Spray formed wear and corrosion resistant precipitation hardened high speed steel

Abstract

The spray forming wear-resistant and corrosion-resistant precipitation hardening high-speed steel contains the following components in percentage by mass: C: 0.1-0.2%; Si: 0.3-0.8%; Cr: 2.0-15.0%; V: 0.05-2.0%; Co: 0-18.0%; W: 0-5.0%; Mo: 8-25.0%; (Mo+W / 2): 10.0-27.0%; the balance being iron and impurities. The precipitated phase in the spray forming wear-resistant and corrosion-resistant precipitation hardening high-speed steel includes a large amount of intermetallic compound (IMC) μ phase and a small amount of MC carbide, wherein the μ phase is of the (Fe, Co)7(Mo+W / 2)6 type, and the MC carbide is of the V(C, N) type. The μ phase and the carbide prepared by the present application are small in size and uniform in distribution, and have excellent comprehensive performance, especially wear resistance and corrosion resistance. The present application is prepared by the spray forming process, which has the advantages of low cost and fast process compared with the powder metallurgy process.

Description

TECHNICAL FIELD

[0001] The present application relates to a precipitation hardening high speed steel, in particular to a spray forming wear-resistant and corrosion-resistant precipitation hardening high speed steel. BACKGROUND

[0002] The precipitation hardening steel is a carbon-free ferritic martensitic precipitation hardening tool alloy, which is a new type of ultra-high strength steel developed in recent years. This kind of steel has good grindability and tempering resistance, good dimensional stability, and is widely used in aerospace and marine chemical industry.

[0003] The hardening effect of the precipitation hardening steel is due to the intermetallic compound (IMC) particles precipitated during aging process, which can improve the tempering resistance of the precipitation hardening high speed steel, and the strength of the matrix and the distribution state and size of the IMC phase can affect the toughness of the steel.

[0004] At present, the precipitation hardening steel is prepared by powder metallurgy process, which can solve the problem of element segregation and obtain uniform microstructure, which is greatly improved compared with traditional casting and forging process, but the powder metallurgy process is complex, long process and high cost, and the wear resistance and corrosion resistance of the existing precipitation hardening steel cannot meet the demand. SUMMARY

[0005] Therefore, the present application provides a spray forming wear-resistant and corrosion-resistant precipitation hardening high speed steel with good microstructure and excellent performance.

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

[0007] A spray forming wear-resistant and corrosion-resistant precipitation hardening high speed steel, characterized in that the steel comprises the following chemical components by mass percentage:

[0008] C: 0.1%-0.2%;

[0009] Si: 0.3%-0.8%;

[0010] Cr: 2.0%-15.0%;

[0011] V: 0.05-2.0%;

[0012] Co: 0%-18.0%;

[0013] W: 0%-5.0%;

[0014] Mo: 8%-25.0%;

[0015] (Mo+W / 2): 10.0%-27.0%;

[0016] The balance is iron and impurities;

[0017] And, the spray forming wear-resistant and corrosion-resistant precipitation hardening high-speed steel includes a large amount of intermetallic compound (IMC) μ phase and a small amount of MC carbide, wherein the μ phase is (Fe, Co) 7 (Mo + W / 2) 6 type, and the MC carbide is V (C, N) type.

[0018] The present application improves the wear resistance and corrosion resistance of the steel by designing the alloy composition.

[0019] Specifically, the content of C (carbon) in the precipitation hardening high-speed steel in the present application needs to be controlled in 0.1%-0.2%, preferably 0.1%-0.18%, to reduce the precipitation of carbide, mainly to realize strengthening by μ phase, and a small amount of C in the steel is used to form carbide, further improving the wear resistance of the precipitation hardening steel.

[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, and the increase of Co content will appropriately reduce the toughness of the steel, and the Co element content in the present application is 0%-18.0%, preferably 0%-16.0%.

[0021] The melting point of W (tungsten) is high, which increases the strength and tempering stability of the steel, the high temperature creep resistance, and the anti-tempering softening ability of the steel, so that the surface layer of the steel has less temperature rise and less hardness drop during processing and use, and the W element content in the present application is 0%-5.0%, preferably 0%-4.0%.

[0022] Mo (molybdenum) has the same effect as W, can completely replace W, and the price is lower than W. On the other hand, the higher the Mo content, the higher the initial precipitation temperature of μ phase, and the larger the particle size of μ phase, and the Mo element content in the present application is 8.0%-25.0%, preferably 8.0%-22.0%.

[0023] The role of Cr (chromium) added to the steel is that it can coarsen the particles, so that the red hardness is reduced and the machinability is improved; on the other hand, part of Cr is dissolved in the matrix, which can improve the corrosion resistance and hardenability of the steel. In the present application, the Cr element content range is 2.0%-15.0%, preferably 2.0%-12.0%.

[0024] V (vanadium) as a strong carbide forming element, its main role is to form MC type carbide with the steel, improve the wear resistance of the steel, and make more Cr dissolve in the matrix to further improve the wear resistance. In order to ensure that the strengthening mechanism of the steel is still dominated by μ phase, and to ensure the grindability of the steel, the V element content in the present application is 0.05%-2.0%, preferably 0.05%-1.7%.

[0025] 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, but too much Si will reduce the plasticity and toughness of the matrix, the Si content of the present application is controlled in 0.3%-0.8%, and preferably 0.3%-0.6%.

[0026] As a limitation of the above-mentioned manner, the spray-formed wear-resistant and corrosion-resistant precipitation-hardened high-speed steel comprises the following chemical components by mass percentage:

[0027] C: 0.1%-0.18%;

[0028] Si: 0.3%-0.6%;

[0029] Cr: 2.0%-12.0%;

[0030] V: 0.05-1.7%;

[0031] Co: 0%-16.0%;

[0032] W: 0%-4.0%;

[0033] Mo: 8.0%-22.0%;

[0034] (Mo+W / 2): 10.0%-22.0%;

[0035] The balance is iron and impurities.

[0036] In order to achieve better comprehensive performance, the chemical components in the spray-formed wear-resistant and corrosion-resistant precipitation-hardened high-speed steel of the present application should be controlled within the required range.

[0037] Further, at least 80% of the volume fraction of the μ phase has a particle size ≤1.5 μm, and the maximum particle size of the μ phase is not more than 12.0 μm.

[0038] Further, the volume fraction of the μ phase in the spray-formed wear-resistant and corrosion-resistant precipitation-hardened high-speed steel is 15-28%.

[0039] Further, at least 80% of the volume fraction of the MC carbide has a size ≤2 μm, and the maximum MC carbide size is not more than 3.0 μm.

[0040] Further, the volume fraction of the MC carbide in the spray-formed wear-resistant and corrosion-resistant precipitation-hardened high-speed steel is 1.0%-2.5%.

[0041] The present application also provides a preparation method for preparing the spray-formed wear-resistant and corrosion-resistant precipitation-hardened high-speed steel as described above, and the preparation method comprises the following steps:

[0042] a. Prepare the liquid of precipitation hardening steel according to the chemical composition requirement and transfer to ladle;

[0043] b. Maintain the superheat of the liquid by heating the protective slag covering the upper surface of the liquid in the ladle, and stir the liquid by blowing inert gas through the bottom of the ladle;

[0044] c. Flow the liquid through the flow guide pipe at the bottom of the ladle into the preheated tundish at a stable flow rate, and apply the protective slag to the upper surface of the liquid when the liquid covers the lower end surface of the flow guide pipe;

[0045] d. Continuously compensate the heating of the tundish to maintain the superheat of the liquid;

[0046] e. Atomize and deposit the liquid by inert gas after the liquid enters the spray deposition chamber from the tundish, and complete the spray deposition to obtain the spray deposition ingot under the stable outlet pressure. Maintain the stability of the liquid temperature and flow rate during the spray deposition process, and slowly lower the spray deposition receiving disc while rotating horizontally. The lowering speed of the spray deposition receiving disc is consistent with the growth speed of the spray deposition ingot to keep the height of the upper end surface of the spray deposition ingot constant. Control the gas inlet and outlet flow rates to maintain the inert gas protective atmosphere in the spray deposition chamber;

[0047] f. Transfer the spray deposition ingot to the protective atmosphere furnace for annealing or directly to the hot forging breakdown process.

[0048] g. Homogenize the spray deposition ingot in a chamber furnace, and forge the spray deposition ingot to break down after discharging from the furnace by multiple heating times and small deformation to obtain the precipitation hardening high speed steel bar.

[0049] The whole process is protected to control the μ phase morphology and optimize the performance of the precipitation hardening high speed steel.

[0050] The protective slag of the ladle has the functions of air insulation and electric heating. The inert gas is blown into the ladle through the air holes at the bottom of the ladle to balance the temperature of the liquid at different positions in the ladle and accelerate the floating and removal of harmful inclusions. The flow guide pipe at the bottom of the ladle plays a role in guiding the flow of the liquid to reduce the turbulence during the flow of the liquid, avoid slag entrapment or reduce the inclusions entering the next process, and avoid the direct contact of the liquid with air to prevent the continuous increase of the oxygen content of the liquid. The protective slag of the tundish prevents the direct contact of the liquid flowing through the tundish with air and reduces the increase of the oxygen content of the liquid. The tundish is preheated before the liquid enters the tundish to prevent local condensation of the liquid when it enters the tundish or cause the precipitation of the second phase in advance. The gas inlet and outlet flow rates are controlled during the spray deposition process to maintain the inert gas protective atmosphere in the spray deposition chamber, which protects the spray deposition ingot.

[0051] The precipitation hardening high speed steel in the application is prepared by the spray forming process, and the preparation cost is lower than that of the powder metallurgy process, which has advantages in reducing the overall cost of the alloy and simplifying the process flow. In addition, the μ phase and a small amount of MC carbide in the spray-formed wear-resistant and corrosion-resistant precipitation hardening high speed steel obtained are fine and uniform, excellent strength and toughness can be obtained, and the precipitation hardening high speed steel has excellent comprehensive performance, especially high wear resistance and corrosion resistance, and can obtain a hardness of more than 63HRC after heat treatment, and is suitable for use in working conditions with hard particles and corrosive medium. BRIEF DESCRIPTION OF DRAWINGS

[0052] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. The accompanying drawings should not be regarded as a proper limitation of the present application. In the drawings:

[0053] Figure 1 Microstructure diagram of the precipitation hardening high speed steel prepared in Example 1 of the present application;

[0054] Figure 2 Microstructure diagram of the precipitation hardening high speed steel prepared in Example 2 of the present application;

[0055] Figure 3 Microstructure diagram of the precipitation hardening high speed steel prepared in Example 4 of the present application;

[0056] Figure 4 Microstructure diagram of the precipitation hardening high speed steel prepared in Example 5 of the present application;

[0057] Figure 5 Microstructure diagram of the precipitation hardening high speed steel prepared in Example 6 of the present application;

[0058] Figure 6 Microstructure diagram of the powder metallurgy process corrosion-resistant high speed steel prepared in Comparative Example A of the present application;

[0059] Figure 7 Microstructure diagram of the electroslag process tool steel prepared in Comparative Example B of the present application; DETAILED DESCRIPTION

[0060] 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.

[0061] The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0062] The present application relates to a group of spray forming wear-resistant and corrosion-resistant precipitation hardening high speed steel, comprising the following chemical components by mass percentage: C: 0.1%-0.2%; Si: 0.3%-0.8%; Cr: 2.0%-15.0%; V: 0.05-2.0%; Co: 0%-18.0%; W: 0%-5.0%; Mo: 8%-25.0%; (Mo+W / 2): 10.0%-27.0%; the balance is iron and impurities.

[0063] As a preferred scheme, the precipitation hardening high speed steel of the present application comprises the following chemical components by mass percentage: C: 0.1%-0.18%; Si: 0.3%-0.6%; Cr: 2.0%-12.0%; V: 0.05-1.7%; Co: 0%-16.0%; W: 0%-4.0%; Mo: 8.0%-22.0%; (Mo+W / 2): 10.0%-22.0%; the balance is iron and impurities.

[0064] The spray forming wear-resistant and corrosion-resistant precipitation hardening high speed steel formed by the above components can obtain ideal wear resistance and corrosion resistance.

[0065] The present application also relates to a method for preparing the above-mentioned precipitation hardening high speed steel, when prepared by using traditional ingot or electroslag process, segregation is easy to occur due to slow solidification speed, which leads to performance decline, and when prepared by using powder metallurgy process, the process is long and the cost is high, under the premise of ensuring that the prepared precipitation hardening high speed steel ingot is uniform in composition and organization, the mu phase is fine and the purity is high, the spray forming process is used to replace the powder metallurgy process to prepare the steel ingot, and then the required rod product is obtained through forging.

[0066] Specifically, the preparation method of the present application comprises the following steps:

[0067] s1. The molten steel of the present application is loaded into a spray forming melting ladle, and the molten steel loading weight is 3.5 tons;

[0068] s1.1. The graphite electrode is used to electrically heat the protective slag covered on the upper surface of the molten steel in the ladle, argon is introduced into the bottom of the ladle to stir the molten steel, and the molten steel overheat degree is opened to 100-200°C to open the molten steel flow guide pipe;

[0069] s1.2. The molten steel is flowed into the tundish preheated to 800-1200°C through the flow guide pipe at the bottom of the ladle at a flow rate of 100Kg / min-200Kg / 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;

[0070] s1.3. The tundish is continuously compensated and heated during the spray deposition process, and the overheat degree of the molten steel is maintained at 100-200°C;

[0071] S1.4 molten steel enters the jet deposition chamber through the bottom of the tundish. The gas injection valve is opened, and nitrogen is used as the gas medium for atomization deposition. The nitrogen purity is ≥99.999%, the oxygen content is ≤2ppm, and the gas nozzle outlet pressure is 1.0MPa-1.5MPa. Under the action of nitrogen injection, the molten steel is broken into semi-solidified droplets, which then mix with the gas to form an atomization cone. The droplets fly to the jet deposition receiving plate and slowly descend while rotating horizontally. The descent speed of the jet deposition receiving plate is consistent with the growth speed of the jet deposition ingot, so that the height of the upper end face of the jet deposition ingot is constant. Before and after the start of jet deposition, a protective nitrogen atmosphere is continuously maintained inside the jet deposition chamber. The gas inlet and outlet flow rates are controlled during the deposition process.

[0072] After the s1.5 spray deposition is completed, a single ingot weighing more than 3 tons and with a size of φ550mm is obtained. The spray-deposited ingot is transferred to a protective atmosphere furnace for annealing and then cooled in the furnace.

[0073] s2. Forging open billet

[0074] The spray-deposition ingot is forged into a billet using multiple heating cycles with small deformation amounts. Each deformation is between 5 and 20 mm, and each heating temperature is between 1170 and 1200℃ for 400 minutes. A total of 4 heating cycles are performed. After the billet is forged, it is promptly placed in tubes for annealing at a temperature of 870-890℃ to finally obtain precipitation-hardening high-speed steel bars.

[0075] The following will further illustrate the spray-formed wear-resistant and corrosion-resistant precipitation-hardening high-speed steel of the present invention and its preparation by specific preparation examples, comparative examples, and corresponding performance tests.

[0076] The particle size and volume fraction of the second phase, heat treatment hardness, wear resistance and corrosion resistance of the spray-formed wear-resistant and corrosion-resistant precipitation-hardening high-speed steel involved in this invention were verified. The particle size and volume fraction of the μ phase and carbides were analyzed based on microstructure images obtained by scanning electron microscopy. The heat treatment hardness, wear resistance and corrosion resistance were tested in accordance with GB / T 230.1, GB / T 12444, JB / T 7901 and GB / T 17899, respectively.

[0077] Two precipitation-hardening high-speed steels with different compositions, Example 1 and Example 2, were obtained using the above preparation method. These were compared with high-Cr spray-formed tool steel (Alloy A) and cast / forged tool steel (Alloy B). The results are as follows:

[0078] Table 1: Comparison of Component Composition

[0079] Alloy C Si Mn Cr Co V W Mo Mo + W / 2 Fe Example 1 0.15 0.45 - 4.01 15.52 0.11 0.01 22.20 22.20 Balance Example 2 0.13 0.39 - 4.67 14.90 0.20 0.01 21.99 21.99 Balance Example 3 0.15 0.45 - 4.01 15.52 0.11 4.0 20.0 22.0 Balance Example 4 0.10 0.30 - 2.0 - 0.05 4.0 8.0 10.0 Balance Example 5 0.20 0.80 - 15.0 18.0 2.0 4.0 25.0 27.0 Balance Example 6 0.18 0.60 - 12.0 16.0 1.70 0 22.0 22.0 Balance Example 7 0.19 0.70 - 13.0 17.0 1.80 2.0 23.0 24.0 Balance Comparative Example A 1.36 0.70 0.43 14.67 0.03 2.42 0.07 1.85 1.88 Balance Comparative Example B 1.15 0.46 0.73 14.73 0.05 0.18 0.23 1.84 1.95 Balance

[0080] (I) Microstructure Analysis

[0081] Figures 1 to 5are microstructure schematic diagrams of the prepared precipitation hardening steel bar embodiments 1, 2, 4, 5, 6 respectively, Figure 6 is a microstructure schematic diagram of alloy A, Figure 7 is a microstructure schematic diagram of alloy B.

[0082] It is obvious that, Figures 1 to 5 The hardening phase dispersed in the matrix in the middle gray white color can significantly improve the wear resistance, toughness and service life of the material. Figure 6 and Figure 7 The microstructure contains two kinds of precipitates, one kind is bright white and large in size, and the other kind is gray white and small in size.

[0083] The precipitate content and particle size of the high speed steel prepared in embodiments 1 to 7 and alloys A and B after heat treatment are compared:

[0084] Table 2: Content and particle size of precipitates

[0085]

[0086] The solid solution system of embodiments 1 to 8 is 1190℃*30 minutes, the aging system is 600℃*3 hours; the quenching system of comparative example A is 1180℃*15 minutes, the tempering system is 550℃*2 hours*2 times; the quenching system of comparative example B is 1185℃*15 minutes, the tempering system is 550℃*1 hour*3 times.

[0087] The precipitates of the high speed steel prepared in embodiments 1 to 7 in the application are analyzed: the precipitates in embodiments 1 to 7 are mainly IMC and MC carbides, 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 strengthening phase in alloys A and B is mainly (Cr, Fe)C type carbide rich in Cr, and in addition, there is VC type carbide.

[0088] The volume fraction of μ phase of the precipitation hardening high speed steel in the application reaches 15%-28%, the particle size is small, most of the μ phase particle size is less than 1.5μm, and the maximum size is not more than 12.0μm; at least 80Vol% of the MC carbide size is ≤2μm, and the maximum size is not more than 3.0μm. These precipitates have small size and large dispersion, and the μ phase also has excellent high temperature aggregation resistance, so that the material has better wear resistance, toughness and service life.

[0089] The MC type carbide size of alloy A prepared by powder metallurgy process and alloy B prepared by traditional electroslag process is close to that of the embodiments, but there are a large number of (Cr, Fe)C type carbides with a size range of 3-12μm in the microstructure, and the coarse carbides have the adverse effect of cutting the matrix.

[0090] (ii) Hardness and wear resistance analysis after heat treatment

[0091] In order to verify the effect of heat treatment system on the properties of the precipitation hardened high speed steel prepared by the present application, the prepared rods are heat treated by setting different solid solution temperatures and aging temperatures.

[0092] The high speed steels prepared in Examples 1 to 7 and alloys A and B are heat treated, and the following hardness and impact toughness comparison results are shown in Table 3.

[0093] Table 3: Comparison of mechanical properties

[0094]

[0095] As can be seen from Table 3, after suitable heat treatment, the hardness of the precipitation hardened high speed steel of the present application reaches more than 63HRC, which can meet the requirements of the application field, and the wear resistance comparison results show that the precipitation hardened high speed steel of the present application has good wear resistance.

[0096] (iii) Corrosion resistance analysis

[0097] Examples 1 to 7 and alloys A and B are immersed in 5% HNO3+1% HC1 solution at room temperature, and then the corrosion rate is measured. Then the polarization curve is measured in 1% NaCl solution, and finally the self-corrosion potential is obtained. The corrosion resistance comparison results are shown in Table 4.

[0098] Table 4: Comparison of corrosion resistance

[0099] Quench and temper / solution age Corrosion rate mm / y Self-corrosion potential E corr ]] Example 1 1190°C oil quench + 600°C * 3h ≤150 -0.488 Example 2 1190°C oil quench + 600°C * 3h ≤150 -0.461 Example 3 1190°C oil quench + 600°C * 3h ≤150 -0.471 Example 4 1190°C oil quench + 600°C * 3h ≤150 -0.425 Example 5 1190°C oil quench + 600°C * 3h ≤150 -0.530 Example 6 1190°C oil quench + 600°C * 3h ≤150 -0.495 Example 7 1190°C oil quench + 600°C * 3h ≤150 -0.516 Comparative Example A 1180°C oil quench + 550°C * 2h * 2 times ≤200 -0.413 Comparative Example B 1185°C oil quench + 550°C * 1h * 3 times ≤200 -0.254

[0100] As can be seen from the comparison data in Table 4, the precipitation hardened steel of the present application shows more excellent corrosion resistance. Because the C content in the precipitation hardened steel in the present application is very small, it basically does not precipitate with Cr in the form of carbide, and most of the Cr elements in the steel are solid-solved in the matrix, which can obtain higher corrosion resistance.

[0101] In addition, due to the limitation of the 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 in the microstructure, 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.

[0102] Due to the specific alloy component design and the spray forming process, the material can obtain better strength and toughness ratio and wear and corrosion resistance, and can meet different application requirements, and can be used for manufacturing (1) cutters for cutting difficult-to-cut materials at high speed; (2) high-precision gauges; (3) wear-resistant and corrosion-resistant parts and the like.

[0103] In summary, the spray-formed wear-resistant and corrosion-resistant precipitation-hardened high-speed steel provided by the present application has excellent comprehensive performance, especially good wear and corrosion resistance. Due to the characteristics of the alloy component, the strengthening mechanism is different from that of the traditional high-speed steel, which leads to the anti-tempering softening capacity being much better than that of the traditional high-speed steel and other tool steels, and at the same time, the wear and corrosion resistance is high, and the preparation cost is lower than that of the powder metallurgy process. The precipitation-hardened high-speed steel in the present application has the characteristics of high efficiency and low cost, and has good practicability.

[0104] 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 and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A spray formed wear and corrosion resistant precipitation hardened high speed steel, characterized in that, The chemical components include, by mass percent: C：0.1％-0.2％； Si: 0.3% - 0.8%; Cr：2.0％-15.0％； V：0.05-2.0％； Co: 0% - 18.0%; W：0％-5.0％； Mo: 8% - 25.0%; (Mo + W / 2): 10.0% - 27.0%; the balance being iron and impurities; and the precipitated phase in the spray-formed wear-resistant and corrosion-resistant 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 spray formed wear and corrosion resistant precipitation hardened high speed steel of claim 1, wherein, The chemical components include, by mass percent: C：0.1％-0.18％； Si: 0.3% - 0.6%; Cr：2.0％-12.0％； V：0.05-1.7％； Co: 0% - 16.0%; W：0％-4.0％； Mo: 8.0% - 22.0%; (Mo + W / 2): 10.0% - 22.0%; the balance being iron and impurities.

3. The spray formed wear and corrosion resistant precipitation hardened high speed steel according to claim 1 or 2, characterized in that: At least 80% of the volume fraction of the μ phase has a particle size ≤ 1.5 μm, and the maximum particle size of the μ phase is not more than 12.0 μm.

4. The spray formed wear and corrosion resistant precipitation hardened high speed steel of claim 1 or 2, characterized in that: The volume fraction of the μ phase in the spray-formed wear-resistant and corrosion-resistant precipitation-hardened high-speed steel is 15% - 28%.

5. The spray formed wear and corrosion resistant precipitation hardened high speed steel of claim 1 or 2, wherein: At least 80% of the volume fraction of the MC carbide has a particle size ≤ 2 μm, and the maximum particle size of the MC carbide is not more than 3.0 μm.

6. The spray formed wear and corrosion resistant precipitation hardened high speed steel of claim 1 or 2, wherein: The volume fraction of the MC carbide in the spray-formed wear-resistant and corrosion-resistant precipitation-hardened high-speed steel is 1.0% - 2.5%. At least 80% of the volume fraction of the μ phase has a particle size ≤ 1.5 μm, and the maximum particle size of the μ phase is not more than 12.0 μm. The volume fraction of the μ phase in the spray-formed wear-resistant and corrosion-resistant precipitation-hardened high-speed steel is 15% - 28%. At least 80% of the volume fraction of the MC carbide has a particle size ≤ 2 μm, and the maximum particle size of the MC carbide is not more than 3.0 μm. The volume fraction of the MC carbide in the spray-formed wear-resistant and corrosion-resistant precipitation-hardened high-speed steel is 1.0% - 2.5%.

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