CN109207693A - A method of improving quenched and tempered state low-alloy nodular bainite steel impact flexibility - Google Patents
A method of improving quenched and tempered state low-alloy nodular bainite steel impact flexibility Download PDFInfo
- Publication number
- CN109207693A CN109207693A CN201710536320.2A CN201710536320A CN109207693A CN 109207693 A CN109207693 A CN 109207693A CN 201710536320 A CN201710536320 A CN 201710536320A CN 109207693 A CN109207693 A CN 109207693A
- Authority
- CN
- China
- Prior art keywords
- low
- tempering
- alloy
- bainite steel
- quenched
- 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
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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/04—Hardening by cooling below 0 degrees Celsius
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- 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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
Abstract
The invention belongs to steel material Field of Heat-treatment, especially a kind of method for improving quenched and tempered state low-alloy nodular bainite steel impact flexibility, it is adapted to solve the low-alloy granular bainite steel part of quenched and tempered state when directly carrying out high tempering, low-temperature impact toughness is relatively low and instability problem.The present invention adds one of preliminary treatment (the pre- tempering of middle low temperature i.e. between subzero treatment or 150~550 DEG C) between traditional quenching, high tempering heat treatment, eliminate the retained austenite in quenching state nodular bainite steel, then tempering is carried out according to original or high tempering heat treatment process through appropriate adjustment, and then realize the low-temperature flexibility for improving the low-alloy nodular bainite steel of quenched and tempered state, and do not reduce the purpose of the strength of materials.Present invention process is simple, and operation is easily achieved, and wide adaptation range.
Description
Technical field
The invention belongs to steel material Field of Heat-treatment, especially a kind of raising quenched and tempered state low-alloy nodular bainite steel punching
The method for hitting toughness.
Background technique
Low-alloy nodular bainite steel has preferable obdurability and excellent hydrogen embrittlement energy, is widely used in nuclear power
The component that cylinder body, large-scale hydrogenator and the certain pairs of strengths of materials, low-temperature flexibility and high temperature resistance have higher requirements
On.Under traditional industry application conditions, the standard heat treatment technique of these low-alloy granular bainite steel parts is returned for quenching+high temperature
Fire.Granular bainite+a small amount of residual austenite body tissue (or there are certain martensitic structures) is obtained after quenching, then directly into
Row high tempering processing appropriate, matches the intensity of material and plasticity and toughness preferably.
However, for the low-alloy granular bainite steel part of actual production, due to macro micro components be unevenly distributed or
Cooling capacity deficiency is quenched in heat treatment process, so that obtaining the residual of the alloying elements such as the enrichment carbon of certain content in quenching structure
Remaining austenite.If when by directly carrying out high tempering to the quenching structure containing more retained austenite, it is coarseer to be easy production
Carbide or carbide group, seriously endanger low-alloy granular bainite steel part low-temperature impact toughness.
Therefore, in the case where quenching structure is certain, how by simple processing method, optimize the height of retained austenite
Warm decomposition product improves the low-temperature impact toughness of low-alloy granular bainite steel part, becomes numerous researchs and actual production concern
Hot spot.
Summary of the invention
The purpose of the present invention is to provide it is a kind of improve quenched and tempered state low-alloy nodular bainite steel impact flexibility method,
Under the premise of not increasing as far as possible or increasing production cost on a small quantity, steel part alloying component or the greatly former tune of change are not changed
Matter heat treatment process, it is residual in steel to eliminate only by increasing preliminary treatment together between quenching heat treatment and high-temperature heat treatment
Remaining austenite avoids retained austenite after high tempering from directly resolving into the carbide or carbide group of ferrite+coarse, in turn
The obdurability of low-alloy nodular bainite steel is set to effectively improve.
The technical scheme is that
A method of quenched and tempered state low-alloy nodular bainite steel impact flexibility is improved, method includes the following steps:
(1) low-alloy granular bainite steel part is quenched according to original quenching heat treatment technique；
(2) after the completion of quenching, subzero treatment is carried out, or steel part is low in 150~550 DEG C of range inside holdings, progress
Warm tempering is cooled to room temperature after heat preservation, eliminates all or part of retained austenite in nodular bainite steel；
(3) by pretreated low-alloy granular bainite steel part carry out high tempering processing, high tempering processing according to
Original conventional high temperature tempering process is adjusted.
The method of the raising quenched and tempered state low-alloy nodular bainite steel impact flexibility, low-alloy nodular bainite steel
Are as follows: alloying element content is no more than low-alloy Cr-Mo or the Cr-Mo-V steel of 5wt.%；Alternatively, alloying element content is no more than
Ni-Cr system, Mn-Mo-Ni system, Si-Mn system, Si-Mn-Mo system, Cr-Mn-Si system, Cr-Mn-Mo system or the Cr-Ni-Mo of 5wt.%
It is steel.
The method of the raising quenched and tempered state low-alloy nodular bainite steel impact flexibility, by weight percentage, low conjunction
Golden nodular bainite steel alloying element mainly includes: C≤0.50%, Mn≤1.5%, Cr≤4%, Mo≤1.5%, V≤0.5%
And the one or more of trace alloying element Nb, Ti, B, the mass fraction summation of alloying element are no more than 5%.
The method of the raising quenched and tempered state low-alloy nodular bainite steel impact flexibility, the quenching structure that step 1) obtains
Are as follows: granular bainite microstructure；Or based on granular bainite microstructure, and contain other types of bainite or martensitic structure.
The method of the raising quenched and tempered state low-alloy nodular bainite steel impact flexibility, the subzero treatment of step (2) are deep
Cold treatment temperature requirement is lower than transition temperature of the retained austenite to martensitic traoformation, controls soaking time, eliminates low conjunction as far as possible
Retained austenite in golden nodular bainite steel quenching state tissue.
The method of the raising quenched and tempered state low-alloy nodular bainite steel impact flexibility, according to actual condition and for warp
Middle lonneal processing in step (2) is incorporated in the high tempering processing heating process of step (3) by the considerations of Ji property,
I.e. in step (3) high tempering processing heating process, steel part is arranged to a heat preservation step within the scope of 150~550 DEG C, sufficiently
After heat preservation, without the cooling high tempering processing for continuing heating and carrying out step (3).
At high tempering in the method and step (3) of the raising quenched and tempered state low-alloy nodular bainite steel impact flexibility
Reason, is adjusted according to original conventional high temperature tempering process, or to conventional high temperature tempering process, by reducing tempering temperature
Or soaking time, so that the low-alloy granular bainite hardness of steel of quenched and tempered state is further improved.
The method of the described raising quenched and tempered state low-alloy nodular bainite steel impact flexibility, to conventional high temperature tempering process into
After row adjustment, tempering temperature reduces by 5~20 DEG C referring to original high tempering temperature and/or soaking time foreshortens to original 1/
2~1/4, the type of cooling is still to carry out according to original high tempering treatment process type of cooling；In the range technological parameter
After inside being handled, it is obviously improved in guarantee low-alloy nodular bainite steel impact flexibility compared with prior heat treatment process impact flexibility
Under conditions of, so that its intensity is improved 10~20%.
The method of the raising quenched and tempered state low-alloy nodular bainite steel impact flexibility, it is preferred that step (1) quenching heat
Treatment process, within the scope of 40 DEG C~100 DEG C of Ac3 or more, soaking time range be 0.5~for 24 hours, the type of cooling be water spray quench
Fire, oil are cold, air-cooled or air-cooled, under the conditions of guaranteeing that workpiece quenching is indehiscent, improve quenching cooling capacity as far as possible.
The method of the raising quenched and tempered state low-alloy nodular bainite steel impact flexibility, it is preferred that low temperature in step (2)
Tempering technique, tempering range be 150~550 DEG C, soaking time range be 0.5~for 24 hours, the type of cooling be it is air-cooled；
2~10h is impregnated in the subzero treatment of step (2) in liquid nitrogen.
Design philosophy and principle of the invention is as follows:
The present invention is based on low-alloy steel under the conditions of quenching cooling rate is relatively slow, and the tissue for obtaining quenching state is granular bainite
When tissue, comprising a certain amount of she blocky type retained austenite rich in alloying elements such as carbon in microscopic structure, if by granular bayesian
Body tissue directly carries out high tempering processing, these block-like retained austenites will resolve into the alloy carbon of ferrite+coarseer
Compound or carbide group, thus impaired low temperature impact toughness.If not changing or not significantly changing original quenching or high tempering
Under process conditions, between the quenching and tempering heat treatment of traditional Tempering and Quenching, one of preliminary treatment is added, low-alloy grain is made
Shape bainitic steel quenching state group is woven in front of high tempering is transformed into a kind of intermediate state tissue in advance, then carries out high tempering heat again
Processing, makes the retained austenite of quenching state first decompose, more interfaces is introduced, then during subsequent high tempering
More nucleation sites are provided for the precipitation of carbide, so that it is more uniform tiny to make Carbide Precipitation, and then reach larger amplitude
The effect of the impact flexibility of the raising steel part of degree.
When preliminary treatment involved in of the invention selects, granular bainite in steel part before being heat-treated according to high tempering
Middle residual austenite content, pattern and stability features, and combine steel part actual production working condition and examining for cost
Consider, allows the retained austenite in quenching structure since the reduction of thermal stability is transformed into martensite, bainite or pseudopearlite etc.
Intermediate state tissue.The present invention lists common three kinds of conditioning treatment technique (as shown in Fig. 1): 1. subzero treatment (i.e. will
Quenched steel part is placed in a certain temperature of room temperature or less for a period of time)；2. the middle pre- tempering of low temperature is (i.e. by steel 150
~550 DEG C of certain temperature tempering heat preservations, are then cooled to room temperature with certain type of cooling)；3. directly heated in high tempering
Middle cold stage setting heat preservation step in journey, allows retained austenite to resolve into intermediate product, is then again heated to high tempering
Temperature carries out high tempering processing.
Illustrating needs described herein to be that above-mentioned three referred to kind preliminary treatment only enumerates some common elimination quenchings
The method of state retained austenite, the related technical personnel for being familiar with the field obviously can be simply to the above-mentioned preliminary treatment enumerated
Technique carry out various modifications, and preliminary treatment principle listed above is applied in other embodiments without by creative
Labour.Therefore, herein especially it should be noted that, the present invention is not limited to above-mentioned three kinds of mentioned preliminary treatment methods, abilities
The related technical personnel in domain announcement according to the present invention does not depart from some modification and improvement that scope is made and all should
By protection of the invention.
It advantages of the present invention and has the beneficial effect that:
1, the present invention is under the conditions of no chemical component for changing low-alloy nodular bainite steel, only by work after quenching
Part carries out conditioning treatment, eliminates all or part of retained austenite in quenching structure, then carries out high tempering processing, can
It realizes under the strength condition for not reducing steel, greatly improves quenched and tempered state low-alloy granular bainite steel part impact flexibility.
2, the present invention is by adding together between the quenching and high-temperature tempering process of low-alloy granular bainite steel part
The characteristics of pretreating process improves a kind of method of quenched and tempered state impact flexibility, and the method can be according to quenching state tissue is (such as: residual
Amount, stability and the pattern of remaining austenite) come selectively using preliminary treatment technique, and then can achieve reduction production cost.
3, the present invention is applied widely, is applicable not only to all large pressurized vessel low-carbon and low-alloy Cr-Mo and Cr-
Mo-V system steel, or alloying element content is no more than Ni-Cr system, Mn-Mo-Ni system, the Si-Mn system, Si-Mn- of 5wt.%
The low-carbon and low-alloys nodular bainite steels such as Mo system, Cr-Mn-Si system, Cr-Mn-Mo system or Cr-Ni-Mo system, common alloy designations
Can be but be not limited to 2.25Cr-1Mo, 2.25Cr-1Mo-0.25V, G18CrMo2-6, SA508-3,15CrMoVA,
42CrMo, 18Cr2Ni4WA, 12CrNi3,35SiMnMo, 15SiMnVTi or 25SiMoVB etc..
Detailed description of the invention
Fig. 1 is the difference schematic diagram of present invention process and normative heat treatment technique.
Fig. 2 is quenching state bloom and the sample XRD spectrum after technique one and technique two pre-process in embodiment 1.
In figure, abscissa is 2 θ (°) of the angle of diffraction, and ordinate Intensity is intensity (a.u.).
Specific embodiment:
Low-alloy nodular bainite steel obdurability matching effect is significantly improved in order to embody present invention process well.?
In subsequent specific embodiment, the present invention also lists prior heat treatment process, for illustrating superiority of the invention, but passes
System heat treatment process is not meant to be limited by protection of the present invention.Meanwhile in order to confirm that the present invention has wider application range
And prospect, and consider that the feasibility of practical operation, the present invention select three kinds of typical low-alloy nodular bainite steels: Yi Zhongwei
Applied to the low-carbon and low-alloy Cr-Mo-V steel (2.25Cr-1Mo-0.25V steel) of large-scale hydrogenator forging, conditioning treatment
It is illustrated respectively for the pre- tempering of low temperature and subzero treatment in；One kind is that nuclear power heavy castings G18CrMo2-6 is low
Carbon and low-alloy heat resisting steel is illustrated for this conditioning treatment is using pre- tempering；One kind is that wind turbine power generation main shaft is forged
Part 42CrMo medium carbon low alloy steel；The setting low temperature in high-temperature tempering process step is used to be tempered heat preservation in advance in this conditioning treatment
Platform.
In the following, by embodiment, the present invention is described in more detail:
Embodiment 1
In the present embodiment, the method for improving quenched and tempered state low-alloy nodular bainite steel impact flexibility is as follows:
(1) to slab sample carry out chemical composition analysis, test result be 0.15C (weight percent, similarly hereinafter),
As a result 0.05Si, 2.46Cr, 1.01Mo, 0.28V, 0.15Ni, 0.006P, 0.002S meet relevant criterion to 2.25Cr-1Mo-
The requirement of 0.25V steel chemical composition, and belong to the scope of application of the present invention.
(2) heavy slab after forging is cut into the heat treatment experiment block of 600 × 400 × 160mm size, is heated to 1050
DEG C heat preservation 2h carry out austenitizing processing, then carry out jet hardening be cooled to room temperature；
(3) after the completion of quenching, by preliminary treatment among slab, consider large forgings preliminary treatment actual condition and this steel
Decomposition situation of the middle retained austenite in preprocessing process, this preliminary treatment are as follows: 350 DEG C (one preliminary treatments of technique) or 455
DEG C (pretreatment of technique two) keeps the temperature 8h, is cooled to room temperature using jet hardening mode.Test quenching, technique one respectively using XRD
Retained austenite after pretreatment and technique two pre-process in bloom is respectively 7.8vol.%, 1.2vol.%, 0vol.% (spectrum
Line is as shown in Figure 2), illustrate that the middle low temperature conditioning treatment designed in the present embodiment can eliminate wholly or largely quenching state steel part
In retained austenite.
(4) will by the steel part after step (3) preliminary treatment according to conventional high-temperature tempering heat treatment process (700 DEG C ×
High tempering processing 16h) is carried out, jet hardening is to room temperature after coming out of the stove；
(5) after the present embodiment technique is third is that be heated to 455 DEG C of heat preservation 8h for quenching state experiment bloom, it is not cooled to room
Temperature, and be directly heated to 700 DEG C of high tempering 16h, jet hardening is to room temperature after coming out of the stove；
(6) it is compared to be handled with heat treatment process of the present invention, in addition one piece of same material, the 2.25Cr-1Mo- with size
0.25V steel tests bloom, is handled using prior heat treatment process, and specific heat treatment process is 1050 DEG C × 8h quenching treatment
+ 700 DEG C × 16h tempering, quenching and the tempering type of cooling are that jet hardening is cooling.
(7) from prior heat treatment process, technique one, technique two and technique three, in four kinds of processing technologys treated slab
Center portion position takes the test block of identical size, processes two tensile samples and six Charpy V-type impact specimens, and it is average to test room temperature respectively
Tensile strength and -18 DEG C of average impact function, test result are as shown in table 1.In terms of experiment test mechanics results of property, using this hair
Bright technique one, technique two and technique three is superior to traditional quenching-and-tempering process.Wherein, technique two will quench forging 455
After DEG C pre- tempering 8h is air-cooled to room temperature, then carry out comprehensive mechanical property that the processing of 700 DEG C × 16h high tempering obtains most
Excellent, i.e., in the case where apparent situation of change does not occur for tensile strength and yield strength, -18 DEG C of low temperature average impact function are from 81.1J
It improves to 179.2J.
Table 1: 2.25Cr-1Mo-0.25V steel thick plate is using present invention process and prior heat treatment process mechanics in embodiment 1
Performance comparison
Embodiment 2
In the present embodiment, when 2.25Cr-1Mo-0.25V structure of steel is granular bainite, before high tempering, using deep cooling
The mode of processing is as preliminary treatment, to eliminate all or part of residual austenite body tissue in granular bainite microstructure, then
High tempering processing is carried out again, is reached and is improved low-temperature impact toughness and improve its stability.The present embodiment and quenched with tradition
It is as follows to be heat-treated the mechanical property comparing result obtained:
(1) the rod iron wire cutting through heat treatment after forging is carried out 940 DEG C × 2h's at the steel disc of 13 × 42 × 60mm size
Austenitizing processing, then dry quenching to room temperature；
(2) after the completion of quenching, sample is subjected to intermediate preliminary treatment, is considered residual in preliminary treatment actual condition and this steel
Transformation situation of the remaining austenite in preprocessing process, this preliminary treatment are as follows: quenching bloom is placed in liquid nitrogen and impregnates 2h progress
Subzero treatment.
It (3) will be by the steel part after step (2) preliminary treatment according to conventional high-temperature tempering heat treatment process (700 DEG C × 4h)
High tempering processing is carried out, is air-cooled to room temperature after coming out of the stove.
(4) in order to be compared with heat treatment process of the present invention processing, by same material, with the 2.25Cr1Mo0.25V steel of size
Piece is handled using traditional quenching-and-tempering process, and specific heat treatment process is+700 DEG C × 4h of 940 DEG C × 2h normalized treatment
High tempering processing, quenching and the tempering type of cooling are air-cooled.
(5) prior heat treatment process, present invention process treated bloom are processed into two tensile samples and six Charpy V
Type impact specimen tests mechanical properties respectively and low temperature (- 18 DEG C, -30 DEG C) impact flexibility, test result is as shown in table 2.
Find out that technique of the present invention is substantially better than prior heat treatment process from the mechanical property result of experiment test.I.e. anti-
Tensile strength and yield strength do not occur under apparent situation of change, make bloom at -18 DEG C and -30 using technique of the invention
Low-temperature impact toughness is improved by a relatively large margin at DEG C, and three sample impact value dispersibilities are small under two test temperatures
In traditional quenching-and-tempering process.
Table 2: 2.25Cr-1Mo-0.25V steel disc is using mechanics after present invention process and traditional handicraft heat treatment in embodiment 2
Performance comparison
Embodiment 3
In the present embodiment, nuclear power is as follows with G18CrMo2-6 steel low pressure (LP) cylinder body optimization of Heat Treatment Process:
(1) the present embodiment is heavy castings, and material is G18CrMo2-6 steel, and thickest 500mm is thick.This reality is detected first
Applying a material therefor main chemical compositions is 0.17C, 0.65Cr, 0.60Mo, 0.73Mn, 0.48Ni etc., meets the present invention and is applicable in
Range.
(2) casting after casting is heated to 940 DEG C of heat preservation 6h and carries out austenitizing processing, then carry out air-blast quenching extremely
Room temperature；
(3) after being quenched, the present embodiment carries out pre- tempering to related casting, and pre- tempering temperature uses two kinds
Different process, it may be assumed that technique one: will quenching green casting be heated to 320 DEG C of heat preservation 6h, then do not cool down, directly heat to 680 DEG C into
The processing of row 10h high tempering, high tempering processing after-blow is air-cooled to room temperature, and quenching state steel part technique two: is heated to 400 DEG C of guarantors
Warm 6h, is then air-cooled to room temperature.
(4) after pre- tempering, the related casting under the present embodiment technique two carries out high tempering processing, high tempering temperature
Degree is 670 DEG C, and soaking time is 8h (more traditional tempering time foreshortens to 1/2), and after heat preservation, blowing is cooled to room temperature.
(5) in order to compare with heat treatment process of the present invention processing, to identical material, the casting of identical size is passed
(940 DEG C × 6h normalized treatment, blowing are cooled to room temperature, and 680 DEG C × 16h tempering is air-cooled to room for heat treatment process of uniting processing
Temperature).
(6) from the casting thickest after prior heat treatment process, present invention process one and technique two, three kinds of process
Place centre takes the test block of identical size, is processed into tensile sample and Charpy V-type impact specimen, test respectively tensile strength and
Room temperature impact performance, test result are as shown in table 3.From experimental results, present invention process one and two room temperature of technique are averagely rushed
It hits function and is apparently higher than prior heat treatment process, and four surveyed impact specimen impact toughness value stability also greatly improves, due to
The present invention process appropriate adjustment high tempering time, it is left to also improve its tensile strength 30MPa while improving impact flexibility
It is right.
Table 3: G18CrMo2-6 steel is compared using mechanical property after present invention process and traditional handicraft heat treatment in embodiment 3
Embodiment 4
In the present embodiment, the optimization of wind turbine power generation main shaft forging 42CrMo steel quenching-and-tempering process is as follows:
(1) it is the owner's axis large forgings of 42CrMo medium carbon low alloy steel wind turbine power generation that the present embodiment, which is material, and forging is most
Major diameter is 820mm.First detection the present embodiment material therefor main chemical compositions be 0.42C, 1.0Cr, 0.2Mo, 0.70Mn,
0.20Si etc. meets the scope of application of the present invention.
(2) 840 DEG C of heat preservation 6h will be heated to by the large forgings of heat treatment after forging and carries out austenitizing processing, and it is laggard
Row oil quenchinng (avoid hardening break without water hardening cooling) is to room temperature.Forging sampling after quenching treatment is carried out micro-
Fabric analysis discovery, with martensitic structure, forging center portion contains a small amount of iron element based on granular bainite microstructure on forging surface
Body tissue.
(3) after being quenched, pre- tempering is carried out to forging, it may be assumed that quenching green casting is heated to 280 DEG C of heat preservation 5h,
Then it does not cool down, directly heats to 660 DEG C of progress 10h high tempering processing, be air-cooled to room temperature after high tempering processing.
(4) in order to compare with heat treatment process of the present invention processing, to identical material, the casting of identical size is passed
(840 DEG C × 6h normalized treatment, oil quenchinng to room temperature, 660 DEG C × 10h tempering are air-cooled to room for heat treatment process of uniting processing
Temperature).
(5) from centre and surface element from prior heat treatment process and present invention process treated forging maximum gauge
Position takes the test block of identical size respectively, is processed into tensile sample (draw direction is along major axes orientation) and Charpy V-type impact specimen (lacks
Mouth direction is perpendicular to major axes orientation), tensile strength and -20 DEG C of low temperature impact properties are tested respectively, and test result is as shown in table 4.
Find out from experimental results, tensile strength heat-treated technique influences unobvious, to handle from two kinds of heat treatment process forging
- 20 DEG C of low temperature impact properties of surface area test are higher and are substantially better than its forging center portion.And it samples and surveys in forging center portion
When examination, through conventional heat treatment process, treated that the larger and average work value of six impact specimen Charpy impact work value dispersion are obviously low
In the forging respective value of present invention process processing.
Table 4: 42CrMo steel is compared using mechanical property after present invention process and traditional handicraft heat treatment in embodiment 4
Embodiment the result shows that, the present invention be adapted to solve quenched and tempered state low-alloy granular bainite steel part directly carry out height
When temperature tempering, low-temperature impact toughness is relatively low and instability problem.The present invention is characterized in that in traditional quenching, high tempering heat
It adds one of preliminary treatment (the pre- tempering of middle low temperature i.e. between subzero treatment or 150~550 DEG C), eliminates between processing
Then retained austenite in quenching state nodular bainite steel is heat-treated according to original or high tempering through appropriate adjustment
Technique carries out tempering, and then realizes the low-temperature flexibility for improving the low-alloy nodular bainite steel of quenched and tempered state and do not reduce material
The purpose of intensity.The simple process, operation are easily achieved, and wide adaptation range.
Claims (10)
1. it is a kind of improve quenched and tempered state low-alloy nodular bainite steel impact flexibility method, which is characterized in that this method include with
Lower step:
(1) low-alloy granular bainite steel part is quenched according to original quenching heat treatment technique；
(2) after the completion of quenching, subzero treatment is carried out, or low temperature returns in 150~550 DEG C of range inside holdings, progress by steel part
Fire processing, is cooled to room temperature after heat preservation, eliminates all or part of retained austenite in nodular bainite steel；
(3) pretreated low-alloy granular bainite steel part is subjected to high tempering processing, high tempering processing is according to original
Conventional high temperature tempering process or be adjusted.
2. the method according to claim 1 for improving quenched and tempered state low-alloy nodular bainite steel impact flexibility, which is characterized in that
Low-alloy nodular bainite steel are as follows: alloying element content is no more than low-alloy Cr-Mo or the Cr-Mo-V steel of 5wt.%；Alternatively, closing
Gold dollar cellulose content is no more than Ni-Cr system, Mn-Mo-Ni system, Si-Mn system, Si-Mn-Mo system, the Cr-Mn-Si system, Cr- of 5wt.%
Mn-Mo system or Cr-Ni-Mo system steel.
3. the method according to claim 1 for improving quenched and tempered state low-alloy nodular bainite steel impact flexibility, which is characterized in that
By weight percentage, low-alloy nodular bainite steel alloying element mainly includes: C≤0.50%, Mn≤1.5%, Cr≤
4%, the one or more of Mo≤1.5%, V≤0.5% and trace alloying element Nb, Ti, B, the quality of alloying element
Score summation is no more than 5%.
4. the method according to claim 1 for improving quenched and tempered state low-alloy nodular bainite steel impact flexibility, which is characterized in that
The quenching structure that step 1) obtains are as follows: granular bainite microstructure；Or based on granular bainite microstructure, and containing other types of
Bainite or martensitic structure.
5. the method according to claim 1 for improving quenched and tempered state low-alloy nodular bainite steel impact flexibility, which is characterized in that
The subzero treatment of step (2), subzero treatment temperature requirement are lower than transition temperature of the retained austenite to martensitic traoformation, and control is protected
Warm time, the as far as possible retained austenite in elimination low-alloy nodular bainite steel quenching state tissue.
6. the method according to claim 1 for improving quenched and tempered state low-alloy nodular bainite steel impact flexibility, which is characterized in that
According to actual condition and for economical reasons, the middle lonneal processing in step (2) is incorporated in the high temperature of step (3)
In tempering heating process, i.e., in step (3) high tempering processing heating process, by steel part within the scope of 150~550 DEG C
One heat preservation step of setting, after abundant heat preservation, without the cooling high tempering processing for continuing heating and carrying out step (3).
7. the method according to claim 1 for improving quenched and tempered state low-alloy nodular bainite steel impact flexibility, which is characterized in that
High tempering processing in step (3), carries out according to original conventional high temperature tempering process, or to conventional high temperature tempering process
Adjustment obtains the low-alloy granular bainite hardness of steel of quenched and tempered state further by reducing tempering temperature or soaking time
Raising.
8. by the method for improving quenched and tempered state low-alloy nodular bainite steel impact flexibility described in claim 6 or 7, feature exists
In, after being adjusted to conventional high temperature tempering process, tempering temperature referring to original high tempering temperature reduce by 5~20 DEG C and/
Or soaking time foreshortens to original 1/2~1/4, the type of cooling is still according to original high tempering treatment process type of cooling
It carries out；After being handled in the range technological parameter, guaranteeing the more traditional heat of low-alloy nodular bainite steel impact flexibility
Under conditions for the treatment of process impact flexibility is obviously improved, its intensity is made to improve 10~20%.
9. the method according to claim 1 for improving quenched and tempered state low-alloy nodular bainite steel impact flexibility, which is characterized in that
Preferably, step (1) quenching heat treatment technique, within the scope of 40 DEG C~100 DEG C of Ac3 or more, soaking time range be 0.5~
For 24 hours, the type of cooling be jet hardening, oil it is cold, air-cooled or air-cooled, guarantee workpiece quenching it is indehiscent under the conditions of, improve as far as possible
Quench cooling capacity.
10. the method according to claim 1 for improving quenched and tempered state low-alloy nodular bainite steel impact flexibility, feature exist
In, it is preferred that lonneal treatment process in step (2), tempering range are 150~550 DEG C, and soaking time range is
0.5~for 24 hours, the type of cooling is air-cooled；2~10h is impregnated in the subzero treatment of step (2) in liquid nitrogen.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710536320.2A CN109207693A (en) | 2017-07-04 | 2017-07-04 | A method of improving quenched and tempered state low-alloy nodular bainite steel impact flexibility |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710536320.2A CN109207693A (en) | 2017-07-04 | 2017-07-04 | A method of improving quenched and tempered state low-alloy nodular bainite steel impact flexibility |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN109207693A true CN109207693A (en) | 2019-01-15 |
Family
ID=64993393
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710536320.2A Pending CN109207693A (en) | 2017-07-04 | 2017-07-04 | A method of improving quenched and tempered state low-alloy nodular bainite steel impact flexibility |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109207693A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111254355A (en) * | 2020-03-18 | 2020-06-09 | 中铁宝桥集团有限公司 | Bainite alloy steel heat and treatment process |
| CN111455284A (en) * | 2020-05-26 | 2020-07-28 | 宜阳县鼎钰耐材有限公司 | Wear-resistant alloy steel bar and heat treatment process thereof |
| CN114182083A (en) * | 2021-11-01 | 2022-03-15 | 大冶特殊钢有限公司 | Method for improving impact toughness of 2.25Cr-1.6W-V-Nb heat-resistant alloy seamless steel pipe |
| CN114517253A (en) * | 2020-11-20 | 2022-05-20 | 中国科学院金属研究所 | Hot working process for eliminating blocky structure in low-alloy steel large forging |
| CN115216605A (en) * | 2021-04-16 | 2022-10-21 | 中国科学院金属研究所 | Method for eliminating black spot tissue in large-scale low-alloy steel forging |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106191389A (en) * | 2016-08-26 | 2016-12-07 | 上海交通大学 | A kind of two-step method tempering process improving nuclear power heavy forging impact flexibility |
-
2017
- 2017-07-04 CN CN201710536320.2A patent/CN109207693A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106191389A (en) * | 2016-08-26 | 2016-12-07 | 上海交通大学 | A kind of two-step method tempering process improving nuclear power heavy forging impact flexibility |
Non-Patent Citations (3)
| Title |
|---|
| 周超: "核电站反应堆压力容器用SA508-4Ni-Cr-Mo钢的组织和性能研究", 《中国优秀硕士学位论文全文数据库 工程科技Ⅰ辑》 * |
| 晏广华 等: "带有偏析的SA508_Gr.3钢核电大锻件在回火过程中的组织演化", 《第十一次全国热处理大会论文集》 * |
| 雷雪 等: "SA508-3钢低温韧性不合格原因分析及工艺改进", 《大型铸锻件》 * |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111254355A (en) * | 2020-03-18 | 2020-06-09 | 中铁宝桥集团有限公司 | Bainite alloy steel heat and treatment process |
| CN111455284A (en) * | 2020-05-26 | 2020-07-28 | 宜阳县鼎钰耐材有限公司 | Wear-resistant alloy steel bar and heat treatment process thereof |
| CN114517253A (en) * | 2020-11-20 | 2022-05-20 | 中国科学院金属研究所 | Hot working process for eliminating blocky structure in low-alloy steel large forging |
| CN115216605A (en) * | 2021-04-16 | 2022-10-21 | 中国科学院金属研究所 | Method for eliminating black spot tissue in large-scale low-alloy steel forging |
| CN115216605B (en) * | 2021-04-16 | 2024-01-19 | 中国科学院金属研究所 | Method for eliminating black spot tissue in large low-alloy steel forging |
| CN114182083A (en) * | 2021-11-01 | 2022-03-15 | 大冶特殊钢有限公司 | Method for improving impact toughness of 2.25Cr-1.6W-V-Nb heat-resistant alloy seamless steel pipe |
| CN114182083B (en) * | 2021-11-01 | 2023-10-03 | 大冶特殊钢有限公司 | Method for improving impact toughness of 2.25Cr-1.6W-V-Nb heat-resistant alloy seamless steel tube |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109207693A (en) | A method of improving quenched and tempered state low-alloy nodular bainite steel impact flexibility | |
| KR101340165B1 (en) | Seamless precision steel tubes with improved isotropic toughness at low temperature for hydraulic cylinders and process for obtaining the same | |
| JP5344454B2 (en) | Steel for warm working, warm working method using the steel, and steel and steel parts obtained thereby | |
| JP4709944B2 (en) | Case-hardened steel, carburized parts, and method for producing case-hardened steel | |
| US20130037182A1 (en) | Mechanical part made of steel having high properties and process for manufacturing same | |
| CN102808073B (en) | There is non-hardened and tempered steel and the manufacture method thereof of Ultra-fine Grained pearlitic structrure | |
| CN100548567C (en) | The manufacture method of ultralow temperature high intensity fine grain simple steel flange | |
| US20240052470A1 (en) | Non-quenched and Tempered Round Steel with High Strength, High Toughness and Easy Cutting and Manufacturing Method Therefor | |
| CN112981277B (en) | Preparation method of ultrahigh-strength medium-carbon nano bainite steel | |
| KR100261664B1 (en) | Intercritical heat treatment process for toughness improvement of sa508 gr.3 steel | |
| CN110157871A (en) | A kind of ductile iron abrading-ball quenching process | |
| Mehrabi et al. | Improvement of AISI 4340 steel properties by intermediate quenching–microstructure, mechanical properties, and fractography | |
| CN109182680B (en) | Method for controlling annealing hardness of martensitic stainless steel rod wire for cold heading | |
| CN110129525B (en) | Preparation method of low-temperature bainite steel | |
| CN103572176B (en) | A kind of low-carbon martensitic steels and prepare the method for suspension ring | |
| CN113151742B (en) | Corrosion-resistant high-strength high-toughness alloy tool steel and heat treatment method and production method thereof | |
| CN110358970A (en) | 1100MPa grades of yield strength of welding structure bainite high-strength steel and preparation method thereof | |
| CN112941274B (en) | Method for improving high-carbon chromium steel strength and toughness and application thereof | |
| CN110205541B (en) | X65-grade high-toughness microbial corrosion-resistant pipeline steel and preparation method thereof | |
| CN111304549A (en) | High-strength high-toughness Cu-containing low-alloy high-strength steel and heat treatment method thereof | |
| Wang et al. | Effect of tempering temperature on the microstructure and properties of Fe-2Cr-Mo-0.12 C pressure vessel steel | |
| CN114369769B (en) | Ultra-high strength and high toughness bainite aging steel and heat treatment process thereof | |
| CN106929756B (en) | Bearing steel and preparation method thereof | |
| CN104988295A (en) | Heat treatment method for improving medium-carbon non-quenched and tempered steel connecting rod cracking performance | |
| JP5747243B2 (en) | Warm working steel |
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 | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20190115 |
|
| RJ01 | Rejection of invention patent application after publication |