CN117165838A - Powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel - Google Patents
Powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel Download PDFInfo
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- 238000004881 precipitation hardening Methods 0.000 title claims abstract description 64
- 229910000997 High-speed steel Inorganic materials 0.000 title claims abstract description 59
- 238000004663 powder metallurgy Methods 0.000 title claims abstract description 41
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910052742 iron Inorganic materials 0.000 claims abstract description 12
- 239000000126 substance Substances 0.000 claims abstract description 10
- 239000012535 impurity Substances 0.000 claims abstract description 9
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 8
- 229910000765 intermetallic Inorganic materials 0.000 claims abstract description 7
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 6
- 239000002245 particle Substances 0.000 claims description 16
- 238000005728 strengthening Methods 0.000 claims description 13
- 150000001247 metal acetylides Chemical class 0.000 claims description 4
- 230000009977 dual effect Effects 0.000 claims 5
- 229910000831 Steel Inorganic materials 0.000 abstract description 65
- 239000010959 steel Substances 0.000 abstract description 65
- 238000000034 method Methods 0.000 abstract description 33
- 238000005496 tempering Methods 0.000 abstract description 10
- 238000009826 distribution Methods 0.000 abstract description 2
- 239000000843 powder Substances 0.000 description 36
- 230000008569 process Effects 0.000 description 28
- 229910045601 alloy Inorganic materials 0.000 description 23
- 239000000956 alloy Substances 0.000 description 23
- 238000010438 heat treatment Methods 0.000 description 19
- 238000001513 hot isostatic pressing Methods 0.000 description 16
- 238000010791 quenching Methods 0.000 description 13
- 230000000171 quenching effect Effects 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 12
- 229910052751 metal Inorganic materials 0.000 description 11
- 239000002184 metal Substances 0.000 description 11
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- 238000003860 storage Methods 0.000 description 11
- 238000005242 forging Methods 0.000 description 10
- 239000000463 material Substances 0.000 description 10
- 239000011159 matrix material Substances 0.000 description 10
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- 239000011261 inert gas Substances 0.000 description 8
- 238000002360 preparation method Methods 0.000 description 8
- 230000032683 aging Effects 0.000 description 7
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- 238000000889 atomisation Methods 0.000 description 6
- 238000001816 cooling Methods 0.000 description 6
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- 239000002893 slag Substances 0.000 description 6
- 239000006104 solid solution Substances 0.000 description 6
- 238000004458 analytical method Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 230000001681 protective effect Effects 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 238000000137 annealing Methods 0.000 description 3
- 238000005266 casting Methods 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
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- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910001315 Tool steel Inorganic materials 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 2
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- 229910052721 tungsten Inorganic materials 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910020630 Co Ni Inorganic materials 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
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- 230000002411 adverse Effects 0.000 description 1
- 229940037003 alum Drugs 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
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- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
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Abstract
The powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel comprises the following chemical components in percentage by mass: c:1.0% -2.6%; si:0% -0.4%; co:10.0% -25.0%; ni:0% -5.5%; (1.39Co+1.4Ni) is more than or equal to 13.0 percent; v:0% -8.0%; w:10% -15.0%; mo:5% -13.0%; (mo+w/2): 10.0% -20.0%; the balance of iron and impurities,the steel is dual-reinforced phase precipitation hardening high-speed steel, and the precipitated phases comprise intermetallic compound (IMC) mu phase and MC carbide, wherein the mu phase is (Fe, co) 7 (Mo+W/2) 6 The MC carbide is of the V (C, N) type. The mu phase and carbide of the precipitation hardening high-speed steel prepared by the method are fine in size and uniform in distribution, have excellent comprehensive performance, particularly outstanding in wear resistance and tempering softening resistance, and meet the requirements of different working conditions.
Description
Technical Field
The invention relates to precipitation hardening high-speed steel, in particular to powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel.
Background
The precipitation hardening steel is a carbon-free iron-based martensitic precipitation hardening tool alloy, has good grindability and tempering softening resistance, has good dimensional stability, and is widely applied to manufacturing cutters of high-speed cutting difficult-to-process materials. In order to be suitable for the working conditions and have long service life, the material must have good toughness matching and high wear resistance.
The wear resistance of steel depends on the hardness of the matrix and the content, morphology and particle size distribution of the hard second phase precipitated in the steel. The hardening effect of precipitation hardening steel is due to intermetallic compound (i.e., IMC) particles precipitated during aging, while the hardness and temper softening resistance of precipitation hardening high speed steel can be improved. And simultaneously combines the mu phase and the MC carbide to form the unique dual-reinforced phase precipitation hardening steel.
When the alloy is prepared by adopting the traditional casting and forging process, the alloy composition is easily segregated in the solidification process due to the limitation of the slow cooling solidification characteristic of molten steel in the process, the bad structure can not be effectively solved by a hot working mode, the bad effect on the alloy performance is generated, the performance of high-speed steel including strength, toughness, wear resistance and the like is in a low level, and the requirements of high-end processing and manufacturing on the material performance and service life are difficult to meet.
Disclosure of Invention
In view of this, the present invention provides a powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel having good structure and excellent properties.
In order to achieve the above purpose, the technical scheme of the invention is realized as follows:
the powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel is characterized by comprising the following chemical components in percentage by mass:
C：1.0％-2.6％；
Si：0％-0.4％；
Co：10.0％-25.0％；
Ni：0％-5.5％；
(1.39Co+1.4Ni)≥13.0％；
V：0％-8.0％；
W：10.0％-15.0％；
Mo：5.0％-13.0％；
(Mo+W/2)：10.0％-20.0％；
the balance of iron and impurities;
and, the strengthening phase in the precipitation hardening high-speed steel comprises intermetallic compound (i.e., IMC phase) mu phase and MC carbide, wherein the mu phase is (Fe, co) 7 (Mo+W/2) 6 The MC carbide is of the V (C, N) type.
The invention improves the tempering softening resistance, toughness and wear resistance of the steel through the design of alloy components.
Co (cobalt) is solid-dissolved in the matrix to make the alloy a martensitic steel, thereby improving the hardness and strength of the ferritic alloy by one grade, and the increase of Co content can properly reduce the toughness of the steel, and in the present invention, the Co element content is in the range of 10.0% -25.0%, preferably 10.0% -24.5%.
Ni (nickel) can replace Co and can improve the thermoplasticity of steel and the hardenability, but because the Ni (nickel) can reduce the Ac1 point, the Ms point is reduced, the annealing hardness of steel is obviously increased, and the residual austenite content and the stability are increased, so that the Ni element content range is 0% -5.5%, and preferably 0% -5.3% in the invention.
The W (tungsten) has high melting point, increases the strength and tempering stability of the steel, increases the creep resistance at high temperature and increases the tempering softening resistance of the steel, so that the steel has less surface layer temperature rise and hardness drop in the process of processing and using, and the W element content range is 10.0-15.0 percent, preferably 10.0-14.7 percent.
The Mo (molybdenum) acts on W identically and the price is lower than W, in the invention, a proper amount of Mo is added to replace W, but the higher the Mo content is, the higher the initial precipitation temperature of the mu phase is, the larger the granularity of the mu phase is, and in order to ensure the granularity of the mu phase to be fine, the content range of Mo element in the invention is 5.0-13.0%, preferably 5.0-12.0%.
A small amount of C (carbon) is added into the steel, one part of the C (carbon) is dissolved in the matrix in a solid manner to improve the strength of the matrix, the other part of the C is combined with carbide forming elements to improve the wear resistance of the material, and the content of C is not less than 0.2% so as to ensure that the carbide forming elements can participate in carbide precipitation to form a double-strengthening phase mechanism; meanwhile, the content of C is not more than 2.6%, so that the reduction of toughness caused by excessive solid solution of C in a matrix is avoided, and the content of C is in the range of 1.0-2.6%, preferably in the range of 1.1-2.5%, so that good matching of wear resistance and toughness can be obtained.
V (alum) is used as a strong carbide forming element and mainly acts on MC carbide formed in steel to improve the wear resistance of the steel, and the content of V element is 0% -8.0%, preferably 0% -7.04% in the invention in order to ensure that the steel is a dual-phase strengthening mechanism of precipitation mu phase and MC carbide and the grindability of the steel is ensured.
Si (silicon) is not a carbide forming element but is used as a deoxidizer and matrix strengthening element to improve the strength and hardness of steel, but Si is excessive to lower the plasticity and toughness of the matrix, and the Si content of the present invention is controlled to 0.4% or less, and preferably 0.32% or less.
As a limitation of the above manner, the powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel comprises the following chemical components in percentage by mass:
C：1.1％-2.5％；
Si：0％-0.32％；
Co：10.0％-24.5％；
Ni：0％-5.3％；
(1.39Co+1.4Ni)≥15.0％；
V：0％-7.04％；
W：10.0％-14.7％；
Mo：5.0％-12.0％；
(Mo+W/2)：10.0％-20.0％；
the balance being iron and impurities.
In order to achieve better comprehensive performance, each chemical component in the powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel is controlled within a required range.
Further, at least 80% of the volume fraction of the μ phase has a particle size of at least 80% of the volume fraction of 1.5 μm or less, and the μ phase has a maximum particle size of not more than 6.0 μm.
Further, the volume fraction of the mu phase in the powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel is 10-20%.
Further, at least 80% of the MC carbide in the volume fraction has a particle size of at least 80% by volume of 2.0 μm or less, and the largest of the MC carbide has a largest particle size of not more than 3.0 μm.
Further, the volume fraction of MC carbide in the powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel is 1.0% -5.0%.
In the invention, precipitation hardening steel is prepared by adopting a powder metallurgy process, the problem of element segregation can be solved, and thus, a uniform tissue structure is obtained, and the main steps of preparing precipitation hardening high-speed steel by adopting the powder metallurgy process comprise: atomizing powder preparation and hot isostatic pressing, the molten steel is rapidly cooled into powder, alloy elements in the molten steel are completely solidified without segregation, and after the powder is solidified into a material, the structure is fine and uniform, so that the performance is greatly improved compared with precipitation hardening high-speed steel produced by the traditional casting or electroslag process.
The invention also provides a preparation method for preparing the powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel, which comprises the following steps:
s1. preparing precipitation hardening molten steel according to the chemical composition requirement and transferring to a ladle;
s1.1. maintaining the superheat degree of molten steel by heating covering slag covered on the upper surface of molten steel in a ladle; introducing inert gas into the bottom of the ladle to stir molten steel;
s1.2, flowing molten steel into a preheated tundish through a flow guide pipe at the bottom of a ladle at a stable flow rate, and applying protective slag to the upper surface of the molten steel when the molten steel enters the lower end surface of the flow guide pipe buried in the tundish;
s1.3. continuously compensating and heating the tundish, and maintaining the superheat degree of molten steel;
s1.4, atomizing the molten steel from the tundish into an atomizing chamber, pulverizing by adopting inert gas, settling the obtained metal powder to the bottom of the atomizing chamber, then entering a powder storage tank body with protective atmosphere, screening the metal powder by a protective screening device, and then entering the powder storage tank body for storage;
and s1.5, transferring the metal powder in the powder storage tank body to a hot isostatic pressing sheath under the protection of inert gas, carrying out vacuum degassing treatment on the hot isostatic pressing sheath after the metal powder is filled and compacted in a vibrating mode, carrying out seal welding treatment on the end portion of the hot isostatic pressing sheath, and then carrying out hot isostatic pressing treatment to enable the metal powder to be fully densified and consolidated to finish a powder metallurgy process.
The powder metallurgy process comprises non-vacuum melting atomization pulverizing and hot isostatic pressing links, and the process adopts full-flow protection to control the oxygen content and the form of precipitated phases and optimize the performance of precipitation hardening steel.
The covering slag of the ladle has the functions of isolating air and conducting and heating. Inert gas is introduced into the bottom of the ladle through the air holes, so that the temperature of molten steel at different positions in the ladle is balanced, and the removal of harmful impurities is accelerated. The flow guiding pipe at the bottom of the steel ladle plays a role in guiding the molten steel, so that turbulence is reduced in the molten steel circulation process, slag is prevented from being rolled up, impurities are prevented from entering the next link, and on the other hand, the flow guiding pipe is prevented from exposing the molten steel to the air, and the oxygen content of the molten steel is prevented from rising. Before molten steel enters the tundish, the tundish needs to be preheated to prevent local condensation or early precipitation of a second phase when the molten steel enters the tundish.
The powder storage tank is internally provided with atmosphere protection and forced cooling functions, the powder protection screening device plays a role in protecting the powder screening process and simultaneously prevents powder from flying, the powder storage tank body is in sealing connection with the hot isostatic pressing sheath, the hot isostatic pressing sheath is filled with inert gas before powder filling to discharge air, and the oxygen content in the powder can be prevented from rising.
The precipitation hardening high-speed steel is prepared by adopting a powder metallurgy process, the component design is reasonable, various effective protection means are adopted in the preparation process to prevent molten steel and powder from being polluted, and the precipitated intermetallic compound mu phase and carbide are fine and uniform due to the specific chemical composition and the rapid condensation process of the powder metallurgy, so that the precipitation hardening high-speed steel has excellent mechanical properties, particularly high tempering softening resistance and wear resistance, can obtain hardness of more than 64HRC after solution aging treatment, and has excellent hardness and wear resistance.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:
FIG. 1 is a microstructure of precipitation hardening high-speed steel prepared in example 1 of the present invention;
FIG. 2 is a microstructure of precipitation hardening high-speed steel prepared in example 2 of the present invention;
FIG. 3 is a microstructure of precipitation hardening high-speed steel prepared in example 4 of the present invention;
FIG. 4 is a microstructure of precipitation hardening high-speed steel prepared in example 5 of the present invention;
FIG. 5 is a microstructure of precipitation hardening high-speed steel prepared in example 6 of the present invention;
FIG. 6 is a microstructure of precipitation hardening high-speed steel prepared in example 7 of the present invention;
FIG. 7 is a microstructure of the high-speed steel of the electroslag process prepared in comparative example A of the present invention;
FIG. 8 is a microstructure of the powder metallurgy process corrosion resistant high speed steel prepared in comparative example B of the present invention.
Detailed Description
It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.
The invention relates to a group of powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel, which comprises the following chemical components in percentage by mass: c:1.0% -2.6%; si:0% -0.4%; co:10.0% -25.0%; ni:0% -5.5%; (1.39Co+1.4Ni) is more than or equal to 13.0 percent; v:0% -8.0%; w:10.0% -15.0%; mo:5.0% -13.0%; (mo+w/2): 10.0% -20.0%; the balance being iron and impurities.
As a preferred solution, the precipitation hardening high-speed steel of the invention comprises the following chemical components in mass percent: c:1.1% -2.5%; si:0% -0.32%; co:10.0% -24.5%; ni:0% -5.3%; (1.39Co+1.4Ni) is more than or equal to 15.0 percent; v:0% -7.04%; w:10.0% -14.7%; mo:5.0% -12.0%; (mo+w/2): 10.0% -20.0%; the balance being iron and impurities. The precipitation hardening high-speed steel of the present invention, which is composed of the above components, can achieve an ideal structure and excellent properties to meet the demands.
In addition, the invention also relates to a method for preparing the precipitation hardening high-speed steel, which is prepared by adopting a traditional ingot casting or electroslag process, and the performance is reduced due to the fact that the solidification speed is slow and segregation is easy to occur. Therefore, in order to ensure that the prepared precipitation hardening high-speed steel ingot has uniform composition and structure, tiny precipitated phase and high purity, the powder metallurgy process is adopted to prepare the steel ingot, and the steel ingot is forged to obtain the required bar product.
Specifically, the preparation method of the invention comprises the following steps:
s1. the precipitation hardening steel liquid of the invention is filled into a smelting ladle, and the loading weight of the liquid steel is 1.5-8 tons;
s1.1. electrifying and heating covering slag covered on the upper surface of molten steel in a steel ladle by adopting a graphite electrode, introducing argon or nitrogen into the bottom of the steel ladle to stir the molten steel, and opening a molten steel guide pipe when the superheat degree of the molten steel reaches 100-200 ℃;
s1.2, flowing molten steel into a tundish preheated to 800-1200 ℃ through a flow guide pipe at the bottom of a ladle at the flow rate of 10-50Kg/min, and applying covering slag when the molten steel enters the tundish and is buried at the lower end face of the flow guide pipe;
s1.3. continuously compensating and heating the tundish in the atomizing powder making process, and maintaining the superheat degree of molten steel at 100-200 ℃;
s1.4, enabling molten steel to enter an atomization chamber through the bottom of a tundish, opening an atomization gas injection valve, atomizing by adopting nitrogen as a gas medium to prepare powder, wherein the purity of the nitrogen is more than or equal to 99.999%, the oxygen content is less than or equal to 2ppm, and the pressure of an outlet of a gas nozzle is 1.0-5.0MPa; the molten steel is crushed into liquid drops under the nitrogen spraying effect, and is rapidly cooled into metal powder, flies to the bottom of an atomization chamber, and then enters a powder storage tank body with protective atmosphere; after atomization powder preparation is finished, cooling the metal powder in the powder storage tank body to room temperature, and screening the metal powder by a protection screening device; the inside of the cavity of the protection screening device is filled with positive-pressure inert gas, and the inside of the powder storage tank is provided with positive-pressure inert gas protection atmosphere;
s1.5, filling metal powder in a powder storage tank body into a hot isostatic pressing sheath, firstly introducing inert gas into the hot isostatic pressing sheath to exhaust air, then hermetically connecting the hot isostatic pressing sheath with the powder storage tank body, and implementing vibration operation in the filling process to increase the filling density of the metal powder; and (3) carrying out vacuumizing and degassing treatment on the hot isostatic pressing sheath after the completion, heating and preserving the hot isostatic pressing sheath at 200-600 ℃ in the vacuumizing process, continuously heating and preserving the heat for more than 2 hours after degassing to 0.01Pa, then carrying out seal welding treatment on the end part of the sheath, finally carrying out hot isostatic pressing treatment on the sheath, and after the hot isostatic pressing temperature is 1100-1180 ℃ and the maintaining time is more than or equal to 1 hour under the pressure of more than or equal to 100MPa, completely compacting and solidifying the metal powder, and then cooling along with a furnace to complete the powder metallurgy process.
S2, forging and opening the blank
The precipitation hardening high-speed steel is further forged and deformed according to the requirement to obtain bars or forgings with certain shapes and sizes, and different heat treatment systems are adopted to obtain different performances, and the heat treatment comprises annealing, solid solution and aging. The annealing treatment is designed to heat the bar or the forging to 870-890 ℃, keep the temperature for more than or equal to 2 hours, then cool the bar or the forging to below 530 ℃ at the speed of less than or equal to 15 ℃/hour, and cool the bar or the forging to below 50 ℃ in a furnace or in a static air cooling way; the solid solution treatment comprises preheating the annealed bar or forging at 810-850 ℃, uniformly placing the bar or forging into 1170-1200 ℃ for heat preservation for 15-40 minutes, and then cooling with oil; aging is then carried out at a temperature in the range 580-650 ℃ for 3-4 hours, followed by air cooling to 50 ℃.
The powder metallurgy wear-resistant dual-reinforced phase precipitation hardening high-speed steel of the present invention and the preparation thereof will be further described below with specific preparation examples and comparative examples, and corresponding performance tests. The particle size and the volume fraction of two precipitated phases, the heat treatment hardness, the impact toughness and the wear resistance of the powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel are verified, wherein the particle size and the volume fraction of mu phase and carbide are analyzed based on tissue images obtained by a scanning electron microscope, and the heat treatment hardness, the wear resistance and the corrosion resistance are tested by referring to GB/T230.1, GB/T229 and GB/T12444 respectively.
Two precipitation hardening high-speed steels having different compositions of examples 1 to 8 were obtained by the above-described production method, and cast forging tool steel (alloy a) and powder metallurgy tool steel (alloy B) were compared, with the following results:
table 1 composition comparison of the components:
| alloy | C | Si | Mn | Cr | Co | Ni | V | W | Mo | Mo+W/2 | 1.39Co+1.4Ni | Fe |
| Example 1 | 1.10 | 0.35 | - | - | 15.78 | 0.10 | 6.44 | 10.65 | 5.72 | 11.04 | 22.07 | Allowance of |
| Example 2 | 1.24 | 0.31 | - | - | 15.05 | 0.08 | 6.18 | 8.23 | 5.33 | 9.44 | 21.03 | Allowance of |
| Example 3 | 1.10 | 0.35 | - | - | 15.78 | 0.10 | 6.44 | 10.0 | 6.0 | 11.0 | 22.07 | Allowance of |
| Example 4 | 1.10 | 0.35 | - | - | 20.0 | 2.0 | 6.44 | 10.65 | 5.72 | 11.04 | 30.60 | Allowance of |
| Example 5 | 1.0 | 0.0 | - | - | 10.0 | 0.0 | 0.0 | 10.0 | 5.0 | 10.0 | 13.90 | Allowance of |
| Example 6 | 2.60 | 0.40 | - | - | 25.0 | 5.5 | 8.0 | 14.0 | 13.0 | 20.0 | 40.2 | Allowance of |
| Example 7 | 2.50 | 0.32 | - | - | 24.5 | 5.30 | 7.04 | 14.70 | 12.0 | 19.35 | 39.55 | Allowance of |
| Example 8 | 2.55 | 0.36 | - | - | 24.6 | 5.40 | 7.5 | 14.8 | 12.50 | 19.90 | 39.54 | Allowance of |
| Comparative example A | 1.09 | 0.33 | 0.31 | 3.84 | 7.95 | 0.13 | 1.11 | 1.47 | 9.35 | 10.08 | 11.23 | Allowance of |
| Comparative example B | 1.61 | 0.42 | 0.34 | 4.72 | 7.97 | 0.17 | 5.05 | 10.22 | 2.15 | 7.26 | 11.31 | Allowance of |
The "-" in the table indicates that the element is not contained, or the element content is little to no analysis.
Wherein, examples 1 to 8 are powder metallurgy precipitation hardening high-speed steel of the invention, which is prepared by adopting a powder metallurgy process, firstly adopting an air atomization powder preparation process to prepare powder, then carrying out hot isostatic pressing densification on the powder, then preparing an ingot blank with the diameter phi of 400mm, and further carrying out thermal deformation processing to obtain bars with the diameter phi of 60 mm.
Comparative example A prepared by an electroslag remelting process, hot deformed to a bar with a diameter of phi 55 mm; comparative example B prepared by powder metallurgy Process, hot deformed to a diameter of 60mm rod
Microstructure analysis
Fig. 1 to 6 are schematic diagrams of microstructures of prepared precipitation hardening steel forgings according to example 1, example 2, example 4, example 5, example 6 and example 7, respectively, fig. 7 is a schematic diagram of a microstructure of alloy a, and fig. 8 is a schematic diagram of a microstructure of alloy B, based on a scanning electron microscope.
Obviously, the off-white hardening phases in fig. 1 to 6 are distributed on the matrix in a fine dispersion manner, so that the wear resistance, toughness and service life of the material can be remarkably improved. FIGS. 7 and 8 contain two precipitated phases, one of which is bright white and of relatively large size and the other of which is off-white and of small size
Examples 1 to 8 after heat treatment were compared with the content of precipitated phases and the particle size in alloy A, B, as shown in table 2.
Table 2: content and particle size of precipitated phase
The solid solution regime of examples 1 to 8 was at 1190 ℃ for 30 minutes, the aging regime was at 600 ℃ for 3 hours; the quenching system of comparative example A is at 1160℃for 15 minutes, the tempering system is at 550℃for 1 hour, and the times are 3 times; the quenching schedule of comparative example B was 1170℃for 15 minutes, the tempering schedule was 550℃for 1 hour, and the number of times was 3.
The high-speed steels prepared in examples 1 to 8 in the present invention were subjected to a precipitated phase analysis: the precipitated phases in examples 1 to 8 were detected as being mainly IMC and MC carbide, wherein the IMC was mainly μ phase of the type (Fe, co) 7 (Mo+W/2) 6 MC carbide is VC type carbide; the precipitated phases in alloy A and alloy B are mainly Cr-enriched (Cr, fe) C-type carbide and VC-type carbide.
The precipitation hardening high-speed steel has the volume fraction of mu phase reaching 10-20%, fine granularity, most mu phase granularity smaller than 1.5 mu m and maximum size not larger than 7.0 mu m, and the precipitation hardening steel has the second strengthening phase MC carbide of V (C, N) type, 1-5% of volume fraction, fine granularity and most MC carbide granularity smaller than 2.0 mu m, and the precipitated phases have fine size and large dispersity, so that the material has better wear resistance, toughness and service life.
The MC carbide in the alloy B prepared by adopting the powder metallurgy process is the most tiny, most MC carbide is 0.5-1.5 mu m, the volume fraction is 2-6%, but the (Cr, fe) C carbide with a large quantity and a size range of 3-12 mu m also exists in the structure. Coarse carbides have the detrimental effect of splitting the matrix. In the A alloy produced by the conventional electroslag process, the MC carbide size is similar to that of the embodiment, but the (Cr, fe) C carbide with a large quantity and a size range of 5-30 μm exists in the tissue, and coarse carbide has the adverse effect of splitting the matrix.
(II) Heat treatment hardness and impact toughness analysis
In order to verify the influence of a heat treatment system on the performance of the precipitation hardening high-speed steel prepared by the method, heat treatment processes with different solid solution temperatures and aging temperatures are set for carrying out heat treatment on the prepared bar.
The hardened steels and alloys A, B obtained in examples 1 to 8 were heat-treated, and the following hardness and impact toughness comparison results were shown in table 3.
Table 3: comparison of mechanical Properties
As can be seen from Table 3, the impact toughness of the precipitation hardened high-speed steel of the present invention is relatively low, but the measured values meet the toughness requirements of the application field, and the precipitation hardened high-speed steel of the present invention is particularly suitable for use in applications with less impact load.
(III) analysis of wear resistance
The abrasion resistance comparison results of examples 1 to 8 and alloy A, B are shown in table 4.
Table 4: comparison of wear resistance
| Alloy | Quenching tempering/solid solution aging | Hardness after heat treatment (HRC) | Wearing mass (mg) |
| Example 1 | 1190 ℃ oil quenching +600 ℃ for 3h | 64 | 44 |
| Example 2 | 1190 ℃ oil quenching +600 ℃ for 3h | 64 | 42 |
| Example 3 | 1190 ℃ oil quenching +600 ℃ for 3h | 64 | 45 |
| Example 4 | 1190 ℃ oil quenching +600 ℃ for 3h | 64.5 | 40 |
| Example 5 | 1190 ℃ oil quenching +600 ℃ for 3h | 64 | 48 |
| Example 6 | 1190 ℃ oil quenching +600 ℃ for 3h | 65 | 39 |
| Example 7 | 1190 ℃ oil quenching +600 ℃ for 3h | 65 | 38 |
| Example 8 | 1190 ℃ oil quenching +600 ℃ for 3h | 65 | 39 |
| Comparative example A | Oil quenching at 1160 deg.c +550 deg.c for 1 hr 3 times | 64 | 190 |
| Comparative example B | 1170 ℃ oil quenching +550 ℃ for 1h for 3 times | 64 | 164 |
As can be seen from the comparative data of table 4, the precipitation hardening steel of the present invention exhibits excellent wear resistance, and is able to withstand high-strength wear for a long period of time during use, thereby greatly improving the service life of the material. According to the requirements of different application occasions on wear resistance, a proper heat treatment system is selected, and the precipitation hardening high-speed steel can have good toughness matching and wear resistance in a wider heat treatment temperature range, so that the application of the corresponding working condition occasions is satisfied.
In addition, the precipitation hardening steel of the present invention is prepared under the above-mentioned implementation conditions due to the limitation of the statistical image analysis software of the number of precipitated phase particles, and the sizes of individual μ phases and MC carbides may exist in the structure exceeding the maximum size, but may be disregarded because the number thereof is very small, without having a substantial effect on the toughness and other mechanical properties of the precipitation hardening steel. In addition, many smaller mu phases of particles cannot be identified by analysis software, and the statistics of volume fraction and granularity are only used as comparison.
The invention adopts specific alloy component design and powder metallurgy process to prepare, has the characteristics of mu phase and MC carbide dual-phase strengthening phase, and has fine granularity and large dispersity of precipitated phases, so that the material has better strength and toughness ratio and longer service life, can meet the application requirements of different types, and can be used for manufacturing (1) cutters for cutting difficult-to-process materials at high speed; (2) high-precision measuring tool; (3) abrasion resistant parts, etc.
In conclusion, the powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel has the characteristics of alloy components, and the reinforcement mechanism is different from that of the traditional high-speed steel, so that the tempering softening resistance of the powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel is greatly superior to that of the traditional high-speed steel and other tool steels, and meanwhile, the powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel has high wear resistance.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Claims (6)
1. The powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel is characterized by comprising the following chemical components in percentage by mass:
C：1.0％-2.6％；
Si：0％-0.4％；
Co：10.0％-25.0％；
Ni：0％-5.5％；
(1.39Co+1.4Ni)≥13.0％；
V：0％-8.0％；
W：10.0％-15.0％；
Mo：5.0％-13.0％；
(Mo+W/2)：10.0％-20.0％；
the balance of iron and impurities;
and the strengthening phase in the powder metallurgy wear-resistant dual-strengthening phase precipitation hardening high-speed steel comprises intermetallic compound and MC carbide, wherein the intermetallic compound is a mu phase, and the type of the mu phase is (Fe, co) 7 (Mo+W/2) 6 The type of MC carbide is type V (C, N).
2. The powder metallurgy wear-resistant dual strengthening phase precipitation hardening high-speed steel according to claim 1, comprising the chemical components in mass percent:
C：1.1％-2.5％；
Si：0％-0.32％；
Co：10.0％-24.5％；
Ni：0％-5.3％；
(1.39Co+1.4Ni)≥15.0％；
V：0％-7.04％；
W：10.0％-14.7％；
Mo：5.0％-12.0％；
(Mo+W/2)：10.0％-20.0％；
the balance being iron and impurities.
3. The powder metallurgy wear resistant dual strengthening phase precipitation hardening high speed steel according to claim 1 or 2, characterized in that: at least 80% of the volume fraction of the mu phase has a particle size of 1.5 mu m or less and the mu phase has a maximum particle size of not more than 6.0 mu m.
4. The powder metallurgy wear resistant dual strengthening phase precipitation hardening high speed steel according to claim 1 or 2, characterized in that: the volume fraction of the mu phase in the powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel is 10-20%.
5. The powder metallurgy wear resistant dual strengthening phase precipitation hardening high speed steel according to claim 1 or 2, characterized in that: at least 80% of the volume fraction of the MC carbides have a particle size of 2.0 μm or less and the MC carbides have a maximum particle size of not more than 3.0 μm.
6. The powder metallurgy wear resistant dual strengthening phase precipitation hardening high speed steel according to claim 1 or 2, characterized in that: the volume fraction of MC carbide in the powder metallurgy wear-resistant dual-reinforcement phase precipitation hardening high-speed steel is 1.0% -5.0%.
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