CN117165867A - Powder metallurgy wear-resistant corrosion-resistant dual-reinforcement phase precipitation hardening high-speed steel - Google Patents
Powder metallurgy wear-resistant corrosion-resistant dual-reinforcement phase precipitation hardening high-speed steel Download PDFInfo
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- 239000000126 substance Substances 0.000 claims abstract description 9
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Abstract
The invention provides powder metallurgy wear-resistant corrosion-resistant dual-reinforcement phase precipitation hardening high-speed steel, which comprises the following chemical components in percentage by mass: c:2.2% -3.0%; si:0% -0.4%; cr:2.0% -8.0%; co:10.0% -30.0%; ni:0% >2.5%; (1.39Co+1.4Ni) is more than or equal to 13.0 percent; v:6% -13.0%; w:5% -12%; mo:5% -16.0%; (mo+w/2): 10.0% -22.0%; the balance of iron and impurities, the steel is dual-reinforced phase precipitation hardening high-speed steel, the reinforced phase comprises intermetallic compound (IMC for short) mu phase, MC carbide and (Cr, fe) C type carbide, wherein the mu phase is (Fe, co) 7 (Mo+W/2) 6 The type of MC carbide is type V (C, N). 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 corrosion 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 corrosion-resistant dual-reinforcement phase precipitation hardening high-speed steel.
Background
In the field of tools for making high-speed cutting difficult-to-machine materials, the tools or parts are required to withstand the wear caused by direct contact of hard abrasive particles in moving parts or working media in addition to the loading and impact of working stresses, and in order to be suitable for these working conditions while having a long service life, the materials must have good toughness matching and high wear resistance.
Precipitation hardening steel is a carbon-free iron-based martensitic precipitation hardening tool alloy, and due to the low content of C in the composition, no substantial carbide precipitation occurs, and the structure is mainly an intermetallic compound (i.e., IMC) of the iron-based matrix and Fe-Co-Mo-W, the hardening effect being due to IMC particles precipitated during aging. The precipitation hardening high-speed steel has good grindability, tempering softening resistance and dimensional stability.
The wear resistance of steel depends on the hardness of a matrix and the content, morphology and particle size distribution of a hard second phase precipitated in the steel, when the steel is prepared by adopting a traditional casting and forging process, the steel is limited by the slow cooling solidification characteristics of molten steel in the process, alloy components are easy to segregate in the solidification process, the bad structure cannot be effectively solved by a hot working mode, bad influences on alloy performance are generated, the performance of high-speed steel including strength, toughness, grindability and the like are in low level, the requirements of high-end processing and manufacturing on the material performance and service life are difficult to meet, and the corrosion resistance of the existing precipitation hardening steel is also difficult to meet the use in the high-end field.
Disclosure of Invention
In view of this, the present invention provides a powder metallurgy wear-resistant corrosion-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 corrosion-resistant dual-reinforcement phase precipitation hardening high-speed steel is characterized by comprising the following chemical components in percentage by mass:
C：2.2％-3.0％；
Si：0％-0.4％；
Cr：2.0％-8.0％；
Co：10.0％-30.0％；
Ni：0％-2.5％；
(1.39Co+1.4Ni)≥13.0％；
V：6％-13.0％；
W：5％-12％；
Mo：5％-16.0％；
(Mo+W/2)：10.0％-22.0％；
the balance of iron and impurities;
and the precipitated phase in the precipitation hardening high-speed steel comprises intermetallic compound (IMC for short) mu phase, MC carbide and (Cr, fe) C type carbide, wherein the mu phase is (Fe, co) 7 (Mo+W/2) 6 The type of MC carbide is type V (C, N).
The invention can promote precipitation of mu phase when preparing precipitation hardening high-speed steel by adopting a powder metallurgy process through reasonable design of alloy components and proportions, thereby improving the wear resistance and corrosion resistance of the steel.
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% -30.0%, preferably 10.0% -28.0%.
The W (tungsten) has high melting point, increases the strength and tempering stability of the steel, increases the high-temperature creep resistance and increases the tempering softening resistance of the steel, so that the steel has less surface layer temperature rise and hardness drop in the processing and using processes, and the W element content range is 5% -12.0%, preferably 5% -9.0% in the invention.
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 is 5% -16.0%, preferably 5% -15.7%.
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 0.5% 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 3.0%, 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 2.2% -3.0%, preferably in the range of 2.2% -2.8%, 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 6% -13.0%, preferably 6% -11.8% 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.
Cr (chromium) is added into steel to act, firstly, particles can be coarsened, so that red hardness is reduced to some extent, and the machinability is improved; on the other hand, part of Cr is dissolved in the matrix, so that the corrosion resistance and hardenability of the steel can be improved. The Cr element content in the present invention is in the range of 2.0% to 8.0%, preferably 2.0% to 7.5%.
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.
Ni (nickel) can replace Co to improve the thermoplasticity of the dual-reinforced phase steel in the injection molding process, but the excessive content of Ni element can lead to the reduction of the hardening effect of the steel, and the content range of Ni element is 0% -2.5%, preferably 0% -2.3% in the invention.
As a limitation of the above manner, the powder metallurgy wear-resistant corrosion-resistant dual-reinforcement phase precipitation hardening high-speed steel comprises the following chemical components in percentage by mass:
C：2.2％-2.8％；
Si：0％-0.32％；
Cr：2.0％-7.5％；
Co：10.0％-28.0％；
Ni：0％-2.3％；
(1.39Co+1.4Ni)≥15.0％；
V：6％-11.8％；
W：5％-9％；
Mo：5％-15.7％；
(Mo+W/2)：10.0％-20.2％；；
the balance being iron and impurities.
In order to achieve better comprehensive performance, each chemical component in the powder metallurgy wear-resistant corrosion-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 mu phase has a particle size of 1.5 mu m or less, the mu phase has a maximum particle size of 6.0 mu m or less, and the volume fraction of the mu phase in the powder metallurgy wear-resistant corrosion-resistant dual-strengthening phase precipitation hardening high-speed steel is 10-20%.
Further, at least 80% of the volume fraction of the MC carbide has a particle size less than or equal to 2.0 μm, the MC carbide has a maximum particle size not exceeding 3.0 μm, and the volume fraction of the MC carbide in the powder metallurgy wear-resistant corrosion-resistant dual-reinforcement phase precipitation hardening high-speed steel is 1% -5%.
Further, the (Cr, fe) C type carbide is a Cr-rich carbide.
Further, at least 80% of the volume fraction of the (Cr, fe) C-type carbide has a particle size of 1-5 μm, the maximum particle size of the (Cr, fe) C-type carbide is not more than 10.0 μm, and the volume fraction of the (Cr, fe) C-type carbide in the powder metallurgy wear-resistant corrosion-resistant dual strengthening phase precipitation hardening high-speed steel is 3-10%.
The invention adopts a powder metallurgy process to prepare precipitation hardening steel, which can solve the problem of element segregation so as to obtain a uniform tissue structure, and the main steps of the powder metallurgy process to prepare precipitation hardening high-speed steel 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 corrosion-resistant dual-reinforcement phase precipitation hardening high-speed steel, which specifically 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, so that the precipitation hardening high-speed steel has excellent mechanical properties, particularly high wear resistance and corrosion resistance, can obtain the hardness of more than 64HRC after solution aging treatment, and is suitable for being used in the working condition with hard particles and corrosive media.
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 corrosion-resistant dual-reinforcement phase precipitation hardening high-speed steel, which comprises the following chemical components in percentage by mass: c:2.2% -3.0%; si:0% -0.4%; cr:2.0% -8.0%; co:10.0% -30.0%; ni:0% -2.5%; (1.39Co+1.4Ni) is more than or equal to 13.0 percent; v:6% -13.0%; w:5% -12%; mo:5% -16.0%; (mo+w/2): 10.0% -22.0%; the balance being iron and impurities.
As a preferred solution in mass percent, the precipitation hardening high-speed steel of the present invention comprises the following chemical components: c:2.2% -2.8%; si:0% -0.32%; cr:2.0% -7.5%; co:10.0% -28.0%; ni:0% -2.3%; (1.39Co+1.4Ni) is more than or equal to 15.0 percent; v:6% -11.8%; w:5% -9%; mo:5% -15.7%; (mo+w/2): 10.0% -20.2%; 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.
Secondly, the present invention also relates to a method for preparing the precipitation hardening high-speed steel, wherein the performance is reduced due to the fact that the solidification speed is slow and segregation is easy to occur when the precipitation hardening high-speed steel is prepared by adopting a traditional ingot casting or electroslag process. 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 corrosion-resistant dual-reinforced phase precipitation hardening high-speed steel and the preparation thereof of the present invention will be further described below with specific preparation examples and comparative examples, and corresponding performance tests.
The strengthening phase granularity and volume fraction, heat treatment hardness, abrasion resistance and corrosion resistance of the powder metallurgy abrasion-resistant corrosion-resistant dual-strengthening phase precipitation hardening high-speed steel are verified, wherein mu phase granularity and volume fraction of carbide are analyzed based on tissue images obtained by a scanning electron microscope, and the heat treatment hardness, abrasion resistance and corrosion resistance are tested by referring to GB/T230.1, GB/T12444, JB/T7901 and GB/T17899 respectively.
Eight precipitation hardening high-speed steels having different compositions of example 1 and example 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 alloy compositions:
| alloy | C | Si | Mn | Cr | Co | Ni | V | W | Mo | Mo+W/2 | 1.39Co+1.4Ni | Fe |
| Example 1 | 2.27 | 0.31 | - | 4.00 | 15.52 | 0.11 | 6.22 | 10.71 | 5.88 | 11.23 | 21.73 | Allowance of |
| Example 2 | 2.44 | 0.30 | - | 3.78 | 14.91 | 0.42 | 6.08 | 10.35 | 5.86 | 10.13 | 21.31 | Allowance of |
| Example 3 | 2.27 | 0.31 | - | 4.00 | 15.52 | 0.11 | 6.22 | 8.0 | 14.0 | 18.0 | 21.73 | Allowance of |
| Example 4 | 2.27 | 0.31 | - | 4.00 | 10.0 | 2.0 | 6.22 | 10.71 | 5.88 | 11.23 | 16.70 | Allowance of |
| Example 5 | 2.20 | - | - | 2.0 | 10.0 | - | 6.0 | 12..0 | 5.0 | 11.0 | 13.90 | Allowance of |
| Example 6 | 3.0 | 0.40 | - | 8.0 | 30.0 | 2.5 | 13.0 | 5.0 | 16.0 | 18.5 | 45.20 | Allowance of |
| Example 7 | 2.8 | 0.32 | - | 7.5 | 28.0 | 2.3 | 11.8 | 9.0 | 15.7 | 20.2 | 42.14 | Allowance of |
| Example 8 | 2.9 | 0.35 | - | 7.8 | 29 | 2.4 | 12 | 11.0 | 15.8 | 20.3 | 41.06 | 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 |
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. Two precipitated phases are included in fig. 7 and 8, one of which is bright white and has a large size, and the other of which is off-white and has a small size.
Table 2 shows the content of precipitated phases, the grain size, and the comparison of examples 1 to 8 with alloy A, B after heat treatment:
table 2: content and particle size of precipitated phase
The solid solution degree of examples 1 to 8 was 1190 ℃ x 30 minutes, and the aging degree was 600 ℃ x 3 hours; the quenching degree of the comparative example A is 1160 ℃ for 15 minutes, and the tempering degree is 550 ℃ for 3 hours; the quenching degree of comparative example B was 1170 ℃ X15 minutes, and the tempering degree was 550 ℃ X3 hours.
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 carbide, wherein the IMC was mainly μ phase of the type (Fe, co) 7 (Mo+W/2) 6 Carbides are classified into two types, VC type carbides and Cr (Cr, fe) C type carbides rich in Cr; the detected strengthening phase in the alloy A and the alloy B is mainly Cr (Cr, fe) C-type carbide rich in Cr, and is VC-type carbide.
The precipitation hardening high-speed steel of the invention 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 6.0 mu m, and meanwhile, the precipitation hardening steel of the invention has another type of strengthening phase, wherein MC carbide type is V (C, N), the volume fraction is 1% -5%, the granularity is fine, and most MC carbide granularity smaller than 2.0 mu m; the (Cr, fe) C-type carbide is Cr-rich carbide, the volume fraction is 3% -10%, and the size of most (Cr, fe) C-type carbide is 1-5 mu m.
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 the size ranging from 5 μm to 30 μm exists in a large number in the tissue, and coarse carbide has the adverse effect of splitting the matrix.
(II) analysis of Heat treatment hardness and abrasion resistance
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 steel and alloy A, B obtained in example 8 of example 1 were heat treated, and the following hardness and abrasion resistance were compared with each other, and the results are shown in table 3.
Table 3: comparison of mechanical Properties
As can be seen from Table 3, the precipitation hardening steel of the present invention has a hardness of 64HRC or more, and exhibits excellent wear resistance, and is capable of withstanding high-strength wear for a long period of time during use, thereby greatly improving the service life of the material.
Analysis of Corrosion resistance
Using 5% HNO 3 The +1% hcl solution was dip etched at room temperature for examples 1 to 8 and alloy A, B, and then the etching rate was measured. The polarization curve was then measured in a 1% NaCl solution, and finally the self-corrosion potential was obtained, and the corrosion resistance was compared as shown in Table 4.
Table 4: comparison of Corrosion resistance
| Alloy | Quenching tempering/solid solution aging | Corrosion rate mm/y | Self-etching potential E corr |
| Example 1 | 1190 ℃ oil quenching +600 ℃ for 3h | ≤150 | -0.477 |
| Example 2 | 1190 ℃ oil quenching +600 ℃ for 3h | ≤150 | -0.462 |
| Example 3 | 1190 ℃ oil quenching +600 ℃ for 3h | ≤150 | -0.470 |
| Example 4 | 1190 ℃ oil quenching +600 ℃ for 3h | ≤150 | -0.491 |
| Example 5 | 1190 ℃ oil quenching +600 ℃ for 3h | ≤150 | -0.432 |
| Example 6 | 1190 ℃ oil quenching +600 ℃ for 3h | ≤150 | -0.502 |
| Example 7 | 1190 ℃ oil quenching +600 ℃ for 3h | ≤150 | -0.495 |
| Example 8 | 1190 ℃ oil quenching +600 ℃ for 3h | ≤150 | -0.487 |
| Comparative example A | Oil quenching at 1160 deg.c +550 deg.c for 1 hr 3 times | ≤300 | -0.222 |
| Comparative example B | 1170 ℃ oil quenching +550 ℃ for 1h for 3 times | ≤300 | -0.261 |
As can be seen from the comparison data in Table 4, the precipitation hardening steel of the present invention exhibits excellent corrosion resistance, and according to the requirements of different applications for corrosion resistance, a suitable heat treatment system should be selected, and in a wider heat treatment temperature range, the precipitation hardening high-speed steel of the present invention can have both good toughness and wear and corrosion resistance, thereby meeting the application in situations with wear and corrosion conditions.
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 carbides may exist in the structure exceeding the maximum size, but since the number thereof is very small, it does not have a substantial influence on the toughness and other mechanical properties of the precipitation hardening steel, and thus it is not considered. 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.
In summary, the powder metallurgy wear-resistant corrosion-resistant dual-reinforcement phase precipitation hardening high-speed steel is prepared by adopting a specific alloy component design and adopting a powder metallurgy process, has the characteristics of mu phase and carbide dual-phase reinforcement phase, and has fine granularity and high dispersity of precipitated phases, so that the material has better toughness proportion and excellent comprehensive performance, particularly good wear-resistant corrosion-resistant performance, and manufactured tools and parts have higher service lives, can meet the application requirements of different types, and can be used for manufacturing (1) tools for cutting difficult-to-process materials at high speed; (2) high-precision measuring tool; and (3) corrosion-resistant parts.
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 corrosion-resistant dual-reinforcement phase precipitation hardening high-speed steel is characterized by comprising the following chemical components in percentage by mass:
C：2.2％-3.0％；
Si：0％-0.4％；
Cr：2.0％-8.0％；
Co：10.0％-30.0％；
Ni：0％-2.5％；
(1.39Co+1.4Ni)≥13.0％；
V：6％-13.0％；
W：5％-12％；
Mo：5％-16.0％；
(Mo+W/2)：10.0％-22.0％；
the balance of iron and impurities;
and the precipitated phase in the powder metallurgy wear-resistant corrosion-resistant dual-reinforcement phase precipitation hardening high-speed steel comprises intermetallic compound (IMC for short) mu phase, MC carbide and (Cr, fe) C carbide, wherein 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 corrosion-resistant dual strengthening phase precipitation hardening high-speed steel according to claim 1, wherein the chemical components thereof comprise, in mass percent:
C：2.2％-2.8％；
Si：0％-0.32％；
Cr：2.0％-7.5％；
Co：10.0％-28.0％；
Ni：0％-2.3％；
(1.39Co+1.4Ni)≥15.0％；
V：6％-11.8％；
W：5％-9％；
Mo：5％-15.7％；
(Mo+W/2)：10.0％-20.2％；
the balance being iron and impurities.
3. The powder metallurgy wear-resistant corrosion-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, the maximum particle size of the mu phase is not more than 6.0 mu m, and the volume fraction of the mu phase in the powder metallurgy wear-resistant corrosion-resistant dual-strengthening phase precipitation hardening high-speed steel is 10-20%.
4. The powder metallurgy wear-resistant corrosion-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 carbide has a particle size less than or equal to 2.0 mu m, the largest particle size of the MC carbide is not more than 3.0 mu m, and the volume fraction of the MC carbide in the powder metallurgy wear-resistant corrosion-resistant dual-reinforcement-phase precipitation hardening high-speed steel is 1% -5%.
5. The powder metallurgy wear-resistant corrosion-resistant dual strengthening phase precipitation hardening high speed steel according to claim 1 or 2, characterized in that: the (Cr, fe) C-type carbide is a Cr-rich carbide.
6. The powder metallurgy wear-resistant corrosion-resistant dual strengthening phase precipitation hardening high speed steel according to claim 1 or 2, characterized in that: at least 80% by volume of the (Cr, fe) C-type carbide has a particle size of 1-5 μm, the (Cr, fe) C-type carbide has a maximum particle size of not more than 10.0 μm, and the (Cr, fe) C-type carbide in the powder metallurgy wear-resistant corrosion-resistant dual strengthening phase precipitation hardening high-speed steel has a volume fraction of 3% -10%.
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