CN112760557A

CN112760557A - High-carbon high-chromium stainless steel for knives and scissors and preparation method thereof

Info

Publication number: CN112760557A
Application number: CN202011412138.4A
Authority: CN
Inventors: 车洪艳; 王铁军; 梁晨; 黄赞军; 秦巍; 周鸿锋; 张宇红
Original assignee: Advanced Technology and Materials Co Ltd
Current assignee: Advanced Technology and Materials Co Ltd
Priority date: 2020-12-04
Filing date: 2020-12-04
Publication date: 2021-05-07
Anticipated expiration: 2040-12-04
Also published as: CN112760557B

Abstract

The invention belongs to the technical field of stainless steel materials, and particularly relates to high-carbon high-chromium stainless steel for knives and scissors and a preparation method thereof. The stainless steel comprises the following components in percentage by weight: c: 1.8-2.0%, Si: 0.5 to 0.7%, Mn: 0.2-0.4%, Cr: 19-21%, Mo: 0.8-1.2%, V: 2-4%, W: 0.3-0.7%, N: 0.15-0.25%, S: less than or equal to 0.01 percent, P: less than or equal to 0.01 percent, O: less than or equal to 0.01 percent, and the balance of Fe and other inevitable impurities. Aiming at the defects of large structure, shrinkage cavity, looseness, component segregation and the like of stainless steel for preparing the scissors by the traditional method, the powder metallurgy method is adopted, the hot isostatic pressing technology is utilized, and the process parameters are reasonably controlled, so that the powder steel which has the same components as the powder, high density, good uniformity, high purity and excellent mechanical property and process property is obtained.

Description

High-carbon high-chromium stainless steel for knives and scissors and preparation method thereof

Technical Field

The invention belongs to the technical field of stainless steel materials, and particularly relates to high-carbon high-chromium stainless steel for knives and scissors and a preparation method thereof.

Background

Since the last 90 s, the hardware manufacturing industry has shown a rapid development trend in the whole China, wherein the knife and shear industry is developed rapidly, and is gradually becoming an important role in the hardware industry. In 2007, the annual output value of the hardware products in China exceeds 2500 hundred million yuan, the annual export amount in the same year reaches 200 hundred million dollars, wherein the knife and scissors industry rapidly grows at a 15% acceleration rate in the year, so that the types and the quantity of the knife and scissors in China stably live ahead in the world, and the knife and scissors become an important production base of the knife and scissors products in the world, but compared with the technically developed countries such as Germany and Japan, the quality of the knife and scissors products in China has a certain gap. Among them, germany, japan and swiss monopolize the market of high-end cutters, the middle-end cutters and the low-end cutters are mainly korean products, the high-end and low-end products in japan have strong competitiveness in asian regions, and the export of the products of chinese cutters is generally at the middle-end and low-end level.

In recent years, the Chinese knife and scissors enterprises begin to transform to high-end markets, and develop high-carbon martensite stainless steel and other steel grades in cooperation with scientific research in colleges and universities. However, the domestic knife scissors have certain differences in sharpness, wear resistance, service life and the like compared with the imported knife scissors. The difference exists in the preparation process of steel for the knife and scissors and is a root cause for restricting the high-quality development of the knife and scissors industry in China.

Disclosure of Invention

The invention aims to provide high-carbon high-chromium stainless steel for knives and scissors and a preparation method thereof, and aims to solve the problems of poor sharpness and wear resistance and short service life of the existing stainless steel for knives and scissors.

In order to achieve the above purpose, the invention provides the following technical scheme:

a high-carbon high-chromium stainless steel for knives and scissors is composed of the following components in percentage by weight: c: 1.8-2.0%, Si: 0.5 to 0.7%, Mn: 0.2-0.4%, Cr: 19-21%, Mo: 0.8-1.2%, V: 2-4%, W: 0.3-0.7%, N: 0.15-0.25%, S: less than or equal to 0.01 percent, P: less than or equal to 0.01 percent, O: less than or equal to 0.01 percent, and the balance of Fe and other inevitable impurities.

Preferably, the stainless steel has C: 1.9-2.0%, Si: 0.5 to 0.55%, Mn: 0.2-0.3%, Cr: 19-20%, Mo: 0.9-1.1%, V: 3-4%, W: 0.5-0.7%, N: 0.15-0.25%, S: less than or equal to 0.01 percent, P: less than or equal to 0.01 percent, O: less than or equal to 0.01 percent.

Room temperature tensile strength R of the stainless steel_mIs 810-890 MPa, and has room-temperature plastic elongation strength R_p0.2450 to 550MPa, 5 to 8 percent of elongation A after room temperature breakage, and KV energy absorbed by room temperature impact₂Is 7 to 10J.

The preparation method of the high-carbon high-chromium stainless steel for the scissors comprises the following steps:

(1) smelting the raw materials according to the formula ratio under a vacuum condition, alloying in a smelting chamber under nitrogen-containing inert gas, and preparing metal powder by utilizing high-pressure argon atomization;

(2) removing impurities from the alloy powder, sieving, and taking undersize;

(3) carrying out hot isostatic pressing treatment on the alloy powder treated in the step (2), and cooling to obtain a billet;

(4) heating and rolling the billet obtained in the step (3) to obtain a plate;

(5) and (4) annealing the plate obtained in the step (4).

Preferably, in the step (1), the vacuum degree of the vacuum condition is less than or equal to 30 Pa;

preferably, in the step (1), the nitrogen-containing inert gas is nitrogen or a mixture of nitrogen and argon;

preferably, in the step (1), the smelting temperature is 1550-1650 ℃.

Preferably, in the step (1), the oxygen content of the alloy powder is 0.004-0.02%;

preferably, in the step (1), the alloy powder is spherical and has a particle size of 0.006-0.35 mm.

Preferably, in the step (3), the hot isostatic pressing pressure is 100-120 MPa, and the heat preservation temperature is 1000-1150 ℃.

Preferably, in the step (3), the pressure and temperature holding time of the hot isostatic pressing is 2-3 h.

Preferably, in step (3), the cooling is: and cooling the mixture from the heat preservation temperature to 250 ℃ at the speed of 2-6 ℃/min, and then discharging the mixture from the furnace for air cooling.

Preferably, in the step (4), the rolling includes hot rolling and cold rolling, the hot rolling temperature is higher than 950 ℃, and the hot rolling is performed by heating the billet and then rolling the billet with a deformation amount of 20-35%.

Preferably, in step (4), the heating is: firstly, heating a billet to 800-850 ℃, preserving heat for 30-60 min, then heating to 1100-1200 ℃, and preserving heat for 30-120 min; preferably, the heating rate of heating the billet to 800-850 ℃ is 7-8 ℃/min.

Preferably, in the step (5), the annealing is spheroidizing annealing.

Preferably, the spheroidizing annealing is: firstly, heating the plate to 950-1050 ℃, preserving heat for 3-4 h, then cooling to 800-850 ℃ at the speed of 3-6 ℃/min, preserving heat for 3-5 h, and cooling along with the furnace.

Compared with the closest prior art, the technical scheme provided by the invention has the following excellent effects:

aiming at the defects of large structure, shrinkage cavity, looseness, component segregation, high cost, low efficiency and the like of stainless steel for preparing the knife scissors by traditional methods such as smelting, casting and the like, the invention adopts a powder metallurgy method, utilizes a hot isostatic pressing technology and reasonably controls process parameters to obtain the powder steel which has the same components as powder, high density (relative density is close to 100 percent), good uniformity, high purity and excellent mechanical property and process property.

The powder metallurgy steel is an ideal material for high-end kitchen knives and outdoor knives due to high hardness, excellent toughness and excellent wear resistance. The main manufacturers of powder metallurgy steel in the world are European and American enterprises such as Austrian Bailu and American smelter sband company, the production of the powder steel for the domestic cutter and scissors is still blank, and the powder steel for the high-end cutter and scissors is basically imported, so that the Chinese cutter and scissors enterprises are in a disadvantage in international competition.

Compared with the majority of the prior manufacturing methods of smelting, casting and the like, the high-carbon high-chromium stainless steel material is atomized into high-purity metal powder by gas, and then sintered by a hot isostatic pressing technology, so that a microstructure with fine and uniformly distributed grains and carbides can be finally obtained, the problems of component segregation, carbide segregation and the like of steel produced by the traditional casting method and the like are solved, the material is higher in purity, higher in wear resistance and corrosion resistance, and simultaneously has excellent polishing performance, and the high-carbon high-chromium stainless steel material is suitable for various high-precision high-requirement and any occasion.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. Wherein:

FIG. 1 is a metallographic structure drawing (a reference drawing) of a high-carbon high-chromium stainless steel for use in scissors and knives in example 1 of the present invention

5000 times);

FIG. 2 is a metallographic structure diagram (magnification ×. 5000) of a stainless steel in comparative example 1 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments that can be derived by one of ordinary skill in the art from the embodiments given herein are intended to be within the scope of the present invention.

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

Generally, the preparation of metal powders mainly includes two major categories, mechanical methods and physicochemical methods. Mechanical methods are those in which the raw material is mechanically comminuted without substantial change in chemical composition; the physicochemical method is to obtain a powder by changing the chemical composition or aggregation state of the raw material by chemical or physical action. The atomization method is one of the most widely applied methods in industrial production, and the metal powder in the invention is mainly smelted in vacuum, alloyed in a smelting chamber under nitrogen-containing inert gas, and atomized by high-pressure argon to prepare powder.

The invention relates to high-carbon high-chromium stainless steel for knives and scissors, which comprises the following components in percentage by weight: c: 1.8-2.0%, Si: 0.5 to 0.7%, Mn: 0.2-0.4%, Cr: 19-21%, Mo: 0.8-1.2%, V: 2-4%, W: 0.3-0.7%, N: 0.15-0.25%, S: less than or equal to 0.01 percent, P: less than or equal to 0.01 percent, O: 0.01% or less (for example 1.93% C, 0.55% Si, 0.28% Mn, 20% Cr, 1.0% Mo, 3.8% V, 0.6% W, 0.15% N, 0.01% or less S, 0.01% or less P, 0.01% or less O, or 1.8% C, 0.7% Si, 0.4% Mn, 19% Cr, 0.8% Mo, 2% V, 0.7% W, 0.15% N, 0.004% or less S, 0.004% or less P, 0.01% or less O, or 2.0% C, 0.6% Si, 0.2% Mn, 19% Cr, 0.8% Mo, 4% V, 0.3% W, 0.25% N, 0.01% or less S, 0.01% or less P, 0.01% or less O, 0.01% or less Fe and the balance unavoidable impurities.

The functions of the respective essential elements in the present invention are described in detail below.

Carbon (C), the most important hardening component, improves the strength of the steel by interstitial solid solution strengthening. At the same time, the increase in carbon content also increases tensile strength and edge retention, improving wear resistance. Too high a C content in steel easily causes precipitation of coarse carbides, and lowers the impact toughness of the material. Depending on the different contents of Cr and C, gamma, alpha, Cr may form₇C₃、Cr₂₃C₆And (3) waiting for different phases, and controlling the content of carbon to be 1.8-2.0%.

Silicon (Si) -can obviously improve the tempering stability and the strength of the material. In addition, the addition of Si element can improve the oxidation resistance and corrosion resistance of the steel. However, when the Si content in the material is too high, the brittleness of the material is increased. Therefore, Si is generally used as a deoxidizer to enter the steel and the content thereof is controlled to be 0.5 to 0.7%.

Manganese (Mn) -is mainly used for deoxidation and desulfurization of steel, but when an excessive amount of manganese element is added to steel, its crystal grains are coarsened, and the corrosion resistance of stainless steel is lowered. In conclusion, the Mn content is controlled to be 0.2-0.4%.

Chromium (Cr) -can improve hardness, wear resistance, and tensile strength of steel. Particularly, when the chromium content in the stainless steel exceeds 12%, the steel material has good high-temperature oxidation resistance and corrosion resistance, but the addition of a large amount of chromium reduces the toughness of the material. Therefore, the concentration of the catalyst is controlled to be 19-21%.

Molybdenum (Mo) -can increase strength, hardness and enhance secondary hardening effect, improve corrosion resistance, and maintain strength of steel at high temperature. In the stainless steel, too much increase of the Mo content promotes the formation of δ ferrite to adversely affect the toughness of the stainless steel, and the Mo content is preferably 0.8 to 1.2%.

Vanadium (V) -contributes to improvement of wear resistance and hardenability. It also has the effects of grain refinement, toughness improvement, and very sharp edge. However, too high a V content in the steel significantly reduces the crack resistance of the steel. In addition, large-particle precipitated phases are easily formed, which affect the mirror-surface properties of the material. Therefore, the preferable V content range: 2-4%.

Tungsten (W) -mainly increases the temper stability, red hardness, heat strength and wear resistance of the steel. Too much W content greatly reduces the corrosion resistance of the steel. Therefore, the tungsten content should be controlled to 0.3-0.7%.

Nitrogen (N) -improves the strength of stainless steel through solid solution strengthening, and does not significantly impair the plasticity and toughness of the steel. The nitrogen element is not easy to combine with the chromium element to form chromium nitride, more free chromium is left in the alloy, and therefore the corrosion resistance of the material is improved. Excessive addition of nitrogen will generate stable M_xThe N-type nitride may agglomerate and reduce the polishing properties of the material. Therefore, the nitrogen content should be controlled within the range of 0.15 to 0.25%.

Sulfur (S) -is generally considered a harmful element, easily forms non-metallic inclusions in the material, and reduces the toughness of the material; in order to reduce the adverse effect of the S element on the material, the content should be reduced as much as possible, and is controlled to be less than 0.01%.

Phosphorus (P) -phosphorus is a harmful element, and P can generate a segregation phenomenon at a crystal boundary in a steel ingot hot working process, so that the brittleness of steel is increased. The content of P is controlled to be less than 0.01 percent, and the lower the content of P is, the more beneficial the toughness of the material is.

Oxygen (O) -oxygen is a harmful element in steel, and oxygen is mainly FeO, MnO and SiO in steel₂And the content thereof should be controlled to 0.01% or less because the inclusion forms reduce the strength, plasticity, and pitting corrosion properties of the steel.

The high-carbon high-chromium stainless steel for the scissors is prepared by the following method:

(1) atomizing to prepare powder: heating a high-carbon high-chromium stainless steel alloy material in a vacuum chamber of atomizing equipment, heating to 1550-1650 ℃ (such as 1550 ℃, 1600 ℃ and 1650 ℃) for smelting, strictly controlling alloy components, reducing non-metallic inclusions, improving the purity of the alloy, wherein the vacuum degree is less than or equal to 30Pa, then filling nitrogen-containing inert gas (such as nitrogen or mixed gas of nitrogen and argon) into the smelting chamber, filling argon into the atomizing chamber, starting high-pressure atomizing gas after the pressure of the smelting chamber is consistent with that of the atomizing chamber, atomizing molten steel flowing out of a tundish into metal powder, and storing the metal powder in a collecting chamber, wherein the oxygen content of the metal powder prepared by adopting the technology is 0.004-0.020%, the powder is mainly spherical, and the powder granularity is 0.006-0.35 mm;

(2) powder purification and sieving: after the metal powder is prepared, the metal powder and the residues in the collection chamber are graded and sieved by a vacuum vibrating screen, the powder and the large alloy residues are separated, non-metal impurities are removed, and then the powder is taken out for sheathing, degassing and seal welding;

(3) hot isostatic pressing ingot making: filling the powder obtained in the step (2) into a metal sheath, placing the sheath subjected to degassing treatment in hot isostatic pressing equipment, applying 100-120 MPa (such as 100MPa, 110MPa and 120MPa) pressure to the sheath in all directions by using argon as a pressurizing medium, applying 1000-1150 ℃ (such as 1000 ℃, 1050 ℃, 1100 ℃ and 1150 ℃) high temperature, keeping the temperature for 2-3 h (such as 2h, 2.5h and 3h) under the action of the highest temperature and pressure, cooling to 250 ℃ at the speed of 2-6 ℃/min, discharging and air cooling, and finally obtaining a high-carbon high-chromium stainless steel ingot;

(4) rolling: before rolling, placing a high-carbon high-chromium stainless steel billet ingot in a heating furnace filled with inert gas protection, in order to prevent the billet from cracking caused by too high heating speed, heating the high-carbon high-chromium stainless steel billet ingot to 800-850 ℃ (such as 800 ℃, 820 ℃, 840 ℃ and 850 ℃) at a heating rate of 7-8 ℃/min, keeping the temperature for 30-60 min (such as 30min, 40min, 50min and 60min), continuously heating to 1100-1200 ℃ (such as 1100 ℃, 1130 ℃, 1160 ℃ and 1200 ℃), keeping the temperature for 30-120 min (such as 30min, 50min, 70min, 90min, 110min and 120min), taking the high-carbon high-chromium stainless steel billet ingot out of the furnace, rolling the high-carbon high-chromium stainless steel billet ingot on a continuous rolling production line provided with induction heating equipment according to 20-35% of deformation (such as 20%, 25%, 30% and 35%), thereby reducing oxidation in the rolling process and effectively controlling the; the rolling comprises hot rolling and cold rolling, the rolling temperature is always kept to be higher than 950 ℃ in the whole hot rolling process (for example, the initial rolling temperature is 1100 ℃, the final rolling temperature is 950 ℃, or the initial rolling temperature is 1150 ℃, the final rolling temperature is 950 ℃, or the initial rolling temperature is 1200 ℃, the final rolling temperature is 950 ℃), and the cold rolling is carried out after the hot rolling to obtain a plate;

(5) and (4) carrying out heat treatment on the plate obtained in the step (4), specifically carrying out vacuum spheroidizing annealing treatment: the annealing temperature is 950-1050 ℃ (such as 950 ℃, 980 ℃, 1000 ℃, 1020 ℃ and 1050 ℃), the heat preservation is carried out for 3-4 h (such as 3h, 3.2h, 3.4h, 3.6h, 3.8h and 4h), the annealing temperature is cooled to 800-850 ℃ (800 ℃, 810 ℃, 820 ℃, 830 ℃, 840 ℃ and 850 ℃) at 3-6 ℃/min (such as 3 ℃/min, 4 ℃/min, 5 ℃/min) and the heat preservation is carried out for 3-5 h (such as 3h, 4h and 5h), and the annealing temperature is cooled with a furnace.

At present, the traditional stainless steel for preparing the knife scissors mostly adopts methods of smelting, casting and the like, the stainless steel material obtained by the traditional preparation method has the defects of thick structure, shrinkage cavity, looseness, component segregation, high cost, low efficiency and the like, the invention aims to adopt a powder metallurgy method and utilize a hot isostatic pressing technology, and the heat treatment used in the invention is vacuum spheroidizing annealing treatment: the vacuum heat treatment can realize the common heat treatment process and simultaneously can effectively reduce the phenomena of oxidation, decarburization, carburization and the like, thereby obtaining the powder steel with bright and clean surface; the spheroidizing annealing aims to separate out carbon and metal elements in the steel in a form of spherical carbide and uniformly distribute the carbon and the metal elements in a ferrite matrix, so that the hardness of the material can be fully reduced, the plasticity is improved, organization preparation is made for final heat treatment, and finally, a powder metallurgy steel which has the same powder components, high density (relative density is close to 100%), good uniformity, high purity, and excellent mechanical property and technological property is obtained, the blank of the powder steel for high-end domestic knife scissors is filled, the domestic industry upgrading is supported, and the high-quality development of the domestic knife scissors industry is promoted.

Example 1

The high-carbon high-chromium stainless steel for the knife and the scissors in the embodiment comprises the following components in percentage by weight: c: 1.9%, Si: 0.5%, Mn: 0.25%, Cr: 20%, Mo: 1.0%, V: 4%, W: 0.6%, N: 0.25%, S: less than or equal to 0.01 percent, P: less than or equal to 0.01 percent, O: 0.004%, and the balance of Fe and other inevitable impurities. The preparation method of the high-carbon high-chromium stainless steel for the knife and the scissors in the embodiment specifically comprises the following steps:

(1) adding materials such as high-carbon chromium, micro-carbon chromium, electrolytic manganese, ferrotungsten, ferromolybdenum, ferrovanadium, pure iron, SiCa powder and the like into a vacuum chamber of atomizing equipment according to designed steel components, heating to 1550 ℃ for melting, filling nitrogen into the melting chamber, filling argon into the atomizing chamber, starting high-pressure argon after the air pressure of the melting chamber and the air pressure of the atomizing chamber are consistent, enabling the molten steel to flow down through a pouring gate, and atomizing in high-pressure argon airflow to obtain metal powder;

(2) grading and sieving the metal powder and the residues by a vacuum vibration sieve of 200 meshes, separating the powder from large alloy residues, removing large non-metal impurities, taking out the powder, and performing sleeving, degassing and sealing welding;

(3) placing metal powder in hot isostatic pressing equipment for pressing, specifically, filling the powder into a metal sheath, placing the degassed sheath in the hot isostatic pressing equipment, applying 110MPa pressure to each direction of the sheath by using argon as a pressurizing medium, applying 1100 ℃ temperature, and keeping the temperature for 2.5 hours; then cooling to 250 ℃ at the speed of 2 ℃/min, discharging and air cooling to obtain a high-carbon high-chromium stainless steel billet ingot;

(4) heating the billet obtained by hot isostatic pressing to 850 ℃, preserving heat for 30min, then continuing to heat to 1150 ℃, preserving heat for 0.5h, and then rolling according to 20% of deformation, wherein the initial rolling temperature is 1100 ℃, and the final rolling temperature is 950 ℃ to obtain a plate;

(5) and (3) carrying out spheroidizing annealing treatment on the obtained plate, specifically heating the plate to 950 ℃, preserving heat for 4h, cooling to 850 ℃ at the speed of 3 ℃/min, preserving heat for 3h, and then slowly cooling to room temperature along with the furnace to obtain the powder steel.

Wherein SiCa powder is used as a deoxidizer and generates a strong exothermic effect after being added into molten steel. Calcium is changed into calcium vapor in the molten steel, stirring effect is generated on the molten steel, nonmetal impurities can float upwards favorably, the calcium is relatively active and has strong affinity with oxygen, and the calcium preferentially reacts with the oxygen to remove the oxygen in the molten steel. After the silicon-calcium alloy is deoxidized, non-metallic inclusions which have larger particles and are easy to float upwards are generated, and finally scum is removed to obtain purer molten steel. Although silicon also has a deoxidizing effect, calcium is consumed firstly, then silicon is consumed, and finally, part of silicon is left to enter molten steel to be used as a constituent element of stainless steel.

The metallographic structure (x 5000 times) of the high-carbon high-chromium stainless steel for scissors prepared in this example, in which the matrix was ferrite and M was contained, is shown in fig. 1₇C₃、M₂₃C₆And the hardness of the MC carbide is HRC 27-28 after annealing, and the content of vanadium nitride in the MC carbide is determined to be 36% -41% by methods such as X-ray diffraction, back scattering electron diffraction and the like. The vanadium carbonitride is taken as a ferrite nucleation core in the phase change process, the content of the vanadium carbonitride can generate important influence on the ferrite nucleation rate, thereby influencing the fine-grain strengthening effect and further influencing the toughness of the material, the average size of the carbide is 0.5-0.8 mu m, the maximum size of the carbide is 1.5-2 mu m, and the average number of the carbide is 0.6-0.7/mu m²The carbides are fine and uniformly distributed.

Example 2

The high-carbon high-chromium stainless steel for the knife and the scissors in the embodiment comprises the following components in percentage by weight: c: 1.75%, Si: 0.67%, Mn: 0.42%, Cr: 19.8%, Mo: 0.82%, V: 2.1%, W: 0.69%, N: 0.14%, S: less than or equal to 0.01 percent, P: less than or equal to 0.01 percent, O: 0.008% and the balance of Fe and other inevitable impurities. The preparation method of the high-carbon high-chromium stainless steel for the knife and the scissors in the embodiment specifically comprises the following steps:

(1) adding materials such as high-carbon chromium, micro-carbon chromium, electrolytic manganese, ferrotungsten, ferromolybdenum, ferrovanadium, pure iron, SiCa powder and the like into an atomizing equipment vacuum chamber according to the design components of steel, heating to 1600 ℃ for melting, filling nitrogen into the melting chamber, filling argon into the atomizing chamber, starting high-pressure argon after the air pressure of the melting chamber and the air pressure of the atomizing chamber are consistent, enabling the molten steel to flow down through a pouring gate, and atomizing in high-pressure argon airflow to obtain metal powder;

(3) placing metal powder in hot isostatic pressing equipment for pressing, specifically, filling the powder into a metal sheath, placing the degassed sheath in the hot isostatic pressing equipment, applying 100MPa pressure to each direction of the sheath by using argon as a pressurizing medium, applying 1000 ℃ temperature, and keeping the temperature for 3 hours; then cooling to 250 ℃ at the speed of 4 ℃/min, discharging and air cooling to obtain a high-carbon high-chromium stainless steel billet ingot;

(4) heating the billet obtained by hot isostatic pressing to 820 ℃, preserving heat for 30min, then continuing to heat to 1100 ℃, preserving heat for 1h, and then rolling according to 25% of deformation, wherein the initial rolling temperature is 1000 ℃, and the final rolling temperature is 950 ℃ to obtain a plate;

(5) and (3) spheroidizing annealing treatment of the obtained plate, specifically heating the plate to 1000 ℃, preserving heat for 3.2h, cooling to 800 ℃ at the speed of 4 ℃/min, preserving heat for 4h, and then slowly cooling to room temperature along with the furnace to obtain the powder steel.

Example 3

The high-carbon high-chromium stainless steel for the knife and the scissors in the embodiment comprises the following components in percentage by weight: c: 1.91%, Si: 0.58%, Mn: 0.22%, Cr: 18.8%, Mo: 0.81%, V: 3.98%, W: 0.58%, N: 0.21%, S: less than or equal to 0.01 percent, P: less than or equal to 0.01 percent, O: 0.006%, and the balance Fe and other unavoidable impurities. The preparation method of the high-carbon high-chromium stainless steel for the knife and the scissors in the embodiment specifically comprises the following steps:

(1) adding materials such as high-carbon chromium, micro-carbon chromium, electrolytic manganese, ferrotungsten, ferromolybdenum, ferrovanadium, pure iron, SiCa powder and the like into a vacuum chamber of atomizing equipment according to the design components of steel, heating to 1650 ℃ for melting, filling nitrogen into the melting chamber, filling argon into the atomizing chamber, starting high-pressure argon after the air pressure of the melting chamber and the air pressure of the atomizing chamber are consistent, and atomizing molten steel in high-pressure argon airflow after the molten steel flows down through a sprue to obtain metal powder;

(3) placing metal powder in hot isostatic pressing equipment for pressing, specifically, filling the powder into a metal sheath, placing the degassed sheath in the hot isostatic pressing equipment, applying 120MPa pressure to each direction of the sheath by using argon as a pressurizing medium, applying 1150 ℃ temperature, and keeping the temperature for 2 h; then cooling to 250 ℃ at the speed of 6 ℃/min, discharging and air cooling to obtain a high-carbon high-chromium stainless steel billet ingot;

(4) heating the billet obtained by hot isostatic pressing to 840 ℃, preserving heat for 30min, then continuing to heat to 1100 ℃, preserving heat for 0.5h, and then rolling according to 35% of deformation, wherein the initial rolling temperature is 1000 ℃, and the final rolling temperature is 950 ℃ to obtain a plate;

(5) and (3) spheroidizing annealing treatment of the obtained plate, specifically heating the plate to 1050 ℃, preserving heat for 3h, cooling to 850 ℃ at the speed of 6 ℃/min, preserving heat for 5h, and then slowly cooling to room temperature along with the furnace to obtain the powder steel.

Comparative example 1

The stainless steel of the comparative example comprises the following components in percentage by weight: c: 1.9%, Si: 0.5%, Mn: 0.25%, Cr: 20%, Mo: 1.0%, V: 3.94%, W: 0.6%, N: 0.15%, S: less than or equal to 0.01 percent, P: less than or equal to 0.01 percent, O: 0.004%, and the balance of Fe and other inevitable impurities.

The stainless steel of this comparative example was prepared by a method different from that of example 1 in that: the processes of smelting, casting and forging are adopted to obtain the ingot, and the rolling and the subsequent heat treatment processes are the same as those in the embodiment 1 and are not described again.

The smelting, casting and forging process comprises the following specific steps:

(1) smelting: adding materials such as high-carbon chromium, micro-carbon chromium, electrolytic manganese, ferrotungsten, ferromolybdenum, ferrovanadium, pure iron, SiCa powder and the like into an induction furnace, heating to 1550-1650 ℃, smelting into molten steel, and removing dross on the surface of the molten steel;

(2) refining: adding molten steel to a refining furnace for refining, adding slag materials such as lime, fluorite and the like into the furnace, heating the slag materials by utilizing an upper electrode of a steel ladle, introducing argon into the steel ladle at the bottom of the steel ladle, refining for 15-20 minutes after all the slag materials are molten, and removing gas and nonmetal impurities in the molten steel. The temperature of the molten steel is in the range of 1550-1600 ℃ for casting;

(3) ingot casting: adopting an ingot mould to cast a steel ingot, cooling the steel ingot to 200-300 ℃, and demoulding to obtain a billet;

(4) forging: forging the cast billet, wherein the size of the forged billet is suitable for hot rolling; the preheating temperature for forging the billet is 1100-1200 ℃, after forging, the billet is placed in a heat preservation box for slow cooling, and the billet is cooled to 200-300 ℃ for air cooling.

The metallographic structure of the high-carbon high-chromium stainless steel for scissors of this comparative example is shown in FIG. 2, and the structure is mainly composed of a ferrite matrix, MC, M₇C₃、M₂₃C₆And the like, wherein the maximum carbide size is 7.7 mu m, the average carbide size is 1.4 mu m, the carbide is coarse, and phenomena such as carbide segregation and shrinkage cavity exist.

Comparative example 2

No nitrogen element is added into the chemical components of the stainless steel of the comparative example, and the hot isostatic pressing ingot making, rolling and subsequent heat treatment processes are the same as those in the example 1 and are not repeated.

The design ingredients of this comparative example consisted of the following components in weight percent: c: 1.9%, Si: 0.5%, Mn: 0.25%, Cr: 20%, Mo: 1.0%, V: 4%, W: 0.6%, S: less than or equal to 0.01 percent, P: less than or equal to 0.01 percent, O: 0.004%, and the balance of Fe and other inevitable impurities.

The preparation method of the high-carbon high-chromium stainless steel for the scissors of the comparative example specifically comprises the following steps: adding high-carbon chromium, micro-carbon chromium, electrolytic manganese, ferrotungsten, ferromolybdenum, ferrovanadium, pure iron, SiCa powder and other materials into an atomizing equipment vacuum chamber according to the designed steel components, heating to 1550 ℃ for melting, filling argon into the melting chamber, then opening an argon system, filling into the atomizing chamber, starting high-pressure argon after the air pressure of the melting chamber and the air pressure of the atomizing chamber are consistent, and enabling the molten steel to flow down through a pouring gate and atomize in high-pressure argon airflow to obtain metal powder.

Comparative example 3

Comparative example 3 differs from example 1 in that: the hot isostatic pressing ingot making, rolling and subsequent heat treatment processes are the same as those in example 1 and are not described again.

The design ingredients of this comparative example consisted of the following components in weight percent: c: 1.9%, Si: 0.5%, Mn: 0.25%, Cr: 20%, Mo: 1.0%, V: 4%, W: 0.6%, N: 0.31%, S: less than or equal to 0.01 percent, P: less than or equal to 0.01 percent, O: 0.004%, and the balance of Fe and other inevitable impurities.

The preparation method of the high-carbon high-chromium stainless steel for the scissors of the comparative example specifically comprises the following steps: adding high-carbon chromium, micro-carbon chromium, electrolytic manganese, ferrotungsten, ferromolybdenum, ferrovanadium, pure iron, SiCa powder and other materials into an atomizing equipment vacuum chamber according to the designed steel components, heating to 1550 ℃ for melting, filling nitrogen or a mixed gas of nitrogen and argon into the melting chamber, then opening an argon system, filling into the atomizing chamber, starting high-pressure argon after the air pressure of the melting chamber and the air pressure of the atomizing chamber are consistent, enabling the molten steel to flow down through a sprue, and atomizing in high-pressure argon airflow to obtain metal powder.

Examples of the experiments

The components of the ingots prepared in the examples 1-3 and the comparative examples 1-3 of the invention are detected by adopting standard methods in GB/T11170-2008 'method for measuring spark discharge atomic emission spectrometry of multi-element content of stainless steel', GB/T20123-2006 'method for measuring infrared absorption after combustion of high-frequency induction furnace of total carbon and sulfur content of steel', and GB/T20124-2006 'method for measuring inert gas melting heat conductivity of nitrogen content of steel', and the detection results are shown in Table 1.

TABLE 1 chemical composition (%)

Material	Cr	Mn	Mo	Si	V	W	C	N	O	S、P
											Example 1	19.8	0.28	0.98	0.52	3.9	0.58	1.93	0.23	0.005	≤0.01
Example 2	19	0.4	0.8	0.7	2	0.7	1.8	0.15	0.0076	≤0.01
											Example 3	19	0.2	0.8	0.6	4	0.3	2.0	0.2	0.0055	≤0.01
Comparative example 1	19	0.4	1.2	0.7	2.7	0.35	1.7	0.23	0.01	≤0.01
											Comparative example 2	19.8	0.28	0.98	0.52	3.9	0.58	1.93	0	0.005	≤0.01
Comparative example 3	19.8	0.28	0.98	0.52	3.9	0.58	1.93	0.3	0.005	≤0.01

Note: (1) the rightmost column in the table indicates S, P levels within that range, respectively;

(2) the parts not listed in the table are Fe and other unavoidable impurities.

Comparing the data in table 1, it can be seen that the composition of the ingot prepared by hot isostatic pressing is closer to the design composition than that of the ingot prepared by the conventional process, and the ingot prepared by the conventional melting and casting process has a certain degree of composition segregation.

The powdered steels prepared in example 1 and comparative examples 1 to 3 of the present invention were tested for tensile properties at room temperature by the standard method of GB/T228.1-2010 "tensile test for metal materials", and the test results are shown in table 2.

TABLE 2 tensile Properties at Room temperature of steels prepared in example 1 of the present invention and comparative examples 1 to 3

The powder steels prepared in example 1 and comparative examples 1 to 3 of the present invention were tested for room temperature impact toughness using the standard method of GB/T229-2007 "metallic material Charpy pendulum impact test method", and the test results are shown in Table 3.

TABLE 3 results of room temperature impact testing of steels prepared in inventive example 1 and comparative examples 1-3

The powder steels prepared in example 1 and comparative examples 1 to 3 of the present invention were tested for room temperature pitting performance by the standard method of GB/T17899-1999 stainless steel pitting potential measuring method, and the test results are shown in Table 4.

TABLE 4 test results of room temperature pitting corrosion properties of steels prepared in inventive example 1 and comparative examples 1-3

Material	Pitting potential at Room temperature (V μ sSCE)
		Example 1	-0.06
Comparative example 1	-0.23
		Comparative example 2	-0.3
Comparative example 3	-0.04

Comparing the properties of the high-carbon high-chromium stainless steel for knife and scissors in example 1 with those of the stainless steel in the comparative example, the stainless steel prepared by the hot isostatic pressing powder metallurgy process of the present invention has high tensile strength, good plasticity and excellent corrosion resistance, and is an ideal choice for the stainless steel for knife and scissors.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The high-carbon high-chromium stainless steel for the knives and scissors is characterized by comprising the following components in percentage by weight: c: 1.8-2.0%, Si: 0.5 to 0.7%, Mn: 0.2-0.4%, Cr: 19-21%, Mo: 0.8-1.2%, V: 2-4%, W: 0.3-0.7%, N: 0.15-0.25%, S: less than or equal to 0.01 percent, P: less than or equal to 0.01 percent, O: less than or equal to 0.01 percent, and the balance of Fe and other inevitable impurities.

2. The high-carbon high-chromium stainless steel for knives and scissors according to claim 1, wherein the ratio of C: 1.9-2.0%, Si: 0.5 to 0.55%, Mn: 0.2-0.3%, Cr: 19-20%, Mo: 0.9-1.1%, V: 3-4%, W: 0.5-0.7%, N: 0.15-0.25%, S: less than or equal to 0.01 percent, P: less than or equal to 0.01 percent, O: less than or equal to 0.01 percent.

3. The high-carbon high-chromium stainless steel for knives and scissors according to claim 1, wherein the stainless steel has a room temperature tensile strength R_mIs 810-890 MPa, and has room-temperature plastic elongation strength R_p0.2450 to 550MPa, 5 to 8 percent of elongation A after room temperature breakage, and KV energy absorbed by room temperature impact₂Is 7 to 10J.

4. A method for producing a high-carbon high-chromium stainless steel for knives and scissors according to any one of claims 1 to 3, comprising the steps of:

(2) removing impurities from the alloy powder, sieving, and taking undersize;

(4) heating and rolling the billet obtained in the step (3) to obtain a plate;

(5) and (4) annealing the plate obtained in the step (4).

5. The method for producing a high-carbon high-chromium stainless steel for knives and scissors according to claim 4, wherein in the step (1), the degree of vacuum of the vacuum condition is less than or equal to 30 Pa;

preferably, the nitrogen-containing inert gas is nitrogen or a mixture of nitrogen and argon;

preferably, the smelting temperature is 1550-1650 ℃.

6. The method for preparing a high-carbon high-chromium stainless steel for knives and scissors according to claim 4, wherein in the step (1), the oxygen content of the alloy powder is 0.004-0.02%;

preferably, the alloy powder is spherical and has a particle size of 0.006-0.35 mm.

7. The method for preparing the high-carbon high-chromium stainless steel for the knives and scissors as claimed in claim 4, wherein in the step (3), the hot isostatic pressing pressure is 100-120 MPa, and the heat preservation temperature is 1000-1150 ℃;

preferably, the pressure and temperature holding time of the hot isostatic pressing is 2-3 h;

8. The method for preparing a high-carbon high-chromium stainless steel for knives and scissors according to claim 4, wherein the rolling in the step (4) comprises hot rolling and cold rolling, the hot rolling is performed at a temperature higher than 950 ℃, and the hot rolling is performed by heating a billet and then rolling the billet with a deformation amount of 20-35%.

9. The method for producing a high-carbon, high-chromium stainless steel for knives and scissors according to claim 4 or 8, wherein in the step (4), the heating is: firstly, heating a billet to 800-850 ℃, preserving heat for 30-60 min, then heating to 1100-1200 ℃, and preserving heat for 30-120 min;

preferably, the heating rate of heating the billet to 800-850 ℃ is 7-8 ℃/min.

10. The method for producing a high-carbon, high-chromium stainless steel for knives and scissors according to claim 4, wherein in the step (5), the annealing is spheroidizing annealing;