufacturing cost of the forge piece is effectively reduced.
The welding part of the die matrix and the multi-gradient functional layer is tested, the connection strength of the welding part exceeds 1250MPa, and the material is used for being matched with a high-performance alloy welding material to prepare a large hot forging die, so that when the large hot forging die is matched with an 8-ten-thousand-ton die forging hydraulic press to form a material which is difficult to deform under the extreme conditions of more than 350 ℃ and more than 650MPa of local instantaneous stress, the material has better strength and hardness under the condition of meeting the performance requirement in the aspect of plasticity/toughness, the problems that the die matrix is severely plastically deformed and cracked and the like due to the rapid reduction of the strength and hardness of the hot forging die under the extreme conditions are avoided, and the problems that the die is severely failed and can not be used any more and the like are avoided; the service life of the hot forging die is obviously prolonged.
Finally, it is noted that the above-mentioned embodiments illustrate rather than limit the invention, and that, while the invention has been described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (3)
1. A high-strength sandwich layer forging die is characterized by comprising a high-strength die forged steel base body, a transition layer and a high-temperature wear-resistant layer, wherein a sandwich layer is built-up welded between the high-strength die forged steel base body and the transition layer; the plasticity range of the sandwich layer is as follows: delta elongation of 14.7 to 20% and psi shrinkage of 31.2 to 36%; the range of the yield strength of the sandwich layer is as follows: the sigma s yield strength is 550 to 570MPa; the plasticity of the sandwich layer is higher than that of the high-strength die forged steel base body and the transition layer, and the yield strength of the sandwich layer is lower than that of the high-strength die forged steel base body and the transition layer;
the high-strength die forged steel base comprises the following components in percentage by mass: 0.5 to 0.7 percent of C, 0.3 to 0.4 percent of Si, 0.7 to 0.9 percent of Mn, 0.8 to 1.0 percent of Cr, 1.5 to 1.8 percent of Ni, 0.1 to 0.3 percent of Mo, 0.1 to 0.2 percent of Cu and the balance of iron; wherein the total amount of impurities is less than 0.12wt.%, wherein P is less than or equal to 0.01%, and S is less than or equal to 0.01%;
the preparation method comprises the following steps: smelting the components of the high-strength die forged steel matrix in an induction furnace, casting the high-strength die forged steel matrix into a steel ingot, heating the steel ingot to the temperature of 1200 +/-10 ℃, preserving the heat for 5-6 hours, forging the steel ingot, wherein the initial forging temperature is 1050 +/-10 ℃, the final forging temperature is more than or equal to 900 ℃, and performing post-forging heat treatment to prepare the high-strength die forged steel matrix;
the preparation method of the high-strength sandwich layer forging die comprises the following steps:
1) Forging a steel matrix by adopting a high-strength die, obtaining a cavity part by machining, and reserving a surfacing allowance;
2) Overlaying a sandwich layer welding material with good plasticity and low yield strength on the high-strength die forged steel substrate obtained in the step 1) along the shape of a reserved overlaying part; overlaying a sandwich layer to cover 40 to 60 percent of the radian of the base layer;
3) On the high-strength die forged steel base welded with the sandwich layer in the step 2), overlaying a transition layer welding material with higher strength and hardness on the high-strength die forged steel base, covering and wrapping the sandwich layer material completely along the shape of the reserved overlaying part and the shape of the sandwich layer, and continuously welding the transition layer welding material to the position 8 to 111mm below the contour line of the die cavity;
4) Overlaying a high-temperature wear-resistant layer welding material on the high-strength die forged steel substrate welded with the transition layer in the step 3), covering a main wear-resistant working area or all wear-resistant areas of the die, and welding to the contour line of the cavity for 4-6 mm;
5) Repeatedly carrying out the tempering and slow cooling process twice on the mold after three times of surfacing, and then placing the mold after the second slow cooling in air for air cooling to room temperature; wherein the tempering temperature is 530 to 570 ℃, and the slow cooling temperature is 160 to 180 ℃;
6) And (5) machining the die after air cooling in the step 5) to enable the sizes of all parts of the die to be in place, and obtaining the high-strength sandwich layer forging die.
2. The high-strength sandwich layer forging die according to claim 1, wherein the thickness of a reserved overlaying allowance in the step 1) is 40 to 90mm.
3. The high-strength sandwich layer forging die according to claim 1, wherein in the step 2), the sandwich layer is welded to the position 14-16mm below the contour line of a die cavity.
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| CN101798661A (en) * | 2010-04-23 | 2010-08-11 | 庄龙兴 | Hot working die steel and preparation method thereof |
| CN104741499B (en) * | 2015-04-13 | 2017-05-24 | 重庆大学 | Sandwich layer forging die and preparation method of forging die sandwich layer surfacing |
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