Powder metallurgy wear resistant double strengthened phase precipitation hardened high speed steel

Abstract

A powder metallurgy wear-resistant double-strengthened phase precipitation hardened high-speed steel, which comprises the following 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%-15.0%; Mo: 5%-13.0%; (Mo+W / 2): 10.0%-20.0%; and the balance of iron and impurities, wherein the steel is a double-strengthened phase precipitation hardened high-speed steel, and the precipitated phases include intermetallic compound (IMC) μ phase and MC carbide, wherein the μ phase is of (Fe, Co)7(Mo+W / 2)6 type, and the MC carbide is of V(C, N) type. The μ phase and the carbide of the prepared precipitation hardened high-speed steel are small in size and uniform in distribution, and the steel has excellent comprehensive performance, especially outstanding wear resistance and tempering softening resistance, and can meet the requirements of different working conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to a precipitation hardening high speed steel, in particular to a powder metallurgy wear-resistant double strengthening phase precipitation hardening high speed steel. BACKGROUND

[0002] The precipitation hardening steel is a carbon-free ferritic martensitic precipitation hardening tool alloy, such steel has good grindability and tempering softening resistance, good dimensional stability, and is widely used for manufacturing high-speed cutting tools for difficult-to-machine materials. In order to be suitable for the above working conditions and have a long service life, the material must have good strength and toughness matching and high wear resistance.

[0003] The wear resistance of the steel depends on the matrix hardness and the content, morphology and particle size distribution of the hard second phase precipitated in the steel. The hardening effect of the precipitation hardening steel is due to the intermetallic compound (i.e. IMC) particles precipitated during aging process, which can improve the hardness and tempering softening resistance of the precipitation hardening high speed steel. At the same time, the unique double strengthening phase precipitation hardening steel is formed by the combined action of mu phase and MC carbide.

[0004] When prepared by traditional casting and forging process, the alloy composition is prone to segregation during solidification process due to the slow cooling and solidification characteristics of the process, and this undesirable structure cannot be effectively solved by hot working method, which will have adverse effects on the performance of the alloy, resulting in low level of performance of the high speed steel, including strength, toughness, wear resistance and other properties, which is difficult to meet the requirements of high-end manufacturing on material performance and service life. SUMMARY

[0005] Therefore, the present application provides a powder metallurgy wear-resistant double strengthening phase precipitation hardening high speed steel with good structure and excellent performance.

[0006] To achieve the above purpose, the technical scheme of the present application is as follows:

[0007] A powder metallurgy wear-resistant double strengthening phase precipitation hardening high speed steel, characterized in that the steel comprises the following chemical components in mass percentage:

[0008] C: 1.0%-2.6%;

[0009] Si: 0%-0.4%;

[0010] Co: 10.0%-25.0%;

[0011] Ni: 0%-5.5%;

[0012] (1.39Co+1.4Ni)≥13.0%;

[0013] V: 0%-8.0%;

[0014] W: 10.0% - 15.0%;

[0015] Mo: 5.0% - 13.0%;

[0016] (Mo + W / 2): 10.0% - 20.0%;

[0017] balance: iron and impurities;

[0018] and, the strengthening phase in the precipitation hardening high speed steel includes intermetallic compound (i.e. IMC phase) μ phase and MC carbide, wherein the μ phase is (Fe, Co)7(Mo + W / 2)6 type and the MC carbide is V(C, N) type.

[0019] The present application improves the tempering softening resistance, toughness and wear resistance of the steel by designing the alloy composition.

[0020] The role of Co (cobalt) is to dissolve in the matrix, making the alloy a martensitic steel, thereby increasing the hardness and strength of the alloy by one level compared to ferritic alloys. Increasing the Co content will appropriately reduce the toughness of the steel. In the present application, the Co element content range is 10.0% - 25.0%, preferably 10.0% - 24.5%.

[0021] Ni (nickel) can replace Co, and also can improve the thermal plasticity of the steel and increase the hardenability, but it can reduce the Ac1 point, thereby reducing the Ms point, so that the annealing hardness of the steel increases significantly, increasing the residual austenite content and stability. Therefore, in the present application, the Ni element content range is 0% - 5.5%, preferably 0% - 5.3%.

[0022] W (tungsten) has a high melting point, which 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 surface layer of the steel has less temperature rise and less hardness drop during processing and use. In the present application, the W element content range is 10.0% - 15.0%, preferably 10.0% - 14.7%.

[0023] Mo (molybdenum) has the same effect as W and is cheaper than W. In the present application, an appropriate amount of Mo is added to replace W, but it should be noted that the higher the Mo content, the higher the μ phase precipitation temperature, and the larger the μ phase particle size. To ensure that the μ phase has a small particle size, the Mo element content range in the present application is 5.0% - 13.0%, preferably 5.0% - 12.0%.

[0024] A small amount of C (carbon) is added to the steel, part of which is dissolved in the matrix to improve the strength of the matrix, and the other part of C combines with the carbide forming element to improve the wear resistance of the material. The content of C is not less than 0.2%, so as to ensure that the carbide forming element can participate in the precipitation of carbide to form a double strengthening phase mechanism; at the same time, the content of C should not be more than 2.6%, to avoid excessive C dissolved in the matrix leading to the decrease of toughness. Within the above-mentioned C content range of 1.0%-2.6%, the preferred range is 1.1%-2.5%, which can obtain good cooperation of wear resistance and toughness.

[0025] V (vanadium) as a strong carbide forming element, its main role is to form MC type carbide with the steel, to improve the wear resistance of the steel. In order to ensure that the steel is a double phase strengthening mechanism of μ phase and MC carbide, and to ensure the grindability of the steel, the content of V element in the present application is 0%-8.0%, preferably 0%-7.04%.

[0026] Si (silicon) is not a carbide forming element, but is used as a deoxidizer and matrix strengthening element, which can improve the strength and hardness of the steel. However, too much Si will reduce the plasticity and toughness of the matrix. The Si content in the present application is controlled to be less than 0.4%, and preferably ≤0.32%.

[0027] As a limitation of the above-mentioned manner, the powder metallurgy wear-resistant double-strengthening phase precipitation hardening high-speed steel comprises the following chemical components by mass percentage:

[0028] C: 1.1%-2.5%;

[0029] Si: 0%-0.32%;

[0030] Co: 10.0%-24.5%;

[0031] Ni: 0%-5.3%;

[0032] (1.39Co+1.4Ni)≥15.0%;

[0033] V: 0%-7.04%;

[0034] W: 10.0%-14.7%;

[0035] Mo: 5.0%-12.0%;

[0036] (Mo+W / 2): 10.0%-20.0%;

[0037] The balance is iron and impurities.

[0038] In order to achieve better comprehensive performance, each chemical component in the powder metallurgy wear-resistant double-strengthening phase precipitation hardening high-speed steel of the present application should be controlled within the required range.

[0039] Further, at least 80% volume fraction of the mu phase has at least 80% volume fraction of particle size ≤1.5 μm, and the maximum particle size of the mu phase is not more than 6.0 μm.

[0040] Further, the volume fraction of the mu phase in the powder metallurgy wear-resistant double-strengthening-phase precipitation-hardened high-speed steel is 10-20%.

[0041] Further, at least 80% volume fraction of the MC carbide has at least 80% volume fraction of particle size ≤2.0 μm, and the maximum particle size of the MC carbide is not more than 3.0 μm.

[0042] Further, the volume fraction of the MC carbide in the powder metallurgy wear-resistant double-strengthening-phase precipitation-hardened high-speed steel is 1.0%-5.0%.

[0043] In the present application, the powder metallurgy process is adopted to prepare the precipitation-hardened steel, which can solve the problem of element segregation and obtain uniform microstructure. The main steps of the powder metallurgy process for preparing the precipitation-hardened high-speed steel include: atomization and powder preparation → hot isostatic pressing forming. The steel liquid is rapidly cooled into powder, and the alloy elements in the steel liquid completely solidify without segregation. After the powder is consolidated into a material, the microstructure is fine and uniform. Compared with the traditional casting or electroslag process for producing the precipitation-hardened high-speed steel, the performance is greatly improved.

[0044] The present application also provides a preparation method of the powder metallurgy wear-resistant double-strengthening-phase precipitation-hardened high-speed steel as described above, and the preparation method comprises the following steps:

[0045] s1. preparing a precipitation-hardened steel liquid according to the above chemical composition requirements and transferring the steel liquid to a ladle;

[0046] s1.1. maintaining the superheat degree of the steel liquid by heating the protective slag covering the upper surface of the steel liquid in the ladle; and introducing inert gas into the bottom of the ladle to stir the steel liquid;

[0047] s1.2. flowing the steel liquid into a preheated tundish through the flow guide pipe at the bottom of the ladle at a stable flow rate, and applying protective slag to the upper surface of the steel liquid when the steel liquid enters the tundish and covers the lower end surface of the flow guide pipe;

[0048] s1.3. continuously compensating and heating the tundish to maintain the superheat degree of the steel liquid;

[0049] s1.4. atomizing and powdering the steel liquid from the tundish into the atomization chamber using inert gas, and then the obtained metal powder is settled at the bottom of the atomization chamber, and then enters a powder storage tank body with a protective atmosphere, and the metal powder is screened through a protective screening device and then enters the powder storage tank body for storage;

[0050] s1.5 Under the protection of inert gas, the metal powder in the powder storage tank is transferred to the hot isostatic pressing jacket, the hot isostatic pressing jacket is subjected to vacuum degassing treatment after the metal powder is vibrated and packed tightly, the end of the hot isostatic pressing jacket is subjected to sealing welding treatment, then the hot isostatic pressing treatment is carried out to make the metal powder completely dense and solidified, and the powder metallurgy process is completed.

[0051] The powder metallurgy process described above comprises non-vacuum melting atomization powder preparation and hot isostatic pressing links, and the whole process is protected to control the oxygen content and the morphology of precipitated phases and optimize the performance of the precipitation hardening steel.

[0052] The protective slag of the ladle has the functions of air insulation and electric heating. Inert gas is introduced into the ladle through the air hole in the bottom of the ladle, so that the temperature of the molten steel at different positions in the ladle is balanced, and the removal of harmful inclusions is accelerated. The flow guide pipe in the bottom of the ladle plays a flow guiding role on the molten steel, reduces the turbulence generated in the molten steel flow process, avoids slag entrainment and prevents inclusions from entering the next link. On the other hand, the flow guide pipe prevents the molten steel from being exposed to air to prevent the oxygen content of the molten steel from rising. Before the molten steel enters the tundish, the tundish needs to be preheated to prevent local condensation or the second phase from precipitating too early when the molten steel enters the tundish.

[0053] The inside of the powder storage tank has the functions of atmosphere protection and forced cooling, the powder protection screening device plays a protective role in the powder screening process and prevents the powder from floating, the powder storage tank body is sealingly connected with the hot isostatic pressing jacket, and inert gas is introduced into the hot isostatic pressing jacket before powder is loaded to discharge air, so that the oxygen content in the powder can be prevented from rising.

[0054] The precipitation hardening high-speed steel prepared by the powder metallurgy process has reasonable component design, various effective protection means are adopted in the preparation process to prevent the molten steel and the powder from being polluted, and due to the specific chemical composition and the rapid condensation process of powder metallurgy, the precipitated intermetallic compound mu phase and carbide are small and uniform, and the steel has excellent mechanical properties, especially high temper softening resistance and wear resistance, and can obtain a hardness of more than 64HRC after solid solution and aging treatment, and has excellent hardness and wear resistance. BRIEF DESCRIPTION OF DRAWINGS

[0055] The accompanying drawings, which form a part of this application, are used to provide further understanding of the application and are incorporated herein for reference. The schematic embodiments of the application and their descriptions are used to explain the application, and do not constitute improper limitations on the application. In the drawings:

[0056] Figure 1 The microstructure diagram of the precipitation hardening high-speed steel prepared in Example 1 of the application;

[0057] Figure 2 The microstructure diagram of the precipitation hardening high-speed steel prepared in Example 2 of the application;

[0058] Figure 3Microstructure of the precipitation hardened high speed steel prepared in Example 4 of the present application;

[0059] Figure 4 Microstructure of the precipitation hardened high speed steel prepared in Example 5 of the present application;

[0060] Figure 5 Microstructure of the precipitation hardened high speed steel prepared in Example 6 of the present application;

[0061] Figure 6 Microstructure of the precipitation hardened high speed steel prepared in Example 7 of the present application;

[0062] Figure 7 Microstructure of the electroslag process high speed steel prepared in Comparative Example A of the present application;

[0063] Figure 8 Microstructure of the powder metallurgy process corrosion resistant high speed steel prepared in Comparative Example B of the present application. DETAILED DESCRIPTION

[0064] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0065] The present application relates to a group of powder metallurgy wear resistant dual strengthened phase precipitation hardened high speed steels, 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)≥13.0%; V: 0%-8.0%; W: 10.0%-15.0%; Mo: 5.0%-13.0%; (Mo+W / 2): 10.0%-20.0%; and the balance is iron and impurities.

[0066] As a preferred scheme, the precipitation hardened high speed steel of the present application 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%; and the balance is iron and impurities. The precipitation hardened high speed steel with the above components used in the present application can obtain ideal structure and excellent performance to meet the requirements.

[0067] In addition, the present application also relates to a method for preparing the above-mentioned precipitation hardening high speed steel, which is prepared by using a traditional ingot or electroslag process, and segregation is prone to occur due to slow solidification speed, thereby leading to performance reduction. Therefore, in order to ensure that the prepared precipitation hardening high speed steel ingot is uniform in composition and organization, fine in precipitated phase and high in purity, a powder metallurgy process is used to prepare the steel ingot, and then the required rod product is obtained through forging.

[0068] Specifically, the preparation method of the present application comprises the following steps:

[0069] s1. The molten steel of the precipitation hardening steel of the present application is loaded into a melting ladle, and the molten steel loading weight is 1.5-8 tons;

[0070] s1.1. The protective slag covered on the upper surface of the molten steel in the ladle is heated by using graphite electrodes, and the molten steel is stirred by introducing argon or nitrogen gas at the bottom of the ladle, and the superheat of the molten steel reaches 100-200 ℃ to open the flow guide pipe of the molten steel;

[0071] s1.2. The molten steel flows into the tundish preheated to 800-1200 ℃ through the flow guide pipe at the bottom of the ladle at a flow rate of 10-50 Kg / min, and the protective slag is applied when the molten steel enters the tundish and covers the lower end surface of the flow guide pipe;

[0072] s1.3. The tundish is continuously compensated and heated during the atomization and powdering process, and the superheat of the molten steel is maintained at 100-200 ℃;

[0073] s1.4. The molten steel enters the atomization chamber through the bottom of the tundish, the atomization gas injection valve is opened, nitrogen gas is used as the gas medium for atomization and powdering, the purity of the nitrogen gas is ≥99.999%, the oxygen content is ≤2 ppm, and the outlet pressure of the gas nozzle is 1.0-5.0 MPa; the molten steel is broken into droplets under the action of nitrogen gas injection, and is rapidly cooled into metal powder, flies to the bottom of the atomization chamber, and then enters the powder storage tank body with a protective atmosphere; after the atomization and powdering is completed, the metal powder in the powder storage tank body is cooled to room temperature, and the metal powder is screened through a protective screening device; the cavity of the protective screening device is filled with a positive pressure inert protective gas, and the inside of the powder storage tank is a positive pressure inert gas protective atmosphere;

[0074] s1.5 Fill the metal powder in the powder storage tank into the hot isostatic pressing bag, first, introduce inert gas into the hot isostatic pressing bag to discharge air, then, tightly connect the hot isostatic pressing bag and the powder storage tank, and perform vibration operation during the filling process to increase the filling density of the metal powder; after completion, perform vacuum degassing treatment on the hot isostatic pressing bag, the hot isostatic pressing bag is heated and kept at 200-600°C during the vacuum process, and after degassing to 0.01 Pa, continue heating and keeping for more than 2 hours, then, perform sealing welding treatment on the end part of the bag, and finally, perform hot isostatic pressing treatment on the bag, the hot isostatic pressing temperature is 1100-1180°C, and the pressure is ≥100 MPa, and the holding time is ≥1 h, so that the metal powder is completely densified and solidified, and then, the furnace is cooled, and the powder metallurgy process is completed.

[0075] s2. Forge open the blank

[0076] According to the need, the precipitation hardening high speed steel of the present application is further forged and deformed to obtain a rod or a forged piece with a certain shape and size, and different properties are obtained by using different heat treatment systems. The heat treatment used includes annealing, solid solution and aging. The annealing treatment involves heating the rod or forged piece to 870-890°C, keeping for ≥2 h, then cooling to below 530°C at a speed of ≤15°C / h, and then furnace cooling or static air cooling to below 50°C; the solid solution treatment involves preheating the annealed rod or forged piece at a temperature of 810-850°C, uniformly heating, then placing it in a temperature of 1170-1200°C for 15-40 min, and then oil cooling; then, aging is performed at a temperature in the range of 580-650°C, and the holding time is 3-4 hours, and then air cooling to 50°C.

[0077] The powder metallurgy wear-resistant double-strengthening-phase precipitation hardening high speed steel and its preparation of the present application will be further described below with specific preparation examples and comparative examples, and corresponding performance detection. The two kinds of precipitated phase particle size and volume fraction, heat treatment hardness, impact toughness and wear resistance of the powder metallurgy wear-resistant double-strengthening-phase precipitation hardening high speed steel involved in the present application are verified, wherein the particle size and volume fraction of μ phase and carbide are analyzed based on the microstructure images obtained by scanning electron microscopy, and the heat treatment hardness, wear resistance and corrosion resistance are tested according to GB / T 230.1, GB / T 229 and GB / T 12444 respectively.

[0078] Two kinds of precipitation hardening high speed steels with different component compositions, cast and forged tool steel (alloy A) and powder metallurgy tool steel (alloy B) are obtained by the above preparation method, and the results are as follows:

[0079] Table 1 Comparison of component composition:

[0080] 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 Balance Example 2 1.24 0.31 - - 15.05 0.08 6.18 8.23 5.33 9.44 21.03 Balance Example 3 1.10 0.35 - - 15.78 0.10 6.44 10.0 6.0 11.0 22.07 Balance Example 4 1.10 0.35 - - 20.0 2.0 6.44 10.65 5.72 11.04 30.60 Balance Example 5 1.0 0.0 - - 10.0 0.0 0.0 10.0 5.0 10.0 13.90 Balance Example 6 2.60 0.40 - - 25.0 5.5 8.0 14.0 13.0 20.0 40.2 Balance Example 7 2.50 0.32 - - 24.5 5.30 7.04 14.70 12.0 19.35 39.55 Balance Example 8 2.55 0.36 - - 24.6 5.40 7.5 14.8 12.50 19.90 39.54 Balance 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 Balance 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 Balance

[0081] "-" in the table means that the element is not contained or the content of the element is small and not analyzed.

[0082] In the table, examples 1 to 8 are powder metallurgy precipitation hardening high speed steels of the present application, prepared by powder metallurgy process, first prepared by gas atomization powdering process, then the powder is densified by hot isostatic pressing, and then an ingot with a diameter of φ400mm is prepared, and further hot deformation processing is carried out to obtain a rod with a diameter of φ60mm.

[0083] Comparative example A prepared by electroslag remelting process, hot deformation processing to a diameter of φ55mm rod; comparative example B prepared by powder metallurgy process, hot deformation processing to a diameter of φ60mm rod

[0084] (I) Microstructure analysis

[0085] Based on the scanning electron microscope to obtain the microstructure image, Figures 1 to 6 respectively, the microstructure of the prepared precipitation hardened steel forgings example 1, example 2, example 4, example 5, example 6, example 7, Figure 7 is the microstructure of alloy A, Figure 8 is the microstructure of alloy B.

[0086] Obviously, Figures 1 to 6 The grayish white hardening phase is distributed in the matrix in a fine and dispersed manner, which can significantly improve the wear resistance, toughness and service life of the material. Figure 7 and Figure 8 Contains two kinds of precipitates, one is bright white and large in size, and the other is grayish white and small in size

[0087] After heat treatment, the content and particle size of the precipitates in examples 1 to 8 and alloys A and B are compared, as shown in table 2.

[0088] Table 2: content and particle size of precipitates

[0089]

[0090] The solid solution system of examples 1 to 8 is temperature 1190℃, time 30 minutes, aging system is temperature 600℃, time 3 hours; the quenching system of comparative example A is temperature 1160℃, time 15 minutes, tempering system is temperature 550℃, time 1 hour, times 3 times; the quenching system of comparative example B is temperature 1170℃, time 15 minutes, tempering system is temperature 550℃, time 1 hour, times 3 times.

[0091] The precipitated phase analysis of the high speed steel prepared in the examples 1 to 8 of the present application is carried out: the precipitated phase in the examples 1 to 8 is mainly IMC and MC carbide, wherein the IMC is mainly μ phase, the type is (Fe, Co)7(Mo+W / 2)6, and the MC carbide is VC type carbide; the precipitated phase in the alloy A and the alloy B is mainly Cr-rich (Cr, Fe)C type carbide, and in addition, there is VC type carbide.

[0092] The volume fraction of μ phase of the precipitation hardening high speed steel of the present application reaches 10%-20%, the particle size is small, most of the μ phase particle size is less than 1.5 μm, and the maximum size is not more than 7.0 μm, meanwhile, the second strengthening phase MC carbide exists in the precipitation hardening steel of the present application, the type is V(C, N) type, the volume fraction is 1%-5%, the particle size is small, most of the MC carbide particle size is less than 2.0 μm, and these precipitated phases have small size and large dispersity, so that the material obtains better wear resistance, toughness and service life.

[0093] The MC type carbide in the alloy B prepared by the powder metallurgy process is the smallest, most of the MC type carbide is 0.5-1.5 μm, the volume fraction is 2-6%, but there is a large number of (Cr, Fe)C type carbide with the size range of 3-12 μm in the structure. The coarse carbide has the adverse effect of cutting the matrix. In the alloy A produced by the traditional electroslag process, the size of the MC type carbide is close to that of the examples, but there is a large number of (Cr, Fe)C type carbide with the size range of 5-30 μm in the structure, and the coarse carbide has the adverse effect of cutting the matrix.

[0094] (II) Hardness and impact toughness analysis after heat treatment

[0095] In order to verify the influence of the heat treatment system on the performance of the precipitation hardening high speed steel prepared by the present application, the heat treatment process with different solid solution temperatures and aging temperatures is set to heat treat the prepared rod.

[0096] The prepared hardening steels in the examples 1 to 8 and the alloys A and B are heat treated, and the following hardness and impact toughness comparison results are shown in Table 3.

[0097] Table 3: mechanical property comparison

[0098] It can be seen from Table 3 that the impact toughness of the precipitation hardening high speed steel of the present application is relatively low, but the measured value meets the demand of the application field on toughness, and the precipitation hardening high speed steel of the present application is especially suitable for the occasions with less impact load operation.

[0099] (III) Wear resistance performance analysis

[0100] The results of the wear resistance comparison of examples 1-8 and alloys A, B are shown in Table 4.

[0101] Table 4: Wear resistance comparison

[0102] Alloy Quench and temper / solution age Hardness after heat treatment (HRC) Wear mass (mg) Example 1 1190°C oil quench + 600°C * 3h 64 44 Example 2 1190°C oil quench + 600°C * 3h 64 42 Example 3 1190°C oil quench + 600°C * 3h 64 45 Example 4 1190°C oil quench + 600°C * 3h 64.5 40 Example 5 1190°C oil quench + 600°C * 3h 64 48 Example 6 1190°C oil quench + 600°C * 3h 65 39 Example 7 1190°C oil quench + 600°C * 3h 65 38 Example 8 1190°C oil quench + 600°C * 3h 65 39 Comparative Example A 1160°C oil quench + 550°C * 1h * 3 times 64 190 Comparative Example B 1170°C oil quench + 550°C * 1h * 3 times 64 164

[0103] As can be seen from the comparison data in Table 4, the precipitation hardened steel of the present application exhibits excellent wear resistance, and can withstand long-term high-strength wear during use, thereby greatly improving the service life of the material. According to the requirements of wear resistance for different application occasions, a suitable heat treatment system should be selected. Within a relatively wide heat treatment temperature range, the precipitation hardened high-speed steel of the present application can have good strength and toughness and wear resistance, thereby meeting the application requirements of the corresponding working conditions.

[0104] In addition, due to the limitations of the precipitated phase particle number statistical image analysis software, under the above implementation conditions, the precipitation hardened steel of the present application may have individual μ phase and MC carbide with a size exceeding the maximum size, but due to the extremely small number, it has no substantial effect on the toughness and other mechanical properties of the precipitation hardened steel, and thus can be ignored. There are many μ phases with smaller particles that cannot be identified by the analysis software, and the statistical results of volume fraction and particle size are only for comparison.

[0105] Due to the use of specific alloy composition design and the use of powder metallurgy process for preparation, the present application has μ phase and MC carbide dual-phase strengthening phase characteristics, with fine precipitated phase particle size and high dispersion, thus making the material have better strength and toughness ratio and better service life, and being able to meet different types of application requirements, and being used for making (1) cutters for cutting difficult-to-machine materials at high speed; (2) high-precision gauges; (3) wear-resistant parts, etc.

[0106] In summary, the powder metallurgy wear-resistant dual-strengthening phase precipitation hardened high-speed steel of the present application, due to its alloy composition characteristics, strengthening mechanism and traditional high-speed steel, has a great advantage in anti-tempering softening capacity over traditional high-speed steel and other tool steels, and also has high wear resistance.

[0107] The above only describes the preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A powder metallurgy wear resistant dual strengthened phase precipitation hardened high speed steel characterized in that, The chemical components include, by mass percent: 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 being iron and impurities; and the strengthening phase in the powder metallurgy wear-resistant double-strengthening phase precipitation hardened high speed steel includes intermetallic compounds and MC carbides, wherein the intermetallic compounds are μ phase, the type of μ phase is (Fe, Co)7(Mo + W / 2)6 type, and the type of MC carbide is V(C, N) type.

2. The powder metallurgy wear-resistant double-strengthening phase precipitation hardened high speed steel according to claim 1, the chemical components of which include, by 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. Powder metallurgical wear resistant dual strengthened phase precipitation hardened high speed steel according to claim 1 or 2, characterized in that: The particle size of at least 80% by volume fraction of the μ phase is ≤ 1.5 μm, and the maximum particle size of the μ phase is no more than 6.0 μm.

4. Powder metallurgical wear resistant dual strengthened phase precipitation hardened high speed steel according to claim 1 or 2, characterized in that: The volume fraction of the μ phase in the powder metallurgy wear-resistant double-strengthening phase precipitation hardened high speed steel is 10% - 20%.

5. Powder metallurgical wear resistant dual strengthened phase precipitation hardened high speed steel according to claim 1 or 2, characterized in that: The particle size of at least 80% by volume fraction of the MC carbide is ≤ 2.0 μm, and the maximum particle size of the MC carbide is no more than 3.0 μm.

6. The powder metallurgy wear resistant dual-strengthened phase precipitation hardened high speed steel of claim 1 or 2, characterized in that: The volume fraction of the MC carbide in the powder metallurgy wear-resistant double-strengthening phase precipitation hardened high speed steel is 1.0% - 5.0%. The particle size of at least 80% by volume fraction of the μ phase is ≤ 1.5 μm, and the maximum particle size of the μ phase is no more than 6.0 μm. The volume fraction of the μ phase in the powder metallurgy wear-resistant double-strengthening phase precipitation hardened high speed steel is 10% - 20%. The particle size of at least 80% by volume fraction of the MC carbide is ≤ 2.0 μm, and the maximum particle size of the MC carbide is no more than 3.0 μm. The volume fraction of the MC carbide in the powder metallurgy wear-resistant double-strengthening phase precipitation hardened high speed steel is 1.0% - 5.0%.

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