CN107630123A - A kind of method of non-carbide bainitic steel tissue preparation - Google Patents
A kind of method of non-carbide bainitic steel tissue preparation Download PDFInfo
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- CN107630123A CN107630123A CN201710251928.0A CN201710251928A CN107630123A CN 107630123 A CN107630123 A CN 107630123A CN 201710251928 A CN201710251928 A CN 201710251928A CN 107630123 A CN107630123 A CN 107630123A
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Abstract
A kind of method of non-carbide bainitic steel tissue preparation provided by the invention, by the temperature short time isothermal under being quickly cooled to Ms points slightly after steel heating complete austenitizing, be warming up to again Ms points slightly on temperature carry out isothermal, then after the temperature short time isothermal under being cooled to Ms points slightly, be warming up to again Ms points slightly on temperature carry out isothermal, so carry out 1~3 time by Ms points slightly descend after temperature short time isothermal to be warming up to Ms points slightly on temperature isothermal process, be finally cooled back to room temperature.Can this method can obviously reduce time of carbide-free Bainite structural transformation, and conveniently control its transformation amount, refinement size and martensite content, it can improve the mechanical property of different-alloy composition non-carbide bainitic steel by adjusting its technological parameter, reach preferable intensity and toughness to coordinate, be advantageous to industrialized production.
Description
Technical field
The present invention relates to a kind of method prepared by structure of steel, more particularly to a kind of non-carbide bainitic steel tissue preparation
Method.
Background technology
For research in recent years personnel to improve the mechanical property of bainitic steel, it is improved intensity improves plasticity and toughness again, right
Bainite structure transformation and tissue morphology have made intensive studies in steel, by the chemical composition and Isothermal treatment work that change steel
Skill, prepares the non-carbide bainitic steel based on carbide-free Bainite tissue, and the mechanical property of this steel is significantly better than
Traditional lower bainite steel.The tissue morphology of carbide-free Bainite is larger to Effect on Mechanical Properties, fine especially nanometer
The carbide-free Bainite of size can make steel obtain high intensity and higher toughness, and the Technology for Heating Processing of its tissue preparation is usually will
Ms points are quickly cooled to after steel austenitizing（Ms (martensite start) point）Slightly upper temperature carries out isothermal transformation, but will be at this
Temperature province, which obtains substantial amounts of carbide-free Bainite, needs longer time, and isothermal temperature is lower（I.e. closer to Ms points）, obtain
The carbide-free Bainite tissue obtained is more tiny, and required fringe time is longer, when generally requiring tens hours or even be several all
Between, this brings difficulty to the production of non-carbide bainitic steel.
Patent US6884306B1 discloses a kind of Fe-C-Si-Mn-Cr-Ni-Mo-V carbides-free shellfishes of nano-grade size
Family name's body steel, has high intensity and a high-fracture toughness, its Technology for Heating Processing be carry out 1 in slightly above Ms points temperature after austenitizing~
The isothermal processes of 3 time-of-weeks；The nanoscale high-carbon non-carbide bainitic steel that CN102112644A is proposed needs to be up to 400 hours
Constant temperature process be made, it is seen that the shortcomings that carbide-free Bainite isothermal transformation overlong time be present in non-carbide bainitic steel.
To accelerate the carbide-free Bainite isothermal transformation time of steel, CN102321852B is by steel first in overcooling austenite temperature
The compression of 590~610 DEG C of 50% drafts of progress in area, then keeps 2.5~3.5h can in a little higher than Ms point temperature isothermal
A large amount of 50~70nm nanostructureds carbide-free Bainites are obtained, this method can accelerate to obtain carbide-free Bainite, but exist
Deforming uneven causes it to change uneven and be unfavorable for the deficiency of scale industrial production.
Patent CN104451408B proposes quickly to cool down after steel austenitizing and at 250~270 DEG C and 280~300
The alternating isothermal transformation of DEG C temperature range obtains carbide-free Bainite for 3~24 hours, and this method is the two of bainite transformation area
Individual temperature range is changed, and technique is convenient, but transition temperature section is wide and transition temperature is high, can make the carbides-free shellfish of transformation
Family name's body size is uneven, limited to carbide-free Bainite transformation facilitation also with faint thermal expansion change,
Accelerate transformation and structure refinement effect smaller to it.
In addition, some documents propose that the transformation that simply cools will be passed through after steel austenitizing（Non-isothermal changes）It is carbon-free to obtain
Compound bainite, such as CN103160736B, CN104087852B, CN102628144A, CN103397273A, these methods can only
Obtain the line and staff control of a small amount of and uneven carbide-free Bainite of size and a large amount of other tissues, it is impossible to effectively embody Non-carbonized
Contribution of the bainite to mechanical property.
The carbide-free Bainite of the good fine uniform of mechanical property be usually close to Ms points slightly on temperature isothermal transformation
Obtain, but the carbide-free Bainite transformation in the humidity province is slow, how to shorten the isothermal transformation of carbide-free Bainite, and
The non-carbide bainitic steel based on carbide-free Bainite tissue is obtained, is important research topic.
The present invention proposes a kind of method of non-carbide bainitic steel tissue preparation, it is intended to ensures carbide-free Bainite
On the basis of fine uniform and excellent mechanical performances, shorten its fringe time, improve the production efficiency of this steel.
The content of the invention
A kind of method of non-carbide bainitic steel tissue preparation provided by the invention, is that steel is heated into complete austenitizing
Afterwards, the cooling velocity do not decomposed with cold austenite is cooled to Ms points（Ms (martensite start) point）Temperature under slightly is in short-term
Between isothermal, then be warming up to Ms points slightly on temperature carry out isothermal, after the temperature short time isothermal under being then cooled to Ms points slightly,
Be warming up to again Ms points slightly on temperature carry out isothermal, so carry out being warming up to after slightly descending temperature short time isothermal by Ms points 1~3 time
Ms points slightly on temperature isothermal process, be finally cooled back to room temperature, you can obtain with fine uniform carbide-free Bainite group
It is woven to main non-carbide bainitic steel.
It is above-mentioned it is described be cooled to Ms points slightly under temperature be 5~20 DEG C lower than Ms point of temperature.This is to utilize Ms points slightly
Under less alternating temperature section obtain a small amount of martensite, for then Ms points slightly on the carbide-free Bainite of temperature change shape be provided
Core condition.
The time of the above-mentioned described temperature short time isothermal that to be cooled to Ms points slightly lower is wanted with ensureing that steel part center portion can reach
Temperature is sought to determine, different sizes（Thickness or diameter）Steel part needed for short time isothermal time it is different, this can pass through heat transfer
Detection or empirical equation determine that for the steel plate less than 16mm, the time of required short time isothermal is usually no more than 10 minutes.
It is above-mentioned it is described be warming up to Ms points slightly on temperature be 5~20 DEG C higher than Ms point of temperature, its isothermal time is 4~
15 hours.This is to improve nucleation rate by the use of a small amount of martensite surface changed in advance as heterogeneous forming core interface, after tested, when etc.
The carbide-free Bainite of temperature 4~6 hours available 50~70% contents of transformation, isothermal transformation 7~10 hours available 70~
The carbide-free Bainite of 90% content, the carbide-free Bainite of isothermal transformation available more than 90% content more than 10 hours.
Above-mentioned described carry out 1~3 time by Ms points slightly under temperature short time isothermal after be warming up to Ms points slightly on temperature
Constant temperature process be each Ms points slightly under temperature value it is identical.Thus increase carries out number, can further improve carbides-free shellfish
The nucleation rate of family name's body transformation, can substantially shorten carbide-free Bainite fringe time, improve carbide-free Bainite in steel
Content.
Above-mentioned described carry out 1~3 time by Ms points slightly under temperature short time isothermal after be warming up to Ms points slightly on temperature
Constant temperature process is that a Ms point slightly descends temperature low 1~10 DEG C before a rear Ms point slightly descends temperature ratio.When an overcooling austenite part
After being changed into carbide-free Bainite, its chemical composition can be changed, and Ms points is decreased, and martensite is gradually reduced for this
Transition temperature, overcooling austenite stability can be overcome gradually to improve the martensite brought and slightly descend temperature to be difficult to change not in Ms points
Foot, so as to be further ensured that carbide-free Bainite nucleation rate.
Above-mentioned described carry out 1~3 time Ms points slightly on isothermal accumulated time in temperature constant temperature process to be no more than 10 small
When.
Above-mentioned described complete austenitizing is ferrite in steel and carbide to be completely transformed into austenite and composition is equal
It is even, reach austenite homogenization.
The principle of the invention is explained further, bainite structure transformation can occur under isothermal conditions in steel, and martensite group
Knitting transformation is formed under the conditions of continuous coo1ing.Carbide-free Bainite is also to change under isothermal conditions, and its isothermal turns
Temperature is lower（Closer to Ms points）, the tissue of acquisition is more tiny（Closer to nano-scale）, mechanical property is better, but changes pregnant
Educate time phase extends therewith, and homogeneous nucleation is difficult, and transformation amount substantially reduces.The present invention will quickly cool down after steel complete austenitizing
Ms points to the steel slightly descend temperature short time isothermal, and austenite both can be carbides-free shellfish with the limited martensite of generation quantity
The transformation of family name's body provides effective heterogeneous forming core condition, can control again martensite transfor mation amount will not >=10%, then raising temperature to Ms
In the slightly upper temperature isothermal processes of point, carbide-free Bainite transformation can be carried out on the basis of the martensite of above-mentioned generation, so as to promote
Enter overcooling austenite to carbide-free Bainite to change, experiment proves, the obvious carbide-free Bainite that shortens of the present invention turns
Become the time, improve transformation efficiency, while also refined carbide-free Bainite tissue, not only increase the intensity of steel, simultaneously
Also improve the toughness of steel.In addition, slightly descend a small amount of martensite of temperature transition in Ms points, not only can subsequent Ms points slightly on
In temperature promote carbide-free Bainite transformation, and a small amount of martensite first changed can in temperature-rise period the row's of generation carbon
Into overcooling austenite, make the reduction of martensite fragility, and substantial amounts of carbide-free Bainite transformation makes the supercooling Austria not changed
Family name's body stability improves, and can effectively suppress martensite transfor mation of the steel when being cooled to room temperature again, further improve fragility.
The advantage of the invention is that：
1）Tiny, uniform carbide-free Bainite structural transformation can be promoted, retained austenite quantity in steel is effectively reduced, carry
Gao Gang mechanical property；
2）The refinement size and uniformity of carbide-free Bainite can be conveniently controlled, final martensite content is reduced, passes through tune
Its whole technological parameter can improve the mechanical property of different-alloy composition non-carbide bainitic steel, reach preferable intensity and toughness
Coordinate.
3）Substantially accelerate carbide-free Bainite fringe time, can be obtained within the shorter Technology for Heating Processing time 90% with
On nano-scale carbide-free Bainite content bainitic steel, be advantageous to industrialized production and good resultant force can be obtained
Learn performance.
Brief description of the drawings
Fig. 1 is the non-carbide bainitic steel heat treatment cycle curve of the embodiment of the present invention 1~2.
Fig. 2 is the non-carbide bainitic steel heat treatment cycle curve of the embodiment of the present invention 3.
Fig. 3 is the X-ray diffraction detection collection of illustrative plates of the non-carbide bainitic steel obtained with the embodiment of the present invention 1~3.
Fig. 4 is the transmission electron microscope pattern of the non-carbide bainitic steel tissue obtained with the present invention, wherein：A is embodiment 1
Transmission electron microscope pattern, b be embodiment 3 transmission electron microscope pattern.
Embodiment
Embodiments of the invention select more typical 60Mn2SiCr non-carbide bainitic steels plate, steel plate thickness 16mm,
Chemical composition wt%：0.5 ~ 0.8C, 1.5 ~ 2.0Si, 1.5 ~ 2.0Mn, Cr0.5 ~ 1.0, S≤0.02, P≤0.01, remaining Fe and not
Impurity can be avoided.Detected with thermal dilatometer and calculate examine the steel Ms points be 253 DEG C.
Embodiment 1
Reference picture 1, steel sample is heated to more than Ac1 T1 temperature and is incubated, homogenized its austenite, T1=900 DEG C can be set
And 40 minutes are incubated, then quickly it is put into after stopping t1=3 minute in the salt bath furnace of T3=245 DEG C（Austenitizing steel is quick at this
The cooling velocity being put into salt bath furnace can be more than 15/s）, place into the salt bath furnace of T2=260 DEG C and carry out isothermal 12 hours, then
It is air-cooled to room temperature.
Embodiment 2
Reference picture 1, steel sample is heated to T1=910 DEG C and is incubated 30 minutes, is then quickly put into the salt bath furnace of T3=235 DEG C and stops
After staying t1=1 minute, isothermal 20 hours in the salt bath furnace of T2=270 DEG C are placed into, are then air-cooled to room temperature.
Embodiment 3
Reference picture 2, steel sample is heated to T1=890 DEG C and is incubated 40 minutes, then short time water cooling is sent again to close to Ms point temperature
Enter after stopping t31=6 minute in the air furnace of T31=248 DEG C, place into isothermal t21=2 hour in the air furnace of T2=260 DEG C；Then
Carry out the 2nd time and be cooled to the cooling heating process ginseng that Ms points slightly descend temperature short time isothermal to be warming up to the slightly upper temperature isothermal of Ms points again
Number is：Wind cooling temperature lowering is simultaneously sent into stop t32=6 minute in the air furnace of T32=245 DEG C, places into isothermal in the air furnace of T2=260 DEG C
T22=3 hour；Then carrying out the cooling heating process parameter of the 3rd time is：Wind cooling temperature lowering and being sent into the air furnace of T33=235 DEG C stops
T33=6 minute are stayed, isothermal t23=4 hour in the air furnace of T2=260 DEG C is placed into, is then air-cooled to room temperature.
Embodiment 4
Reference picture 2, steel sample is heated to T1=900 DEG C and is incubated 40 minutes, then short time water cooling is sent again to close to Ms point temperature
Enter after stopping t31=10 minute in the air furnace of T31=240 DEG C, place into isothermal t21=4 hour in the air furnace of T2=265 DEG C；With
It is identical with the 1st time to carry out the cooling heating process parameter of the 2nd time again afterwards, is then air-cooled to room temperature.
Detected by X-ray diffractometer and obtain the diffraction spectral line of the steel sample of embodiment 1~3 as shown in Fig. 3, can using the spectral line
Remained austenite content is calculated, is figure by the microscopic structure of transmission electron microscope observation to embodiment 1 and the steel sample of embodiment 3
Shown in 4（The microscopic structure of the steel sample of embodiment 2 is similar）, test the mechanical property of each embodiment steel sample in addition, and with it is existing
There is method（Directly in 260 DEG C of isothermal transformation i.e. after steel austenitizing）Contrast, draw detected average data for shown in following table：
| Retained austenite wt% | Bainite width nm | Hardness Hv | Toughness J | |
| Embodiment 1 | 5.70% | 61.1 | 770 | 16.3 |
| Embodiment 2 | 4.81% | 65.5 | 733 | 15.1 |
| Embodiment 3 | 4.63% | 60.8 | 775 | 15.6 |
| Embodiment 4 | 4.71% | 62.6 | 756 | 15.2 |
| Existing method | 7.99% | 105.4 | 650 | 14.7 |
By finding out in table, the remained austenite content that sample is prepared with the embodiment of the present invention significantly reduces, and tissue size is because of forming core
Increase and generally reduce, hardness is significantly improved, and toughness is also improved.
Claims (5)
1. a kind of method of non-carbide bainitic steel tissue preparation, it is characterized in that after steel is heated into complete austenitizing, with cold
The cooling velocity that austenite is not decomposed be cooled to Ms points slightly under temperature short time isothermal, then be warming up to Ms points slightly on
Temperature carries out isothermal, after the temperature short time isothermal under being then cooled to Ms points slightly, then be warming up to Ms points slightly on temperature enter
Row isothermal, so carry out 1~3 time by Ms points slightly descend after temperature short time isothermal to be warming up to Ms points slightly on temperature isothermal mistake
Journey, finally it is cooled back to room temperature.
2. the method as described in claim 1, it is characterized in that it is described be cooled to Ms points slightly under temperature be lower than Ms point 5~
20 DEG C of temperature.
3. the method as described in claim 1, it is characterized in that it is described be warming up to Ms points slightly on temperature be higher than Ms point by 5
~20 DEG C of temperature, its isothermal time are 4~15 hours.
4. the method as described in claim 1, it is characterized in that described carry out 1~3 time by Ms points slightly under the temperature short time
Be warming up to after isothermal Ms points slightly on temperature constant temperature process be each Ms points slightly under temperature value it is identical.
5. the method as described in claim 1, it is characterized in that described carry out 1~3 time by Ms points slightly under the temperature short time
Be warming up to after isothermal Ms points slightly on temperature constant temperature process be after a Ms point slightly descend temperature ratio before a Ms point slightly descend temperature low 1
~10 DEG C.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111961811A (en) * | 2020-09-04 | 2020-11-20 | 燕山大学 | Method for preparing impact-resistant steel part by using phase change speed difference |
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2017
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| CN102002558A (en) * | 2010-11-26 | 2011-04-06 | 清华大学 | Step quenching-distribution heat treatment technology of steels containing carbide formation inhibiting elements |
| CN102108433B (en) * | 2011-04-01 | 2012-07-25 | 瓦房店轴承集团有限责任公司 | Method for quenching bearing steel |
| CN104357632A (en) * | 2014-10-10 | 2015-02-18 | 天津大学 | Method for refining martensite lath through secondary heat treatment in metastable two-phase region of T92 steel |
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Non-Patent Citations (1)
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| 郭明阳等: "Q＆P 工艺对60Mn2SiCr 钢中超级贝氏体组织转变的影响", 《材料热处理学报》 * |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111961811A (en) * | 2020-09-04 | 2020-11-20 | 燕山大学 | Method for preparing impact-resistant steel part by using phase change speed difference |
| CN111961811B (en) * | 2020-09-04 | 2022-05-24 | 燕山大学 | Method for preparing impact-resistant steel part by using phase change speed difference |
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