WO2016184009A1

WO2016184009A1 - Powder metallurgy wear-resistant tool steel

Info

Publication number: WO2016184009A1
Application number: PCT/CN2015/091285
Authority: WO
Inventors: 李小明; 吴立志; 钟海林; 王学兵; 况春江; 方玉诚
Original assignee: 安泰科技股份有限公司; 河冶科技股份有限公司
Priority date: 2015-05-15
Filing date: 2015-09-30
Publication date: 2016-11-24
Also published as: CN104894483A; US10385428B2; US20170211167A1; CN104894483B

Abstract

Powder metallurgy wear-resistant tool steel, comprising the following chemical components in percentage by mass: 12.2 to 16.2% of V, 1.1 to 3.2% of Nb, 2.6 to 4.0% of C, no more than 2.0% of Si, 0.2 to 1.5% of Mn, 4.0 to 5.6% of Cr, no more than 3.0% of Mo, 0.1 to 1.0% of W, 0.05 to 0.5% of Co, 0.05 to 0.7% of N and the balance of iron and impurities. The powder metallurgy wear-resistant tool steel comprises MX carbide of a face-centered cubic structure, wherein M is mainly composed of elements V and Nb, and X is mainly composed of elements C and N.

Description

Powder metallurgy wear-resistant tool steel

Technical field

The invention relates to a tool steel, in particular to a powder metallurgy wear-resistant tool steel.

Background technique

Tool steel is widely used in the field of processing and manufacturing. In order to make the tool steel tool have a long service life, the tool steel should have excellent performance in four aspects including wear resistance, impact toughness, bending strength and hardness. Under normal conditions of use, the wear resistance determines the length of service life. The wear resistance of the tool steel depends on the hardness of the matrix and the content, morphology and particle size distribution of the hard second phase present in the steel. The hard second phase present in the steel includes M ₆ C, M ₂ C, M ₂₃ C ₆ , M ₇ C ₃ and MX carbides. The microhardness of the MX carbide is higher than that of other carbides. Better protection of the substrate, thus reducing the occurrence of wear and increasing the service life of the mold. The impact toughness and bending strength of tool steel are important indicators of toughness. The presence of coarse carbides in steel causes stress concentration, which reduces the toughness of tool steel, resulting in fracture under low external force loading. In order to improve the toughness of tool steel, Reducing the carbide content or refining the carbide particle size is an important means. In order to avoid the occurrence of plastic deformation, tool steel usually requires a hardness of more than HRC60.

At present, the tool steel is mainly prepared by the traditional casting and forging process. The preparation of the tool steel by the casting and forging process is limited by the slow cooling and solidification characteristics of the molten steel in the process. The alloy composition is prone to segregation during the solidification process, forming a coarse carbide structure even if After the subsequent forging process, the bad structure still has a bad influence on the properties of the alloy, which leads to the performance of the cast and forged die steel including the strength, toughness, wear resistance and grindability, which are difficult to meet the high-end. Manufacturing requirements for material performance and life stability. The powder metallurgy process is used to prepare the tool steel to solve the problem of alloy element segregation. The main steps of the powder metallurgy process for preparing the tool steel include: atomization milling and powder consolidation forming. In the above atomization and milling process, the molten steel is quickly Cooled into powder, the alloying elements in the molten steel are less than segregation and completely solidified. After the powder is consolidated into a material, the microstructure is fine and uniform, which is greatly improved compared with the properties of the cast-forged alloy. Highly demanding high-alloy tool steels can only be prepared by powder metallurgy. The preparation of tool steel by powder metallurgy process has been reported, but the design of some steel components is not reasonable enough, and the organization and performance need to be further improved.

Summary of the invention

The present invention aims to solve at least one of the technical problems in the related art to some extent. Accordingly, it is an object of the present invention to provide a powder metallurgy wear resistant tool steel having excellent properties.

In order to achieve the above object, an embodiment of the present invention provides a powder metallurgy wear-resistant tool steel. The chemical composition of the powder metallurgy wear-resistant tool steel includes: V: 12.2% - 16.2%, Nb: 1.1% - 3.2 %, C: 2.6% - 4.0%, Si: ≤ 2.0%, Mn: 0.2% - 1.5%, Cr: 4.0% - 5.6%, Mo: ≤ 3.0%, W: 0.1% - 1.0%, Co: 0.05% -0.5%, N: 0.05%-0.7%, the balance is iron and impurities; the carbide composition of the powder metallurgy wear-resistant tool steel is MX carbide, and the MX carbide is NaCl-type face-centered cubic lattice structure, MX The M element in the carbide includes V and Nb, and the X element includes C and N.

The powder metallurgy wear-resistant tool steel according to the embodiment of the invention is designed by the alloy composition to obtain a high wear-resistant tool steel, and at the same time has high impact toughness, bending strength and hardness. Adding a large amount of vanadium and carbon alloy elements to form MX carbide to improve wear resistance, while adding a certain amount of alloying elements such as chromium, molybdenum and silicon to strengthen the matrix and promote precipitation of more MX carbides, in addition to the above alloys In addition to the elements, the present invention adds a certain amount of niobium and nitrogen alloy elements, and is dissolved in MX carbide to form a composite MX carbide whose main constituent elements are C, N, V, Nb, and the type of MX carbide is (V, Nb) (C, N), the purpose is to increase the nucleation rate of MX carbide, so that the precipitated MX carbide can be made finer and improve the toughness of the tool steel. The amount of niobium and nitrogen added needs to be controlled within a suitable range to avoid formation of high stability carbides NbC, VN, NbN, and the like.

In some embodiments, the chemical composition of the powder metallurgy wear-resistant tool steel has a V equivalent V _{eq of from} 13.0% to 16.0%, and said V _eq =V+0.65 Nb.

In some embodiments, the impurities comprise O,O content of no more than 0.01%.

In some embodiments, the chemical composition of the powder metallurgy wear-resistant tool steel comprises, by mass percent: V: 13.0%-16.0%, Nb: 1.2%-2.5%, C: 2.8%-3.7%, Si: ≤1.3%, Mn: 0.2%-1.5%, Cr: 4.8%-5.4%, Mo: ≤2.0%, W: 0.1% - 0.5%, Co: 0.1% - 0.4%, N: 0.05% - 0.4%, O content not exceeding 0.008%, and the balance being iron and impurities.

In some embodiments, the impurities comprise S, S content of no more than 0.1%.

In some embodiments, the impurities comprise P and the P content does not exceed 0.03%.

In some embodiments, the MX carbide has a volume fraction of from 16% to 25%.

In some embodiments, at least 80% of the MX carbides have a size in the range of 0.5 to 1.3 μm by volume percent.

In some embodiments, the MX carbide has a maximum dimension of no more than 5.0 μm.

detailed description

The embodiments of the present invention are described in detail below, and the examples of the embodiments are illustrated in the drawings, wherein the same or similar reference numerals are used to refer to the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are intended to be illustrative of the invention and are not to be construed as limiting.

Embodiments of the present invention provide a powder metallurgy wear-resistant tool steel having excellent properties. The chemical composition of the powder metallurgy wear-resistant tool steel according to the embodiment of the present invention includes: V: 12.2% - 16.2%, Nb: 1.1% - 3.2%, C: 2.6% - 4.0%, Si: ≤ 2.0. %, Mn: 0.2% - 1.5%, Cr: 4.0% - 5.6%, Mo: ≤ 3.0%, W: 0.1% - 1.0%, Co: 0.05% - 0.5%, N: 0.05% - 0.7%, balance It is iron and impurities; the carbide composition of powder metallurgy wear-resistant tool steel is MX type carbide, MX is NaCl type face-centered cubic lattice structure, the main elements of M in MX carbide are V and Nb, and the main elements of X are C and N.

The embodiment of the invention achieves a high wear-resistant tool steel by designing the alloy composition, and at the same time has high impact toughness, bending strength and hardness.

The use of the V element is very important for improving the wear resistance, and V is the main element for forming the MX type carbide, and the V content is controlled in the range of 12.2% to 16.2%.

The action of Nb is similar to that of V, and participates in the formation of MX carbide. The Nb of the present invention is solid-dissolved in MX carbide, which increases the number of nucleation when MX carbide is precipitated, promotes precipitation and refinement of MX carbide, and improves wear resistance; Nb addition The upper limit of the content is to avoid precipitation of Nb-rich MX carbide; the embodiment of the present invention controls the content of Nb in the range of 1.1% to 3.2%.

The C element is one of the constituent elements of MX carbide, and the content of C is not less than 2.6% to ensure that the alloying element can fully participate in the precipitation of carbides, and the maximum content of C does not exceed 4.0%, avoiding excessive C solid solution in the matrix, The above C content is in the range of 2.6% to 4.0%, and a combination of maximum wear resistance and toughness can be obtained.

Si does not participate in carbide formation and is used as a deoxidizer and a matrix strengthening element. Too much Si reduces the toughness of the matrix, so the Si content range is limited to Si ≤ 2.0%.

When Mn is added as a deoxidizing agent, sulfur can be reduced to reduce hot brittleness, and manganese can increase hardenability. The Mn content in the examples of the present invention ranges from 0.2% to 1.5%.

On the one hand, the effect of Cr is dissolved in the matrix to increase the hardness of the matrix, and on the other hand, a small amount of solid solution is dissolved in the MX carbide, which causes more MX carbide to precipitate, so the Cr content is 4.0% to 5.6%.

The action of Mo and W is similar to Cr. The content of Mo in the embodiment of the present invention is Mo ≤ 3.0%, and the content of W is in the range of 0.1% to 1.0%.

Co is mainly dissolved in the matrix, promotes carbide precipitation, and refines the carbide particle size, and the Co content ranges from 0.05% to 0.5%.

N participates in the formation of MX carbides. Under rapid cooling conditions, N promotes nucleation of MX carbides without causing excessive growth of MX carbides, which is beneficial to improve wear resistance. The N content is limited to 0.05%-0.7%.

The powder metallurgy wear-resistant tool steel according to the embodiment of the invention forms MX carbide by adding a large amount of vanadium and carbon alloy elements to improve wear resistance, and at the same time, adding a certain amount of alloying elements such as chromium, molybdenum and silicon to strengthen the matrix Acting and promoting the precipitation of more MX carbides, in addition to the above alloying elements, the present invention adds a certain amount of niobium and nitrogen alloy elements, solid solution in MX carbides, forming a composite of the main constituent elements of C, N, V, Nb Type MX carbide, MX carbide type (V, Nb) (C, N), the purpose is to improve the nucleation rate of MX carbide, so that the precipitation of MX carbide can be more fine, improve the toughness of tool steel. The amount of niobium and nitrogen added needs to be controlled within a suitable range to avoid high stability carbonization. The substances NbC, VN, NbN and the like are formed.

In some embodiments, the chemical composition of the powder metallurgy wear resistant tool steel has a V equivalent of Veq: 13.0% to 16.0%, and Veq = V + 0.65 Nb.

In some embodiments, the impurities include O, O < 0.01%. If the O is too high, the toughness of the tool steel is lowered, and the embodiment of the present invention controls the O content to be ≤0.01% to ensure the excellent performance of the steel.

In some embodiments, the chemical composition thereof includes, by mass percentage, V: 13.0% to 16.0%, Nb: 1.2% to 2.5%, C: 2.8% to 3.7%, Si: ≤ 1.3%, and Mn: 0.2%. -1.5%, Cr: 4.8% - 5.4%, Mo: ≤ 2.0%, W: 0.1% - 0.5%, Co: 0.1% - 0.4%, N: 0.05% - 0.4%, O ≤ 0.008%, balance Iron and impurities.

In order to achieve better overall performance, the chemical components in the powder metallurgy wear-resistant tool steel of the embodiments of the present invention should be controlled within the required range.

In some embodiments, the impurities include S, S < 0.1%.

In some embodiments, the impurities include P, P < 0.03%.

In some embodiments, the volume fraction of MX carbide is between 16% and 25%.

In some embodiments, at least 80% by volume of the MX carbide has a size of from 0.5 to 1.3 [mu]m.

In some embodiments, the MX carbide has a maximum dimension of no more than 5.0 [mu]m.

The powder metallurgy wear-resistant tool steel according to an embodiment of the present invention can be prepared by the following method, the method comprising the following steps:

a. Prepare the tool steel molten steel according to the above chemical composition requirements and transfer to the ladle;

b. energizing and heating the slag covered by the upper surface of the molten steel in the ladle to maintain the superheat of the molten steel; stirring the molten steel by introducing an inert gas at the bottom of the ladle;

c. passing the molten steel through the diversion tube at the bottom of the ladle to flow into the preheated tundish at a steady flow rate, and applying the protective slag to the upper surface of the molten steel when the molten steel enters the lower end surface of the intermediate embedding draft tube;

d. Continuously compensate and heat the tundish to maintain the superheat of the molten steel;

e. After the molten steel enters the atomization chamber from the tundish, the inert gas is used for atomization and milling, and the obtained metal powder is settled to the bottom of the atomization chamber, and then enters the storage tank with protective atmosphere, and the metal is protected by the screening device. After the powder is sieved, it is stored in the storage tank body;

f. Under the protection of inert gas, transfer the metal powder in the powder storage tank to the hot isostatic pressure jacket. After the metal powder is vibrated and packed, the hot isostatic pressure jacket is vacuumed and degassed. The part is subjected to a sealing welding process, followed by hot isostatic pressing to completely compact the metal powder to complete the powder metallurgy process.

The above powder metallurgy process includes non-vacuum smelting atomization milling and hot isostatic pressing. The process uses full process protection to control oxygen content and carbide morphology to optimize tool steel performance. The ladle protection slag has the function of insulating air and conductive heating; the bottom of the ladle is filled with inert gas through the vent hole to balance the temperature of the molten steel at different positions in the ladle, and accelerate the removal of harmful inclusions; the diversion tube at the bottom of the ladle is on the one hand The liquid acts as a diversion to reduce turbulence during the flow of molten steel, avoiding slag and preventing inclusions from entering the next step. On the other hand, the diversion tube protects the molten steel from exposure to air and prevents the oxygen content of the molten steel from rising; The protective slag of the bag prevents the molten steel flowing through the tundish from directly contacting with the air, thereby reducing the increase of the oxygen content of the molten steel; pre-heating the tundish before the molten steel enters the tundish, preventing partial condensation of the molten steel into the tundish or causing the first The two phases are preliminarily precipitated; the inside of the powder storage tank has an atmosphere protection and a forced cooling and cooling function; the powder protection screening device protects the powder screening process while preventing the powder from flying; the powder storage tank is tightly connected with the hot isostatic envelope. The hot isostatic pressing sleeve is supplied with an inert gas to discharge air before the powder is charged to control the oxygen content.

In summary, the powder metallurgy wear-resistant tool steel obtained by the technical solution of the invention has excellent wear resistance and high impact toughness, bending strength and hardness. The tool steel of the embodiment of the present invention has a specific chemical composition and a rapid cooling solidification process of powder metallurgy, and the type of MX carbide formed is (V, Nb) (C, N), so that the precipitated MX carbide is finer and improved. The toughness of tool steel can obtain hardness above HRC60 after heat treatment, which can meet different types of application requirements and has wide application. The tool steel of the invention is prepared by powder metallurgy process, and the process adopts various effective protection means to prevent the steel liquid and the powder from being contaminated. Compared with the tool steel prepared by general powder metallurgy, the MX carbide content is similar, and the invention is implemented according to the invention. Example tool steel MX carbide is smaller and more tough Sex.

To make the present invention clearly understand the present invention, several specific embodiments in accordance with the aspects of the present invention are given below.

Embodiment 1

This embodiment relates to a group of powder metallurgy wear-resistant tool steels, the chemical composition of which is shown in Table 1.1:

Table 1.1 Example 1 Chemical composition table of powder metallurgy wear-resistant tool steel

The following preparation steps are used:

a, the tool steel molten steel of the present invention is loaded into a molten steel ladle, and the loading load of the molten steel is 1.5-8 tons;

b. The graphite electrode is used to heat the protective slag covered by the upper surface of the molten steel in the ladle, and the vent hole at the bottom of the ladle is filled with argon or nitrogen to stir the molten steel in the ladle. When the superheat of the molten steel reaches 100 □-200 □, the molten steel liquid guide is opened. Flow tube

c. Pass the molten steel through the diversion pipe at the bottom of the ladle and flow into the tundish preheated to 800 °C-1200 °C to control the inlet size of the diversion pipe so that the flow rate of the molten steel is 10kg/min-50kg/min, and the molten steel enters the tundish. Applying mold flux when the lower end surface of the steel liquid guiding tube is buried;

d. The atomization and milling process continuously compensates the heating of the tundish to maintain the superheat of the molten steel at 100 □-200 □;

e. The molten steel enters the atomization chamber through the opening of the bottom of the tundish, opens the atomizing gas nozzle valve, and uses nitrogen as the atomizing gas for atomization and milling. The purity of nitrogen is ≥99.999%, the oxygen content is ≤2ppm, and the gas pressure is 1.0. MPa-5.0MPa; the molten steel is broken into droplets under the action of inert gas, and simultaneously cooled to metal powder, and settled into the spray chamber by flight. The bottom enters the powder storage tank through the bottom of the atomization chamber; after the atomization and milling, the metal powder in the powder storage tank is cooled to room temperature, and sieved by a protective screening device; the positive pressure inside the chamber of the protection screening device is provided Inert protective gas, the inside of the powder storage tank is a positive pressure inert gas protection atmosphere;

f. Loading the metal powder in the powder storage tank to the hot isostatic pressure jacket, first introducing an inert gas into the hot isostatic pressure jacket to remove the air, and then sealingly connecting the hot isostatic pressure jacket and the powder storage tank, filling The process is subjected to vibration operation to increase the packing density of the metal powder; after completion, the hot isostatic pressing jacket is subjected to vacuum degassing treatment, and the hot isostatic pressing jacket is heated and maintained at 200 ° C - 600 ° C, and degassed to 0.01. After Pa, the heating is kept for ≥2h, then the end of the jacket is sealed and welded. Finally, the jacket is subjected to hot isostatic pressing. The hot isostatic pressing temperature is 1100°C-1160°C, and the holding time is ≥100MPa. After 1 h, the metal powder was completely densely consolidated and cooled with the furnace.

According to the need, the tool steel of the present invention is further forged and deformed to obtain a certain shape and size, and different heat treatment systems are used to obtain different properties, and the heat treatment used includes annealing, quenching and tempering. The annealing treatment involves heating the forging to 870 ° C - 890 ° C, holding time for 2 hours, then cooling to 530 ° C at ≤ 15 ° C / hour, and then cooling the furnace or still air to below 50 ° C; quenching involves The annealed forging piece is preheated at a temperature of 815 ° C - 845 ° C, the temperature is uniform, and then kept at a temperature of 1000 ° C - 1200 ° C for 15-40 minutes, then quenched to 530 ° C - 550 ° C, and then air cooled to below 50 ° C; The tempering treatment involves heating the quenched forgings to a temperature of 540-670 ° C and holding for 1.5-2 hours, followed by air cooling to below 50 ° C, thus repeating 2 to 3 times.

The obtained powder metallurgy wear-resistant tool steel of the embodiment 1.1-1.4, the alloy oxygen content increment of the preparation process is ≤30ppm, and the fully dense tool steel with the relative density of 100% is obtained after the thermal deformation, and the bar is made into a bar with a diameter of 50 mm. .

Embodiment 2

The embodiment relates to the verification of heat treatment hardness, impact toughness, flexural strength, wear resistance, carbide content and particle size of the powder metallurgy wear-resistant tool steel of the first embodiment, wherein the carbide content and the particle size are obtained by scanning electron microscopy to obtain a tissue image. Analysis, heat treatment hardness, impact toughness, flexural strength, wear resistance, respectively, refer to GB/T 230.1, GB/T 229, GB/T 14452-93, GB/T 12444-2006 for testing.

The powder metallurgy wear-resistant tool steels of Examples 1.1 and 1.2 were compared with the purchased powder metallurgical tool steel (Alloy A) and cast forging tool steel (Alloy B). The results are as follows:

Table 2.1 Comparison of the composition of the alloys A and B in Examples 1.1 and 1.2

The powder metallurgy wear-resistant tool steel of Examples 1.1 and 1.2 has an oxygen content of 50-60 ppm before preparation, an oxygen content of 60-80 ppm after preparation, and an oxygen content increment of ≤30 ppm in the preparation process.

Table 2.2 Comparison of Heat Treatment Hardness, Impact Toughness and Bending Strength of Examples 1.1 and 1.2 and Alloys A and B

As can be seen from Table 2.2, the powder metallurgy wear resistant tool steel of the present invention has an optimum combination of strength toughness.

Table 2.3 Comparison of Wear Resistance of Examples 1.1 and 1.2 with Alloys A and B

It can be seen from Table 2.3 that the wear resistance of the powder metallurgy wear-resistant tool steel of the embodiment of the present invention is similar to that of the alloy A, which is much higher than the wear resistance of the alloy B.

Table 2.4 Comparison of Carbide Content and Particle Size of Examples 1.1 and 1.2 with Alloys A and B

The carbide size in the above table is the size of the carbide of at least 80% by volume.

For the analysis of the carbide of the tool steel, the powder metallurgy wear-resistant tool steel of the present invention and the alloy A carbide composition are MX carbide. The MX carbide type of the tool steel of the present invention is (V, Nb) (C, N), and the main component composition is V, Nb, C, N and a small amount of alloying elements such as Fe and Cr. As can be seen from Table 2.4, the tool steel MX carbide volume fraction of the present invention reaches 16%-25%, and the presence of a large amount of MX carbide is advantageous for obtaining high wear resistance compared to Alloy B. Invention worker The steel carbide has a very fine particle size. Most of the MX carbides have a size of less than 1.3 μm and the maximum MX carbide size does not exceed 5 μm. Fine carbides contribute to the toughness of the tool steel.

In summary, the powder metallurgy wear-resistant tool steel of the invention has excellent wear resistance, and has excellent impact toughness, bending strength and hardness, and can obtain hardness of HRC60 or more after heat treatment, and can meet different types of application requirements. Wide range of applications, such as hard powder pressing, stamping and cutting dies, industrial shear blades, wood processing tools, wear parts, screws, screw sleeves, screw heads and other plastic machinery parts. Compared with ordinary cast-forged tool steel, the advantage is that the wear resistance is excellent, and the service life will be greatly improved. Compared with ordinary powder metallurgy tool steel, the carbide of the tool steel of the present invention is finer than the carbide content. The alloy exhibits higher toughness. The powder metallurgy preparation process of the invention adopts various effective protection means to prevent the molten steel and powder from being contaminated in the preparation process, and the oxygen content increment is ≤30ppm, which provides a guarantee for finally obtaining high-performance alloy ingot.

In the description of the present specification, the terms "first" and "second" are used for descriptive purposes only, and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, features defining "first" and "second" may include one or more of the features either explicitly or implicitly. In the description of the present invention, the meaning of "a plurality" is two or more unless specifically and specifically defined otherwise.

In the description of the present specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means a specific feature described in connection with the embodiment or example. A structure, material or feature is included in at least one embodiment or example of the invention. In the present specification, the schematic representation of the above terms is not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Those skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without departing from the scope of the invention.

Although the embodiments of the present invention have been shown and described, it is understood that the above-described embodiments are illustrative and are not to be construed as limiting the scope of the invention. The embodiments are subject to variations, modifications, substitutions and variations.

Claims

A powder metallurgy wear-resistant tool steel, characterized in that the chemical composition of the powder metallurgy wear-resistant tool steel comprises: V: 12.2% - 16.2%, Nb: 1.1% - 3.2%, C: 2.6 %-4.0%, Si: ≤2.0%, Mn: 0.2%-1.5%, Cr: 4.0%-5.6%, Mo: ≤3.0%, W:0.1%-1.0%, Co:0.05%-0.5%,N : 0.05%-0.7%, the balance is iron and impurities; the carbide composition of the powder metallurgy wear-resistant tool steel is MX carbide, the MX carbide is a NaCl-type face-centered cubic lattice structure, and the M element in the MX carbide Including V and Nb, the X elements include C and N.
The powder metallurgy wear-resistant tool steel according to claim 1, wherein the chemical composition of the powder metallurgy wear-resistant tool steel has a V equivalent V eq : 13.0% - 16.0%, and the V eq = V + 0.65 Nb.
The powder metallurgy wear-resistant tool steel according to claim 1 or 2, wherein the impurities comprise O, O content of not more than 0.01%.
The powder metallurgy wear-resistant tool steel according to any one of claims 1 to 3, wherein the chemical composition of the powder metallurgy wear-resistant tool steel comprises, by mass percentage, V: 13.0% - 16.0%, Nb : 1.2% - 2.5%, C: 2.8% - 3.7%, Si: ≤ 1.3%, Mn: 0.2% - 1.5%, Cr: 4.8% - 5.4%, Mo: ≤ 2.0%, W: 0.1% - 0.5% , Co: 0.1% - 0.4%, N: 0.05% - 0.4%, O content not exceeding 0.008%, and the balance being iron and impurities.
A powder metallurgy wear-resistant tool steel according to any one of claims 1 to 4, wherein the impurities comprise S, S content of not more than 0.1%.
The powder metallurgy wear-resistant tool steel according to any one of claims 1 to 5, wherein the impurities include P and the P content does not exceed 0.03%.
The powder metallurgy wear-resistant tool steel according to any one of claims 1 to 6, wherein the MX carbide has a volume fraction of 16% to 25%.
The powder metallurgy wear-resistant tool steel according to any one of claims 1 to 7, characterized in that at least 80% of the MX carbides have a size of 0.5 to 1.3 μm in terms of volume percent.
A powder metallurgy wear-resistant tool steel according to any one of claims 1-8, wherein the MX carbide has a maximum dimension of no more than 5.0 μm.