CN114395678A - Rapid solid solution and rapid cooling aging composite heat treatment method - Google Patents
Rapid solid solution and rapid cooling aging composite heat treatment method Download PDFInfo
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/78—Combined heat-treatments not provided for above
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D11/00—Process control or regulation for heat treatments
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/02—Hardening by precipitation
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
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Abstract
The invention provides a rapid solid solution and rapid cooling aging composite heat treatment method. The method comprises the following steps: a rapid solid solution treatment process and a rapid cooling and aging compound heat treatment process. The scheme of the invention can solve the special heat treatment technical problems of poor quality stability, low qualified product rate, low hardness, low mechanical property, poor consistency, long heating time, low efficiency, poor heating reliability of heat treatment equipment, low service life of high-temperature components, high cost and the like in the conventional heat treatment of austenitic stainless steel.
Description
Technical Field
The invention relates to the technical field of material heat treatment, in particular to a rapid solid solution and rapid cooling aging composite heat treatment method.
Background
The heat treatment principle of austenitic stainless steel is quite different from that of alloy structural steel: the alloy structural steel can generate high-temperature austenite structure transformation under the high-temperature condition, so that the alloy structural steel is very easy to greatly improve the hardness (or mechanical property) of the material by quenching and tempering heat treatment methods; however, austenitic stainless steel cannot generate high-temperature austenitic structure transformation (only can an alloying element strengthening phase be dissolved and precipitated) under high-temperature conditions, so that the austenitic stainless steel is extremely difficult to greatly improve the hardness (or mechanical property) of the material by a solid solution and aging heat treatment method.
The meaning of solution heat treatment is: heating austenitic stainless steel to a certain temperature and keeping the temperature, rapidly dissolving the excess phase, then rapidly cooling to obtain a supersaturated solid solution, obtaining a supersaturated strengthened solid solution, preparing a structure for precipitation hardening treatment, eliminating stress, and performing work hardening between forming procedures; the meaning of the aging heat treatment is: after the workpiece is subjected to solution treatment, the workpiece is kept at room temperature or over room temperature, a solute atom segregation area is formed in a supersaturated solid solution, and/or a heat treatment process is carried out, wherein the second phase particles are precipitated, dispersed, distributed and excessive, and are precipitated, so that the material is hardened.
The main strengthening phase of austenitic stainless steel is alloy carbide, and the weakening term is intermetallic compound (such as Fe)2W、Fe2Mo, CuO, FeS, FeO, MnS, etc.); the type, amount, size, shape, distribution, melting point, brittleness, hardness and the like of the strengthening phase of even the same metal element of different materials are different according to the adopted solid solution and aging heat treatment methods, and the more the alloy elements are, the more the difference isThe greater the anisotropy.
The relative stability of carbides formed by alloy elements such as nickel, chromium, tungsten, molybdenum, vanadium, titanium, aluminum, niobium and the like in steel is arranged from high to low in the sequence: hf, Zr, Ti, Ta, Nb, V, W, Mo, Cr, Mn, Fe, Co, Ni, whereby dissolution of the above-mentioned alloying elements in the steel results in limited dissolution of (Fe, Cr)3C、(Fe，Cr)7C3、(W，Mo)6C and (Fe, Cr, Ni, Mn, W, Mo)23C6Isoalloyed cementite and fully miscible Mn3C、Fe3C、(Fe，Mn)3C、VC、Ta、NbC、(V，Ta，Nb)C、Mo2C、W2C、Fe3W3C、Fe3Mo3C、Fe3(W，Mo)3C, and the like; when the solid solution temperature is more than or equal to 1000 ℃ and more than or equal to 1050 ℃, most carbide phases are respectively basically dissolved and completely dissolved (the aging process is correspondingly influenced); the most important point is that the heating temperature of the existing traditional mainstream austenitic stainless steel solid solution technology is the highest theoretical solid solution temperature, and ideal types and amounts of solid solution dissolved carbide strengthening phases and intermetallic compound strengthening phases cannot be obtained. Therefore, the rapid solid solution temperature is not a simple constant single-point temperature value, but a complex and variable multi-point temperature range.
The traditional mainstream austenitic stainless steel solution heat treatment method is a one-stage single-point fixed isothermal solution heat treatment method under the condition that the heating temperature (the highest theoretical solution temperature) and the time are the only conditions. The prior mainstream solution heat treatment method for austenitic stainless steel can only effectively improve the solution dissolving capacity, range, quality, efficiency and the like of one or a few alloy element strengthening phases in austenitic stainless steel, can not greatly improve the solution dissolving capacity, range, quality, efficiency and the like of most other alloy element strengthening phases, even if the solid solution time is increased, the effect is very small (after the time reaches a certain degree, the solid solution dissolving capacity, range, quality, efficiency and the like of the solid solution strengthening phase of one or a few alloy elements reach a limit saturation state), the solid solution dissolving capacity, range, quality, efficiency and the like of the solid solution strengthening phase of the alloy elements can only reach a very limited state, therefore, the conventional mainstream austenitic stainless steel solution heat treatment method is a one-stage fixed limited solution heat treatment method, and is a heat treatment method which is considered as a ' comprehensive non- ' overall ' in a biased manner.
The austenitic stainless steel mainly precipitates the extremely small needle-like carbide with larger grain size at the aging temperature of lower than 500 ℃ and mainly precipitates (Fe, Cr, Ni, Mn, W, Mo) at the temperature of 550-740 DEG C23C6Carbide of the same composite alloy is mainly precipitated (Fe, Cr, Ni, Mn, W, Mo) at 625-670 deg.C23C6The carbide of the compound alloy is uniformly distributed in the crystal, the carbide begins to grow sharply at the temperature of about 700 ℃, and is mainly precipitated at the temperature of 800 ℃ (Fe, Cr, Ni, Mn, W, Mo)7C6When the temperature of the composite alloy carbide is higher than 900 ℃, the precipitation amount of the precipitated lamellar carbide is increased to influence the metal hardness and the mechanical property; the most important point is that the aging heating temperature of the traditional mainstream austenitic stainless steel is the highest aging theoretical temperature, and the aging precipitation carbide strengthening phase and the intermetallic compound strengthening phase with ideal type and quantity cannot be obtained. Therefore, the aging temperature is not a simple constant single-point temperature value, but a complex and variable multi-point temperature range.
The traditional mainstream austenitic stainless steel aging heat treatment method is a one-stage single-point fixed isothermal aging heat treatment method under the condition that the heating temperature (the highest aging theoretical temperature) and the time are the only conditions. The existing traditional mainstream austenitic stainless steel aging heat treatment method can only effectively improve the aging precipitation capability, range, quality, efficiency and the like of one or a few alloy element strengthening phases in austenitic stainless steel, can not effectively improve the aging precipitation capability, range, quality, efficiency and the like of most other alloy element strengthening phases, even if the aging time is increased, the effect is very small (after the time reaches a certain degree, the aging precipitation capacity, the range, the quality, the efficiency and the like of the solid solution strengthening phase or the minor alloy elements can reach a limit saturation state), the alloy element strengthening phase can only reach very limited aging precipitation capacity, range, quality, efficiency and the like, therefore, the conventional main flow austenitic stainless steel aging heat treatment method is a one-stage single-point fixed limited aging heat treatment method, and is a heat treatment method which is considered as a whole in a non-overall manner in a biased approximation manner.
The heat treatment manufacturability of the austenitic stainless steel is directly influenced by the following complex factors, particularly different hot working methods such as smelting, steel rolling, forging, heat treatment and the like of raw materials in steel plants and manufacturing plants: the comprehensive actions of the raw material quality, chemical composition (such as the characteristics and content of alloy elements such as C, Ti, Ta, Nb, V, W, Mo, Cr, Mn, Fe, Co, Ni, Cu) and the specification, batch state, hot working state and original heat treatment delivery state, including the hot working state parameters such as the starting and finishing temperature, heating time, operating time and cooling medium of the raw material forging, hot rolling or smelting related to the furnace batch, and the hot treatment delivery state including the original annealing, solution, aging, quenching and tempering) related to the hot working such as the forging and heat treatment related to the manufacturing plant, the forging deformation degree, the starting and finishing temperature, the heating time, the cooling medium, the type and condition of the heating equipment, the field environment temperature and other hot working methods directly influence the heat treatment manufacturability of the austenitic stainless steel.
Based on the above complex influence factors, the conventional mainstream austenitic stainless steel solid solution and aging heat treatment technology is difficult to solve the following special heat treatment technical theory and practice problems of 'one long one high three difference five low':
firstly, the heat treatment quality stability is poor, the qualified product rate is low: when the heat treatment quality stability is good, the primary heat treatment qualified product rate can only reach 99 percent (especially, the hardness value and the mechanical property can only reach the lower limit value even if the primary heat treatment qualified product rate is qualified); when the heat treatment quality stability is poor, the primary heat treatment yield is highly likely to fail by 100%.
Secondly, the hardness (or mechanical property) of the heat treatment is low and the consistency is poor: the solid solution and aging heat treatment can easily reach the middle and low hardness value of 20.0 HRC-26.5 HRC, can hardly reach the middle and high hardness value of 27.0 HRC-28.0 HRC, can hardly reach the high hardness value of 28.5 HRC-32.0 HRC, and even can generate the paradoxical phenomenon that the Brinell hardness is qualified and the Rockwell hardness is unqualified.
Thirdly, the heating time of the heat treatment is long, and the efficiency is low: the heating time under the highest temperature conditions of solid solution and aging is long, and the requirement of quick production is difficult to realize; passively increasing the times of heat treatment reworking and repairing to solve the problem of unqualified solid solution and aging heat treatment.
Fourthly, the service life of high-temperature components of the heating equipment is low: the high-temperature components of the heating equipment have long retention time under the highest temperature conditions of solid solution and aging and bear large high-temperature load, so that the service life is short.
Fifthly, the reliability of heat treatment heating is poor: the traditional mainstream austenitic stainless steel box type resistance furnace equipment (only has the functions of conduction and radiation heat transfer) has poor heating reliability, and the heating reliability of the traditional mainstream austenitic stainless steel box type resistance furnace equipment is far lower than that of heating equipment (simultaneously has the functions of conduction, radiation and convection heat transfer) such as a fluidized bed furnace, a salt bath furnace, a vacuum furnace and the like.
Sixthly, the heat treatment cost is high: the combination of the above disadvantages ultimately results in high heat treatment costs.
In summary, the conventional mainstream solid solution and aging heat treatment methods for austenitic stainless steel cannot solve the problems of poor heat treatment quality stability, low qualified product rate, low hardness (or low mechanical properties) and consistency, long heating time, low efficiency, poor heating reliability of heat treatment equipment, low service life of high-temperature components and parts, and high cost of the conventional mainstream solid solution and aging heat treatment methods for austenitic stainless steel.
Disclosure of Invention
The invention aims to solve the technical problem of providing a rapid solid solution and rapid cooling aging composite heat treatment method. The method can solve the problems of poor quality stability, low qualified product rate, low hardness (or low mechanical property) and consistency, long heating time, low efficiency, poor heating reliability of heat treatment equipment, low service life of high-temperature components, high cost and the like of the conventional mainstream austenitic stainless steel solid solution and aging heat treatment.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a rapid solid solution and rapid cooling aging composite heat treatment method comprises the following steps:
performing a rapid solution heat treatment process, the rapid solution heat treatment process comprising: heating and heat preservation are carried out when the temperature of the austenitic stainless steel is raised from room temperature to the maximum temperature of rapid solid solution within a specified time in a heating furnace, heating and heat preservation are carried out when the temperature of the austenitic stainless steel is continuously reduced from the maximum temperature of rapid solid solution to the intermediate temperature of rapid solid solution, heating and heat preservation are carried out when the temperature of the austenitic stainless steel is continuously reduced from the intermediate temperature of rapid solid solution to the minimum temperature of rapid solid solution, and finally cooling is carried out when the temperature of the austenitic stainless steel is reduced from the minimum temperature of rapid solid solution to the maximum temperature of rapid temperature reduction and aging by continuously adopting a specific cooling mode;
after the rapid solid solution heat treatment process is finished, the rapid cooling aging composite heat treatment is continuously carried out, wherein the rapid cooling aging composite heat treatment process comprises the following steps: heating and heat preservation are carried out on the austenitic stainless steel at the highest theoretical temperature of rapid cooling and aging within a specified time in a heating furnace, heating and heat preservation are carried out when the austenitic stainless steel is continuously cooled from the highest theoretical temperature of rapid cooling and aging to the intermediate aging temperature of rapid cooling and aging, heating and heat preservation are carried out when the austenitic stainless steel is continuously cooled from the intermediate aging temperature of rapid cooling and aging to the lowest temperature of rapid cooling and aging, and cooling is carried out when the austenitic stainless steel is continuously cooled from the lowest temperature of rapid cooling and aging to room temperature by adopting a specific cooling mode.
Optionally, the multi-stage temperature interval of the 3-stage rapid solution heat treatment refers to: and a 3-stage temperature reduction and heating temperature interval which starts from the stage of raising the temperature from room temperature to the maximum solid solution temperature Tfmax, then lowers the temperature to the intermediate solid solution temperature Tsfm, and finally lowers the temperature to the minimum solid solution temperature Tfmin.
Optionally, the final cooling mode of the rapid solution heat treatment is as follows: opening the furnace door or adopting other cooling modes to quickly cool the workpiece without discharging the workpiece out of the furnace.
Alternatively, the rapid cooling aging heat treatment method is a rapid cooling aging heat treatment method performed continuously in a multi-stage heating temperature zone, a multi-stage heating sequence, a multi-stage heating time, a multi-stage heating frequency, a specific cooling method, and the like after the rapid solution heat treatment is completed.
Optionally, when the rapid cooling aging time is performed according to an equal time method, the total rapid cooling aging heating time τ of the equal time methodafNHeating time tau in each stage of aging corresponding to heating temperature intervals of 1 st, 2 nd, 3 rd, … …, and nth stages of heatingafnThe mathematical relationship of (a) is:
τafN＝∑τafn＝∑τafN/N
in the formula tauafNThe total time of rapid cooling, aging and heating is equal time method, min or h; tau isafnHeating temperature intervals of the 1 st stage, the 2 nd stage, the 3 rd stage, … … and the nth stage for rapid cooling are corresponding to heating time of each stage of aging, min/time or h/time, and are respectively tauaf1、τaf2、τaf3、τaf4、τaf5、τaf6、τaf7，τaf1＝τaf2＝τaf3＝τaf4＝τaf5＝τaf6＝τaf7(ii) a N is the total number of stages of rapid cooling and aging heating, and is more than or equal to 3 and less than or equal to 7; n is the number of the nth stage of rapid cooling and aging heating, and n is more than or equal to 1 and less than or equal to 7.
Optionally, when the rapid cooling aging time is performed according to an increasing time method, the total rapid cooling aging heating time tau of the increasing time methodafNHeating time tau in each stage of aging corresponding to heating temperature intervals of 1 st, 2 nd, 3 rd, … …, and nth stages of heatingafnThe mathematical relationship of (a) is:
τafN＝∑τafn＝∑[τaf1+(n–1)τaf0]
in the formula tauafNThe total time of rapid cooling, aging and heating is an increasing time method, and is min or h; n is the total number of stages of rapid cooling and aging heating, and is more than or equal to 3 and less than or equal to 7; tau isafnHeating time of each stage of rapid cooling and aging is min/time or h/time, which are tau respectivelyaf1、τaf2、τaf3、τaf4、τaf5、τaf6Or τaf7，τaf1＞τaf2＞τaf3＞τaf4＞τaf5＞τaf6Or > tauaf7(ii) a n is the number of the nth stage of rapid cooling and aging heating, and n is more than or equal to 1 and less than or equal to 7; tau isaf1Heating time in a first stage of rapid cooling and aging for min/time or h/time; tau isaf0The heating time is increased by grade difference, min/time or h/time, for rapid cooling and aging, and the values are the same and unchangeable specific values.
Optionally, the rapid cooling aging heat treatment method includes the following steps: step 1, start heating process S1: after the rapid solution heat treatment is finished, continuously heating and preserving the austenitic stainless steel within the range of the maximum temperature Tafmax of rapid cooling and aging in a heating furnace within a specified time; step 2, intermediate heating process S2: continuously cooling the austenitic stainless steel in the heating furnace from the cooling and ageing highest temperature range Tafmax to n-2 rapid cooling and ageing middle ageing temperature Tafm ranges in sequence, and heating and preserving heat in the time specified by the process in sequence; and (N-1), finishing the heating process S (N-1): then continuously cooling the austenitic stainless steel in the heating furnace from the range of the rapid cooling aging intermediate aging temperature Tafm to the range of the rapid cooling aging minimum temperature Tafmin, and heating and preserving heat within the time specified by the process; step N, final cooling process SN: and continuously discharging the austenitic stainless steel out of the furnace, and cooling the austenitic stainless steel in the air at room temperature at the minimum rapid aging temperature Tafmin.
Optionally, the 3-stage rapid solution heat treatment process comprises: the first stage is as follows: heating the austenitic stainless steel from room temperature to a rapid solid solution maximum temperature Tsfmax in a heating furnace; and a second stage: continuously cooling the austenitic stainless steel from the maximum rapid solid solution temperature Tfmax to the intermediate solid solution temperature Tsfm; and a third stage: continuously cooling the austenitic stainless steel from the rapid solid solution intermediate solid solution temperature Tsfm to the rapid solid solution minimum temperature Tsfmin; and finally, continuously adopting a furnace door opening or other cooling modes to cool the austenitic stainless steel from the minimum rapid solid solution temperature Tsfmin to the maximum rapid cooling aging temperature Tafmax in the heating furnace.
Optionally, the 4-stage rapid solution heat treatment process comprises: the first stage is as follows: heating the austenitic stainless steel from room temperature to a rapid solid solution maximum temperature Tsfmax in a heating furnace; and a second stage: continuously cooling the austenitic stainless steel from the maximum rapid solid solution temperature Tfmax to the first stage rapid solid solution temperature Tsfm1(ii) a And a third stage: continuously dissolving the austenitic stainless steel from the rapid solid solution intermediate solid solution first stage temperature Tsfm1Cooling to the second stage temperature Tsfm of rapid solid solution and intermediate solid solution2(ii) a A fourth stage: continuously dissolving the austenitic stainless steel from the rapid solid solution intermediate solid solution second stage temperature Tsfm2Cooling to the minimum temperature Tsfmin for rapid solid solution; finally, continuously adopting a furnace door opening or other cooling modes to cool the austenitic stainless steel from the minimum rapid solid solution temperature Tsfmin to the maximum rapid cooling aging temperature Tafmax in the heating furnace; .
Optionally, the rapid cooling and aging heating temperature interval is as follows: n stages which start from the aging highest heating stage Tafmax, sequentially pass through n-2 aging intermediate cooling and heating stages Tafm and finally end at the aging lowest cooling and heating stage Tafmin; and (5) cooling and heating the temperature range.
The scheme of the invention at least comprises the following beneficial effects:
(1) the rapid solid solution and rapid cooling aging composite heat treatment method has the advantages of technical feasibility, process adaptability, quality reliability, economic rationality and use safety, and can fundamentally solve the specific heat treatment technical theory and practical problems of poor quality stability, low qualified product rate, low hardness (or low mechanical property) and consistency, long heating time, low efficiency, poor heating reliability of heat treatment equipment, low service life of high-temperature components, high cost and the like of 'one long one high three poor five low'.
(2) The rapid solid solution and rapid cooling aging composite heat treatment method can effectively improve the solid solution dissolution and aging precipitation capacity, range, quality, efficiency and the like of all alloy element different types of strengthening phases in austenitic stainless steel.
(3) According to the rapid solid solution and rapid cooling aging composite heat treatment method, the final heat treatment hardness qualified rate is up to 100%.
(4) The rapid solid solution and rapid cooling aging composite heat treatment method can effectively obtain the range of the optimized heat treatment hardness (or mechanical property) with the upper limit distribution and the tolerance less than or equal to 3.0 HRC.
(5) The rapid solid solution and rapid cooling aging composite heat treatment method can effectively improve the heat treatment efficiency (such as the maximization of furnace charging amount and the requirement of mass production can be realized, the total time of solid solution and aging heat preservation is reduced, and the like).
Drawings
FIG. 1 is a schematic view of a prior art austenitic stainless steel involved in the present invention showing a solution and aging heat treatment process (including heating, holding, cooling processes and time used for solution and aging heat treatments, etc.) consisting of 1-stage 1-solution treatment in total at the highest solution temperature and 1-stage 1-aging treatment in total at the highest aging temperature;
FIG. 2 is a schematic flow chart of the rapid solid solution and rapid cooling aging composite heat treatment method of the invention;
FIG. 3 is a schematic diagram of the combined rapid solid solution and rapid cooling aging heat treatment process (including the heating, heat preservation, cooling processes and the time used for rapid solid solution and rapid aging heat treatment) of austenitic stainless steel of the present invention, which consists of 1 time of rapid solid solution in 3 stages in the equal time method under the condition of rapid solid solution temperature and 1 time of rapid cooling aging in 4 stages in the equal time method under the condition of rapid aging temperature.
Detailed Description
In order to make the objects, contents and advantages of the present invention clearer, the following description will explain in detail a specific embodiment of the present invention with reference to the accompanying drawings.
In the present invention, the rapid solid solution and rapid cooling aging composite heat treatment method described in this embodiment includes "a rapid solid solution heat treatment method" and "a rapid cooling aging heat treatment method" which continuously use composite compositions, "a rapid solid solution and rapid cooling aging composite heat treatment method"; the method comprises the following steps: firstly, carrying out the first part of rapid solution heat treatment, and finally, continuously carrying out the second part of rapid cooling aging heat treatment. The first partial rapid solution heat treatment process: by means of the first partial rapid solution heat treatment process: the rapid solution heat treatment process comprises the steps of heating and heat preservation in a heating furnace within a specified time from room temperature to the maximum rapid solution temperature, heating and heat preservation in a process of continuously cooling the austenitic stainless steel from the maximum rapid solution temperature to the intermediate rapid solution temperature, heating and heat preservation in a process of continuously cooling the austenitic stainless steel from the intermediate rapid solution temperature to the minimum rapid solution temperature, cooling in a process of continuously cooling the austenitic stainless steel out of the furnace from the minimum rapid solution temperature to the maximum rapid cooling aging temperature in a specific cooling mode, and the like; and the second part is subjected to rapid cooling and aging heat treatment: and after the first part of rapid solution heat treatment is finished, the second part of rapid cooling aging heat treatment is continued, and the rapid cooling aging heat treatment process depends on a rapid cooling aging heat treatment process, which comprises a plurality of process steps of heating and heat preservation of the austenitic stainless steel at the maximum theoretical temperature of rapid cooling aging in a heating furnace within a specified time, heating and heat preservation of the austenitic stainless steel from the maximum theoretical temperature of rapid cooling aging to the intermediate aging temperature of rapid cooling aging, heating and heat preservation of the austenitic stainless steel from the intermediate aging temperature of rapid cooling aging to the minimum temperature of rapid cooling aging, cooling of the austenitic stainless steel from the minimum temperature of rapid cooling aging to room temperature by adopting a specific cooling mode, and the like.
In the present invention, the first partial rapid solution heat treatment method is a first partial solution heat treatment method performed under conditions such as a multistage heating temperature range, a multistage heating sequence, a multistage heating time, a multistage heating frequency, a specific cooling method, and the like.
In the present invention, the total number of solid solutions of the first rapid solid solution heat treatment is 1.
In the present invention, the first partial rapid solution heat treatment method is divided into a 3-stage rapid solution heat treatment method or a 4-stage rapid solution heat treatment method.
In the present invention, the multi-stage temperature interval of the first part 3-stage rapid solution heat treatment means: and a 3-stage temperature reduction and heating temperature interval which starts from the stage of raising the temperature from room temperature to the maximum solid solution temperature Tfmax, then lowers the temperature to the intermediate solid solution temperature Tsfm, and finally lowers the temperature to the minimum solid solution temperature Tfmin.
In the present invention, the multi-stage temperature interval of the first part 4-stage rapid solution heat treatment means: starting from the stage of raising the temperature from room temperature to the maximum solid solution temperature Tfmax, and then sequentially lowering the temperature to the first stage temperature Tsfm of intermediate solid solution1And a second stage temperature of intermediate solid solution Tsfm2And finally cooling to a 4-stage cooling and heating temperature interval ending at the stage of the lowest solid solution temperature Tsfmin.
In the present invention, the first portion of the rapid solution heat treatment has a multi-stage temperature interval, and the number of stages of the rapid solution heating temperature interval is moderate: the solid solution heating temperature range is narrow (the effective temperature range is between 100 ℃ and 200 ℃), for example, the solid solution capacity of the stage number of the solid solution heating temperature interval is 1 (the existing solid solution technology), the solid solution capacity of the stage 2 is better, and the solid solution capacity of the stage more than or equal to 6 is excessive, so that the embodiment sets the first part of the solid solution temperature interval to be 3 stages or 4 stages, can greatly improve the solid solution capacity, the quality, the efficiency and the like, and particularly can greatly increase the solid solution strengthening phase, reduce or inhibit the solid solution weakening phase, reduce the high-temperature heating time, improve the efficiency, prolong the service life of high-temperature components of heating equipment and the like.
In the invention, the mathematical relation between the minimum heating temperature Tsfmin for rapid solid solution and the minimum theoretical heating temperature Tsftmin for solid solution is as follows: tsfmin is Tsftmin;
tsfmin is the lowest heating temperature for rapid solid solution, DEG C; tsftmin is the minimum theoretical heating temperature for rapid solution at, DEG C.
In the invention, the mathematical relation between the maximum heating temperature for rapid solid solution Tsfmax and the maximum theoretical heating temperature for solid solution Tsfmax is as follows: tsfmax is Tsftmax;
wherein Tsfmax is the maximum heating temperature of rapid solid solution, DEG C; tsfmax is the maximum theoretical heating temperature for rapid solution at, DEG C.
In the invention, the mathematical relation between the intermediate solid solution heating temperature Tsfm in the 3-stage rapid solid solution, the maximum solid solution heating temperature Tfmax and the minimum solid solution heating temperature Tfmin is as follows:
Tsfm＝(Tsfmax+Tsfmin)/2
wherein Tsfm is the heating temperature of the intermediate solid solution stage of rapid solid solution, DEG C, and is also the heating temperature of the second stage of rapid solid solution; tsfmax is the maximum heating temperature of rapid solid solution, DEG C, and is also the heating temperature at the beginning stage of rapid solid solution; tsfmin is the minimum heating temperature for rapid solid solution, DEG C, and is also the heating temperature at the final stage of rapid solid solution.
In the invention, the heating temperature Tsfm of the first stage of 4-stage fast solid solution intermediate solid solution1And intermediate solid solution second stage heating temperature Tsfm2The mathematical relations with the solid solution maximum heating temperature Tfmax and the solid solution minimum heating temperature Tfmin are respectively as follows:
Tsfm1＝2/3(Tsfmax–Tsfmin)+Tsfmin
Tsfm2＝1/3(Tsfmax–Tsfmin)+Tsfmin
in the formula Tsfm1The heating temperature of the first stage of rapid solid solution intermediate solution is the heating temperature of the second stage of rapid solid solution, and the temperature is the heating temperature of the second stage of rapid solid solution; tsfm2The heating temperature of the second stage of rapid solid solution intermediate solid solution is lower than the heating temperature of the third stage of rapid solid solution; tsfmax is the maximum heating temperature of rapid solid solution, DEG C, and is also the heating temperature at the beginning stage of rapid solid solution; tsfmin is the minimum heating temperature for rapid solid solution, DEG C,and also the heating temperature of the final stage of rapid solid solution.
In the present invention, the first partial rapid solid solution multi-stage time zone and the rapid solid solution multi-stage temperature zone are also set to 3 stages or 4 stages in correspondence; the rapid solid solution time is neither too long nor too short: if the solution is too long, the rate of dissolution exceeds the limit of dissolution of the strengthening phase, and if the solution is too short, the solution is not rapidly dissolved.
In the present invention, when the rapid solid-solution time is performed by the uniform time method, the total time τ of rapid solid-solution heating in multiple stages of the uniform time methodsfNAnd heating time tau of each stage of rapid solid solutionsfnThe mathematical relationship of (a) is:
τsfN＝∑τsfn＝∑τsfN/N
in the formula tausfNThe total time of multi-stage rapid solid solution heating is equal time method, min or h; tau issfnHeating time of each stage for rapid solution, min or h, when the solution is divided into tausf1、τsf2、τsf3At 3 stages in time, τsf1＝τsf2＝τsf3When dividing τsf1、τsf2、τsf3、τsf4At 4 stages in time, τsf1＝τsf2＝τsf3＝τsf4(ii) a N is the total stage number of rapid solid solution heating, and N is 3 or 4; n is the number of the n stages of the rapid solid solution heating, and n is 1, 2, 3 or 4.
In the present invention, when the rapid solid-solution time is conducted in accordance with the incremental time method, the total time τ of the rapid solid-solution heating in multiple stages of the incremental time methodsfNAnd heating time tau of each stage of rapid solid solutionsfnThe mathematical relationship of (a) is:
τsfN＝∑τsfn＝∑[τsf1+(n–1)τsf0]
in the formula tausfNThe total time of multi-stage rapid solid solution heating is an incremental time method, and is min or h; n is the total stage number of rapid solid solution heating, and N is 3 or 4; tau issfnHeating time of each stage for rapid solution, min or h, is divided into tausf1、τsf2、τsf3Or τsf4，τsf1＞τsf2＞τsf3Or > tausf4(ii) a n is the number of the nth stage of rapid solid solution heating, and n is 1, 2, 3 or 4; tau issf1Heating time for the first stage of rapid solid solution is min or h; tau issf0The time step difference, min or h, is decreased for rapid solid solution heating, and is the same and unchanging specific numerical value.
In the present invention, when the rapid solid-solution time is performed in a decreasing time method, the total time τ of the multi-stage rapid solid-solution heating of the decreasing time methodsfNAnd heating time tau of each stage of rapid solid solutionsfnThe mathematical relationship of (a) is:
τsfN＝∑τsfn＝∑[τsf1–(n–1)τsf0]
in the formula tausfNThe total time of multi-stage rapid solid solution heating is a decreasing time method, and is min or h; n is the total stage number of rapid solid solution heating, and N is 3 or 4; tau issfnHeating time of each stage for rapid solution, min or h, is divided into tausf1、τsf2、τsf3Or τsf4，τsf1＜τsf2＜τsf3Or < tausf4；τsf1Heating time for the first stage of rapid solid solution is min or h; n is the number of the nth stage of rapid solid solution heating, and n is 1, 2, 3 or 4; tau issf0The time step difference, min or h, is decreased for rapid solid solution heating, and is the same and unchanging specific numerical value.
In the present invention, the first rapid solution heat treatment final cooling method is: opening the furnace door or adopting other cooling modes to quickly cool the workpiece without discharging the workpiece out of the furnace.
In the invention, the first part 3-stage rapid solution heat treatment process comprises the following steps: the first stage is as follows: heating the austenitic stainless steel from room temperature to a rapid solid solution maximum temperature Tsfmax in a heating furnace (heating and heat preservation within the time specified by the process); and a second stage: continuously cooling the austenitic stainless steel from the maximum rapid solid solution temperature Tfmax to the intermediate solid solution temperature Tsfm (and heating and preserving heat within the time specified by the process); and a third stage: continuously cooling the austenitic stainless steel from the rapid solid solution intermediate solid solution temperature Tsfm to the rapid solid solution minimum temperature Tsfmin (and heating and preserving heat within the time specified by the process); and finally, continuously adopting a furnace door opening or other cooling modes to cool the austenitic stainless steel from the minimum rapid solid solution temperature Tsfmin to the maximum rapid cooling aging temperature Tafmax in the heating furnace (and heating and preserving heat within the time specified by the process).
In the invention, the first part 4-stage rapid solution heat treatment process comprises the following steps: the first stage is as follows: heating the austenitic stainless steel from room temperature to a rapid solid solution maximum temperature Tsfmax in a heating furnace (heating and heat preservation within the time specified by the process); and a second stage: continuously cooling the austenitic stainless steel from the maximum rapid solid solution temperature Tfmax to the first stage rapid solid solution temperature Tsfm1(and heating and holding the temperature within the time specified by the process); and a third stage: continuously dissolving the austenitic stainless steel from the rapid solid solution intermediate solid solution first stage temperature Tsfm1Cooling to the second stage temperature Tsfm of rapid solid solution and intermediate solid solution2(and heating and holding the temperature within the time specified by the process); a fourth stage: continuously dissolving the austenitic stainless steel from the rapid solid solution intermediate solid solution second stage temperature Tsfm2Cooling to the minimum temperature Tsfmin for rapid solid solution (and heating and preserving heat within the time specified by the process); and finally, continuously adopting a furnace door opening or other cooling modes to cool the austenitic stainless steel from the minimum rapid solid solution temperature Tsfmin to the maximum rapid cooling aging temperature Tafmax in the heating furnace (and heating and preserving heat within the time specified by the process).
In the present invention, the second rapid thermal aging treatment method is a rapid thermal aging treatment method performed under conditions such as a multistage heating temperature zone, a multistage heating sequence, a multistage heating time, a multistage heating frequency, a specific cooling method, and the like, continuously after the first rapid solution heat treatment is completed.
In the invention, the total aging times of the second part rapid cooling aging heat treatment is 1 time.
In the invention, the temperature interval of rapid cooling and aging heating is as follows: and (3) cooling and heating temperature intervals of n stages (n is more than or equal to 3 and less than or equal to 7, namely n is 3, 4, 5, 6 or 7) starting from the highest aging heating stage Tafmax, sequentially passing through n-2 intermediate aging cooling and heating stages Tafm and finally ending at the lowest aging cooling and heating stage Tafmin.
In the invention, because the aging temperature range of the austenitic stainless steel is narrow (between 170 ℃ and 230 ℃), the rapid cooling aging temperature range is neither too small nor too large: the aging temperature range of the 1 stage belongs to the prior art (no temperature difference), and the aging capability is too poor; in the aging temperature range of 2 stages (the temperature difference is large), the aging capability is increased but is still insufficient; when the temperature is within the aging temperature range of not less than 8 stages (the temperature difference is too small), the aging capability is excessive (in fact, a certain aging capability is still provided in each temperature rise or decrease transition stage where the temperature difference is too small). Therefore, the rapid cooling aging temperature interval is set to be 3-7, namely n is 3, 4, 5, 6 or 7 stages, which is more beneficial to improving the aging capacity, range, quality, efficiency and the like.
In the invention, the mathematical relation between the rapid cooling and aging minimum heating temperature Tafmin and the aging minimum theoretical heating temperature Taftmin is as follows: tafmin ═ Taftmin;
in the formula, Tafmin is the lowest heating temperature of rapid cooling and aging at DEG C; taftmin is the minimum theoretical heating temperature of aging, DEG C.
In the invention, the mathematical relation between the maximum heating temperature Tafmax of rapid cooling and aging and the maximum theoretical heating temperature Taftmax of aging is as follows: tafmax is Taftmax;
in the formula, Tafmin is the highest heating temperature of rapid cooling and aging at DEG C; taftmin is the maximum theoretical heating temperature of aging at deg.C.
In the invention, the mathematical relation between the intermediate heating temperature Tafm and the aging minimum heating temperature Tafmin and the aging maximum heating temperature Tafmax in each stage of rapid cooling and aging is as follows:
Tafm＝Tafmin+ni(Tafmax–Tafmin)/(n–1)
in the formula, Tafm is the intermediate heating temperature and DEG C of each stage of rapid cooling and aging, and is also the cooling and agingStage-specific temperatures from stage 2 to stage 2 last; tafmin is the lowest heating temperature of rapid cooling and aging at DEG C, and is also the heating temperature of the last stage of cooling and aging; n isiThe specific nth heating temperature interval from high to low for the 2 nd to the 2 nd last stagesiNumber of stages, n being not less than 1iN is less than or equal to 5i1, 2, 3, 4 or 5; tafmax is the maximum heating temperature of aging at DEG C, and is also the heating temperature of the 1 st stage of cooling aging; (Tafmax-Tafmin)/n is a specific value of decreasing temperature and decreasing temperature difference, and DEG C is unchanged; n is the total number of stages starting from the aging maximum heating temperature Tafmax and ending at the aging minimum heating temperature Tafmin, n is more than or equal to 3 and less than or equal to 7, namely n is 3, 4, 5, 6 or 7.
In the invention, the total time of the cooling and aging can be neither too short nor too long: if the time is too short, the alloy element strengthening phase can only reach limited aging precipitation capacity, quality, efficiency and the like; if the time length is too long, the aging capability, quality, efficiency and the like of the alloy element strengthening phase can reach a saturated or limit state.
In the present invention, when the rapid cooling aging time is performed by the equal time method, the total rapid cooling aging heating time τ by the equal time methodafNHeating time tau in each stage of aging corresponding to heating temperature intervals of 1 st, 2 nd, 3 rd, … …, and nth stages of heatingafnIs a mathematical relationship ofafN＝∑τafn＝∑τafN/N；
In the formula tauafNThe total time of rapid cooling, aging and heating is equal time method, min or h; tau isafnHeating temperature intervals of the 1 st stage, the 2 nd stage, the 3 rd stage, … … and the nth stage for rapid cooling are corresponding to heating time of each stage of aging, min/time or h/time, and are respectively tauaf1、τaf2、τaf3、τaf4、τaf5、τaf6Or τaf7，τaf1＝τaf2＝τaf3＝τaf4＝τaf5＝τaf6Or τaf7(ii) a N is the total number of stages of rapid cooling and aging heating, and N is more than or equal to 3 and less than or equal to 7 (namely N3, 4, 5, 6 or 7); n is the number of the nth stage of rapid cooling and aging heating, and n is more than or equal to 1 and less than or equal to 7 (namely n is 1, 2, 3, 4, 5, 6 or 7).
In the invention, when the rapid cooling aging time is carried out according to the increasing time method, the total time tau of rapid cooling aging heating of the increasing time methodafNHeating time tau in each stage of aging corresponding to heating temperature intervals of 1 st, 2 nd, 3 rd, … …, and nth stages of heatingafnThe mathematical relationship of (a) is: tau isafN＝∑τafn＝∑[τaf1+(n–1)τaf0]
In the formula tauafNThe total time of rapid cooling, aging and heating is an increasing time method, and is min or h; n is the total number of stages of rapid cooling and aging heating, and is more than or equal to 3 and less than or equal to 7 (namely N is 3, 4, 5, 6 or 7); tau isafnHeating time of each stage of rapid cooling and aging is min/time or h/time, which are tau respectivelyaf1、τaf2、τaf3、τaf4、τaf5、τaf6Or τaf7，τaf1＞τaf2＞τaf3＞τaf4＞τaf5＞τaf6Or > tauaf7(ii) a n is the number of the nth stage of rapid cooling and aging heating, and n is more than or equal to 1 and less than or equal to 7 (namely n is 1, 2, 3, 4, 5, 6 or 7); tau isaf1Heating time in a first stage of rapid cooling and aging for min/time or h/time; tau isaf0The heating time is increased by grade difference, min/time or h/time, for rapid cooling and aging, and the values are the same and unchangeable specific values.
In the invention, when the rapid cooling aging time is carried out according to a decreasing time method, the total time tau of rapid cooling aging heating of the decreasing time methodafNHeating time tau in each stage of aging corresponding to heating temperature intervals of 1 st, 2 nd, 3 rd, … …, and nth stages of heatingafnThe mathematical relationship of (a) is: tau isafN＝∑τafn＝∑[τaf1–(n–1)τaf0]；
In the formula tausfNThe total time of rapid cooling, aging and heating is a decreasing time method, and is min/time or h/time; n is the total number of stages of rapid cooling and aging heatingN is 3 ≦ N ≦ 7 (i.e., N — 3, 4, 5, 6, or 7); tau isafnHeating temperature intervals of the 1 st stage, the 2 nd stage, the 3 rd stage, … … and the nth stage for rapid cooling are corresponding to heating time of each stage of aging, min/time or h/time, and are respectively tauaf1、τaf2、τaf3、τaf4、τaf5、τaf6Or τaf7，τaf1＜τaf2＜τaf3＜τaf4＜τaf5＜τaf6Or < tauaf7(ii) a n is the number of the nth stage of rapid cooling and aging heating, and n is more than or equal to 1 and less than or equal to 7 (namely n is 1, 2, 3, 4, 5, 6 or 7); tau isaf1Heating for a first stage of rapid cooling and aging for min/time or h/time; tau isaf0The time level difference is decreased for the rapid cooling and the aging heating, and the time level difference is min/time or h/time and is the same and unchangeable specific numerical value.
In the invention, the final cooling mode of the second part of rapid cooling aging heat treatment is as follows: cooling in air at room temperature.
In the invention, the rapid cooling aging heat treatment method comprises the following processes: step 1, start heating process S1: after the first part of rapid solution heat treatment is finished, continuously heating and preserving the austenitic stainless steel within the range of the maximum temperature Tafmax of rapid cooling and aging in a heating furnace within a specified time; step 2, intermediate heating process S2: continuously cooling the austenitic stainless steel in the heating furnace from the cooling and ageing highest temperature range Tafmax to n-2 rapid cooling and ageing middle ageing temperature Tafm ranges (n is more than or equal to 3 and less than or equal to 7, namely n is 3, 4, 5, 6 or 7) in sequence, and heating and preserving heat in the time specified by the process in sequence; and (N-1), finishing the heating process S (N-1): then continuously cooling the austenitic stainless steel in the heating furnace from the range of the rapid cooling aging intermediate aging temperature Tafm to the range of the rapid cooling aging minimum temperature Tafmin, and heating and preserving heat within the time specified by the process; step N, final cooling process SN: and continuously discharging the austenitic stainless steel out of the furnace, and cooling the austenitic stainless steel in the air at room temperature at the minimum rapid aging temperature Tafmin.
According to the technical scheme, the invention fundamentally solves the special heat treatment technical theory and practical problems of poor quality stability, low qualified product rate, low hardness (or low mechanical property), poor consistency, long heating time, low efficiency, poor heating reliability of heat treatment equipment, low service life of high-temperature components, high cost and the like which cannot be solved by the traditional mainstream austenitic stainless steel technical method.
Although the invention is researched by taking the heat treatment method of austenitic stainless steel (the used heating equipment is the conventional box-type resistance heating furnace) as a research object, the invention is also applicable to heat treatment methods of other types of stainless steel, high-temperature alloy and the like (the heating equipment can also be selected from other types of resistance heating furnaces, high-medium and low-frequency heating furnaces, salt bath heating furnaces, gas-fuel oil heating furnaces, fluid particle heating furnaces, vacuum heating furnaces and the like); similarly, the method is also suitable for the heat treatment method related in the technical fields of hot working engineering such as austenitic stainless steel smelting, steel rolling, forging, heat treatment and the like related in steel mills and manufacturing plants; meanwhile, it should be noted that: it will be apparent to those skilled in the art that several arrangements, combinations, modifications, improvements (especially, the solution and aging heating temperature and time, and the cooling medium can be properly adjusted or changed according to the grade of austenitic stainless steel, the use performance, the heating equipment, etc.) without departing from the technical principle of the present invention, etc. should also be considered as the protection scope of the present invention.
Claims (10)
1. A rapid solid solution and rapid cooling aging composite heat treatment method is characterized by comprising the following steps:
performing a rapid solution heat treatment process, the rapid solution heat treatment process comprising: heating and heat preservation are carried out when the temperature of the austenitic stainless steel is raised from room temperature to the maximum temperature of rapid solid solution within a specified time in a heating furnace, heating and heat preservation are carried out when the temperature of the austenitic stainless steel is continuously reduced from the maximum temperature of rapid solid solution to the intermediate temperature of rapid solid solution, heating and heat preservation are carried out when the temperature of the austenitic stainless steel is continuously reduced from the intermediate temperature of rapid solid solution to the minimum temperature of rapid solid solution, and finally cooling is carried out when the temperature of the austenitic stainless steel is reduced from the minimum temperature of rapid solid solution to the maximum temperature of rapid temperature reduction and aging by continuously adopting a specific cooling mode;
after the rapid solution treatment process is finished, the rapid cooling aging composite heat treatment is continuously carried out, wherein the rapid cooling aging composite heat treatment process comprises the following steps: heating and heat preservation are carried out on the austenitic stainless steel at the highest theoretical temperature of rapid cooling and aging within a specified time in a heating furnace, heating and heat preservation are carried out when the austenitic stainless steel is continuously cooled from the highest theoretical temperature of rapid cooling and aging to the intermediate aging temperature of rapid cooling and aging, heating and heat preservation are carried out when the austenitic stainless steel is continuously cooled from the intermediate aging temperature of rapid cooling and aging to the lowest temperature of rapid cooling and aging, and cooling is carried out when the austenitic stainless steel is continuously cooled from the lowest temperature of rapid cooling and aging to room temperature by adopting a specific cooling mode.
2. The rapid solid solution and rapid cooling aging composite heat treatment method according to claim 1, wherein the multi-stage temperature interval of the 3-stage rapid solid solution heat treatment is: and a 3-stage temperature reduction and heating temperature interval which starts from the stage of raising the temperature from room temperature to the maximum solid solution temperature Tfmax, then lowers the temperature to the intermediate solid solution temperature Tsfm, and finally lowers the temperature to the minimum solid solution temperature Tfmin.
3. The rapid solid solution and rapid cooling aging composite heat treatment method according to claim 1, characterized in that the final cooling manner of the rapid solid solution heat treatment is as follows: opening the furnace door or adopting other cooling modes to quickly cool the workpiece without discharging the workpiece out of the furnace.
4. The rapid solid solution and rapid cooling aging composite heat treatment method according to claim 1, wherein the rapid cooling aging heat treatment method is a rapid cooling aging heat treatment method performed in a multi-stage heating temperature zone, a multi-stage heating sequence, a multi-stage heating time, a multi-stage heating frequency, a specific cooling method, and the like, in succession after the rapid solid solution heat treatment is completed.
5. The rapid solid solution and rapid cooling aging composite heat treatment method according to claim 1, wherein when the rapid cooling aging time is performed by the uniform time method, the total rapid cooling aging heating time τ by the uniform time method isafNHeating time tau in each stage of aging corresponding to heating temperature intervals of 1 st, 2 nd, 3 rd, … …, and nth stages of heatingafnThe mathematical relationship of (a) is:
τafN＝∑τafn＝∑τafN/N
in the formula tauafNThe total time of rapid cooling, aging and heating is equal time method, min or h; tau isafnHeating temperature intervals of the 1 st stage, the 2 nd stage, the 3 rd stage, … … and the nth stage for rapid cooling are corresponding to heating time of each stage of aging, min/time or h/time, and are respectively tauaf1、τaf2、τaf3、τaf4、τaf5、τaf6、τaf7，τaf1＝τaf2＝τaf3＝τaf4＝τaf5＝τaf6＝τaf7(ii) a N is the total number of stages of rapid cooling and aging heating, and is more than or equal to 3 and less than or equal to 7; n is the number of the nth stage of rapid cooling and aging heating, and n is more than or equal to 1 and less than or equal to 7.
6. The rapid solid solution and rapid cooling aging composite heat treatment method according to claim 1, wherein when the rapid cooling aging time is performed according to the increasing time method, the total time τ of rapid cooling aging heating according to the increasing time methodafNHeating time tau in each stage of aging corresponding to heating temperature intervals of 1 st, 2 nd, 3 rd, … …, and nth stages of heatingafnThe mathematical relationship of (a) is:
τafN＝∑τafn＝∑[τaf1+(n–1)τaf0]
in the formula tauafNFor increasing the speed of timeQuickly cooling, aging and heating for the total time of min or h; n is the total number of stages of rapid cooling and aging heating, and is more than or equal to 3 and less than or equal to 7; tau isafnHeating time of each stage of rapid cooling and aging is min/time or h/time, which are tau respectivelyaf1、τaf2、τaf3、τaf4、τaf5、τaf6Or τaf7，τaf1＞τaf2＞τaf3＞τaf4＞τaf5＞τaf6Or > tauaf7(ii) a n is the number of the nth stage of rapid cooling and aging heating, and n is more than or equal to 1 and less than or equal to 7; tau isaf1Heating time in a first stage of rapid cooling and aging for min/time or h/time; tau isaf0The heating time is increased by grade difference, min/time or h/time, for rapid cooling and aging, and the values are the same and unchangeable specific values.
7. The rapid solid solution and rapid cooling aging composite heat treatment method according to claim 1, characterized in that the rapid cooling aging heat treatment method comprises the following processes: step 1, start heating process S1: after the rapid solution heat treatment is finished, continuously heating and preserving the austenitic stainless steel within the range of the maximum temperature Tafmax of rapid cooling and aging in a heating furnace within a specified time; step 2, intermediate heating process S2: continuously cooling the austenitic stainless steel in the heating furnace from the cooling and ageing highest temperature range Tafmax to n-2 rapid cooling and ageing middle ageing temperature Tafm ranges in sequence, and heating and preserving heat in the time specified by the process in sequence; and (N-1), finishing the heating process S (N-1): then continuously cooling the austenitic stainless steel in the heating furnace from the range of the rapid cooling aging intermediate aging temperature Tafm to the range of the rapid cooling aging minimum temperature Tafmin, and heating and preserving heat within the time specified by the process; step N, final cooling process SN: and continuously discharging the austenitic stainless steel out of the furnace, and cooling the austenitic stainless steel in the air at room temperature at the minimum rapid aging temperature Tafmin.
8. The rapid solid solution and rapid cooling aging composite heat treatment method according to claim 1, characterized in that the 3-stage rapid solid solution heat treatment process comprises: the first stage is as follows: heating the austenitic stainless steel from room temperature to a rapid solid solution maximum temperature Tsfmax in a heating furnace; and a second stage: continuously cooling the austenitic stainless steel from the maximum rapid solid solution temperature Tfmax to the intermediate solid solution temperature Tsfm; and a third stage: continuously cooling the austenitic stainless steel from the rapid solid solution intermediate solid solution temperature Tsfm to the rapid solid solution minimum temperature Tsfmin; and finally, continuously adopting a furnace door opening or other cooling modes to cool the austenitic stainless steel from the minimum rapid solid solution temperature Tsfmin to the maximum rapid cooling aging temperature Tafmax in the heating furnace.
9. The rapid solid solution and rapid cooling aging composite heat treatment method according to claim 1, characterized in that the 4-stage rapid solid solution heat treatment process comprises: the first stage is as follows: heating the austenitic stainless steel from room temperature to a rapid solid solution maximum temperature Tsfmax in a heating furnace; and a second stage: continuously cooling the austenitic stainless steel from the maximum rapid solid solution temperature Tfmax to the first stage rapid solid solution temperature Tsfm1(ii) a And a third stage: continuously dissolving the austenitic stainless steel from the rapid solid solution intermediate solid solution first stage temperature Tsfm1Cooling to the second stage temperature Tsfm of rapid solid solution and intermediate solid solution2(ii) a A fourth stage: continuously dissolving the austenitic stainless steel from the rapid solid solution intermediate solid solution second stage temperature Tsfm2Cooling to the minimum temperature Tsfmin for rapid solid solution; and finally, continuously adopting a furnace door opening or other cooling modes to cool the austenitic stainless steel from the minimum rapid solid solution temperature Tsfmin to the maximum rapid cooling aging temperature Tafmax in the heating furnace.
10. The rapid solid solution and rapid cooling aging composite heat treatment method according to claim 1, wherein the rapid cooling aging heating temperature range is as follows: n stages which start from the aging highest heating stage Tafmax, sequentially pass through n-2 aging intermediate cooling and heating stages Tafm and finally end at the aging lowest cooling and heating stage Tafmin; and (5) cooling and heating the temperature range.
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