CN112795743A - Critical solid solution and critical starting low-temperature alternating aging heat treatment method - Google Patents
Critical solid solution and critical starting low-temperature alternating aging heat treatment method Download PDFInfo
- Publication number
- CN112795743A CN112795743A CN202011427530.6A CN202011427530A CN112795743A CN 112795743 A CN112795743 A CN 112795743A CN 202011427530 A CN202011427530 A CN 202011427530A CN 112795743 A CN112795743 A CN 112795743A
- Authority
- CN
- China
- Prior art keywords
- temperature
- critical
- heating
- solid solution
- aging
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000010438 heat treatment Methods 0.000 title claims abstract description 464
- 230000032683 aging Effects 0.000 title claims abstract description 301
- 239000006104 solid solution Substances 0.000 title claims abstract description 233
- 238000000034 method Methods 0.000 title claims abstract description 154
- 229910000963 austenitic stainless steel Inorganic materials 0.000 claims abstract description 104
- 230000008569 process Effects 0.000 claims abstract description 62
- 239000011557 critical solution Substances 0.000 claims abstract description 55
- 238000001816 cooling Methods 0.000 claims description 53
- 238000004321 preservation Methods 0.000 claims description 30
- 238000004090 dissolution Methods 0.000 claims description 28
- 230000000087 stabilizing effect Effects 0.000 claims description 27
- 230000003247 decreasing effect Effects 0.000 claims description 26
- 239000000243 solution Substances 0.000 claims description 23
- 229910001220 stainless steel Inorganic materials 0.000 claims description 21
- 239000010935 stainless steel Substances 0.000 claims description 20
- 229910001566 austenite Inorganic materials 0.000 claims description 19
- 230000005496 eutectics Effects 0.000 claims description 15
- 102000020897 Formins Human genes 0.000 claims description 10
- 108091022623 Formins Proteins 0.000 claims description 10
- 229910000881 Cu alloy Inorganic materials 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 239000002826 coolant Substances 0.000 claims description 6
- 238000007599 discharging Methods 0.000 claims description 6
- 230000006641 stabilisation Effects 0.000 claims description 5
- 238000011105 stabilization Methods 0.000 claims description 5
- 230000008859 change Effects 0.000 claims description 2
- 229910000831 Steel Inorganic materials 0.000 abstract description 10
- 239000010959 steel Substances 0.000 abstract description 10
- 238000005494 tarnishing Methods 0.000 abstract description 8
- 230000008901 benefit Effects 0.000 abstract description 5
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 238000003723 Smelting Methods 0.000 abstract description 3
- 238000005242 forging Methods 0.000 abstract description 3
- 238000005096 rolling process Methods 0.000 abstract description 3
- 229910045601 alloy Inorganic materials 0.000 description 25
- 239000000956 alloy Substances 0.000 description 25
- 238000005728 strengthening Methods 0.000 description 22
- 239000011651 chromium Substances 0.000 description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 15
- 229910052804 chromium Inorganic materials 0.000 description 12
- 238000001556 precipitation Methods 0.000 description 12
- 238000002844 melting Methods 0.000 description 11
- 230000008018 melting Effects 0.000 description 11
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 10
- 229910052750 molybdenum Inorganic materials 0.000 description 9
- 239000007787 solid Substances 0.000 description 9
- 229910052759 nickel Inorganic materials 0.000 description 8
- 229910052721 tungsten Inorganic materials 0.000 description 8
- 230000003313 weakening effect Effects 0.000 description 8
- 238000005260 corrosion Methods 0.000 description 7
- 229910052742 iron Inorganic materials 0.000 description 7
- 229910052748 manganese Inorganic materials 0.000 description 7
- 230000007797 corrosion Effects 0.000 description 6
- 239000011572 manganese Substances 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 230000035882 stress Effects 0.000 description 6
- 230000006870 function Effects 0.000 description 5
- 230000002068 genetic effect Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 239000002131 composite material Substances 0.000 description 4
- 230000002349 favourable effect Effects 0.000 description 4
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 4
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 3
- 229910000746 Structural steel Inorganic materials 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 3
- 239000010955 niobium Substances 0.000 description 3
- 230000000630 rising effect Effects 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 229910001567 cementite Inorganic materials 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000005087 graphitization Methods 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000001376 precipitating effect Effects 0.000 description 2
- 238000004881 precipitation hardening Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 229910016807 Mn3C Inorganic materials 0.000 description 1
- 229910003178 Mo2C Inorganic materials 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229910001361 White metal Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 229910052797 bismuth Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- RYZCLUQMCYZBJQ-UHFFFAOYSA-H lead(2+);dicarbonate;dihydroxide Chemical compound [OH-].[OH-].[Pb+2].[Pb+2].[Pb+2].[O-]C([O-])=O.[O-]C([O-])=O RYZCLUQMCYZBJQ-UHFFFAOYSA-H 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000000803 paradoxical effect Effects 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- GPPXJZIENCGNKB-UHFFFAOYSA-N vanadium Chemical compound [V]#[V] GPPXJZIENCGNKB-UHFFFAOYSA-N 0.000 description 1
- 239000010969 white metal Substances 0.000 description 1
Images
Classifications
-
- 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
- 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
-
- 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
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
The invention provides a critical solid solution and critical low-temperature alternative aging heat treatment method, which comprises the following steps: the critical solution heat treatment process and the critical start from the low-temperature alternate aging heat treatment process. The scheme of the invention has technical feasibility, process adaptability, quality reliability, economic rationality and use safety, can effectively make good use of the advantages and disadvantages of the traditional mainstream heat treatment method of austenitic stainless steel, fundamentally solves the unique heat treatment technical problems of poor quality stability, low qualified product rate, low hardness, low mechanical property, poor consistency, poor anti-tarnishing resistance, long heating time, low efficiency, poor heating reliability of heat treatment equipment, low service life of high-temperature components, high cost and the like, namely one long step, one high step, four steps, five steps, and the like of the conventional heat treatment of austenitic stainless steel, and is particularly suitable for the heat treatment engineering technical fields of smelting, steel rolling, forging, heat treatment and the like of austenitic stainless steel in steel factories and manufacturing plants.
Description
Technical Field
The invention relates to the technical field of material heat treatment, in particular to a critical solid solution and critical starting low-temperature alternating aging 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 (good heat treatment manufacturability) under the high-temperature condition, so that the alloy structural steel is very easy to greatly improve the hardness (or mechanical property) by quenching and tempering heat treatment methods; however, austenitic stainless steel cannot generate high-temperature austenitic structure transformation (only limited dissolution and precipitation of alloy element strengthening phases, and poor heat treatment manufacturability) under high-temperature conditions, so that the austenitic stainless steel is extremely difficult to greatly improve the hardness (or mechanical property) through heat treatment methods such as solid solution and aging.
The meaning of solution heat treatment is: the heat treatment process comprises the following steps of heating austenitic stainless steel to a certain temperature, keeping the temperature, fully dissolving excess phases, and then rapidly cooling to obtain a supersaturated solid solution, wherein the heat treatment process mainly has the main functions of obtaining a supersaturated strengthened solid solution, preparing a structure for precipitation hardening treatment, eliminating stress and carrying out work hardening between forming procedures; the meaning of the aging heat treatment is: after the austenitic stainless steel is subjected to solution treatment, the austenitic stainless steel is kept at room temperature or a temperature higher than the room temperature, so that solute atom segregation areas are formed in supersaturated solid solutions and/or second-phase particles are precipitated, dispersed and distributed to form excessive phases, and the austenitic stainless steel is mainly subjected to precipitation hardening.
The austenitic stainless steel has a main strengthening phase of carbide of alloying elements and a weakening phase of intermetallic compounds (such as Fe)2W、Fe2Mo, CuO, FeS, FeO, MnS, etc.); even if the type, the number, the size, the shape, the distribution, the melting point, the brittleness, the hardness and the like of the strengthening phase and the weakening phase of the same material are different due to different solid solution and aging heat treatment methods, the more the austenitic stainless steel alloy elements are, the larger the difference is.
Carbide formed by alloy elements such as nickel, chromium, tungsten, molybdenum, vanadium, titanium, aluminum, niobium and the like in austenitic stainless steelThe relative stability in the steel is arranged from high to low in the order: hf > Zr > Ti > Ta > Nb > V > W > Mo > Cr > Mn > Fe > Co > Ni, so that dissolution of the above-mentioned alloy elements in austenitic stainless steel results in limited dissolution (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); because the solution heating temperature of the existing traditional mainstream austenitic stainless steel is the highest theoretical solution temperature, the unfavorable critical temperature intervals of 700 ℃ -815 ℃ (sensitized intercrystalline corrosion critical temperature region), 940 ℃ (FeS-FeO eutectic melting point and dissolution genetic critical temperature region), 985 ℃ (Fe-FeS eutectic melting point and dissolution genetic critical temperature region), 1083 ℃ (weakened phase copper alloy dissolution critical temperature region), 1164 ℃ (FeS-MnS eutectic melting point and dissolution genetic critical temperature region) and the like can not be quickly avoided, so that the solid solution capacity, range, quality, efficiency and the like of the carbide strengthened phase can not be effectively improved. In fact, the austenitic stainless steel solid solution temperature is not a simple and unchangeable single-point temperature value, but a complex and changeable multi-point temperature range; the existing traditional mainstream solution heat treatment method has the advantages that: the solid solution capability, the range, the quality, the efficiency and the like of one or a few alloy elements in the austenitic stainless steel can be effectively improved; the existing traditional mainstream solution heat treatment method has the following defects: the solid solution capacity, range, quality, efficiency and the like of most alloy element strengthening phases cannot be effectively improved, even if the solid solution time is increased, the effect is very small (when the time reaches a certain degree, the solid solution capacity, range, quality, efficiency and the like of one or a few alloy element solid solution strengthening phases can reach a limit saturation state), and the alloy element strengthening phases can only reach the limit solid solution capacity, range, quality, efficiency and the like. Thus, the existing legacy mastersThe solution heat treatment method of the fluid austenitic stainless steel is essentially a one-stage single-point fixed limited solution heat treatment method under the condition that the heating temperature and the heating time are the only conditions, and is a heat treatment method which is totally ' not ' comprehensively considered by the approximation '.
The aging heat treatment temperature of the austenitic stainless steel is different due to different use requirements such as anti-rust corrosion capability, high-temperature strength, hardness, mechanical property and the like: if the temperature is lower than 500 ℃, the trace amount of needle-shaped carbide with larger grain size is mainly precipitated, and if the temperature is between 550 and 740 ℃, the carbide (Fe, Cr, Ni, Mn, W, Mo) is mainly precipitated23C6Carbide 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 about 800 ℃ (Fe, Cr, Ni, Mn, W, Mo)7C6When the temperature of the composite alloy carbide is about 880 ℃, a small amount of (Fe, Cr, Ni, Mn, W, Mo) C composite alloy carbide is mainly precipitated, and when the temperature is higher than 900 ℃, the precipitation amount of the precipitated lamellar carbide is increased to influence the metal hardness and the mechanical property; because the aging heating temperature of the traditional mainstream austenitic stainless steel is the highest aging theoretical temperature, the capability, range, quality, efficiency and the like of precipitating carbide strengthening phases by aging cannot be effectively improved. In fact, the aging temperature of austenitic stainless steel is not a simple and unchangeable single-point temperature value, but a complex and changeable multi-point temperature range; the existing traditional mainstream aging heat treatment method has the advantages that: the aging precipitation capacity, range, quality, efficiency and the like of one or a few alloy element strengthening phases in the austenitic stainless steel can be effectively improved; the prior aging heat treatment method has the following defects: the aging precipitation capacity, range, quality, efficiency and the like of most alloy element strengthening phases cannot be effectively improved, the effect is very small even if the aging time is increased (after the time reaches a certain degree, the aging capacity, range, quality, efficiency and the like of one or a few alloy element strengthening phases can reach a limit saturation state), and the alloy element strengthening phases can only reach the limited aging precipitation capacity, range, quality, efficiency and the like.Therefore, the existing traditional mainstream austenitic stainless steel aging heat treatment method is a one-stage single-point fixed limited aging heat treatment method under the condition that the heating temperature and the heating time are the only conditions, and is a heat treatment method which is considered as a whole under the condition of being not in a comprehensive mode.
Although austenitic stainless steel belongs to the stainless steel material series, the phenomenon of 'discoloring and rusting a metal surface' is generated to different degrees by 'bright silvery white metal surface' after machining and staying for a certain time, and the main reasons for the generation are considered to be from the conventional mainstream known viewpoints: the chemical components of austenitic stainless steel do not meet the standard of procurement materials; secondly, the content of Cr, Ni, W and other anti-corrosion metals in the austenitic stainless steel is relatively low or the content of C, P, As, Sb, Bi and other metal elements which are easy to discolor and corrode is relatively high; thirdly, the surface of the austenitic stainless steel is discolored or corroded (generally referred to as corrosion) due to chemical reaction or electrochemical reaction between metal on the surface of the austenitic stainless steel and substances such as oxygen, water, acid, alkali, salt and the like in the atmosphere, wherein the original steel surface is a layer of firm, fine and extremely thin silver white light bright chromium-rich oxide film substance which is destroyed to form loose heterogeneous substances; fourthly, the surface roughness of the austenitic stainless steel is caused; fifthly, the austenitic stainless steel part is caused by working at the temperature of 300-800 ℃. In fact, besides the discolored rusting of austenitic stainless steels, it is also involved in a cause that is not yet recognized to be very important: the method is caused by the improper hot working methods of smelting, steel rolling, forging, heat treatment and the like of the austenitic stainless steel in steel mills and manufacturing plants, particularly the comprehensive action of a plurality of hot working complex factors such as material, chemical components, furnace batch, hot working temperature, time, cooling medium and the like to generate more alloy carbides and non-carbides which are easy to discolor and rust, and the like, and the method is one of the most fundamental reasons which directly influence the final effect of the heat treatment of the austenitic stainless steel.
Based on the comprehensive influence of a plurality of complex factors, the conventional austenitic stainless steel heat treatment technology is difficult to solve the following special heat treatment technical theory and practice problems of 'one long, one high, four different and 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 reach the medium and low hardness value of 20.0-26.5 HRC, the medium and high hardness value of 27.0-28.0 HRC, the high hardness value of 28.5-32.0 HRC, and even the paradoxical phenomenon of qualified Brinell hardness and unqualified Rockwell hardness.
Thirdly, the tarnish resistance is poor: the austenitic stainless steel has strong sensitivity and high speed for changing 'bright silvery white' into 'color change rust' after the metal surface is machined and stays for a certain time.
Fourthly, 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 batch production is difficult to realize; in order to remove residual cold and hot processing stress generated before, during and after the solid solution and aging process, an independent annealing process with longer heating time is required; in order to solve the problems of unqualified solid solution and aging heat treatment, rework and repair are forced to be carried out.
Fifthly, the heating reliability of the heat treatment equipment is poor: the existing box-type resistance furnace equipment has poor heating reliability (only has the functions of conduction and radiation heat transfer), and is far inferior to equipment such as a fluidized bed furnace, a salt bath furnace, a vacuum furnace and the like (simultaneously has the functions of conduction, radiation and convection heat transfer) in heating reliability.
Sixthly, the service life of the high-temperature component of the heat treatment equipment is short: the service life of the high-temperature components of the equipment is low due to large high-temperature load and long retention time under the conditions of highest temperature of solid solution and aging.
Seventhly, the heat treatment cost is high: the combination of the above disadvantages ultimately results in high heat treatment costs.
In conclusion, the conventional mainstream austenitic stainless steel heat treatment method cannot solve the problems of poor quality stability, low qualified product rate, low hardness (or low mechanical property) and poor consistency, poor anti-tarnishing resistance, long heating time, low efficiency, poor heating reliability of heat treatment equipment, low service life of high-temperature components and high cost and the like which are unique heat treatment technology theory and practice of one step, four steps and five steps in the heat treatment of austenitic stainless steel.
Disclosure of Invention
The invention aims to provide a method for performing low-temperature alternate aging heat treatment on critical solid solution and critical starting materials. Solves the special heat treatment technical problems of poor quality stability, low qualified product rate, low hardness, low mechanical property, poor consistency, poor anti-tarnishing capability, 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 prior heat treatment of austenitic stainless steel.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a critical solid solution and critical start low temperature alternate aging heat treatment method comprises:
a critical solution heat treatment process, the critical solution heat treatment process comprising: critical preheating heating and heat preservation before solid solution are carried out when the temperature of austenitic stainless steel is raised to the preheating temperature from room temperature at a medium speed in a heating furnace within a specified time, then critical stabilizing heating and heat preservation before solid solution are carried out when the temperature of austenitic stainless steel is raised to the stabilizing temperature, critical solid solution minimum temperature heating and heat preservation are carried out when the temperature of austenitic stainless steel is raised to the solid solution minimum temperature, critical solid solution maximum temperature heating and heat preservation are carried out when the temperature of austenitic stainless steel is raised to the solid solution maximum temperature, and solid solution cooling is carried out when the temperature of austenitic stainless steel is lowered to the room temperature by a specific cooling mode;
after the critical solution heat treatment is finished, the critical solution heat treatment process is continued to start at the low-temperature alternate aging heat treatment process, and the critical solution heat treatment process starting at the low-temperature alternate aging heat treatment process comprises the following steps: the 1 st critical process begins with the low temperature alternating aging process: the method specifically comprises the following steps that 1, the first half part of the process is critical, starts from low temperature to high temperature and has no alternating aging process: firstly heating and preserving the austenite stainless steel at the critical aging lowest temperature when the temperature of the austenite stainless steel is raised to the critical aging lowest temperature from room temperature at a medium speed in a heating furnace within a specified time, then continuously heating and preserving the austenite stainless steel at the critical aging middle temperature when the temperature of the austenite stainless steel is raised to the aging middle temperature, then continuously heating and preserving the austenite stainless steel at the critical aging highest temperature when the temperature of the austenite stainless steel is raised to the final aging highest temperature, and then continuing the 1 st half of the process from the high temperature to the low temperature alternating aging process: firstly, continuously heating and preserving heat at critical aging intermediate temperature when the austenitic stainless steel is rapidly cooled from the critical aging maximum temperature to the aging intermediate temperature in a heating furnace within the specified time, and then continuously heating and preserving heat at critical aging minimum temperature when the austenitic stainless steel is rapidly cooled from the critical aging intermediate temperature to the critical aging minimum temperature in the heating furnace within the specified time;
after the 1 st critical starting from low temperature and ending with the low temperature alternating aging process, the 2 nd, 3 rd, … … th and Nth critical alternating aging processes are carried out again: critical alternating aging for the 2 nd time, sequentially and reversely repeating the 1 st half critical time from the high temperature to the low temperature alternating aging process for 1 time, critical alternating aging for the 3 rd time, sequentially and reversely repeating the 2 nd critical alternating aging process for 1 time, … …, and so on, and sequentially and reversely repeating the N-th critical alternating aging process for 1 time;
and (3) after the 2 nd, 3 rd, … … th and Nth critical start from low temperature to high temperature or critical start from high temperature to low temperature, the last cooling process is continued: and (3) cooling the austenitic stainless steel discharged from the furnace by opening a furnace door or other cooling modes when the temperature is rapidly reduced to room temperature from the critical temperature beginning at the low temperature and ending at the high temperature alternating ageing highest temperature or beginning at the high temperature and ending at the low temperature alternating ageing lowest temperature.
Optionally, the total number of solid solutions of the critical solid solution heat treatment is 1.
Optionally, the critical solid solution temperature interval is: and a 4-stage critical solid solution heating temperature range which starts from the stage of raising the temperature from room temperature to the critical pre-solid solution preheating temperature Tsccp, continues to raise the temperature to the critical pre-solid solution stabilizing temperature Tscs, continues to raise the temperature to the critical solid solution lowest temperature Tcmin, and finally raises the temperature to the critical solid solution highest temperature Tcmax.
Optionally, the mathematical relationship between the critical pre-solid solution preheating temperature Tscp and the solid solution minimum theoretical heating temperature Tscmin is as follows: ttscp is Tsctmin- (330-350) DEG C;
wherein Tsscp is the preheating temperature before critical solid solution, and the unit is; tsctmin is the critical solution minimum theoretical heating temperature in degrees Celsius.
Optionally, the mathematical relationship between the critical pre-solid solution stabilization heating temperature Tscs and the solid solution minimum theoretical heating temperature Tscmin is as follows: tscs is Tsctmin- (120-150) DEG C;
wherein Tscs is the stabilizing heating temperature before critical solid solution, and the unit is; tsctmin is the critical solution minimum theoretical heating temperature in degrees Celsius.
Optionally, the mathematical relationship between the critical solid solution minimum heating temperature Tscmin and the solid solution minimum theoretical heating temperature Tsctmin and the copper alloy dissolution critical temperature is as follows:
Tsctmin+(5～10)℃≤Tscmin≤1083℃–(13～15)℃
wherein Ttscmin is the critical solid solution minimum heating temperature, and the unit is; tsctmin is the critical solid solution minimum theoretical heating temperature, and the unit is; 1083 ℃ is the copper alloy dissolution critical temperature in units of ℃.
Optionally, the mathematical relation between the critical solid solution maximum heating temperature Tscmax and the solid solution maximum theoretical heating temperature Tsctmax and the FeS-MnS eutectic dissolution critical temperature is as follows:
Tscmax≤Tsctmax≤1164℃–(12～14)℃
wherein Tsmax is the critical solid solution maximum heating temperature, and the unit is; tstmax is the critical solid solution maximum theoretical heating temperature, and the unit is; the temperature of 1164 ℃ is the dissolution critical temperature of the FeS-MnS eutectic, and the unit is ℃.
Optionally, the critical solid solution is divided into 4 stages of heating time: and 4-stage heating time of critical pre-solid solution preheating, critical pre-solid solution stabilizing, critical solid solution lowest temperature and critical solid solution highest temperature corresponding to the critical 4-stage solid solution temperature.
Optionally, the critical solid solution time is performed according to a decreasing time method, and the heating time τ is at each stage of the decreasing time methodscnPreheating heating time tau before solid solutionsc1And decreasing the time step difference τsc0The mathematical relationship of (a) is:
τscn＝[τsc1–(n–1)τsc0]
wherein, tauscnHeating time, min or h, tau, at each stage of the critical solid solution decreasing time methodscnIs divided into tausc1、τsc2、τsc3、τsc4，τsc1＞τsc2＞τsc3＞τsc4；τsc1Preheating heating time before solid solution in a critical solid solution first stage, wherein the preheating heating time is min or h; tau issc2Stabilizing and heating time before solid solution in a second stage of critical solid solution for min or h; tau issc3Heating time is the critical solid solution minimum temperature of the critical solid solution third stage, and min or h; tau issc4Heating time of maximum solution temperature in the fourth stage of critical solution treatment, min or h, tausc4Less than or equal to 5 min; n is the number of the nth stage of the critical solution heating, and n is 1, 2, 3, 4; tau issc0The decreasing time step difference of the critical solid solution heating, min or h, is the same and unchanging specific numerical value.
Optionally, the critical solution heat treatment process includes:
the first stage is as follows: austenitic stainless steel is placed in a furnace for a process-defined time τsc1Heating from room temperature to a critical preheating temperature Tsccp at a medium speed, and performing critical preheating heating and heat preservation before solid solution;
and a second stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tausc2Rapidly heating from the critical preheating temperature Tspc to the critical stabilizing temperature Tscs for critical stabilizing heating and heat preservation before solid solution;
and a third stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tausc3Rapidly heating from the critical stabilization temperature Tscs to the critical solid solution minimum temperature Tcmin to carry out critical solid solution minimum temperature heating and heat preservation;
a fourth stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tausc4Rapidly heating from the critical solid solution minimum temperature Tcmc to the critical solid solution maximum temperature Tcmax, and heating and preserving the critical solid solution maximum temperature;
and finally, continuously and quickly discharging the austenitic stainless steel from the furnace from the critical solid solution highest temperature Tcmc ax, and quickly cooling the austenitic stainless steel in cooling medium room-temperature water.
The scheme of the invention at least comprises the following beneficial effects:
(1) the method for heat treatment of the austenitic stainless steel by the low-temperature alternating aging treatment has the advantages of technical feasibility, process adaptability, quality reliability, economic rationality and use safety, effectively draws the advantages and disadvantages of the traditional mainstream austenitic stainless steel heat treatment method, and fundamentally solves the special heat treatment technical problems of poor quality stability, low qualified product rate, low hardness (or low mechanical property) and consistency, poor anti-tarnishing capability, long heating time, low efficiency, poor heating reliability of heat treatment equipment, low service life of high-temperature components, high cost and the like, namely one step, four steps and five steps.
(2) The method for the low-temperature alternating aging heat treatment of the critical solid solution and critical phase has good heat treatment manufacturability, can effectively increase the solid solution and aging strengthening phase, reduce or inhibit the solid solution and aging weakening phase and reduce the residual cold and hot processing stress and deformation, and can meet the service performance requirements of austenitic stainless steel.
(3) The method for the low-temperature alternating aging heat treatment of the critical solid solution and critical heat treatment starts from the low-temperature alternating aging heat treatment method, has good quality stability and high reliability, can accurately, effectively and quickly obtain the optimized heat treatment hardness (or mechanical property) with the distribution interval range of the middle limit or the upper limit and the tolerance of less than or equal to 2.5HRC, and can ensure that the qualified rate of the hardness (or mechanical property) of the one-time heat treatment reaches 100 percent.
(4) The critical solid solution and critical phase of the invention start from the low-temperature alternating aging heat treatment method, which can effectively improve the surface tarnish resistance of the austenitic stainless steel after machining.
(5) The critical solid solution and critical temperature of the invention starts from the low-temperature alternating aging heat treatment method, and can effectively improve the heat treatment efficiency (especially can be used for full-load furnace charging and rapid production, and can reduce the total time of solid solution and aging heat treatment by at least 40 percent, etc.).
(6) The critical solid solution and critical start low-temperature alternating aging heat treatment method can effectively prolong the service life of high-temperature components of heating equipment.
(7) The critical solid solution and critical phase of the invention start from the low-temperature alternating aging heat treatment method, and the heat treatment cost of the austenitic stainless steel can be effectively reduced.
Drawings
FIG. 1 is a schematic diagram of the prior austenitic stainless steel showing the solution and aging heat treatment process (including the heating, heat preservation, cooling processes, time used and the like of the solution and aging heat treatment) consisting of 1 time 1-stage solution treatment at the highest solution temperature and 1 time 1-stage aging treatment at the highest aging temperature;
FIG. 2 is a schematic flow diagram of the critical solution and critical onset low temperature alternate aging heat treatment process of the present invention;
FIG. 3 is a schematic diagram of the austenitic stainless steel consisting of 1 time of 4-stage critical solution treatment under the condition of critical solution temperature and 1 time of 3 times of equal time under the condition of critical aging temperature (wherein, the 1 st time of 4-stage temperature rise has no alternation, the 2 nd time of 4-stage temperature decrease alternation, the 3 rd time of 4-stage temperature rise alternation) and the critical solution treatment start from the low-temperature alternating aging heat treatment process (including the temperature rise, heat preservation, temperature decrease, cooling process and the used time of the critical solution treatment and the critical aging heat treatment).
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
As shown in fig. 2, an embodiment of the present invention provides a method for critical solution and critical start low temperature alternating aging heat treatment, comprising: step 21, critical solution heat treatment process; and step 22, starting the low-temperature alternating ageing heat treatment process.
The method comprises the following steps: first, the first part of critical solution heat treatment is carried out, and finally, the second part of critical solution heat treatment is carried out by low-temperature alternate aging heat treatment.
The first part of the critical solution heat treatment process: the critical solution heat treatment process comprises the steps of critical solution heat treatment process comprising critical preheating heating and heat preservation before solid solution when the temperature of austenitic stainless steel is raised from room temperature to the preheating temperature at a medium speed in a heating furnace within a specified time, critical stabilizing heating and heat preservation before solid solution when the temperature of austenitic stainless steel is raised to the stabilizing temperature, critical solution lowest temperature heating and heat preservation when the temperature of austenitic stainless steel is raised to the solution lowest temperature, critical solution highest temperature heating and heat preservation when the temperature of austenitic stainless steel is raised to the solution highest temperature, solid solution cooling when the temperature of austenitic stainless steel is lowered to room temperature by a specific cooling mode, and the like;
the second part of critical treatment begins in the low-temperature alternating ageing heat treatment process: namely, after the first part of critical solution heat treatment is finished, continuing to perform the second part of critical start low-temperature alternate aging heat treatment, depending on the process that the critical start low-temperature end high-temperature and the critical start high-temperature end low-temperature alternate aging heat treatment, the method comprises the 1 st critical start low-temperature alternate aging process: the method specifically comprises the following steps that 1, the first half part of the process is critical, starts from low temperature to high temperature and has no alternating aging process: firstly heating and preserving the austenite stainless steel at the critical aging lowest temperature when the temperature of the austenite stainless steel is quickly raised to the critical aging lowest temperature from room temperature in a heating furnace within a specified time, secondly continuously heating and preserving the austenite stainless steel at the critical aging middle temperature when the temperature of the austenite stainless steel is quickly raised to the aging middle temperature, and thirdly continuously heating and preserving the austenite stainless steel at the critical aging highest temperature when the temperature of the austenite stainless steel is quickly raised to the final aging highest temperature (the first half part of the 1 st time is critically started at low temperature and ends at high temperature without alternating aging process), and then continuing the second half part of the 1 st time, which is started at high temperature and ends at low temperature alternating aging process: firstly, continuously heating and preserving at critical aging intermediate temperature when the austenitic stainless steel is rapidly cooled from the critical aging maximum temperature to the aging intermediate temperature in a heating furnace within a specified time, and then continuously heating and preserving at critical aging minimum temperature when the austenitic stainless steel is rapidly cooled from the critical aging intermediate temperature to the critical aging minimum temperature in the heating furnace within the specified time (the 1 st half critical is started from high temperature to low temperature alternating aging process and the 1 st critical is started from low temperature alternating aging process and is also completely finished); after the 1 st critical starting from low temperature and ending with the low temperature alternating aging process, the 2 nd, 3 rd, … … th and Nth critical alternating aging processes are carried out again: critical alternating aging for 2 times, sequentially and reversely repeating the first half part of critical aging from high temperature to low temperature alternating aging for 1 time (the second critical aging from low temperature to high temperature alternating aging), critical alternating aging for 3 times, sequentially and reversely repeating the critical alternating aging for 2 times for 1 time (the third critical aging from high temperature to low temperature alternating aging), … …, and so on, and sequentially and reversely repeating the critical alternating aging for N times for 1 time (the Nth critical aging from low temperature to high temperature or critical from high temperature to low temperature alternating aging); and (3) after the 2 nd, 3 rd, … … th and Nth critical start from low temperature to high temperature or critical start from high temperature to low temperature, the last cooling process is continued: the method is characterized in that the method adopts a furnace door opening or other cooling modes to rapidly cool the austenitic stainless steel along with the furnace from the critical point starting from the process steps of cooling when the temperature is finally the highest temperature of high-temperature alternating ageing or the temperature is finally the lowest temperature of low-temperature alternating ageing and rapidly cooled to room temperature, and the like, and the critical point starts from the process of low-temperature alternating ageing heat treatment.
In an embodiment of the present invention, the first partial critical solution heat treatment method is a 4-stage critical solution heat treatment method performed under conditions such as a 4-stage heating temperature range, a 4-stage heating sequence, a 4-stage heating time, a 4-stage heating frequency, a specific cooling method, and the like.
In an embodiment of the present invention, the total number of solid solutions of the first part of the critical solid solution heat treatment is 1.
In an embodiment of the invention, the first portion of critical solid solution is a 4-stage heating time: and 4-stage heating time of critical pre-solid solution preheating, critical pre-solid solution stabilizing, critical solid solution lowest temperature and critical solid solution highest temperature corresponding to the critical 4-stage solid solution temperature.
In the embodiment of the invention, the critical solid solution time is carried out according to a decreasing time method, and the heating time tau at each stage of the decreasing time methodscnPreheating heating time tau before solid solutionsc1And decreasing the time step difference τsc0The mathematical relationship of (a) is: tau isscn＝[τsc1–(n–1)τsc0]；
Wherein, tauscnHeating time, min or h, tau, at each stage of the critical solid solution decreasing time methodscnIs divided into tausc1、τsc2、τsc3、τsc4，τsc1＞τsc2＞τsc3＞τsc4；τsc1Preheating heating time before solid solution in a critical solid solution first stage, wherein the preheating heating time is min or h; tau issc2Stabilizing and heating time before solid solution in a second stage of critical solid solution for min or h; tau issc3Heating time is the critical solid solution minimum temperature of the critical solid solution third stage, and min or h; tau issc4Heating time of maximum solution temperature in the fourth stage of critical solution treatment, min or h, tausc4Less than or equal to 5 min; n is the number of the nth stage of the critical solution heating, and n is 1, 2, 3, 4; tau issc0Is the decreasing time step difference of critical solid solution heating, min or h is the phaseThe same specific numerical value is not changed.
In an embodiment of the present invention, the first part critical solution heat treatment final cooling method is: cooled in room temperature water.
In an embodiment of the present invention, the first part of the critical solution heat treatment process is:
the first stage is as follows: austenitic stainless steel is placed in a furnace for a process-defined time τsc1Heating from room temperature to a critical preheating temperature Tsccp at a medium speed, and performing critical preheating heating and heat preservation before solid solution;
and a second stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tausc2Rapidly heating from the critical preheating temperature Tspc to the critical stabilizing temperature Tscs for critical stabilizing heating and heat preservation before solid solution;
and a third stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tausc3Rapidly heating from the critical stabilization temperature Tscs to the critical solid solution minimum temperature Tcmin to carry out critical solid solution minimum temperature heating and heat preservation;
a fourth stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tausc4Rapidly heating from the critical solid solution minimum temperature Tcmc to the critical solid solution maximum temperature Tcmax, and heating and preserving the critical solid solution maximum temperature;
and finally, continuously and quickly discharging the austenitic stainless steel from the furnace from the critical solid solution highest temperature Tcmax, and quickly cooling the austenitic stainless steel in cooling medium room-temperature water (and placing the cooled austenitic stainless steel on a room-temperature working site).
In the embodiment of the invention, the number of the first part solution heating temperature interval stages is moderate: for example, the solid solubility in the 1 stage is too poor, the solid solubility in the 2 stage is good, and the solid solubility in the 6 or more stages is excessive, so in this embodiment, a 4-stage critical solid solubility heating temperature range is set in which the preheating temperature before solid solubility Tscp, the stabilization temperature before solid solubility Tscs, the minimum solid solubility temperature Tscmin, and the maximum solid solubility temperature Tscmax are different: the pre-solid solution preheating temperature Tsccp range of the critical solid solution first stage is not only effective gramThe austenitic stainless steel is subjected to a most favorable heating temperature interval with low thermal conductivity and severe high-temperature expansion and reduced thermal stress and deformation below 700-800 ℃, and is also quickly avoided from a most favorable heating temperature interval of 450-500 ℃ (a chromium-poor precipitation critical temperature area and a large-granularity needle-rod-shaped carbide precipitation critical temperature area), 475 ℃ (a cold brittleness critical temperature area and a large-granularity needle-rod-shaped carbide precipitation critical temperature area), 550-670 ℃ (graphitization, intergranular corrosion or crystal brittle fracture critical temperature area) and the like in a heating stage; the stabilizing temperature Tscs interval before solid solution of the second stage of critical solid solution is not only used for reducing the deformation and residual stress of the workpiece and facilitating the solid solution of Cr but also used for dissolving Cr without forming Cr23C6The steel is characterized in that the steel forms a stable TiC or NbC most favorable heating and heat preservation temperature interval by the aid of the strengthening phase (the strengthening phase is not precipitated in the intergranular region and does not lean chromium in the grain boundary), and also quickly avoids 700-815 ℃ (a sensitized intercrystalline corrosion critical temperature region), 940 ℃ (a FeS-FeO eutectic melting point and a dissolution genetic critical temperature region), 985 ℃ (a Fe-FeS eutectic melting point and a dissolution genetic critical temperature region) and a most favorable heating temperature interval close to an effective solid solution minimum temperature Tcmc and the like in a temperature raising stage; the solid solution minimum temperature Tcmc interval of the critical solid solution third stage is an effective solid solution minimum temperature interval, and is also an optimum heating temperature interval which rapidly avoids 940 ℃ (FeS-FeO eutectic melting point and dissolution inheritance critical temperature zone), 985 ℃ (Fe-FeS eutectic melting point and dissolution inheritance critical temperature zone), 1083 ℃ (weakening phase copper alloy dissolution and inheritance critical temperature zone), 1164 ℃ (FeS-MnS eutectic melting point and dissolution inheritance critical temperature zone) and the like in the temperature rising stage; the solid solution highest temperature Tsccax interval of the critical solid solution fourth stage is an effective solid solution highest temperature interval, and is also an optimal heating temperature interval which rapidly avoids 1083 ℃ (a weakened phase copper alloy dissolution and heredity critical temperature area), 1164 ℃ (a FeS-MnS eutectic melting point and dissolution heredity critical temperature area), 1193 ℃ (a FeS compound melting point and a dissolution heredity critical temperature area) and the like in the temperature rising stage. The final results show that: the critical solid solution is set to be in the temperature intervals with different stages 4, so that the potential special function of solid solution can be fully excavated, the solid solution capacity, the quality, the efficiency and the like can be greatly improved, and particularly, the critical solid solution can be usedThe solid solution strengthening phase is greatly increased, the solid solution weakening phase is reduced or inhibited, the heating stress is reduced, the high-temperature heating time is reduced, the anti-tarnishing capacity is improved, the efficiency is improved, the service life of high-temperature components of heating equipment is prolonged, and the like.
In the embodiment of the invention, the mathematical relation between the critical pre-solid solution preheating temperature Tsccp and the solid solution minimum theoretical heating temperature Tcmin is as follows: ttscp is Tsctmin- (330-350) DEG C;
wherein Tspc is the preheating temperature before critical solid solution, DEG C, and is also the heating temperature of the first stage of critical solid solution; tsctmin is the critical solution minimum theoretical heating temperature, DEG C.
In the embodiment of the invention, the mathematical relation between the critical pre-solid solution stabilizing heating temperature Tscs and the solid solution minimum theoretical heating temperature Tcmin is as follows: tscs is Tsctmin- (120-150) DEG C;
wherein Tscs is the stabilizing heating temperature before critical solid solution, DEG C, and is also the heating temperature of the second stage of critical solid solution; tsctmin is the critical solution minimum theoretical heating temperature, DEG C.
In an embodiment of the present invention, the mathematical relationship between the critical solid solution minimum heating temperature Tscmin, the solid solution minimum theoretical heating temperature Tsctmin, and the copper alloy dissolution critical temperature is as follows:
Tsctmin+(5～10)℃≤Tscmin≤1083℃–(13～15)℃
tscomin is the critical solid solution minimum heating temperature, DEG C, and is the heating temperature of the critical solid solution third stage; tsctmin is the critical solution minimum theoretical heating temperature, DEG C; 1083 ℃ is the copper alloy dissolution critical temperature, DEG C.
In the embodiment of the invention, the mathematical relation between the critical solid solution maximum heating temperature Tcmax and the solid solution maximum theoretical heating temperature Tctmax and the FeS-MnS eutectic dissolution critical temperature is as follows:
Tscmax≤Tsctmax≤1164℃–(12～14)℃
wherein Tsmax is the critical solid solution maximum heating temperature, DEG C, and is also the heating temperature of the fourth stage of the critical solid solution; tstmax is the critical maximum theoretical heating temperature of solid solution, DEG C; the temperature of 1164 ℃ is the dissolution critical temperature of the FeS-MnS eutectic, and the temperature is lower.
In the examples of the present invention, the critical solution time is divided into 4 stages: and 4-stage heating time of critical pre-solid solution preheating, critical pre-solid solution stabilizing, critical solid solution lowest temperature and critical solid solution highest temperature corresponding to the critical solid solution 4-stage heating temperature respectively.
In the embodiment of the invention, the critical solid solution time is not too long nor too short: when the temperature is too long, the solid solution is sufficient but exceeds the solubility limit degree of the strengthening phase, the weakening phase is increased, and the high-temperature load time of the high-temperature component of the equipment is also increased; if too short, the solid solution strengthening phase is not sufficiently dissolved, and therefore, the 4-stage critical solid solution heating time is performed by a decreasing time method, i.e., preheating before solid solution, stabilizing before solid solution, sufficiently dissolving the lowest temperature, and heating at the highest temperature of solid solution are performed by τs1＞τs2＞τs3＞τs4The method can effectively and rapidly dissolve and increase the solid solution strengthening phase, reduce or inhibit the solid solution weakening phase, effectively reduce the heating stress, reduce the heating time under the highest temperature condition, improve the anti-tarnishing capacity, improve the heat treatment efficiency and prolong the service life of high-temperature components of heating equipment.
In the embodiment of the invention, the critical solid solution time is carried out according to a decreasing time method, and the heating time tau at each stage of the decreasing time methodsnPreheating heating time tau before critical solid solutions1And decreasing the time step difference τs0The mathematical relationship of (a) is: tau issn＝[τs1–(n–1)τs0]；
In the formula tausnHeating time, min or h, tau, at each stage of the critical solid solution decreasing time methodsnIs divided into taus1、τs2、τs3、τs4，τs1＞τs2＞τs3＞τs4；τs1Preheating heating time before solid solution in a critical solid solution first stage, wherein the preheating heating time is min or h; tau iss2Stabilizing and heating time before solid solution in a second stage of critical solid solution for min or h; tau iss3Heating time is the lowest solid solution temperature of the third stage of critical solid solution for min or h; tau iss4Is critical solid solutionMaximum solution temperature heating time of the fourth stage, min or h, taus4Less than or equal to 5 min; n is the number of the nth stage of the critical solution heating, and n is 1, 2, 3, 4; tau iss0The decreasing time step difference of the critical solid solution heating, min or h, is the same and unchanging specific numerical value.
In an embodiment of the present invention, the first part critical solution heat treatment final cooling method is: cooled in room temperature water.
In an embodiment of the present invention, the first part of the critical solution heat treatment process is:
in the first stage, the austenitic stainless steel is heated to the preheating temperature Tsccp at a medium speed from room temperature in a heating furnace for critical preheating heating before solid solution (and the heating time tau specified by the process is useds1Heating and preserving heat within the range);
in the second stage, the austenitic stainless steel is continuously heated from the preheating temperature Tsccp to the stabilizing temperature Tscs rapidly for critical stabilizing heating before solid solution (and heating time tau specified by the process is carried outs2Heating and preserving heat within the range);
in the third stage, the austenitic stainless steel is continuously heated from the stabilizing temperature Tscs to the solid solution minimum temperature Tcmin rapidly to carry out the critical solid solution minimum temperature heating (and within the time tau specified by the process)s3Heating and preserving heat within the range);
and in the fourth stage, the austenitic stainless steel is rapidly heated from the solid solution minimum temperature Tcmin to the solid solution maximum temperature Tcmax for critical solid solution maximum temperature heating (and the heating time tau specified by the process is useds4Heating and preserving heat within the range);
and finally, continuously discharging the austenitic stainless steel from the furnace at the maximum solid solution temperature Tcmax, and rapidly cooling the austenitic stainless steel in cooling medium room-temperature water (and placing the cooled workpiece on a working site under room-temperature conditions).
In an embodiment of the invention, the second part of the critical is initiated by the low temperature alternating ageing heat treatment method: the method is a low-temperature alternate aging heat treatment method starting from the second stage heating temperature interval, the multi-stage heating sequence, the multi-stage heating time, the multi-stage heating times, the specific cooling mode and other conditions.
In the embodiment of the invention, the total number of the alternate aging times of the second part critical starting from the low temperature and ending at the high temperature alternate aging heat treatment is 1 time, 1 time comprises 1 or more and less than or equal to 5 times of N, N is 1, or 2, 3, or 4, 5, and finally, the alternate aging process is ended in N is 1, 3 or 5 times (each alternate aging process at least comprises 1 time of temperature rise and 1 time of temperature drop at the same time).
In the embodiment of the invention, the total number of the alternate aging times of the second part starting from the low temperature and ending at the low temperature alternate aging heat treatment is 1 time, wherein 1 time comprises 2 ≤ N ≤ 6 times, N ≤ 2, or 3, 4, or 5, 6 times, and finally the alternate aging process is ended with N ═ 2, 4, or 6 times (each alternate aging process at least comprises 1 time of temperature rise and 1 time of temperature fall at the same time).
In the embodiment of the present invention, the second part of the critical point starts in the multi-stage temperature-increasing aging temperature section relating to low-temperature alternating aging: the method comprises a 1 st critical multi-stage non-alternating temperature-rise aging temperature interval: starting from a critical multi-stage heating and aging minimum heating temperature interval Tacmin (marked as Tacmin-1), sequentially passing through n-2 critical multi-stage aging intermediate heating temperature intervals Tacm (marked as Tacm-1) and finally ending to a critical multi-stage aging maximum heating temperature interval Tacmax (marked as Tacmax-1), wherein n is more than or equal to 3 and less than or equal to 7, namely n is 3, 4, 5, 6 or 7; critical multi-stage temperature rise alternating aging temperature interval of 2 nd, 3 rd or 4 th time: the critical temperature-rising aging process is sequentially repeated, and the relation of the numerical values of the critical multi-stage temperature-rising alternating aging lowest temperature interval of the 1 st time, the 2 nd time, the 3 rd time and the 4 th time is as follows: tacmin-1-2-3-4, and the relation of the intermediate heating temperature interval values of the 1 st, 2 nd, 3 rd and 4 th heating time is as follows: the relationship of the maximum temperature interval value of the 1 st, 2 nd, 3 rd and 4 th critical multi-stage temperature rise alternating aging is as follows: tacmax-1 ═ Tacmax-2 ═ Tacmax-3 ═ Tacmax-4.
In the embodiment of the invention, the second part starts from a multi-stage temperature reduction and aging temperature interval related to low-temperature alternating aging: the method comprises a 1 st critical multi-stage non-alternating cooling aging temperature interval: starting from a critical multi-stage cooling and aging highest heating temperature interval Tacmax (marked as Tacmax-1), sequentially passing through n-2 critical multi-stage aging intermediate heating temperature intervals Tacm (marked as Tacm-1) and finally ending to a critical multi-stage aging lowest heating temperature interval Tacmin (marked as Tacmin-1), wherein n is more than or equal to 3 and less than or equal to 7, namely n is 3, 4, 5, 6 or 7; critical multi-stage cooling alternating aging temperature interval of 2 nd, 3 rd or 4 th time: the critical multi-stage cooling and aging process is sequentially repeated, and the relation of the numerical values of the critical multi-stage cooling alternating aging lowest temperature interval of the 1 st time, the 2 nd time, the 3 rd time and the 4 th time is as follows: tacmin-1 ═ Tacmin-2 ═ Tacmin-3 ═ Tacmin-4, and the relation of the values of the intermediate heating temperature interval of the 1 st, 2 nd, 3 rd and 4 th critical multi-stage cooling alternating aging is as follows: the relationship formula of the highest temperature interval value of the 1 st, 2 nd, 3 rd and 4 th critical multi-stage cooling alternating ageing is as follows: tacmax-1 ═ Tacmax-2 ═ Tacmax-3 ═ Tacmax-4.
In the embodiment of the invention, because the ageing temperature range of the austenitic stainless steel is narrow (between 170 ℃ and 230 ℃), the critical starting point is neither too small nor too much in the low-temperature alternating ageing temperature range: when the aging temperature range is 1 stage (no temperature difference), 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, setting the critical starting point low-temperature alternating aging temperature interval to be 3 ≦ n ≦ 7, i.e. n ≦ 3, 4, 5, 6, or 7 stages may be more beneficial to improve aging capability, range, quality, efficiency, etc.
In the embodiment of the invention, the second part of critical starting from the low temperature alternating ageing temperature region has the following main functions: wherein, the critical aging minimum heating staged temperature Tacmin interval is the minimum temperature interval of effective aging, and is also the most beneficial heating and heat preservation temperature interval which rapidly avoids 450 ℃ -500 ℃ (chromium-poor precipitation critical temperature area and large-particle-size needle-rod carbide precipitation critical temperature area), 475 ℃ (cold brittleness critical temperature area and large-particle-size needle-rod carbide precipitation critical temperature area), 550 ℃ -670 ℃ (graphitization, intercrystalline corrosion or along crystal brittleness critical temperature area) and the like in the temperature rising and cooling stage; the critical intermediate aging n-2 staged temperature Tacm intervals are the optimal heating and heat preservation temperature intervals between a critical temperature-raising aging minimum heating temperature Tacmin interval and a critical temperature-raising aging maximum heating temperature Tacmax interval; the critical aging maximum heating temperature Tacmax interval is the maximum temperature interval of effective aging, and is also the critical temperature interval of rapidly avoiding 850 ℃ -900 ℃ in the cooling and heating stages (forming a sigma phase critical temperature area, and slightly precipitating (Fe, Cr, Ni, Mn, W, Mo) C composite alloy carbide or lamellar carbide). Therefore, setting the critical starting point low-temperature alternating ageing temperature interval as n staged intervals can more effectively increase the ageing strengthening phase, reduce or inhibit the ageing weakening phase, obtain the optimized hardness interval range with good quality stability, high reliability and good consistency of heat treatment hardness, improve the anti-tarnishing capacity, improve the heat treatment efficiency and the like.
In the embodiment of the invention, the second part of the critical starting point is that the mathematical relation between the low-temperature alternating aging maximum heating temperature Tacmax and the aging maximum theoretical heating temperature Tactmax is as follows:
Tacmax＝Tactmax–(20～30)℃
wherein Tacmax is the critical temperature starting from the highest heating temperature of low-temperature alternating aging at DEG C; tactmax is the maximum theoretical heating temperature of aging at DEG C.
In the embodiment of the invention, the second part of the critical starting point is represented by the mathematical relation between the low-temperature alternating aging minimum heating temperature Tacmin and the aging minimum theoretical heating temperature Tactmin:
Tacmin＝Tactmin+(20～30)℃
in the formula, Tacmin is the critical temperature starting from the lowest heating temperature of low-temperature alternating aging at DEG C; tactmin is the lowest theoretical heating temperature of aging at DEG C.
In the embodiment of the invention, the mathematical relation between the intermediate heating temperature Tacm of the second part starting from each stage of the low-temperature alternating ageing and the ageing minimum heating temperature Tacmin and the ageing maximum heating temperature Tacmax is as follows: tacm ═ Tacmin + ni(Tacmax–Tacmin)/(n–1)；
Wherein Tacm is the intermediate heating temperature and DEG C of each stage of low-temperature alternating aging, and is the specific stage temperature from the 2 nd stage to the 2 nd last stage of low-temperature heating or cooling alternating aging; tacmin is the critical temperature starting from low temperature heating or cooling alternating aging minimum heating temperature, DEG C; n isiThe specific nth heating temperature interval from the 2 nd to the 2 nd last stages from low to high or from high to lowiNumber of stages, n being not less than 1iN is less than or equal to 5i1, 2, 3, 4 or 5; tacmax is the critical maximum heating temperature of alternating aging at low temperature heating or cooling; (Tacmax-Tacmin)/n is a specific constant value starting from the critical point of increasing or decreasing the temperature at low temperature by increasing or decreasing the temperature difference at a certain degree; n is the total number of stages starting from the critical aging minimum temperature Tacmin and ending at the critical aging maximum heating temperature Tacmax or starting from the critical aging maximum heating temperature Tacmax and ending at the critical aging minimum heating temperature Tacmin, 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 embodiment of the invention, the mathematical relation between the critical starting low-temperature alternating aging working heating temperature Tacw and the workpiece use temperature Tw, the critical starting low-temperature alternating aging minimum heating temperature Tacmin and the critical starting low-temperature alternating aging maximum heating temperature Tacmax is as follows:
Tacmin＜Tw+(60～100)℃≤Tacw≤Tacmax
wherein Tacw is critical starting from the low-temperature alternating aging working heating temperature, DEG C, and Tacw at least occurs once in each critical intermediate aging heating temperature Tacm interval; tw is the workpiece use temperature, DEG C; tacmin is the critical temperature starting from the lowest heating temperature of low-temperature alternating aging at DEG C; tacmax is the critical temperature starting from the maximum heating temperature of low-temperature alternating aging at DEG C.
In the embodiment of the present inventionThe second part of the critical period starts at a total time of low-temperature alternate ageing which can be neither too short nor too long: if the time is too short, the alloy element strengthening phase can only reach the limited aging precipitation capacity, range, quality, efficiency and the like; if the aging capacity, range, quality, efficiency and the like of the alloy element strengthening phase are too long, the alloy element strengthening phase can reach a saturated or limit state. The critical point begins with the total time tau of low-temperature alternating ageingacNAnd the total time tau of theoretical agingaNtThe mathematical relationship of (a) is: tau isacN＝(1/2～1/3)τaNt；
In the formula tauacNThe critical starting time is the total time of low-temperature alternating aging, min or h; tau isaNtThe theoretical total aging time is min or h.
In the embodiment of the invention, when the critical starting from the low-temperature alternating ageing time is carried out according to the equal time method, the critical starting from the low-temperature alternating ageing heating total time tau of the equal time methodacNHeating time tau in each stage corresponding to heating temperature intervals of 1 st, 2 nd, 3 rd, … …, and nth stagesacnThe mathematical relationship of (a) is: tau isacN＝∑τacn＝∑τacN/N；
In the formula tauacNThe critical point of the equal time method is the total time of low-temperature alternating aging heating, min or h; tau isacnHeating time of each stage corresponding to aging in heating temperature ranges of 1 st stage, 2 nd stage, 3 rd stage, … … and nth stage of low-temperature alternating aging is determined as tauac1、τac2、τac3、τac4、τac5、τac6、τac7，τac1＝τac2＝τac3＝τac4＝τac5＝τac6＝τac7(ii) a N is the total number of stages from the critical start of low-temperature alternating 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); n is the number of the nth stage starting from the low-temperature alternating ageing 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 embodiment of the invention, the time method is increased according to the increasing time method when the critical point begins to be low-temperature alternating aging timeIn the process, the critical point of the increasing time method begins from the total time tau of low-temperature alternating ageing heatingacNHeating time tau in each stage of aging corresponding to heating temperature intervals of 1 st, 2 nd, 3 rd, … …, and nth stages of heatingacnThe mathematical relationship of (a) is: tau isacN＝∑τacn＝∑[τac1+(n–1)τac0]；
In the formula tauacNStarting from the total heating time of low-temperature alternating aging for min or h as the critical point of the increasing time method; n is-critical, starting from the heating time of each stage of low-temperature alternating ageing, min/time or h/time, and is respectively tauac1、τac2、τac3、τac4、τac5、τac6、τac7，τac1＞τac2＞τac3＞τac4＞τac5＞τac6＞τac7(ii) a n is the number of the nth stage from the critical start of low-temperature alternating 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 isac1Heating time is in a first stage of low-temperature alternating ageing for min/time or h/time; tau isac0The critical point is started from the increasing grade difference of the low-temperature alternating aging heating time, min/time or h/time, and the critical point is the same and unchangeable specific numerical value.
In the embodiment of the invention, when the critical starting from the low-temperature alternating ageing time is carried out according to a decreasing time method, the critical starting from the low-temperature alternating ageing heating total time tau of the decreasing time methodacNHeating time tau in each stage corresponding to heating temperature intervals of 1 st, 2 nd, 3 rd, … …, and nth stagesacnThe mathematical relationship of (a) is: tau isacN＝∑τacn＝∑[τac1–(n–1)τac0]；
In the formula tauscNThe criticality of the decreasing time method is started from the total time of low-temperature alternating aging heating for min/time or h/time; n is the total number of stages from the critical start of low-temperature alternating 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 isacnHeating temperature regions for the 1 st, 2 nd, 3 rd, … …, nth phases of low-temperature alternating agingHeating time at each stage of time aging, min/time or h/time, respectively is tauac1、τac2、τac3、τac4、τac5、τac6、τac7，τac1＜τac2＜τac3＜τac4＜τac5＜τac6＜τac7(ii) a n is the number of the nth stage from the critical start of low-temperature alternating 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 isac1Heating for min/time or h/time at the critical point in the first stage of low-temperature alternating ageing; tau isac0The critical point is started from low temperature alternating aging heating and time level difference is decreased for min/time or h/time, and the time level difference is the same and unchanged specific numerical value.
In the embodiment of the invention, the mathematical relation between the final cooling starting temperature Tacch of the second part starting from the low temperature and ending from the high temperature alternating ageing and the maximum temperature Tacmax of the second part starting from the low temperature alternating ageing is as follows: tacch ═ Tacmax- (60-90) DEG C;
wherein, the Tacch is the critical starting temperature from low temperature to high temperature alternating aging and the final cooling starting temperature is DEG C; tacmax is the critical point starting from the maximum temperature of low-temperature alternating aging, DEG C.
In the embodiment of the invention, the mathematical relation between the final cooling starting temperature Tacch of the second part starting from the low temperature and ending at the low temperature alternating ageing and the minimum temperature Tacmin of the second part starting from the low temperature and ending at the low temperature alternating ageing is as follows: tacch ═ Tacmin + (60-90) DEG C;
wherein, the Tacch is the critical starting temperature from low temperature to low temperature alternating aging and the final cooling starting temperature at DEG C; tacmin is the critical point starting from the highest temperature of low-temperature alternating aging at DEG C.
In the embodiment of the invention, the final cooling mode of the second part of the alternating ageing heat treatment starting from the low temperature and ending at the high temperature is as follows: opening a furnace door or adopting other cooling modes without discharging from the furnace, quickly cooling from the critical temperature beginning at the low temperature and ending at the high temperature alternating aging highest temperature Tacmax to the critical temperature beginning at the low temperature and ending at the high temperature alternating aging and final cooling starting temperature Tacch, then discharging without heat preservation, and cooling in room temperature water.
In the embodiment of the invention, the cooling mode of the second part of the alternating aging from the low temperature to the low temperature is as follows: the furnace door is opened or other cooling modes are adopted to rapidly raise the temperature from the critical temperature beginning at the low temperature and ending at the low temperature aging minimum temperature Tacmin to the critical temperature beginning at the low temperature and ending at the low temperature aging final cooling start temperature Taccl without preserving the temperature and then cooling in room temperature water.
In an embodiment of the invention, the second part of the critical process starts with a low temperature alternating ageing heat treatment process comprising the following steps: the 1 st critical process begins with the low temperature alternating aging process: the method specifically comprises the following steps that 1, the first half part of the process is critical, starts from low temperature to high temperature and has no alternating aging process: firstly, in a specified time, the temperature of the austenitic stainless steel after the first critical solid solution process is finished is quickly raised to a critical aging lowest temperature range Tacmin from room temperature in a heating furnace, heating and heat preservation are carried out, secondly, the critical aging middle temperature heating and heat preservation are carried out when the austenitic stainless steel is quickly raised to the aging middle temperature, and thirdly, the critical aging highest temperature heating and heat preservation are carried out when the austenitic stainless steel is quickly raised to the final aging highest temperature (the first half critical starting at low temperature and the high temperature non-alternating aging process ending at the first 1 time), and then, the second half of the first 1 time is continued to start at high temperature and end at low temperature alternating aging process: firstly, continuously heating and preserving at critical aging intermediate temperature when the austenitic stainless steel is rapidly cooled from the critical aging maximum temperature to the aging intermediate temperature in a heating furnace within a specified time, and then continuously heating and preserving at critical aging minimum temperature when the austenitic stainless steel is rapidly cooled from the critical aging intermediate temperature to the critical aging minimum temperature in the heating furnace within the specified time (the 1 st half critical is started from high temperature to low temperature alternating aging process and the 1 st critical is started from low temperature alternating aging process and is also completely finished); after the 1 st critical starting from the low temperature and ending the low temperature alternating aging process, the 2 nd, 3 rd, … … th or Nth critical alternating aging process is carried out again: critical alternating aging for 2 times, sequentially and reversely repeating the first half part of critical time from the high temperature to the low temperature alternating aging process for 1 time (the critical time for 2 times from the low temperature to the end of the high temperature alternating aging process), or critical alternating aging for 3 times, sequentially and reversely repeating the critical alternating aging process for 2 times for 1 time (the critical time for 3 times from the high temperature to the end of the low temperature alternating aging process), … …, and so on, or critical alternating aging for N times, and sequentially and reversely repeating the critical alternating aging process for 1 time from N to 1 time (the critical time for N times from the low temperature to the high temperature or the critical time from the high temperature to the end of the low temperature alternating aging process); and (3) after the 2 nd, 3 rd, … … th or Nth critical start from low temperature to high temperature or the critical start from high temperature to low temperature, the end of the alternating aging process, continuing the final cooling process: the method is characterized in that the method adopts a furnace door opening or other cooling modes to rapidly cool the austenitic stainless steel along with the furnace from the critical process steps of starting from the low temperature to the high temperature alternating aging highest temperature or starting from the high temperature to the low temperature alternating aging lowest temperature to the room temperature, and the like, and the critical process starts from the low temperature alternating aging heat treatment process (the second part of critical process starts from the end of the whole process of the low temperature alternating aging heat treatment process).
According to the technical scheme, the invention fundamentally solves the special heat treatment technical theory and practical problems of 'one long, one high, four poor and five low', such as poor quality stability, low qualified product rate, low hardness (or low mechanical property) and poor consistency, poor anti-tarnishing capacity, long heating time, low efficiency, poor heating reliability of heat treatment equipment, low service life of high-temperature components and high cost ', and the like' which cannot be solved by the conventional austenitic stainless steel heat treatment technology.
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 heat treatment methods 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 critical solid solution and critical start low temperature alternate aging heat treatment method is characterized by comprising the following steps:
a critical solution heat treatment process, the critical solution heat treatment process comprising: critical preheating heating and heat preservation before solid solution are carried out when the temperature of austenitic stainless steel is raised to the preheating temperature from room temperature at a medium speed in a heating furnace within a specified time, then critical stabilizing heating and heat preservation before solid solution are carried out when the temperature of austenitic stainless steel is raised to the stabilizing temperature, critical solid solution minimum temperature heating and heat preservation are carried out when the temperature of austenitic stainless steel is raised to the solid solution minimum temperature, critical solid solution maximum temperature heating and heat preservation are carried out when the temperature of austenitic stainless steel is raised to the solid solution maximum temperature, and solid solution cooling is carried out when the temperature of austenitic stainless steel is lowered to the room temperature by a specific cooling mode;
after the critical solution heat treatment is finished, the critical solution heat treatment process is continued to start at the low-temperature alternate aging heat treatment process, and the critical solution heat treatment process starting at the low-temperature alternate aging heat treatment process comprises the following steps: the 1 st critical process begins with the low temperature alternating aging process: the method specifically comprises the following steps that 1, the first half part of the process is critical, starts from low temperature to high temperature and has no alternating aging process: firstly heating and preserving the austenite stainless steel at the critical aging lowest temperature when the temperature of the austenite stainless steel is raised to the critical aging lowest temperature from room temperature at a medium speed in a heating furnace within a specified time, then continuously heating and preserving the austenite stainless steel at the critical aging middle temperature when the temperature of the austenite stainless steel is raised to the aging middle temperature, then continuously heating and preserving the austenite stainless steel at the critical aging highest temperature when the temperature of the austenite stainless steel is raised to the final aging highest temperature, and then continuing the 1 st half of the process from the high temperature to the low temperature alternating aging process: firstly, continuously heating and preserving heat at critical aging intermediate temperature when the austenitic stainless steel is rapidly cooled from the critical aging maximum temperature to the aging intermediate temperature in a heating furnace within the specified time, and then continuously heating and preserving heat at critical aging minimum temperature when the austenitic stainless steel is rapidly cooled from the critical aging intermediate temperature to the critical aging minimum temperature in the heating furnace within the specified time;
after the 1 st critical starting from low temperature and ending with the low temperature alternating aging process, the 2 nd, 3 rd, … … th and Nth critical alternating aging processes are carried out again: critical alternating aging for the 2 nd time, sequentially and reversely repeating the 1 st half critical time from the high temperature to the low temperature alternating aging process for 1 time, critical alternating aging for the 3 rd time, sequentially and reversely repeating the 2 nd critical alternating aging process for 1 time, … …, and so on, and sequentially and reversely repeating the N-th critical alternating aging process for 1 time;
and (3) after the 2 nd, 3 rd, … … th and Nth critical start from low temperature to high temperature or critical start from high temperature to low temperature, the last cooling process is continued: and (3) cooling the austenitic stainless steel discharged from the furnace by opening a furnace door or other cooling modes when the temperature is rapidly reduced to room temperature from the critical temperature beginning at the low temperature and ending at the high temperature alternating ageing highest temperature or beginning at the high temperature and ending at the low temperature alternating ageing lowest temperature.
2. The method of claim 1, wherein the critical solution heat treatment is performed for a total number of solution times of 1.
3. The method of claim 1, wherein the critical solution temperature interval is defined as: and a 4-stage critical solid solution heating temperature range which starts from the stage of raising the temperature from room temperature to the critical pre-solid solution preheating temperature Tsccp, continues to raise the temperature to the critical pre-solid solution stabilizing temperature Tscs, continues to raise the temperature to the critical solid solution lowest temperature Tcmin, and finally raises the temperature to the critical solid solution highest temperature Tcmax.
4. The method of claim 1, wherein the mathematical relationship between the critical solution preheating temperature Tscp and the solution minimum theoretical heating temperature Tscmin is as follows: ttscp is Tsctmin- (330-350) DEG C;
wherein Tsscp is the preheating temperature before critical solid solution, and the unit is; tsctmin is the critical solution minimum theoretical heating temperature in degrees Celsius.
5. The method of claim 1, wherein the mathematical relationship between the critical solution heating temperature before solid solution Tscs and the solution minimum theoretical heating temperature Tcmin is as follows: tscs is Tsctmin- (120-150) DEG C;
wherein Tscs is the stabilizing heating temperature before critical solid solution, and the unit is; tsctmin is the critical solution minimum theoretical heating temperature in degrees Celsius.
6. The critical solid solution and multiple temperature rise and temperature change aging heat treatment method according to claim 1, wherein the mathematical relationship between the critical solid solution minimum heating temperature Tcmc, the solid solution minimum theoretical heating temperature Tsctmin and the copper alloy dissolution critical temperature is as follows:
Tsctmin+(5～10)℃≤Tscmin≤1083℃–(13～15)℃
wherein Ttscmin is the critical solid solution minimum heating temperature, and the unit is; tsctmin is the critical solid solution minimum theoretical heating temperature, and the unit is; 1083 ℃ is the copper alloy dissolution critical temperature in units of ℃.
7. The method for the low-temperature alternating aging heat treatment for critical solid solution and critical start according to claim 1, wherein the mathematical relationship between the critical solid solution maximum heating temperature Tcmc and the solid solution maximum theoretical heating temperature Tctmax and the FeS-MnS eutectic dissolution critical temperature is as follows:
Tscmax≤Tsctmax≤1164℃–(12～14)℃
wherein Tsmax is the critical solid solution maximum heating temperature, and the unit is; tstmax is the critical solid solution maximum theoretical heating temperature, and the unit is; the temperature of 1164 ℃ is the dissolution critical temperature of the FeS-MnS eutectic, and the unit is ℃.
8. The method of claim 1, characterized in that the critical solid solution is divided into 4 stages of heating time: and 4-stage heating time of critical pre-solid solution preheating, critical pre-solid solution stabilizing, critical solid solution lowest temperature and critical solid solution highest temperature corresponding to the critical 4-stage solid solution temperature.
9. The method of claim 1, wherein the critical solution time is determined by a decreasing time method, wherein the heating time τ is determined for each step of the decreasing time methodscnPreheating heating time tau before solid solutionsc1And decreasing the time step difference τsc0The mathematical relationship of (a) is:
τscn＝[τsc1–(n–1)τsc0]
wherein, tauscnHeating time, min or h, tau, at each stage of the critical solid solution decreasing time methodscnIs divided into tausc1、τsc2、τsc3、τsc4，τsc1＞τsc2＞τsc3＞τsc4；τsc1Preheating and heating time before solid solution for critical solid solution, wherein the time is min or h; tau issc2Stabilizing and heating time before solid solution for critical solid solution, min or h; tau issc3Heating time which is the critical solid solution minimum temperature of critical solid solution for min or h; tau issc4Heating time of maximum solution temperature for critical solid solution, min or h, tausc4Less than or equal to 5 min; n is the number of the nth stage of the critical solution heating, and n is 1, 2, 3, 4; tau issc0Decreasing time step difference of critical solution heating, minOr h, are the same constant specific values.
10. The method of critical solution and critical start low temperature alternating age heat treatment of claim 1, wherein the critical solution heat treatment process comprises:
the first stage is as follows: austenitic stainless steel is placed in a furnace for a process-defined time τsc1Heating from room temperature to a critical preheating temperature Tsccp at a medium speed, and performing critical preheating heating and heat preservation before solid solution;
and a second stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tausc2Rapidly heating from the critical preheating temperature Tspc to the critical stabilizing temperature Tscs for critical stabilizing heating and heat preservation before solid solution;
and a third stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tausc3Rapidly heating from the critical stabilization temperature Tscs to the critical solid solution minimum temperature Tcmin to carry out critical solid solution minimum temperature heating and heat preservation;
a fourth stage: then the austenitic stainless steel is continuously placed in the heating furnace for the specified time tausc4Rapidly heating from the critical solid solution minimum temperature Tcmc to the critical solid solution maximum temperature Tcmax, and heating and preserving the critical solid solution maximum temperature;
and finally, continuously and quickly discharging the austenitic stainless steel from the furnace from the critical solid solution highest temperature Tcmc ax, and quickly cooling the austenitic stainless steel in cooling medium room-temperature water.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011427530.6A CN112795743A (en) | 2020-12-07 | 2020-12-07 | Critical solid solution and critical starting low-temperature alternating aging heat treatment method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011427530.6A CN112795743A (en) | 2020-12-07 | 2020-12-07 | Critical solid solution and critical starting low-temperature alternating aging heat treatment method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112795743A true CN112795743A (en) | 2021-05-14 |
Family
ID=75806458
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011427530.6A Pending CN112795743A (en) | 2020-12-07 | 2020-12-07 | Critical solid solution and critical starting low-temperature alternating aging heat treatment method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112795743A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114196801A (en) * | 2021-11-29 | 2022-03-18 | 中国科学院金属研究所 | Heat treatment method for improving intergranular corrosion resistance and mechanical property of carbon-controlled austenitic stainless steel |
-
2020
- 2020-12-07 CN CN202011427530.6A patent/CN112795743A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114196801A (en) * | 2021-11-29 | 2022-03-18 | 中国科学院金属研究所 | Heat treatment method for improving intergranular corrosion resistance and mechanical property of carbon-controlled austenitic stainless steel |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112553431A (en) | Critical solid solution and critical high-temperature alternative aging and annealing heat treatment method | |
| CN112795743A (en) | Critical solid solution and critical starting low-temperature alternating aging heat treatment method | |
| CN112725580A (en) | Critical solid solution and critical starting low-temperature multiple-temperature alternating aging heat treatment method | |
| CN114395668A (en) | Critical solid solution and critical multiple cooling and temperature varying aging and annealing composite heat treatment method | |
| CN112779394A (en) | Critical solid solution and critical cooling aging and annealing heat treatment method | |
| CN112725587A (en) | Critical solid solution and critical cooling and heating temperature-changing aging and annealing heat treatment method | |
| CN112695161A (en) | Multiple alternating ageing heat treatment method for critical solid solution and critical starting from low temperature | |
| CN114410922A (en) | Critical solid solution and critical multiple-temperature-rise variable-temperature aging composite heat treatment method | |
| CN114395686A (en) | Full solid solution and full high-temperature variable-temperature alternating aging composite heat treatment method | |
| CN114410915A (en) | Critical solid solution and critical starting low-temperature alternating aging composite heat treatment method | |
| CN114395682A (en) | Critical solid solution and critical multiple heating aging composite heat treatment method | |
| CN112725581A (en) | Critical solid solution and critical temperature-changing alternating aging heat treatment method starting from low temperature | |
| CN112779397A (en) | Critical solid solution and critical temperature rise and drop aging heat treatment method | |
| CN114410914A (en) | Critical solid solution and critical starting low-temperature multiple alternating aging composite heat treatment method | |
| CN112795750A (en) | Critical solid solution and multiple temperature rise variable temperature aging heat treatment method | |
| CN114410925A (en) | Critical solid solution and multiple variable temperature alternate aging composite heat treatment method starting from low temperature | |
| CN112779396A (en) | Critical solid solution and critical temperature rise and drop variable temperature aging heat treatment method | |
| CN112695173A (en) | Critical solid solution and critical temperature rise aging heat treatment method | |
| CN114395670A (en) | Critical solid solution and critical temperature-variable alternating aging composite heat treatment method | |
| CN112725579A (en) | Critical solid solution and critical multiple-heating aging heat treatment method | |
| CN114395676A (en) | Critical solid solution and critical temperature rise aging composite heat treatment method | |
| CN112553432A (en) | Multiple alternate ageing and annealing heat treatment method for critical solid solution and critical starting at high temperature | |
| CN112553430A (en) | Critical solid solution and high-temperature multiple variable-temperature alternating aging and annealing heat treatment method | |
| CN112795742A (en) | Critical solid solution and critical multiple cooling aging and annealing heat treatment method | |
| CN114410907A (en) | Critical solid solution and critical cooling aging and annealing composite heat treatment method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |