CN115505851A - High-hardness and high-nitrogen martensitic stainless steel cutter material and preparation method thereof - Google Patents
High-hardness and high-nitrogen martensitic stainless steel cutter material and preparation method thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of metal and heat treatment thereof, and relates to a high-hardness and high-nitrogen martensitic stainless steel tool material which comprises the following raw materials in percentage by weight: 0.45 to 1.6% of N,0 to 0.65% of C,13.5 to 25% of Cr,0 to 24% of Mn,0 to 5.5% of Ni,0 to 5.5% of Mo,0 to 1.5% of V,0 to 0.5% of Nb,0 to 1.5% of W,0 to 3.5% of Cu, 0 to 0.03% of S, 0 to 0.03% of P,0 to 0.5% of Si, the balance being Fe. According to the invention, through the design of the chemical components of the stainless steel material, the chemical components of the austenite structure in the stainless steel material are adjusted, and the high-nitrogen austenitic stainless steel is subjected to solid-state phase transformation to prepare the martensitic stainless steel with high-nitrogen supersaturation solid solubility, so that the overflow loss of molten metal alloying element nitrogen caused by the limitation of a solidification mode in solidification of the high-nitrogen martensitic stainless steel under normal pressure is overcome, the smelting process is simplified, and the cost is reduced.
Description
Technical Field
The invention belongs to the technical field of metal and heat treatment thereof, and relates to a high-hardness and high-nitrogen martensitic stainless steel cutter material and a preparation method thereof.
Background
Martensitic stainless steel is a stainless steel that can be heat treated (quenched, tempered) to adjust its properties, and is a type of hardenable stainless steel that has become the main material of kitchen, sport, and hunting tools because of its high hardness, which can ensure the sharpness and basic durability of the tool, and its bright or decorative design can be maintained. The basic composition martensitic stainless steel 410 and the further developed martensitic stainless steel 440C, have gained basic and universal application. In order to enrich the innovation of the cutter technology and make the cutter sharper, corrosion resistant and durable, the composition design and preparation technology is continuously pursued, wherein the development of high-nitrogen martensitic stainless steel cutter material is one direction of the current cutter innovation.
At present, the existing high-nitrogen martensitic stainless steel is difficult to dissolve nitrogen, is difficult to directly smelt and manufacture martensitic stainless steel with nitrogen content of more than 0.4 percent, and generally needs to be prepared under pressurization in order to ensure high nitrogen content, however, the pressurized preparation needs very complicated equipment, the preparation process is complicated, the cost is high, and the large-scale popularization is not facilitated.
Disclosure of Invention
The invention aims to provide a high-hardness and high-nitrogen martensitic stainless steel tool material and a preparation method thereof, and aims to solve the technical problems that the existing high-nitrogen martensitic stainless steel is difficult to dissolve nitrogen, needs to be prepared under pressurization, is complex in preparation process and high in cost, and is not beneficial to large-scale popularization.
In order to realize the purpose, the specific technical scheme of the high-hardness and high-nitrogen martensitic stainless steel tool material and the preparation method thereof is as follows:
a high-hardness high-nitrogen martensitic stainless steel tool material comprises the following raw materials in percentage by weight: 0.45 to 1.6% of N,0 to 0.65% of C,13.5 to 25% of Cr,0 to 24% of Mn,0 to 5.5% of Ni,0 to 5.5% of Mo,0 to 1.5% of V,0 to 0.5% of Nb,0 to 1.5% of W,0 to 3.5% of Cu, 0 to 0.03% of S, 0 to 0.03% of P,0 to 0.5% of Si, the balance being Fe.
The invention is also characterized in that:
a preparation method of a high-hardness and high-nitrogen martensitic stainless steel tool material comprises the following specific steps:
step 1, designing chemical components of a stainless steel material;
step 2, carrying out metallurgical processing on the stainless steel material to enable the stainless steel material to be processed into a cutter blank;
step 3, placing the cutter blank in a heat treatment furnace for high-temperature solution heat treatment, heating the cutter blank to a high-temperature single-phase austenite phase region, and obtaining the toolA tool blank with a uniform austenitic structure, then carrying out ageing heat treatment on the tool blank, and precipitating nitride Cr after the ageing heat treatment 2 A compound with N as a main body, so that the structural characteristics of the obtained cutter blank are that the compound is distributed in an austenite structure;
and 4, carrying out quenching heat treatment on the cutter blank subjected to the aging heat treatment to convert an austenite structure in the cutter blank into a martensite structure.
Wherein the design steps of the chemical components of the stainless steel material in the step 1 are as follows:
step 1.1, calculating chemical components of the stainless steel according to the following calculation formula:
Cr eq ＝Cr+1.5Mo+1.5W+0.48Si+2.3V+1.75Nb+2.5Al (1)
Ni eq ＝Ni+Co+0.1Mn+0.01Mn 2 +18N+30C (2)
wherein, cr eq Is chromium equivalent, ni eq Is the equivalent of nickel;
step 1.2, with Cr 2 N is the main aging precipitate, the mass ratio of Cr to N is calculated according to the atomic weight, the nickel equivalent coefficient of N in the formula (2) is 18, and the reduction number of 0.5 mass unit of N is calculated to obtain Cr eq And Ni eq The equivalence ratio of (a);
step 1.3, the composition design has two directions, one is the high equivalent weight down composition design, from high Cr eq And high Ni eq The high-nitrogen austenitic stainless steel has aging precipitation amount in consideration, and the aging precipitation amount is reduced to low Cr eq And low Ni eq The contents of Cr and N are adjusted downwards, and the components are adjusted to meet the requirements of the high-nitrogen austenitic stainless steel; the second is low equivalent weight upward component design, firstly selecting martensitic stainless steel material and adjusting the design to high Cr eq And high Ni eq The high-nitrogen austenitic stainless steel adjusts the amount of Cr and N upwards, and meets the adjustment of a phase region of a Scheffler phase diagram.
Wherein the metallurgical processing in the step 2 is one or more of smelting, centrifugal casting, cast tube cutting flattening and rolling.
Wherein, nitrogen or vacuum protection is needed when the cutter blank is placed in the heat treatment furnace in the step 3.
Wherein the temperature of the high-temperature solution heat treatment in the step 3 is 1030-1250 ℃, and the time of the high-temperature solution heat treatment is 10 min-8 h.
Wherein the temperature of the aging heat treatment in the step 3 is 750-1020 ℃, and the time of the aging heat treatment is 1-21 h.
Wherein the aging heat treatment adopts three-stage heating:
in the first stage, the heating temperature is 830-950 ℃, and the time is 0.5-3 h;
in the second stage, the heating temperature is 950-1020 ℃ and the time is 0.5-12 h;
in the third stage, the heating temperature is 750-950 ℃ and the time is 0.5-6 h.
Wherein the quenching in the step 4 is any one of oil quenching, gas quenching, air cooling and furnace cooling.
The high-hardness and high-nitrogen martensite stainless steel cutter material and the preparation method thereof have the following advantages:
firstly, through the design of chemical components of a stainless steel material, the chemical components of an austenite structure in the stainless steel material are adjusted, and the high-nitrogen austenitic stainless steel is subjected to solid-state phase transformation to prepare the martensitic stainless steel with high nitrogen supersaturation solid solubility, so that the overflow loss of molten metal alloying element nitrogen caused by the limitation of a solidification mode in solidification of the high-nitrogen martensitic stainless steel under normal pressure is overcome, the smelting process is simplified, and the cost is reduced;
secondly, the invention develops a heat treatment technology, forms a new heat treatment combination of solution-aging-quenching, provides a processing technology of a new cutter material, and the conventional solution-aging heat treatment is generally applied to the strengthening of nonferrous metals capable of being strengthened by heat treatment after cooling or applied to precipitation hardening austenitic stainless steel to obtain a precipitated phase distributed in a structural phase matrix after solution treatment;
thirdly, the martensitic stainless steel material prepared by the invention has the performance potential of ultrahigh strength steel, and through the heat treatment technology of the invention, the nitride precipitated phase is adjusted to be dispersed in the matrix in a granular manner during aging heat treatment, so that the dispersion-strengthened high-strength martensite is obtained, the toughness of a high-hardness metal material is improved, and technical support is provided for manufacturing higher-performance high-strength stainless steel.
Drawings
FIG. 1 is a Shefler phase diagram of Speidel and Uggowitzer updated in 1993;
FIG. 2 is a process diagram of the heat treatment technique characteristic and the main target of each stage of the process;
FIG. 3 is a microstructure diagram of example 1;
Detailed Description
In order to better understand the purpose, structure and function of the present invention, the martensitic stainless steel tool material with high hardness and high nitrogen content and the manufacturing method thereof according to the present invention will be described in further detail below with reference to the accompanying drawings.
The invention relates to a high-hardness and high-nitrogen martensite stainless steel cutter material which comprises the following raw materials in percentage by weight: 0.45-1.6% N, 0-0.65% C, 13.5-25% Cr, 0-24% Mn, 0-5.5% Ni, 0-5.5% Mo, 0-1.5% V, 0-0.5% Nb, 0-1.5% W, 0-3.5% Cu, 0-0.03% S, 0-0.03% P, 0-0.5% Si, the balance being Fe.
The invention relates to a preparation method of a high-hardness and high-nitrogen martensitic stainless steel cutter material, which comprises the following specific steps of:
step 1, designing chemical components of a stainless steel material;
step 2, carrying out metallurgical processing on the stainless steel material to enable the stainless steel material to be processed into a cutter blank;
step 3, placing the cutter blank into a heat treatment furnace for high-temperature solution heat treatment, heating the cutter blank to a high-temperature single-phase austenite phase region to obtain the cutter blank with a uniform austenite structure, and then performing aging heat treatment on the cutter blankCr nitride precipitated after aging heat treatment 2 N is a main body compound, so that the structural characteristics of the obtained cutter blank are that nitrides are distributed in an austenite structure;
and 4, carrying out quenching heat treatment on the cutter blank subjected to the aging heat treatment to convert an austenite structure in the cutter blank into a martensite structure.
As shown in fig. 1, the present invention is used to illustrate the correspondence between composition adjustment and coordinate equivalent phase region change, wherein a represents austenite, F represents ferrite, and M represents martensite, and the chemical composition design steps of the stainless steel material in step 1 are as follows:
step 1.1, calculating chemical components of the stainless steel material according to the following calculation formula:
Cr eq ＝Cr+1.5Mo+1.5W+0.48Si+2.3V+1.75Nb+2.5Al (1)
Ni eq ＝Ni+Co+0.1Mn+0.01Mn 2 +18N+30C (2)
wherein, cr eq Is chromium equivalent, ni eq Is nickel equivalent;
step 1.2, with Cr 2 N is the main aging precipitate, the mass ratio of Cr to N is calculated according to the atomic weight (108: 14 ≈ 7.7: 1), the nickel equivalent coefficient 18 of N in the formula (2) is calculated, and the reduction number of 0.5 mass unit of N is calculated to obtain Cr eq And Ni eq The equivalence ratio of (a) to (b), i.e.: cr (chromium) component eq ＝7.7×0.5＝3.85，Ni eq =18 × 0.5=9, whereby Cr eq ∶Ni eq ＝3.85∶9；
Step 1.3, the composition design has two directions, one is the high equivalent weight down composition design, from high Cr eq And high Ni eq The high-nitrogen austenitic stainless steel has aging precipitation amount in consideration, and the aging precipitation amount is reduced to low Cr eq And low Ni eq The martensite stainless steel is prepared by downwards regulating the Cr and N content and carrying out component regulation to meet the requirement of the high-nitrogen austenite stainless steel; the second is low equivalent weight upward component design, firstly selecting martensitic stainless steel material and adjusting the design to high Cr eq And high Ni eq The high-nitrogen austenitic stainless steel adjusts the amount of Cr and N upwards, and meets the adjustment of a phase region of a Scheffler phase diagram.
Wherein, the metallurgical processing in the step 2 is one or more of smelting, centrifugal casting, cast tube cutting flattening and rolling.
As shown in fig. 2, when the tool blank is placed in the heat treatment furnace in step 3, nitrogen or vacuum protection is needed to reduce the oxidation of the surface of the tool blank during heating, the heat treatment is closely related to the design of components, and aging precipitates are obtained through the heat treatment, simultaneously, the components of an austenite matrix are changed, the matrix is transformed into martensite after cooling, and the tool blank has the characteristics of quenched martensite and high hardness, is not the precipitation transformation characteristics of the solid solution-aging heat treatment and is superimposed with the characteristics of quenched martensite transformation.
Wherein the temperature of the high-temperature solution heat treatment in the step 3 is 1030-1250 ℃, the time of the high-temperature solution heat treatment is 10 min-8 h, the aim of the solution heat treatment is to homogenize alloy components to form a uniform austenite structure, and provide tissues and component conditions for uniform precipitation during aging heat treatment, the aim of the tissues is to obtain a single-phase austenite structure with uniform components, particularly uniform nitrogen distribution, and then the tissues can reduce nitrides distributed at grain boundaries after solidification, fracture into granules, improve the plasticity and toughness of the material, and if high-temperature ferrite exists, the high-temperature ferrite must be converted into austenite after the solution heat treatment.
Wherein the temperature of the aging heat treatment in the step 3 is 750-1020 ℃, the time of the aging heat treatment is 1-21 h, and spherical or granular aging precipitates can be obtained through the sectional design of the aging process temperature in the aging heat treatment, and the effect is different from the effect of the heat treatment for obtaining granular pearlite.
The aging heat treatment adopts three-stage heating: in the first stage, the heating temperature is 830-950 ℃, and the time is 0.5-3 h; in the second stage, the heating temperature is 950-1020 ℃ and the time is 0.5-12 h; and the third stage, the heating temperature is 750-950 ℃, the time is 0.5-6 h, an aging heat treatment curve is designed in a segmented mode, the single-phase austenite with uniform components obtained by the solution heat treatment is cooled to the aging temperature, supersaturation precipitation occurs, but the precipitation is generally cellular discontinuous precipitation developing along grain boundaries into grains, the mechanical properties of the stainless steel are seriously damaged, disconnected lamellar nitrides must be dissolved into grains, spheroidization is carried out on the effective precipitation compounds, granular cores are provided for continuous aging precipitation later, then the precipitation is continued in the subsequent continuous aging process until the requirements of quenching heat treatment on the components of the austenite phase are met, the precipitation amount is controlled through temperature and time adjustment, the requirements are not limited, the basic requirements are that the aged components change to martensite at room temperature after quenching, the requirement of residual austenite amount tissue control is met, or the better control target is that the nitrogen content in a determined component range is obtained after aging, and the components and tissue control targets of the martensite matrix are met after quenching.
Wherein, the quenching in the step 4 is any one of oil quenching, gas quenching, air cooling and furnace cooling, and the determination mode of controlling the cooling is that the matrix obtains martensite and the quenching residual stress is reduced.
The invention also does not limit the specific cooling rate or cooling time of the quenching heat treatment, as long as the cooling speed is controlled to be larger than the critical quenching speed (the cooling speed is tested by adopting a metallographic method, namely, a sample with the same size and characteristics as the effective thickness of an actually processed part is adopted, and after the solid solution-aging heat treatment of a set process, air blowing cooling, oil cooling and water cooling are respectively adopted, metallographic observation is carried out on the sample, so that compounds precipitated by aging except martensite, residual austenite do not have other structures, or the hardness of the sample is detected, the water quenching hardness is taken as a reference, and a quenching medium with the slowest cooling speed or the lowest quenching intensity which does not obviously reduce the hardness is selected, so that the quenching stress is reduced and the quenching distortion is reduced.
Wherein, still include in step 3: cold or cryogenic heat treatment, (staying below room temperature, supercooled austenite continuing to transform, generally distinguishing cold heat treatment from cryogenic heat treatment at minus 130 ℃), the temperature range from the austenite component to the martensite transformation temperature after aging heat treatment may be lower, the martensite transformation amount is improved by cold or cryogenic heat treatment, and the martensite transformation starting point Ms can be calculated or determined by experimental detection. The invention does not limit the temperature and the specific time of refrigeration or cryogenic heat treatment, can be referenced or determined experimentally according to the actually established process temperature and time, and the specific parameters meet the detection limit requirements of high efficiency and retained austenite amount, and the recommended cold and cryogenic temperatures are-40 to-196 ℃, and the heat preservation time is 3min to 48h.
After quenching or cold/cryogenic heat treatment, in the tempering heat treatment, the temperature of the tempering heat treatment and the specific time of a heat preservation stage are not limited, the temperature and the specific time can be set according to the actual process temperature and time, reference or experimental determination is available, specific parameters meet the requirements of high efficiency and detection, the tempering temperature is 150-550 ℃ and the heat preservation time is 1-3 h in the tempering heat treatment process. Generally, low-temperature tempering is adopted, wherein the low-temperature tempering heat treatment is mainly used for releasing or reducing quenching residual stress, and the temperature range is 150-250 ℃. However, for some tool materials, including Mo, V, etc., which are temper resistant or possibly post-hardened, higher temperature tempering is used, even with two or more stages of tempering processes.
Example 1
Step 1, selecting a high-nitrogen austenitic stainless steel material
This example uses a high nitrogen austenitic stainless steel material, 0Cr21Mn17Mo2.5N0.85 (marked according to the main alloying components), which is a nickel-free high nitrogen austenitic stainless steel with ultra-high nitrogen content, and has excellent corrosion resistance, and the chemical components are listed as follows (mass percent/wt.%):
TABLE 1 chemical composition (wt.%) of high nitrogen austenitic stainless steel 0Cr21Mn17Mo2.5N0.85
The aim is to reduce the Cr and N content of the austenitic structure by solution-ageing heat treatment, to fall within the martensite region of the Scheffler diagram by calculation, and to transform into martensite during subsequent cooling (after quenching), to obtain the particulate age-precipitated compound Cr 2 N, distributed in the quenched martensite.
Step 2, hot rolling the plate
Taking a strip material with the length, width and thickness of 200 multiplied by 50 multiplied by 10 (mm), carrying out hot rolling, heating the strip material at the temperature of 1150 ℃ per pass, keeping the temperature for 10 minutes to 1 hour, reducing the deformation of the thickness of 10 to 30 percent per pass by the hot rolling, rolling the strip material at the temperature of not less than 950 ℃ to form a plate with the thickness of 2.5mm, cutting a cutter blank, linearly cutting a cutter plate blank with a certain shape according to a given kitchen cutter, and then primarily grinding the edge part to obtain the edge part with a primary size and design shape.
Step 3, heat treatment
The vacuum heat treatment furnace is adopted, the maximum use temperature reaches 1250 ℃, and the heating and pressurized gas quenching operation can be performed by programming. The heat treatment process sequence and other more specific process parameters are as follows:
1) Solid solution heat treatment, wherein the solid solution temperature is 1140 ℃, and the heat preservation time is 4h.
2) Aging heat treatment, after the solution heat treatment, the aging starts, and the three-stage temperature/time is as follows: 930 ℃/1 h-1020 ℃/1.5 h-850 ℃/4h.
3) Quenching heat treatment, namely pressurizing nitrogen to quench, namely pressurizing the nitrogen and introducing the nitrogen into a cooling chamber to cool the cutter plate blank, wherein the pressurizing pressure and the flow rate are the conventional operation parameters of the equipment. After solution-aging-quenching heat treatment, metallographic specimens were made, electrolytically corroded with picric acid corrosion solution, and observed that the particulate nitrides were more uniformly distributed in a grey martensitic matrix, as shown in fig. 3. And (3) quenching hardness inspection, after solid solution-aging-quenching heat treatment, performing spot inspection on 5 cutter plate blanks by Rockwell hardness inspection, and inspecting the hardness of each opposite angle at 5 points uniformly, wherein the final average hardness reaches 61.3HRC.
As shown in fig. 3, after the solution-aging-quenching heat treatment, samples were metallographically observed, electrolytic etching was performed using an oxalic acid etchant, and particulate nitrides were distributed in the martensitic matrix.
4) Tempering heat treatment, wherein the tempering temperature is 170 ℃, and the heat preservation time is 2 hours.
Example 2
Step 1, selecting 1.4116 martensitic stainless steel material (DIN X50CrMoV 15), adjusting chemical components according to component design, and reducingLow C content, increased Cr content and addition of N, supplementary ageing heat treatment elements, such as Cr 2 N is the main age precipitates, 4.6% of Cr is calculated by adding 0.6% of N in accordance with a Cr/N mass ratio of about 7.7/1, and 1.4116 martensitic stainless steel is adjusted in consideration of partial solid solution of increased nitrogen by designing the composition.
TABLE 2 chemical composition (wt.%) of high nitrogen austenitic stainless steel 35Cr20Mn16Mo2.5VN0.7
The aim is to reduce the Cr and N content of the austenitic structure by solution-ageing heat treatment, to fall within the martensite region of the Scheffler diagram by calculation, and to transform into martensite during subsequent cooling (after quenching), to obtain the granular age-precipitated compound Cr 2 N, distributed in the quenched martensite.
Step 2, metallurgical processing
1) Preparation of
A stainless steel pipe having a pipe blank size of phi 330/290X 2000mm was cast, and the alloy composition was as specified in Table 2.
Preparing materials: according to the alloy components, the yield of alloy elements in metallurgy and the weight of cast tubes, pure iron, high-quality carbon structural steel, chromium iron nitride, pure manganese, ferromolybdenum and ferrovanadium are weighed, and the contents of non-alloying elements such as Si, P, S and the like are controlled within the range shown in table 2 by material preparation attention.
Preparation of casting mold and casting machine: and (3) rolling and hanging 2-3 mm of coating on the inner surface of the casting mold by adopting a horizontal centrifugal casting machine, wherein the casting mold temperature is 200 ℃ during casting (the casting mold temperature range is 120-250 ℃).
2) Melting
The process procedure of smelting the high-nitrogen austenitic stainless steel under normal pressure (patent publication No. CN101285148A; name: a manufacturing method of the high-nitrogen nickel-free austenitic stainless steel) is followed, important operation parameters including feeding sequence, smelting temperature, power and the like are included, and the patent implementation mode is referred.
The smelting temperature is controlled to 1550-1650 ℃ in the early stage, and the smelting temperature is reduced and the power is controlled and adjusted in the later stage according to the feeding reaction and nitrogen protection.
3) Centrifugal casting
The procedure for centrifugal casting of high nitrogen austenitic stainless steel pipes at atmospheric pressure was followed (previously filed patent publication No.: CN 105108098B; name: process for centrifugal casting of high nitrogen austenitic stainless steel pipes at atmospheric pressure).
And when the smelting is finished, quickly adjusting the temperature of the high-nitrogen austenitic stainless steel metal liquid to the pouring temperature, and connecting the pouring steps within 90 seconds. The casting temperature selected in this example was 1530 ℃. In the embodiment, the single-tube pouring time is 16 seconds, and all the molten metal is poured within 3 minutes.
The rotating speed of the casting mold is 530rpm in the embodiment during casting, and the rotating speed is gradually reduced after the casting is finished; the casting temperature of the casting tube is controlled to be 800-1000 ℃.
The quality of the steel pipe is tested item by item, and the components of the steel pipe are shown in the following table 3:
TABLE 3 chemical composition (wt.%) of high nitrogen austenitic stainless steel 35Cr20Mn16Mo2.5VN0.7
The component detection result meets the control target.
4) Cast tube cutting and flattening
Cleaning, and removing the surface layer, the two end parts of the cast tube and the inner surface layer by adopting a proper mechanical processing method to obtain the steel tube with uniform components, surface smoothness meeting the rolling requirement of a steel plate, and the size of phi 325/295 multiplied by 1900mm.
In the embodiment, the cast pipe is subjected to circular cutting, the width of the steel ring is 200mm, 1 straight seam is cut along the axial direction of the steel ring, and the steel ring is mechanically flattened.
5) Rolling of
Hot rolling, wherein the heating temperature of each pass is 1150-1220 ℃, the heat preservation time is 10-30 minutes, the rolling reduction of each pass is 8-35%, the final rolling temperature is not lower than 980 ℃, and the steel plate is rolled into a plate with the thickness of 2.04-2.05 mm.
6) Cutting out
Cutting a cutter blank, and cutting the cutter blank according to a given kitchen cutter and a line.
7) Preliminary edge grinding
And grinding to enable the blade part to present an initial size design shape and reserve the final accurate grinding amount.
Step 3, heat treatment
The vacuum heat treatment furnace is adopted, the maximum use temperature reaches 1250 ℃, and the heating and pressurized gas quenching operation can be programmed. The heat treatment process sequence and other more specific process parameters are as follows:
1) Solid solution heat treatment, wherein the solid solution temperature range is 1140 ℃, and the heat preservation time is 6h.
2) Aging heat treatment, after the solution heat treatment, the aging is started, and the three-stage temperature/time is as follows: 940 ℃/1 h-1020 ℃/1.5 h-800 ℃/4h.
3) Quenching heat treatment, namely pressurizing nitrogen for quenching, namely pressurizing the nitrogen and introducing the nitrogen into a cooling chamber to cool the cutter plate blank, wherein the pressurizing pressure and the pressurizing flow are the conventional operating parameters of the equipment.
4) The cryogenic heat treatment has higher content of alloy elements compared with the original martensitic stainless steel material, so the cryogenic heat treatment has lower Ms point, and the martensitic stainless steel cutter material needs higher requirement of martensite transformation amount, so the cryogenic heat treatment is added after quenching. Placing into a deep cooling tank, keeping the temperature at-130 deg.C for 24 hr, then placing into 60 deg.C water for 1 hr, taking out, blow-drying, namely, placing into a hot furnace, and making into a tempering heat treatment step.
5) After solid solution-aging-quenching heat treatment and deep cooling heat treatment, sampling and checking the granular characteristics of the structure, and meeting the structure requirements.
6) And (4) tempering heat treatment, wherein the tempering temperature is 230 ℃, and the heat preservation time is 3h.
7) The heat treatment quality inspection of the cutter shows that the average value of the hardness is 60.5HRC, the deviation is within 2HRC, and other inspection results are slight.
The high-hardness and high-nitrogen martensite stainless steel cutter material and the preparation method thereof have the following advantages:
firstly, through the design of chemical components of a stainless steel material, the chemical components of an austenite structure in the stainless steel material are adjusted, and the high-nitrogen austenitic stainless steel is subjected to solid-state phase transformation to prepare the martensitic stainless steel with high-nitrogen supersaturation solid solubility, so that the overflow loss of molten metal alloying element nitrogen caused by the limitation of a solidification mode in solidification of the high-nitrogen martensitic stainless steel under normal pressure is overcome, the smelting process is simplified, and the cost is reduced;
secondly, the invention develops a heat treatment technology, forms a new heat treatment combination of solution-aging-quenching, provides a processing technology of a new cutter material, and the conventional solution-aging heat treatment is generally applied to the strengthening of heat-treatable strengthened nonferrous metals or precipitation hardening austenitic stainless steel after cooling to obtain a precipitated phase distributed in a structural phase matrix after solution treatment, and the quenching is a common strengthening or hardening method of steel or cast iron, and heats and preserves heat to obtain austenite which is then cooled at a speed higher than a critical cooling speed to transform the austenite into martensite;
thirdly, the martensitic stainless steel material prepared by the invention has the performance potential of ultrahigh strength steel, and through the heat treatment technology of the invention, the nitride precipitated phase is adjusted to be dispersed in a matrix in a granular manner during aging heat treatment, so that the dispersion-strengthened high-strength martensite is obtained, the toughness of a high-hardness metal material is improved, and technical support is provided for manufacturing higher-performance high-strength stainless steel.
It is to be understood that the present invention has been described with reference to certain embodiments, and that various changes in the features and embodiments, or equivalent substitutions may be made therein by those skilled in the art without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (9)
1. The high-hardness high-nitrogen martensitic stainless steel tool material is characterized by comprising the following raw materials in percentage by weight: 0.45 to 1.6% of N,0 to 0.65% of C,13.5 to 25% of Cr,0 to 24% of Mn,0 to 5.5% of Ni,0 to 5.5% of Mo,0 to 1.5% of V,0 to 0.5% of Nb,0 to 1.5% of W,0 to 3.5% of Cu, 0 to 0.03% of S, 0 to 0.03% of P,0 to 0.5% of Si, the balance being Fe.
2. A preparation method of the high-hardness and high-nitrogen martensitic stainless steel tool material is characterized by being used for preparing the high-hardness and high-nitrogen martensitic stainless steel tool material as claimed in claim 1, and comprising the following specific steps:
step 1, designing chemical components of a stainless steel material;
step 2, carrying out metallurgical processing on the stainless steel material to enable the stainless steel material to be processed into a cutter blank;
step 3, placing the cutter blank in a heat treatment furnace for high-temperature solution heat treatment to heat the cutter blank to a high-temperature single-phase austenite phase region for heating to obtain the cutter blank with a uniform austenite structure, then performing aging heat treatment on the cutter blank, and precipitating nitride Cr after the aging heat treatment 2 A compound with N as a main body, so that the structural characteristics of the obtained cutter blank are that the compound is distributed in an austenite structure;
and 4, carrying out quenching heat treatment on the cutter blank subjected to the aging heat treatment to convert an austenite structure in the cutter blank into a martensite structure.
3. The method for preparing the martensitic stainless steel tool material with high hardness and high nitrogen as claimed in claim 2, wherein the design steps of the chemical compositions of the stainless steel material in the step 1 are as follows:
step 1.1, calculating chemical components of stainless steel according to the following calculation formula:
Cr eq ＝Cr+1.5Mo+1.5W+0.48Si+2.3V+1.75Nb+2.5Al (1)
Ni eq ＝Ni+Co+0.1Mn+0.01Mn 2 +18N+30C (2)
wherein, cr eq Is chromium equivalent, ni eq Is nickel equivalent;
step 1.2, with Cr 2 N is the main aging precipitate, the mass ratio of Cr to N is calculated according to the atomic weight, the nickel equivalent coefficient of N in the formula (2) is 18, and the reduction number of 0.5 mass unit of N is calculated to obtain Cr eq And Ni eq The equivalence ratio of (a);
step 1.3, the composition design has two directions, one is the high equivalent weight down composition design, from high Cr eq And high Ni eq The high-nitrogen austenitic stainless steel has aging precipitation amount in consideration, and the aging precipitation amount is reduced to low Cr eq And low Ni eq The martensite stainless steel is prepared by downwards regulating the Cr and N content and carrying out component regulation to meet the requirement of the high-nitrogen austenite stainless steel; the second is low equivalent weight upward component design, firstly selecting martensitic stainless steel material and adjusting the design to high Cr eq And high Ni eq The amount of Cr and N in the high-nitrogen austenitic stainless steel is adjusted upwards, and the adjustment of a phase region of a Scheffler phase diagram is met.
4. The method for preparing the martensitic stainless steel tool material with high hardness and high nitrogen as claimed in claim 2, wherein the metallurgical processing in the step 2 is one or more of smelting, centrifugal casting, cast tube cutting and flattening and rolling.
5. The method for preparing the martensitic stainless steel with high hardness and high nitrogen as claimed in claim 2, wherein the step 3 requires nitrogen or vacuum protection when the tool blank is placed in a heat treatment furnace.
6. The method for preparing the martensitic stainless steel tool material with high hardness and high nitrogen as claimed in claim 2, characterized in that the temperature of the high-temperature solution heat treatment in the step 3 is 1030-1250 ℃, and the time of the high-temperature solution heat treatment is 10 min-8 h.
7. The method for preparing the martensitic stainless steel with high hardness and nitrogen as claimed in claim 2, wherein the temperature of the aging heat treatment in the step 3 is 750-1020 ℃, and the time of the aging heat treatment is 1-21 h.
8. The method for preparing the martensitic stainless steel tool material with high hardness and high nitrogen content as claimed in claim 7, wherein the aging heat treatment adopts three-stage heating:
in the first stage, the heating temperature is 830-950 ℃, and the time is 0.5-3 h;
in the second stage, the heating temperature is 950-1020 ℃ and the time is 0.5-12 h;
in the third stage, the heating temperature is 750-950 ℃ and the time is 0.5-6 h.
9. The method for preparing a martensitic stainless steel tool material with high hardness and high nitrogen as claimed in claim 2, wherein the quenching in the step 4 is any one of oil quenching, gas quenching, air cooling and furnace cooling.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001107195A (en) * | 1999-10-01 | 2001-04-17 | Daido Steel Co Ltd | Low carbon high hardness and high corrosion resistance martensitic stainless steel and its producing method |
| CN1352319A (en) * | 2000-11-15 | 2002-06-05 | 浦项产业科学研究院 | Martensitic stainless steel with high mechanical strength and anti-corrosion |
| KR20080034903A (en) * | 2005-06-28 | 2008-04-22 | 피오트르 알. 쉘러 | High-strength, lightweight austenitic-martensitic steel and the use thereof |
| CN106086631A (en) * | 2016-08-23 | 2016-11-09 | 钢铁研究总院 | High-hardness, wearable height nitrogen martensite stainless bearing steel and preparation method thereof |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001107195A (en) * | 1999-10-01 | 2001-04-17 | Daido Steel Co Ltd | Low carbon high hardness and high corrosion resistance martensitic stainless steel and its producing method |
| CN1352319A (en) * | 2000-11-15 | 2002-06-05 | 浦项产业科学研究院 | Martensitic stainless steel with high mechanical strength and anti-corrosion |
| KR20080034903A (en) * | 2005-06-28 | 2008-04-22 | 피오트르 알. 쉘러 | High-strength, lightweight austenitic-martensitic steel and the use thereof |
| CN106086631A (en) * | 2016-08-23 | 2016-11-09 | 钢铁研究总院 | High-hardness, wearable height nitrogen martensite stainless bearing steel and preparation method thereof |
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