CN104641006B - The microprocessor and micro-structural of the ferrous alloy of carbide-containing - Google Patents

The microprocessor and micro-structural of the ferrous alloy of carbide-containing Download PDF

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CN104641006B
CN104641006B CN201380033764.4A CN201380033764A CN104641006B CN 104641006 B CN104641006 B CN 104641006B CN 201380033764 A CN201380033764 A CN 201380033764A CN 104641006 B CN104641006 B CN 104641006B
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temperature
bainite
steel
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CN104641006A (en
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加里·M·科拉
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • 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
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
    • C21D1/20—Isothermal quenching, e.g. bainitic hardening
    • 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
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
    • C21D1/22—Martempering
    • 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
    • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
    • 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
    • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
    • C21D1/607—Molten salts
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • 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

Abstract

There is provided herein for technique and device of the micro-treating iron-based alloy to be changed and/or shaped, and by ferrous alloy described in microprocessor come handle mild steel, medium carbon steel and high-carbon steel and other ferrous alloys with least formed containing martensite, bainite and undissolved carbide and also containing include bainite, coalesce bainite, acicular ferrite, retained austenite and/or martensite with and combinations thereof part polynary steel micro-structural mixing micro-structural and the resulting materials that obtain.

Description

The microprocessor and micro-structural of the ferrous alloy of carbide-containing
The cross reference of related application
This application claims U.S. Provisional Patent Application No.61/651,992 and U.S. Utility Patent application No.12/ 485,785 rights and interests, it is incorporated herein by reference.
Technical field
The present invention relates to treated ferrous alloy, and more particularly relate to be changed and/or shape Technique and mild steel, medium carbon steel and high-carbon steel and other metal ingredients and other are handled by ferrous alloy described in microprocessor Ferrous alloy with least formed containing martensite, bainite and undissolved carbide and can also contain include bainite, gather Tie bainite, pearlite, ferrite, acicular ferrite, retained austenite and/or martensite with and combinations thereof part it is polynary The mixing micro-structural of steel micro-structural and thus obtained various fine structure materials.
Background technology
Traditionally, metallurgist is desirable with low-quality metal such as mild steel, and (including is moved back by cheap processing Fire, quenching and tempering etc.) it is transformed into high-quality steel and more preferably product.The success that trial in the past obtains has very much Limit, because they not always produce preferable product.It is other to attempt due to high processing cost or need finally to combine excessively Expensive alloying and can not carry out on a large scale.
The processing of high strength steel generally require capital-intensive equipment, high cost, costly and hazardous heating fluid (such as Quenching oil and quenching salt), and tempering/annealing process, it is including the use of smelting furnace, firing equipment and more than the cast molten steel Heat.These quenching programs are intended to the hardness of steel bringing up to desired value.Bainite and martensite can pass through these technique systems Make and be ideal material for the application of some high intensity because they it is general have about more than 20 Rockwell C Hardness (Rockwell C hardness).Hardness increase is related to the comparable increase of tensile strength.
Typical AHSS generally comprises bainite and/or martensitic phase.Bainite be usually by ferrite with The needle-like steel that the combination of carbide is formed, it shows sizable toughness, while is combined with high intensity and high ductibility.From history On see, although commercially preparing bainite, bainite using austempering by very long austempering thermal cycle It is a kind of ideal product.One practical advantage of bainitic steel is, after bainite transformation generation, without further heat Processing is achieved with relatively high strength level and enough ductility.Such steel is easy to when being manufactured with low-carbon alloy Welding.It has been found that bainite is anti-be tempered and may be formed in the heat affected area adjacent with welding metal, so as to reduce crackle Incidence simultaneously provides fragility less weld seam.In addition, these steel with compared with low carbon content tend to improve weldability and reduced The caused stress due to transformation.When forming the bainite of austempering in medium carbon steel and high-carbon steel, due to higher Carbon equivalent content and cause weldability to reduce.
Another conventional high strength steel composition martensite is the hard supersaturation in the BCT of iron by carbon Another acicular microstructure that solid solution is formed.It is typically during the phase in version of martensite transfor mation or shearing transformation is referred to as The metastable state transition structure of formation, in the phase in version, larger austenitizing steel workpiece can be quenched to be turned in martensite Temperature and holding in the range of change are subsequently cooled to room temperature at said temperatures to reach overall balanced temperature.Relatively thin section Martensite be typically in quenching-in water.Because chemical process accelerates at relatively high temperatures, therefore martensite is easy to pass through application Heat and be tempered to much lower intensity.In some alloys, by add element such as tungsten that interference cementite nucleus formed come This effect is reduced, but this phenomenon is often utilized on the contrary.Because quenching is likely difficult to control, most of steel is by quenching Fire produces excessive martensite, is then tempered gradually to reduce its intensity, until realizing hardness/extension suitable for intended application Property structure.
The content of the invention
To be in band, piece, rod, plate, line, pipe, section bar, work using the cost of minimum, time and efforts according to the present invention The inferior grade ferroalloy of the forms such as part is changed into multiphase high strength steel.Two-phase and more polynary phase can be realized by implementing the present invention Material.Because the duration that ferrous alloy is heated to temperature selected by peak value from upper limit austenitizing temperature is short, Yi Jineng Enough quick achievement unit Fen Beishi bulk microstructures, therefore this method has been referred to as " quick bainite processing ".
There is provided for extremely rapidly the method and apparatus of microprocessor low-carbon ferrous alloy and by those alloys manufacture simultaneously Article containing those alloys.Iron-based or ferroalloy/article start have first micro- knot containing carbide before microprocessor Structure, and by the quick heating at least a portion of the alloy/article and high strength steel quickly is cooled to be changed into More than second yuan of micro-structural.
Disclose it is a kind of be used for quick micro-treating iron-based alloy to form the method for the high-strength alloy of at least one phase, its Described in method include to the first micro-structural ferrous alloy provide austenite transformation temperature the step of.This first micro- knot Structure can be by being higher than from being quickly heated up to less than austenite transformation temperature with high speed such as 300 ℉/second to 5000 ℉/second The selected temperature of austenite transformation temperature and be changed into include above-mentioned phase the second micro-structural ferrous alloy.Due to upper Lacking the time on limit austenitizing temperature makes the alloying element in the ferrous alloy of carbide-containing homogenize, therefore known this Second micro-structural is heterogeneous.For given alloy, the duration of the thermal cycle caused by by quickly heating is short, Therefore traditional austenite transformation temperature rise.This elevated austenitizing temperature is due to indivedual difficult to understand to a certain extent The equalization of the austenitizing temperature of existing a variety of alloy concentrations in steel in family name's body crystal grain.Because different concentration of carbons have Different upper limit austenitizing temperature, so concentration of carbon will be to austenitizing temperature present in most of previously austenite crystals Degree has maximum effect.The ferrous alloy being mainly made up of ferrite containing extremely low concentration of carbon will have closest in pure iron Ferritic relatively high upper limit austenitizing temperature.
This heating stepses include since less than the temperature of upper limit austenitizing temperature almost adding ferrous alloy immediately Heat is extremely higher than the selected temperature of its austenite transformation temperature.Then, once reaching temperature selected by peak value, just with heating unit phase In adjacent quenching unit, at least a portion of ferrous alloy, alloy is substantially quenched immediately, at high temperature without any reality Matter soak, it is most often in the speed being exceedingly fast, i.e. 300 ℉/second to 5,000 ℉/under the second.In some cases, it is desirable to compared with Slow or interruption quenching changes to formulate the continuous cooling transformation of the ferrous alloy of carbide-containing or time-temperature.This program exists The high-strength alloy of at least one phase is formed in desired region, depending on the position handled.Extremely fast quenching The high-strength alloy of at least one phase will be formed, as described more fully below.
Quenching can by various method and apparatus almost moment complete, including water-bath, water smoke, be cooled and shaped mould, air knife, Open air convection current, final operation cooling continuous mould, terminal stage cooling line mould, chill roll mould and quenching hydraulic pressure Shaping etc..By using fuse salt, oil, steam, heated gaseous solution, Cooling Quenching roller and many well known by persons skilled in the art Other mechanisms, relatively slow or interruption cooling is possible.It is unrelated with process for quenching, it is necessary to after heating-up temperature selected by peak value is reached Quenching is substantially immediately begun to homogenize to limit carbon diffusion, carbide dissolution and alloy.
Brief description of the drawings
Desired extent and the property of various embodiments and further understanding for advantage for the present invention, should be referred to following It is described in detail, and when being carried out with reference to accompanying drawing, wherein identical part is provided with identical reference, and wherein：
Figure 1A is the FEGSEM microphotos for the bainite processed according to the present invention；
Figure 1B is the FEGSEM microphotos for the bainite processed according to the present invention；
Fig. 2A is the curve map in the representative temperature measurement result of the inwall of processing pipe；
Fig. 2 B are cooling circulation time/temperature profiles of process according to the invention；
Fig. 2 C are to simulate heating and cooling circulation that austenite crystal develops with the time；
Fig. 3 is Transformation Analysis curve map of the temperature to temperature differential；
Fig. 4 A are the heterogeneous analyses of machinery of raw material；
Fig. 4 B are the similar analysis of the material of rapid processing；
Fig. 5 is curve map of the elongation to peak value heating-up temperature；
Fig. 6 is curve map of the stress to strain of various materials Examples；
Fig. 7 A are optics and SEM image of the steel before and after the processing of quick bainite；
Fig. 7 B are the transmission electron microscope images of the steel of quick bainite processing；
Fig. 8 shows the initial boundary conditions of simulation；
Fig. 9 A, 9B, 9C and 9D are the dissolutions modeled under the different rates of heat addition；
Figure 10 is the concentration gradient [C and Cr] at room temperature and at 1000 DEG C；And
Figure 11 is the continuous coo1ing figure of Fe-0.03C-0.3Cr weight % ferrous alloys.
Embodiment
According to the present invention, a kind of new method of metal processing is disclosed, it is by extremely rapidly heating metal, then standing Material rapid quenching is caused inferior grade ferrous alloy being changed into high strength steel.Gained steel is at least martensite, bayesian The heterogeneous composition of body, ferrite and the other structures discussed in greater detail below.
Thus, our experiment demonstrates that, after quick austenitizing and then rapid quenching have proven to be formed it is double Weight hardness micro-structural, as illustrated in the accompanying drawings.Experiment display, the rapid processing with the material of AISI4130 titles obtain about Multiple hardness peaks of 525 and 625 Vickers hardnesses (Vickers hardness).The combination of hardness passes through single-sensor differential thermal Analysis is confirmed, and two temperature ranges change during it is shown in single hardening step.In AISI 4130, in water Change during quenching from 1202 ℉ to 1022 ℉ and in addition from 860 ℉ to 680 ℉.
Although do not fully understand a variety of theories be present for the phenomenon of this dual-cooled transformation.The first is steel quilt It is quick to heat and also put down without generation carbon flow.Therefore, a variety of carbon and alloy concentrations be present under individual other grain size yardstick. Minimum carbon is contained in the former ferrite area, and the region of the former pearlite and carbide-containing has abundant carbon.Carbon is rich Integrate regions transform as martensite, and carbon starvation areas is changed into bainite.After quick bainite machines, previous carbonization Thing is generally almost completely present.
Alternatively possible theory is upper transformation temperature when austenite is changed into nanoscale platelet be present.Cooling down The second transformation that period occurs is that platelet is agglomerated into larger piece.
This dual transformation concept makes us obtain another aspect of the present invention.Due to dual transformation be present, can permit Perhaps the first transformation occurs, and stops the second transformation.For example, ferrous alloy is quickly heated up into selected peak temperature, after several seconds, Ferroalloy is quenched in the hardening media for changing start temperature less than the first transformation end temp but higher than second.The material The first transformation will be completed, but postpones the second transformation.
This can cause the quick bainite for for example forming the first stage, for example, the only non-coalescence bayesian body phase of nanometer, but stay Another phase of lower significant quantity, it may be possible to retained austenite, or the sub- product of some other austenites.Then material can be made from Temperature between one transformation end temp (i.e. 1022 ℉) and the second transformation start temperature (i.e. 860 ℉) reduces.Notice and carried The temperature of confession is from the heterogeneous experiment based on 4130 chemical steel.For other steel alloys with different chemical property, First and second transformation beginning and end temperature will be different and known to those skilled in the art.
There is known different steel alloy different optimal peak value heating-up temperatures to obtain maximum ductility result.Work as peak value When heating-up temperature is higher, the steel with less carbon will keep highest ductility, and when peak value heating-up temperature is not high enough, have compared with The steel of more carbon will keep highest ductility.In the case where carbon is 0.035 weight % 1008 ordinary carbon steels, when the peak that steel reaches When value heating-up temperature is 2225-2275 ℉, the A50 elongations of metallic plate are optimized for 8% to 10%.It is 0.41 weight %'s in carbon In the case of 4140 chrome-molybdenum steel, when the peak value heating-up temperature that steel reaches is 1925-1975 ℉, the A50 elongations of metallic plate obtain To optimization.For steel of the carbon content between above two example, experiment has found the almost line that optimal peak temperature be present Sexual intercourse, therefore when being heated to 1950-2000 ℉, 0.30 weight % carbon steels obtain best result.When being heated to 2025- During 2075 ℉, the steel with 0.20 weight % carbon obtains best result.When being heated to 2125-2175 ℉, there is 0.10 weight The steel for measuring % carbon obtains best result.Pass through linear interpolation, it may be determined that preferable ductility peak value heating-up temperature.Just because of such as This, therefore preferred peak heating-up temperature that 0.15 weight % carbon steels will have 2075 ℉ -2125 ℉.When processing is in pearlite/iron During steel in ferritic state or in nodularization state, these optimal peak temperatures are applicable.Have been subjected to cold rolling and then it is inabundant Normalization/annealing and therefore keep hardening steel, due to assigning its stress by energy storage in wherein.In these situations Under, optimal peak value heating-up temperature can reduce up to 100-200 ℉ from above-mentioned defined peak value heating-up temperature.
Have found, add and be known as the alloying element of strong carbide binder and be beneficial to the engineering properties of final micro-structural. These alloying elements include but is not limited to chromium, molybdenum, vanadium, silicon, aluminium, boron, tungsten and titanium.By two 1020 steel plates based on common carbon Carry out quick bainite processing.Unique significant difference in steel chemistries is a kind of chromium for adding and having 0.33 weight %.Several Steel is quickly heated up into 2050 ℉ in second.After the ℉ of peak value 2050 is reached, steel is quenched to room temperature in water smoke.In 1500- The modification 1020 with 0.33 weight % chromium tested under 1600MPa is with 9% to 10%A50 elongations.In 1350- The steel of common carbon 1020 (Chrome-free) tested under 1450MPa has 7.5% to 8.5%A50 elongations.In view of sole experiment difference There is 0.33 weight % chromium in modified 1020 chemical constitutions, due to adding chromium, the improvement of engineering properties into 1020 alloys It is attributable to chromium carbide and molybdenum carbide be present.Similarly, 1050 ordinary carbon steels and 6150 chrome alum steel alloys are compared.In rapid processing To 1900 ℉, 6150 steel have the elongation than common high about 1% to 2% percentage point of the steel of carbon 1050.The 6150 of rapid processing Intensity also have than rapid processing 1050 high 100MPa yield strength and high 150MPa ultimate tensile strength.Send out It is existing, it is typical that commercially available ordinary carbon steel has 7.5% to 9.5% percentage of total elongation once by the processing of quick bainite.Contain The steel of carbide formers alloy is intended to excessive more than 9-11% percentage of total elongation.4140 steel of quick bainite processing produce 1600MPa yield strengths, 2100MPa tensile strengths and 10% total A50 elongations.When use complete 1/2, " width A50 samples exist When 1/4 " testing 4130 under thickness, the total A50 of 11-12% are produced under 1500MPa yield strengths and 1900MPa ultimate tensile strengths Elongation.
It has also been found that the nodularization of previous micro-structural is beneficial to the engineering properties for strengthening the steel of quick bainite processing.It is thought that By the way that carbon tissue is entered in spheroid, nodularization can further limit carbon diffusion, it is known that spheroid is that geometrically most having on surface area The capacity storage mode of effect.By limiting carbon diffusion via nodularization, the percentage of bainite can control.In steel formed texture with Control previous austenite grain size and have turned out to be beneficial with other methods of the interaction of migration of element.For example, In the case of 4130 steel, for armor-piercing bullet and other miniweapon bullets, finding the striated 4130 of heat has than 75% nodularization 4130 low 10-15% bullet-proof.
, it is necessary to control initial microstructures to realize these unique micro-structurals before the processing of quick bainite.Use meter Calculate the above-mentioned hypothesis of thermodynamics and kineticses model evaluation.In this model, it is contemplated that contain ferrite (a) and cementite (M3C) system.It is assumed that linear heating rate is 1,10 and 100Ks-1, calculate austenite growth kinetics.Display is calculated, In the case of Fe-C systems, in 10Ks-1Lower generation Fe3C quick dissolving.Comparatively speaking, even in 1Ks-1Under, M3C (enrichments Cr rate of dissolution) is also slow.The above results support the Microstructure Evolution during quick bainite is processed proposed Mechanism.
The first aspect of the invention is to provide a kind of cheap, method rapidly and simply to manufacture containing considerable percentage The nano-scale piece crystal bainite of ratio and there is the low of some desired engineering properties of the martensite lath of nano-scale simultaneously Carbon, middle carbon or high-carbon ferrous alloy.Although other thermomechanical processing technologies need very long hot-working to obtain polynary shellfish Family name's body-martensite microstructure, but quick bainite processing can be operated using single rapid quenching to carry out, and it was spent less than 10 seconds Lower limit Martensite temperature is brought down below from higher than lower limit austenitic temperature.Other longer duration methods set forth herein can carry For other desired metallurgical results, condition is substantially to occur to terminate less than bainite immediately after peak value heating-up temperature is reached First quenching Step of temperature.
The second aspect of the present invention is to provide for microprocessor low-carbon, middle carbon or high-carbon ferrous alloy to obtain wherein bayesian Body and martensite are dispersed in the polynary micro-structural of the quick bainite processing of the desired amount of the previous austenite crystal intragranular of identical The method and apparatus of material.For different applications, low-carbon, middle carbon or high-carbon ferrous alloy by microprocessor can have difference Thickness, and can easily weld, while there is high tensile, and material is minimized and reduced the ability of weight. The present invention be used on the one side that temperature is interrupted in elevated quenching at a temperature of this can be fuse salt, super-heated gas or Heat the hardening media of oil etc..This aspect causes the first ferrous alloy as caused by fuse salt to change, but temperature is higher than second Change initial temperature, to cause the temperature of fuse salt to slow down the second transformation.After initial slow down, by continuous cooling transformation or when Between temperature transition and all other ferroalloy transformation intentionally occurs in fuse salt.From this temperature (in the feelings of 4130 steel It is less than 1022 ℉ under condition), steel can be cooled down as follows, wherein further changing or being changed into using the minimum of generation Other sub- phases of desired austenite, make retained austenite be down to environment temperature.
Another aspect of the present invention is related to heating and quenching unit.Other patent applications on device previously submitted Carry out coolant using single or multiple heating and hardening head.The inventive method heats multiple sheet using single heating unit Material.For example, rectangle induction coil can make material by wherein and heating coil it is inside and outside.If coil has appropriate chi Very little, then rectangular tube can be heated in coil inside, and other, such as bar piece can simultaneously load coil outside quilt Heating.
Another aspect of the present invention is related to the heating of part between material.Removed for example, band can have from its shape Multiple otch.These pieces can manufacture under soft condition, and then quick bainite is processed into its final hardness state.Sometimes, When such band is heated, by centralized head load and turning is melted close to the edge of otch.The present aspect of the present invention will allow The plug of similar material is maintained at discontinuities to absorb heat.Therefore this will prevent from melting turning.Even if when plug is not used, due to Heating and quenching are so fast, therefore the turning of the ferrous alloy shaped does not melt.
Quick heating, the concept for quenching, reheating and quenching are discussed at me in the priority patent submitted on June 16th, 2008 In application, the application is incorporated herein by reference, and it refers to ferrous alloy composition.Methods described applies also for gold The rolling band of category.Use and be referred to as quenching thermal technology similar with partition.Quenching and partition technology will within a few minutes Steel austenitizing dissolves carbide and the alloy distribution in steel is homogenized, then quenching and partition are quenched to low with levelling carbon In martensite start temperature, it is maintained at described and is less than martensite start temperature or reheats just above martensite start temperature, Then it is quenched to environment temperature.The reason for being so incubated is the partition of carbon to reach the retained austenite of desired amount in the final product Family name's body.Quenching and partition technology are that steel austenitizing is quenched to and started less than martensite within a few minutes on the other hand Temperature, reheating are higher than martensite start temperature and bainite end temp, are then quenched after the transformation of desired amount occurs To environment temperature.The innovation is the new technology of quenching/partition technology.For rapid quenching and partition, all aspects all with routine Quenching it is identical with partition, wherein exception for use Rapid Heating Cyclic rapidity.High speed such as 300 ℉/second extremely 5000 ℉/ quickly heated under the second, once reach peak austenite temperature, just starting quenching.Compared to traditional quenching and match somebody with somebody The novel part divided is that heterogeneous, Heterogenization, austenitizing steel is quenched.As previously mentioned with respect to ferrous alloy part, band Or material is quenched and be higher than the transformation of martensite finish temperature to formulate by part, heater by the quick austenitizing of steel, the is utilized Two heaters or the hardening media of heating are incubated or are again heated to less than austenitic temperature with stable or change existing micro- knot Structure, then it is quenched to room temperature using second of quenching.Known such method can provide the retained austenite of desired amount.
Depending on the placement of processing described below and claimed, gained high strength steel may include by coalescence bainite, Upper bainite, lower bainite, martensite, ferrite, retained austenite, pearlite, ferrite, acicular ferrite and/or its pair At least a portion of weight or the gained high-strength material of polynary combined composition.
Polynary phase material, such as martensite and bainite close to ferrite and pearlite positioning can be manufactured.By only with Different types quench, make it that one can be manufactured in the desired region on the surface and/or cross section of the article after being heated The high strength steel of kind pattern, and these highly desirable polynary phase materials are realized in identical workpiece.By only quenching given zone Domain, it is possible to realize multiple material phases in multiple positions when needed.
Combined reference Figure 1A and Figure 1B first, it is seen that quick bainite include showing highly desirable intensity, ductility and The dual model distribution of the bainite platelet or piece of the combination of toughness.The rapid processing of the present invention can produce almost distortionless flat Plate, rod, piece and straight tube.As visible in these accompanying drawings, micro-structural produces fine grained structure in the dual model distribution of micro-structural, its Obtain surprising intensity and ductility.
Referring to Fig. 2A, drafting temperature (DEG C) is shown to the curve map of time (second) to illustrate when wherein in a test tube Cooling circulation during wall processing.The representative temperature measurement result of this inwall shows low-down temperature/time-histories ratio be present. In this specific embodiment, there is relatively low temperature/time-histories ratio using the sheetmetal pipes of AISI 4130.
Referring now to Fig. 2 B, curve map of the temperature to the time is shown, in addition to continuous annealing temperature/time-histories of routine, its Also show rapid processing temperature/time-histories ratio.Obviously, temperature/time-histories of continuous annealing is than the ratio much larger than rapid processing.
Fig. 2 C show the austenite growth during quick bainite processes thermal cycle.Region I shows previous Ovshinsky Body crystal grain.Region II shows austenite growth.Region III shows heterogeneous austenite crystal.It is previous that region IV is shown in identical The bainite of austenite crystal intragranular and the multicomponent mixture of martensite.
Fig. 3 shows analysis of the temperature (DEG C) to temperature change (DEG C).This analysis is shown during cooling 1022 Between ℉ and 1202 ℉ and 680 ℉ to 860 ℉ transformation.This analysis shows, we possess two kinds of different changing conditions, Cause very local micro-structural heterogeneous, but show homogenieity on a macroscopic scale.
Now referring also to Fig. 4 A and Fig. 4 B, it is seen that the heterogeneous analysis display of two kinds of machineries, according to the present invention, raw material with Two kinds of different microstructure areas between the material of rapid processing be present.These discoveries are consistent with previous analysis, are shown in fast Transformation independent twice during fast procedure.It is all curve map of the normalized frequency to hardness to scheme A and figure B, it illustrates The distribution of hardness.Fig. 4 A show that base metal hardness distribution is very elongated, and the material being processed via rapid processing exists High rigidity area and soft area are shown in wider range of hardness distribution.
Referring now to Fig. 5, another aspect of the present invention with the materials of AISI 1010 of rapid processing fully add Illustrate by force.This curve map shows that elongation to peak value fast temperature, shows that highest elongation appears in peak value fast temperature At 1180 DEG C, there is 7.9% A50 elongations.Under 1010 DEG C of peak value fast temperature, elongation percentage is 5.6.It is higher than 1180 DEG C of temperature has the elongation less than 7.9%.The visible optimum elongation rate under medium to larger grain size, this and crystalline substance The intuition idea of grain refinement is opposite.The chemical composition (percentage by weight) of this material be 0.10C, 0.31Mn, less than 0.01Si, Sulphur, phosphorus, and 99.41 iron.
Referring to Fig. 6, it is curve map of the tensile strength (KSI) to elongation strain (percentage).On being tempered to 400 It is modified after different temperatures in the range of to 700 DEG C with the AISI 1020 processed including the quick bainite of 0.32 weight % chromium Example, display with different in width (inch) 8 examples.This experiment is shown, after being tempered 300 seconds under 932 ℉, The AISI 1020+Cr of rapid processing will keep the 79% of its " during quenching " tensile strength.In addition, in the tempering less than 5 seconds Under, elongation does not reduce ± 5%.
In fig. 7, there is provided initial sample (ferrite and carbide) and final rapid processing sample (lath form and Carbide) sample micro-structural.In order to verify mechanism and observed micro-structural from theoretical point view, the life of diffusion control has been carried out Long modeling.It is the microstructure image being imaged before and after rapid processing from optics and backscattered electron in fig. 7.Square Shape marked the position of scanning electron microscope image.In figure 7b, perspective electron microscope is disclosed from previous austenite The bainite sheave of grain boundary growth, which confirms hypothesis above.
Austenite Transformation Kinetics model again
Using purchased from Thermo-Calc Software, Inc. (McMurray, PA) DICTRA softwares are simulated fast Austenite Transformation Kinetics again during fast heating condition.The software is pre- using the thermokinetics and dynamics data of critical evaluation The boundary velocity during phase in version is surveyed.
Austenitizing condition again is evaluated using two kinds of conditions.In first condition, it is contemplated that cementite (Fe3C) in Fe- Dissolving in C system.
In second condition, rich Cr cementites (M is considered in Fe-C-Cr systems3C dissolving).For typical 4130 steel, calculated based on body Cr and C concentration (0.3 weight %C and 0.88 weight %Cr) under 1292 ℉ (nodularization temperature) The initial composition of ferrite and cementite.The boundary condition of simulation is shown schematically in Fig. 8.In 1,10 and 100Ks-1Speed under 1832 ℉ are heated to from 1292 ℉ to be simulated.So that in (α/M3C) interface forms austenite and grows to cementite and iron In ferritic.
Fe3C dissolution kinetics：
In 1 and 10Ks-1The rate of heat addition under, preceding simulative display twice, cementite is completely dissolved into a- ferrites, even Before nucleus is formed and austenite is grown in ferrite (Fig. 9 A and Fig. 9 B).When with 100Ks-1Speed heating when, carburizing Body is completely dissolved into ferrite (Fig. 9 C) without time enough.Therefore, austenitic formation is in cementite-austenite circle At face and grow in cementite and both ferrites.It is interesting that even if under these conditions, disappeared in ferrite by austenite Before consumption, cementite cmpletely dissolves.These situations permission more time makes carbon perfectly homogenousization of austenite.
M3C dissolution kinetics：
Similar DICTRA simulations are carried out in Fe-Cr-C systems.In these calculating, for all rates of heat addition (bag Include 1Ks-1) all it is visible slowly dissolving.Those skilled in the art are it has also been reported that similar slow mechanism dissolved in the case where being enriched with Cr.Come From 1Ks-1The details of result be presented in Fig. 9 D.Fig. 9 D show that the minimum of cementite is dissolved with austenite in ferrite carburizing Nucleus at body interface is formed.However, after reaching 1000 DEG C, the dissolving of cementite is also incomplete.At room temperature It is compared to the concentration gradient [C and Cr] at 1000 DEG C in Figure 10.As temperature is slowly increased, austenite slowly consumes iron Ferritic.Under these conditions, big Cr concentration peaks are generated in interface and in the austenite formed recently.When analysis carbon During concentration profile, it is clear that carbon spread is substantially subjected to Cr diffusions and the control at interface.This will produce latent under low-carbon austenite Rich Cr austenites situation.
In the intermediate steps during rapid processing, according to the present invention, carbon diffusion and carbide dissolution obtain many differences Steel coexist composition.Composition coexists in these can be due to the office occurred on the whole body of handled material on atomic level Portion's heat gradient and exist.Can be by using the carbon with about 0.01 to about 0.05 weight % and about 0.2 to about 0.5 weight % The alloy of chromium and predict these compositions to a certain extent.If for example, use the carbon and 0.90 for example containing 0.40 weight % 4140 steel of weight % chromium, then it can control and it is possible that localizing on austenite crystal yardstick, in the different of high multiplicity 0.02 weight % carbon and 0.3 weight % chromium are can reach in matter chemistry.In addition, it is for example expectable, using with 0.02 weight 1002 steel of % carbon and 0.3 weight % chromium are measured, in the austenitizing of extension and after homogenizing, then with 200 DEG C/sec and 3000 Speed rapid quenching between DEG C/sec, almost 100% bayesian bulk microstructure will be obtained.
0.01 to 0.05 weight % carbon and 0.2 to 0.5 weight % are used in the ferrous alloy precursor material of carbide-containing This combination of chromium and the quenching rate between 200 DEG C/sec and 3000 DEG C/sec produces heterogeneous micro- knot including at least bainite Structure.It is preferred that quenched with water.
Use quality tension metrics, the composition of body austenite will contain after being quenched with 1000 DEG C/sec of cooldown rate 0.01-0.03 weight %C and 0.33 weight %Cr.Use the mould of the Dr.Harry Bhadeshia exploitations by univ cambridge uk Type calculates the gained CCT charts (Figure 11) of this austenite.When result of calculation and the cooldown rate (1000 from rapid processing ℃s-1) it is overlapping when, the formation for showing bainite is possible.Meanwhile with Cr the and C rich regions close to carbide interface Body regions should be able to be changed into martensite because the T in this region0Temperature (the ferritic free energy of same composition Under temperature equivalent to austenite) be 730 DEG C.These results are supported there are the quick of the Spheroidized Steels of carbide or other steel The feasibility of the mixing micro-structural of bainite, martensite and carbide is obtained during processing.It is important to note that, should be taken into account The further evaluation of different initial microstructures conditions (i.e. pearlite, quasi-equilibrium cementite and other alloying elements) and exist Implement the possibility of the Different Results of quick bainite processing method.
Industrial usability
The present invention can be used for metal treatment industry and be particularly useful for processing and manufacture high intensity in high volume to process In the steel processing application of steel.
The described above of the preferred aspect of the present invention is presented for the purpose of illustration and description.It is not intended to detailed Or limit the invention to exact form disclosed.In view of the above-mentioned teaching on particular aspects, it will be apparent that change or change Change is possible.Select and describe the aspect with the principle and its practical application of the best illustration present invention, so that ability Field technique personnel can utilize in various aspects and best under the various modifications as appropriate for the special-purpose covered this hair It is bright.It is expected that the scope of the present invention is to be defined by the claims.

Claims (5)

  1. A kind of 1. gold for being used to for the ferrous alloy of the carbide-containing with austenite transformation temperature to be changed into multiphase high strength steel Belong to processing method, this method includes：
    The precursor material of the ferrous alloy of carbide-containing is provided；
    Selected temperature from less than austenite transformation temperature to higher than the austenite transformation temperature, with 149 DEG C/sec to 2760 DEG C/ The alloy is heated at least 1000 DEG C by the speed of second, to localize on austenite crystal yardstick in the heterogeneous of high multiplicity Reach 0.01 weight % to 0.05 weight % carbon and 0.2 weight % to 0.5 weight % chromium in chemistry；
    The alloy is quenched with 200 DEG C/sec to 3000 DEG C/sec of speed immediately, thus occurs a variety of to be changed into a variety of austenites Sub- phase, and at least produce the mixing for containing martensite, bainite and undissolved carbide and also containing polynary steel micro-structural Micro-structural, the polynary steel micro-structural include bainite, coalescence bainite, acicular ferrite, retained austenite and/or martensite with And combinations thereof part.
  2. 2. according to the method for claim 1, wherein the step of providing ferrous alloy is by comprising selected from following at least one Carbide formers agent is planted to complete：Chromium, molybdenum, vanadium, silicon, aluminium, boron, tungsten, titanium, and combinations thereof.
  3. 3. according to the method for claim 1, wherein the step of providing ferrous alloy is by providing the iron-based in nodularization state Alloy is completed.
  4. 4. according to the method for claim 1, wherein cancellation step can be by using at least one following hardening media Almost moment completes：Water-bath, water smoke, it is cooled and shaped mould, air knife, open air convection current, final operation cooling continuous mould, most Whole stage cooling line mould, quenching hydroforming, fuse salt, oil, steam, heated gaseous solution, Cooling Quenching roller, and these sides The combination of method.
  5. 5. according to the method for claim 1, obtain nano-scale wherein providing ferrous alloy and being operated with single rapid quenching Piece crystal bainite, the single rapid quenching operation is spent was brought down below lower limit horse less than 10 seconds from higher than lower limit austenitic temperature Family name's temperature.
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