CN115505851B - High-hardness high-nitrogen martensitic stainless steel tool material and preparation method thereof - Google Patents
High-hardness high-nitrogen martensitic stainless steel tool 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 high-nitrogen martensitic stainless steel cutter material which comprises the following raw materials in percentage by weight: 0.45 to 1.6 percent of N,0 to 0.65 percent of C,13.5 to 25 percent of Cr,0 to 24 percent of Mn,0 to 5.5 percent of Ni,0 to 5.5 percent of Mo,0 to 1.5 percent of V,0 to 0.5 percent of Nb,0 to 1.5 percent of W,0 to 3.5 percent of Cu, 0 to 0.03 percent of S, 0 to 0.03 percent of P,0 to 0.5 percent of Si and the balance of Fe. According to the invention, through designing chemical components of the 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 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 high-nitrogen martensitic stainless steel tool material and a preparation method thereof.
Background
Martensitic stainless steel, which is a type of stainless steel that can be heat treated (quenched, tempered) to adjust its properties, is also known as a type of hardenable stainless steel, has now become the subject material for kitchen, sports, hunting tools because of the high hardness that can ensure sharpness and basic durability of the tools and the maintenance of bright or decorative patterns. The basic component martensitic stainless steel 410 and the further developed martensitic stainless steel 440C, find fundamental and universal application. In order to enrich the innovation of the cutter technology and also in order to make the cutter sharper, corrosion resistant and durable, component design and preparation technology are continuously pursued, wherein the development of high-nitrogen martensitic stainless steel cutter materials is one direction of the current cutter innovation.
At present, the development of the existing high-nitrogen martensitic stainless steel has difficulty in dissolving nitrogen, is difficult to directly smelt and manufacture martensitic stainless steel with the nitrogen content exceeding 0.4%, and generally needs to be prepared under pressurization in order to ensure the high nitrogen content, however, the pressurization preparation needs very complex equipment, the preparation process is complex, the cost is high, and the large-scale popularization is not facilitated.
Disclosure of Invention
The invention aims to provide a high-hardness high-nitrogen martensitic stainless steel tool material and a preparation method thereof, which are used for solving the technical problems that nitrogen dissolution is difficult, preparation is needed under pressurization, the preparation process is complex, the cost is high, and large-scale popularization is not facilitated in the development of the existing high-nitrogen martensitic stainless steel.
In order to achieve the above purpose, the specific technical scheme of the high-hardness high-nitrogen martensitic stainless steel tool material and the preparation method thereof are 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 percent of N,0 to 0.65 percent of C,13.5 to 25 percent of Cr,0 to 24 percent of Mn,0 to 5.5 percent of Ni,0 to 5.5 percent of Mo,0 to 1.5 percent of V,0 to 0.5 percent of Nb,0 to 1.5 percent of W,0 to 3.5 percent of Cu, 0 to 0.03 percent of S, 0 to 0.03 percent of P,0 to 0.5 percent of Si and the balance of Fe.
The invention is also characterized in that:
a preparation method of a high-hardness high-nitrogen martensitic stainless steel tool material comprises the following specific steps:
step 1, designing chemical components of a stainless steel material;
step 2, metallurgical processing is carried out on the stainless steel material, so that the stainless steel material is 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 to obtain the cutter blank with a uniform austenite structure, then performing aging heat treatment on the cutter blank, and separating out Cr nitride after the aging heat treatment 2 A compound with N as the main body, such that the structural characteristics of the resulting tool blank are such that the compound is distributed in an austenitic structure;
and 4, quenching the cutter blank subjected to aging heat treatment to convert the austenitic structure in the cutter blank into a martensitic structure.
The design steps of the chemical components of the stainless steel material in the step 1 are as follows:
step 1.1, calculating the chemical components of the stainless steel, wherein the calculation formula is as follows:
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 is eq Is chromium equivalent, ni eq Is nickel equivalent;
step 1.2, cr 2 N is the main aging precipitate, the mass ratio of Cr to N is calculated according to atomic weight, cr is calculated according to the nickel equivalent coefficient 18 of N in the formula (2) and the reduction number of 0.5 mass unit of N eq With Ni eq Equivalent ratio of (2);
step 1.3, component design has two directions, one is high equivalent weight downward component design, from high Cr eq And high Ni eq The aging yield is considered to be low in the high-nitrogen austenitic stainless steel of (2) toward low Cr eq And low Ni eq The Cr and N amounts are downwards regulated, and the composition is adjusted to meet the requirement of the high-nitrogen austenitic stainless steel; secondly, the design of the components with low equivalent weight upwards is carried out, firstly, martensitic stainless steel materials are selected and the design is adjusted to be towards high Cr eq And high Ni eq The Cr and N amounts are adjusted upwards to meet the adjustment of the phase region of the Sheffir phase diagram.
Wherein the metallurgical processing in the step 2 is one or more of smelting, centrifugal casting, cast tube dividing, flattening and rolling.
Wherein in the step 3, nitrogen or vacuum protection is needed when the cutter blank is placed in a heat treatment furnace.
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 sections of heating:
the first stage, heating temperature is 830-950 ℃ and time is 0.5-3 h;
the second stage, heating temperature is 950-1020 deg.c for 0.5-12 hr;
and 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 high-nitrogen martensitic stainless steel tool material and the preparation method thereof have the following advantages:
firstly, through the design of chemical components of stainless steel materials, the chemical components of an austenite structure in the stainless steel materials are adjusted, and the high-nitrogen austenitic stainless steel is subjected to solid 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 solid solution-aging-quenching heat treatment combination, provides a processing technology of a new tool material, generally applies the conventional solid solution-aging heat treatment to the strengthening aspect of nonferrous metal which can be strengthened by heat treatment after cooling or applies the conventional solid solution-aging heat treatment to precipitation hardening austenitic stainless steel, obtains a precipitated phase which is distributed in a structural phase matrix after solid solution treatment, and adopts a common strengthening or hardening method of steel or cast iron, heats and holds heat to obtain austenite and then cools at a speed higher than critical cooling speed, and austenite is transformed into martensite.
Thirdly, the martensitic stainless steel material prepared by the invention has the performance potential of ultra-high strength steel, and through the heat treatment technology of the invention, the nitride precipitated phase is adjusted to be dispersed and distributed in a matrix in a granular form during aging heat treatment, so that the dispersion strengthening high strength martensite is obtained, the toughness of the high hardness metal material is improved, and technical support is provided for manufacturing the high strength stainless steel with higher performance.
Drawings
FIG. 1 is a Sheffir phase diagram of Speidel and Uggowitzer updated in 1993;
FIG. 2 is a graph of the heat treatment process and the main objects of each stage of process;
FIG. 3 is a microstructure of example 1;
Detailed Description
In order to better understand the purpose, structure and function of the present invention, the following describes in detail a high-hardness high-nitrogen martensitic stainless steel tool material and a preparation method thereof with reference to the accompanying drawings.
The invention discloses a high-hardness high-nitrogen martensitic stainless steel tool material, which comprises the following raw materials in percentage by weight: 0.45 to 1.6 percent of N,0 to 0.65 percent of C,13.5 to 25 percent of Cr,0 to 24 percent of Mn,0 to 5.5 percent of Ni,0 to 5.5 percent of Mo,0 to 1.5 percent of V,0 to 0.5 percent of Nb,0 to 1.5 percent of W,0 to 3.5 percent of Cu, 0 to 0.03 percent of S, 0 to 0.03 percent of P,0 to 0.5 percent of Si and the balance of Fe.
The invention relates to a preparation method of a high-hardness high-nitrogen martensitic stainless steel tool material, which comprises the following specific steps:
step 1, designing chemical components of a stainless steel material;
step 2, metallurgical processing is carried out on the stainless steel material, so that the stainless steel material is 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 to obtain the cutter blank with a uniform austenite structure, then performing aging heat treatment on the cutter blank, and separating out Cr nitride after the aging heat treatment 2 A compound with N as the main body, so that the structural characteristics of the obtained tool blank are such that nitrides are distributed in the austenitic structure;
and 4, quenching the cutter blank subjected to aging heat treatment to convert the austenitic structure in the cutter blank into a martensitic structure.
As shown in fig. 1, the invention is used for illustrating the correspondence between composition adjustment and change of coordinate equivalent phase region, wherein a represents austenite, F represents ferrite, 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, wherein the calculation formula is as follows:
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 is eq Is chromium equivalent, ni eq Is nickel equivalent;
step 1.2, cr 2 N is the main aging precipitate, the mass ratio of Cr to N is calculated according to the atomic weight (108:14.apprxeq.7.7:1), the nickel equivalent coefficient of N in the formula (2) is 18, and the Cr is calculated according to the reduction number of 0.5 mass units of N eq With Ni eq Equivalent ratio of (2), namely: cr (Cr) eq ＝7.7×0.5＝3.85，Ni eq =18×0.5=9, thus Cr eq ∶Ni eq ＝3.85∶9；
Step 1.3, component design has two directions, one is high equivalent weight downward component design, from high Cr eq And high Ni eq The aging yield is considered to be low in the high-nitrogen austenitic stainless steel of (2) toward low Cr eq And low Ni eq The Cr and N amounts are downwards regulated, and the composition is adjusted to meet the requirement of the high-nitrogen austenitic stainless steel; secondly, the design of the components with low equivalent weight upwards is carried out, firstly, martensitic stainless steel materials are selected and the design is adjusted to be towards high Cr eq And high Ni eq The Cr and N amounts are adjusted upwards to meet the adjustment of the phase region of the Sheffir phase diagram.
The metallurgical processing in the step 2 is one or more of smelting, centrifugal casting, cast tube dividing, flattening and rolling.
As shown in fig. 2, in step 3, nitrogen or vacuum protection is required when the tool blank is placed in a heat treatment furnace, oxidation of the surface of the tool blank during heating is reduced, the heat treatment is closely related to composition design, ageing precipitates are obtained through the heat treatment, meanwhile, the composition of an austenitic matrix is changed, the matrix is transformed into martensite after cooling, the martensitic high hardness characteristic is quenched, the precipitation transformation characteristic which is not solution-ageing heat treatment is already added, and the characteristic of quenched martensitic transformation is superposed.
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 solution heat treatment aims at homogenizing the alloy components to form a uniform austenite structure, providing structure and component conditions for uniform precipitation during aging heat treatment, the structure aims at obtaining a single-phase austenite structure with uniform components, especially uniform nitrogen distribution, and reducing nitrides distributed at grain boundaries after solidification during the next step, breaking into particles, improving the plasticity and toughness of the material, and if high-temperature ferrite exists, the alloy 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, spherical or granular aging precipitates can be obtained by the sectional design of the aging process temperature in the aging heat treatment, and the effect of the section is different from that of the heat treatment for obtaining granular pearlite.
The aging heat treatment adopts three sections of heating: the first stage, heating temperature is 830-950 ℃ and time is 0.5-3 h; the second stage, heating temperature is 950-1020 deg.c for 0.5-12 hr; and in the third stage, heating temperature is 750-950 ℃ and time is 0.5-6 h, an aging heat treatment curve is designed in a segmented way, supersaturation precipitation is generated by cooling single-phase austenite with uniform components obtained by solution heat treatment to aging temperature, but the precipitation is generally cellular discontinuous precipitation which develops into crystals along grain boundaries, so that the mechanical properties of stainless steel are seriously damaged, broken lamellar nitrides must be dissolved to be granular, immediate effect precipitation compounds are subjected to spheroidization, granular cores are provided for subsequent continuous aging precipitation, then continuous aging precipitation is carried out until the component requirements of quenching heat treatment on an austenite phase are met, the precipitation amount is controlled by temperature and time, the limitation is not carried out, the basic requirement is that martensite is obtained at room temperature after aging, the control requirement of residual austenite amount is met, or better control targets are that nitrogen content of a determined component range is obtained after aging, and the component and tissue control targets of a martensitic 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 is a determination mode of taking the obtained martensite of the matrix and reducing the quenching residual stress as control cooling.
The invention also does not limit the specific cooling rate or cooling time of the quenching heat treatment, as long as the cooling rate is controlled to be larger than the critical quenching rate (the cooling rate is tested by adopting a metallographic method, namely, a sample with the same size characteristics as the effective thickness of an actual treatment piece is adopted, after solid solution-aging heat treatment of a set process, the sample is subjected to metallographic observation by adopting air blast cooling, oil cooling and water cooling respectively, other structures are not generated except for martensite, residual austenite and compounds separated by aging, or the hardness of the sample is detected, the water quenching hardness is taken as a reference, and the quenching medium with the slowest cooling rate 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, step 3 further comprises: cold or cryogenic heat treatment (residence below room temperature, supercooled austenite continues to transform, cold and cryogenic heat treatment is generally distinguished at minus 130 ℃), the range of austenite components after aging heat treatment to martensite transformation temperature may be low, 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 used for reference or experimental determination according to the actual process temperature and time, and specific parameters are required to meet the requirements of high efficiency and residual austenite amount detection limit, and the recommended refrigeration and cryogenic temperature is between-40 and-196 ℃, and the heat preservation time is between 3 minutes and 48 hours.
After quenching or cold/cryogenic heat treatment, the invention does not limit the specific time of the temperature and heat preservation stage of tempering heat treatment, and can be determined by reference or experiment according to the actual established process temperature and time, the specific parameters are in accordance with the high efficiency and detection requirements, 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, and the low-temperature tempering heat treatment is mainly used for releasing or reducing the quenching residual stress, and the temperature range is 150-250 ℃. However, for some tool materials, including Mo, V, etc., tempering resistant or possibly secondary hardening, higher temperature tempering is employed, even with two or more stage tempering processes.
Example 1
Step 1, selecting a high-nitrogen austenitic stainless steel material
The embodiment adopts a high-nitrogen austenitic stainless steel material, 0Cr21Mn17Mo2.5N0.85 (marked by main alloying components), is the nickel-free high-nitrogen austenitic stainless steel with ultrahigh nitrogen content, has excellent corrosion resistance, and has the following chemical components in percentage by weight:
table 1. Chemical composition (wt.%) of high nitrogen austenitic stainless steel 0Cr21Mn17Mo2.5N0.85
The object is to reduce the Cr and N contents of the austenitic structure after the solution-aging heat treatment, so as to be calculated to fall into the martensitic region of the Sheffir phase diagram, thereby being transformed into martensite in the subsequent cooling (after quenching) and obtaining the granular aging compound Cr 2 N is distributed in the quenched martensite.
Step 2, hot rolled sheet
Taking a strip material with the length, width and thickness of 200 multiplied by 50 multiplied by 10 (mm), hot rolling, wherein the heating temperature of each pass is 1150 ℃, the heat preservation time is 10 minutes to 1 hour, the deformation of each hot rolling with the reduced thickness of each pass is 10 to 30 percent, the finishing temperature is not lower than 950 ℃, rolling into a plate with the thickness of 2.5mm, cutting a cutter blank, linearly cutting the cutter blank with a certain shape according to a given kitchen cutter, and then grinding a preliminary blade part, wherein the blade part presents the design shape of the preliminary dimension.
Step 3, heat treatment
And adopting a vacuum heat treatment furnace, wherein the highest use temperature reaches 1250 ℃, and carrying out heating and pressurized gas quenching operation in a programmable manner. The heat treatment process sequence and other more specific process parameters are as follows:
1) And solution heat treatment, wherein the solution temperature is 1140 ℃, and the heat preservation time is 4 hours.
2) Aging heat treatment, after solution heat treatment, aging starts, three-stage temperature/time: 930 ℃/1h to 1020 ℃/1.5h to 850 ℃/4h.
3) Quenching heat treatment, pressurized nitrogen quenching, namely, pressurizing nitrogen and introducing the nitrogen into a cooling chamber to cool a cutter plate blank, wherein the pressurizing pressure and flow take the conventional operation parameters of the equipment. After the solution-aging-quenching heat treatment, a metallographic specimen was prepared, and electrolytic corrosion was carried out with picric acid etching solution, and it was observed that the granular nitrides were more uniformly distributed in the grey martensitic matrix, as shown in fig. 3. After quenching hardness inspection and solid solution-aging-quenching heat treatment, the spot check 5 performs Rockwell hardness inspection on the cutter plate blank, each piece of the cutter plate blank has even diagonal 5-point hardness inspection, and finally the average hardness reaches 61.3HRC.
As shown in fig. 3, after the solution-aging-quenching heat treatment, a metallographic observation was taken, electrolytic etching was performed using an oxalic acid etchant, and the granular nitride was 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, reducing C content, increasing Cr content, adding N, and supplementing aging heat treatment element, such as Cr 2 N is the main aging precipitate, cr is increased by 4.6% by adding 0.6% of N according to the mass ratio of Cr/N of about 7.7/1, and the 1.4116 martensitic stainless steel is adjusted according to the composition design and considering the partial solid solution of the increased nitrogen.
Table 2. Chemical composition (wt.%) of high nitrogen austenitic stainless steel 35Cr20Mn16Mo2.5VN0.7
The object is to obtain a granular ageing compound Cr by reducing the Cr and N contents of the austenitic structure after the solution-ageing heat treatment, calculated as the martensitic region falling into the Sheffir phase diagram, and thus transformed into martensite during the subsequent cooling (after quenching) 2 N is distributed in the quenched martensite.
Step 2, metallurgical processing
1) Preparation of
Stainless steel pipes with the dimensions of phi 330/290 x 2000mm are cast, and the alloy compositions are designed as shown in Table 2.
And (3) batching: according to the alloy components and the alloy element yield in metallurgy and the cast tube weight, weighing pure iron, high-quality carbon structural steel, chromium nitride iron, pure manganese, ferromolybdenum and ferrovanadium, and controlling the content of non-alloying elements such as Si, P, S and the like in the range of the table 2.
Casting and casting machine preparation: adopting a horizontal centrifugal casting machine to roll and hang 2-3 mm of paint on the inner surface of a casting mould, and selecting the casting mould temperature to be 200 ℃ (the casting mould temperature ranges from 120 ℃ to 250 ℃), during casting.
2) Smelting
The technical procedure of smelting high-nitrogen austenitic stainless steel under normal pressure (patent publication No. CN101285148A; the name: a manufacturing method of high-nitrogen nickel-free austenitic stainless steel) is followed, and the method comprises the important operation parameters of charging sequence, smelting temperature, power and the like, and refers to patent implementation modes.
In the embodiment, the early-stage control target of the smelting temperature is 1550-1650 ℃, and the later stage reduces the smelting temperature and controls and adjusts the power according to the feeding reaction and nitrogen protection.
3) Centrifugal casting
The procedure of centrifugal casting of high nitrogen austenitic stainless steel pipes at normal pressure (patent publication No. CN 105108098B, name: process of centrifugal casting of high nitrogen austenitic stainless steel pipes at normal pressure) was followed.
When smelting is completed, the temperature of the high-nitrogen austenitic stainless steel molten metal is quickly adjusted to the casting temperature, and the casting step is connected within 90 seconds. The casting temperature selected in this example was 1530 ℃. In the embodiment, the single tube casting time is 16 seconds, and all molten metal is cast within 3 minutes.
The casting mold rotating speed is 530rpm in this example, and the rotating speed gradually decreases after the casting is finished; the temperature of the casting tube is controlled between 800 and 1000 ℃.
The steel pipe components are detected item by item according to the quality requirement of the steel pipe, and the steel pipe components are shown in table 3:
table 3 chemical composition (wt.%) of high nitrogen austenitic stainless steel 35Cr20Mn16Mo2.5VN0.7
The component detection result accords with the control target.
4) Cast tube dividing and flattening
Cleaning, removing the surface layer, the two end parts of the cast tube and the inner surface layer by adopting a proper machining method to obtain the steel tube with uniform components and the surface finish degree meeting the rolling requirement of the steel plate, wherein the size is phi 325/295 multiplied by 1900mm.
In the embodiment, the cast tube is subjected to circular cutting, the width of the steel ring is 200mm, and 1 straight slit is cut on the steel ring along the axial direction, so that the steel ring is mechanically flattened.
5) Rolling
The hot rolling is carried out at 1150-1220 ℃ for 10-30 minutes at each pass, the rolling reduction is 8-35% each time, the final rolling temperature is not lower than 980 ℃, and the plate with the thickness of 2.04-2.05 mm is obtained by rolling.
6) Cutting out
Cutting a cutter blank, and linearly cutting the cutter blank according to a given kitchen cutter.
7) Preliminary edge grinding
Grinding to make the blade part present the design shape of preliminary dimension, and reserving the final accurate grinding amount.
Step 3, heat treatment
And adopting a vacuum heat treatment furnace, wherein the highest use temperature reaches 1250 ℃, and carrying out heating and pressurized gas quenching operation in a programmable manner. The heat treatment process sequence and other more specific process parameters are as follows:
1) And solution heat treatment, wherein the solution temperature range is 1140 ℃, and the heat preservation time is 6h.
2) Aging heat treatment, after solution heat treatment, aging starts, three-stage temperature/time: 940 ℃/1h to 1020 ℃/1.5h to 800 ℃/4h.
3) Quenching heat treatment, pressurized nitrogen quenching, namely, pressurizing nitrogen and introducing the nitrogen into a cooling chamber to cool a cutter plate blank, wherein the pressurizing pressure and flow take the conventional operation parameters of the equipment.
4) Compared with the original martensitic stainless steel material, the alloy has higher alloy element content, so that the alloy has lower Ms point, and the martensitic stainless steel tool material needs higher martensitic transformation amount, so that the alloy is added with the cryogenic treatment after quenching. Placing into a deep cooling tank, preserving heat at-130deg.C for 24 hr, then placing into 60deg.C water, maintaining for 1 hr, taking out, blow-drying, and loading into a tempering heat treatment step.
5) After solid solution, aging, quenching heat treatment and deep cooling heat treatment, sampling and checking the granular structure characteristics, and meeting the structure requirement.
6) Tempering heat treatment, wherein the tempering temperature is 230 ℃, and the heat preservation time is 3 hours.
7) And (3) checking the heat treatment quality of the cutter, wherein the average hardness is 60.5HRC, the deviation is within 2HRC, and other checking results are slightly.
The high-hardness high-nitrogen martensitic stainless steel tool material and the preparation method thereof have the following advantages:
firstly, through the design of chemical components of stainless steel materials, the chemical components of an austenite structure in the stainless steel materials are adjusted, and the high-nitrogen austenitic stainless steel is subjected to solid 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 solid solution-aging-quenching heat treatment combination, provides a processing technology of a new tool material, generally applies the conventional solid solution-aging heat treatment to the strengthening aspect of nonferrous metal which can be strengthened by heat treatment after cooling or applies the conventional solid solution-aging heat treatment to precipitation hardening austenitic stainless steel, obtains a precipitated phase which is distributed in a structural phase matrix after solid solution treatment, and adopts a common strengthening or hardening method of steel or cast iron, heats and holds heat to obtain austenite and then cools at a speed higher than critical cooling speed, and austenite is transformed into martensite.
Thirdly, the martensitic stainless steel material prepared by the invention has the performance potential of ultra-high strength steel, and through the heat treatment technology of the invention, the nitride precipitated phase is adjusted to be dispersed and distributed in a matrix in a granular form during aging heat treatment, so that the dispersion strengthening high strength martensite is obtained, the toughness of the high hardness metal material is improved, and technical support is provided for manufacturing the high strength stainless steel with higher performance.
It will be understood that the invention has been described in terms of several embodiments, and that various changes and equivalents may be made to these features and embodiments 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 (10)
1. A preparation method of a high-hardness high-nitrogen martensitic stainless steel tool material is characterized in that,
step 1, the components are designed as follows: 0.023wt.% of C, 21.43wt.% of Cr, 16.87wt.% of Mn, 2.43wt.% of Mo, 0.26wt.% of Ni, 0.83wt.% of N, less than or equal to 0.012wt.% of P, less than or equal to 0.004wt.% of S, 0.27wt.% of Si, and the balance of Fe;
step 2, hot rolled sheet
The heating temperature of each pass is 1150 ℃, the heat preservation time is 10 min-1 h, and the finishing temperature is not lower than 950 ℃;
step 3, heat treatment
1) Solution heat treatment;
2) Aging heat treatment: after solution heat treatment, aging starts, wherein the aging heat treatment adopts three-section heating and three-section temperature/time: 930 ℃/1h to 1020 ℃/1.5h to 850 ℃/4h;
3) Quenching heat treatment: quenching by pressurized nitrogen;
4) And (5) tempering heat treatment.
2. The method for producing a high-hardness high-nitrogen martensitic stainless steel tool material according to claim 1, wherein in step 2, a strip material having a length-width thickness of 200mm x50 mm x 10mm is taken, hot rolled, reduced deformation per pass of hot rolling is 10 to 30%, rolled into a plate having a thickness of 2.5mm, cut into a tool blank, and ground into a primary blade portion.
3. The method for producing a high-hardness high-nitrogen martensitic stainless steel tool material according to claim 1, wherein in step 3, said heat treatment is performed by a vacuum heat treatment furnace;
for the solution heat treatment, the solution temperature is 1140 ℃, and the heat preservation time is 4 hours;
and for the tempering heat treatment, the tempering temperature is 170 ℃, and the heat preservation time is 2 hours.
4. A high hardness high nitrogen martensitic stainless steel tool material prepared by the method of any one of claims 1 to 3.
5. A preparation method of a high-hardness high-nitrogen martensitic stainless steel tool material is characterized in that,
step 1, the components are designed as follows: 0.35wt.% of C, 19.5wt.% of Cr, 16wt.% of Mn, 2.5wt.% of Mo, 0.15wt.% of V, 0.7wt.% of N, less than or equal to 0.02wt.% of P, less than or equal to 0.003wt.% of S, less than or equal to 0.5wt.% of Si, and the balance of Fe;
step 2, metallurgical processing
1) Batching;
2) Smelting;
3) Centrifugal casting;
4) Cast tube segmentation and flattening: performing ring cutting on the cast tube to obtain a steel ring, cutting 1 straight slit on the steel ring along the axial direction, and mechanically flattening;
5) Rolling: hot rolling, wherein the heating temperature of each pass is 1150-1220 ℃, the heat preservation time is 10-30 min, and the final rolling temperature is not lower than 980 ℃;
step 3, heat treatment
1) Solution heat treatment;
2) Aging heat treatment, namely aging is started after solution heat treatment, wherein the aging heat treatment adopts three-section heating and three-section temperature/time: 940 ℃/1h to 1020 ℃/1.5h to 800 ℃/4h;
3) Quenching heat treatment: quenching by pressurized nitrogen;
4) And (3) deep cooling and heating treatment: placing into a deep cooling tank, preserving heat at-130 ℃ for 24 hours, then placing into water at 60 ℃ for 1 hour, taking out and drying;
5) And (5) tempering heat treatment.
6. The method according to claim 5, wherein in step 2, pure iron, carbon structural steel, chromium nitride iron, pure manganese, ferromolybdenum, ferrovanadium are weighed according to the yield of the ingredients and the alloy elements in metallurgy and the cast tube weight for the ingredients.
7. The method for producing a martensitic stainless steel tool material with high hardness and high nitrogen as claimed in claim 5, wherein in said step 2, said centrifugal casting is performed by a horizontal centrifugal casting machine, the casting temperature is 1530 ℃, the casting mold temperature is 200 ℃, the casting mold rotation speed is 530rpm, and the casting tube outlet temperature is controlled between 800 ℃ and 1000 ℃.
8. The method for producing a high-hardness high-nitrogen martensitic stainless steel tool material according to claim 5, wherein in step 2, the rolling reduction is 8 to 35% each time, a plate having a thickness of 2.04 to 2.05mm is rolled, a tool blank is cut, and a preliminary blade portion is ground.
9. The method for producing a high-hardness high-nitrogen martensitic stainless steel tool material according to claim 5, wherein in step 3, said heat treatment is performed by a vacuum heat treatment furnace;
for the solution heat treatment, the solution temperature is 1140 ℃, and the heat preservation time is 6 hours;
and for the tempering heat treatment, the tempering temperature is 230 ℃, and the heat preservation time is 3 hours.
10. A high hardness high nitrogen martensitic stainless steel tool material prepared by the method of any one of claims 5 to 9.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| 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 |
| 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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| DE102005030413C5 (en) * | 2005-06-28 | 2009-12-10 | Technische Universität Bergakademie Freiberg | High-strength austenitic-martensitic lightweight steel and its use |
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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 |
| 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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