CN108285955A - A kind of method that sample is annealed before 18CrNiMo7-6 carburizers - Google Patents
A kind of method that sample is annealed before 18CrNiMo7-6 carburizers Download PDFInfo
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- CN108285955A CN108285955A CN201810184503.7A CN201810184503A CN108285955A CN 108285955 A CN108285955 A CN 108285955A CN 201810184503 A CN201810184503 A CN 201810184503A CN 108285955 A CN108285955 A CN 108285955A
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- sample
- 18crnimo7
- carburizers
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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
- C21D1/26—Methods of annealing
-
- 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
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
-
- 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
- C21D2211/005—Ferrite
-
- 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
- C21D2211/009—Pearlite
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Investigating And Analyzing Materials By Characteristic Methods (AREA)
- Sampling And Sample Adjustment (AREA)
Abstract
The invention belongs to carburizing steel annealing technology fields, and in particular to a kind of method that sample is annealed before 6 carburizers of 18CrNiMo7 is specifically, (1) first by equipped with cast-iron scrap sample box and sample be placed in trial furnace and be heated to 890 910 DEG C；(2) by sample it is rapid it is buried enter sample box in, and in 9 11min of trial furnace inside holding；(3) stop heating after keeping the temperature, open fire door natural cooling；(4) fire door and 9 11min of Heat preservation are closed when furnace temperature is cooled to 640 660 DEG C；(5) sample is taken out out of sample box air-cooled.After above-mentioned annealing, carburizing steel surface and center portion obtain statenchyma, are conducive to accurately detect surface carbon concentration and layer depth index.
Description
Technical field
The invention belongs to carburizing steel annealing technology fields, and in particular to sample is annealed before a kind of 18CrNiMo7-6 carburizers
Method.
Background technology
With the pole sample of product material, specified quantity is placed per carburizing heat in carburizer sample aperture, in each technique
90min comes out of the stove annealing before end cycle, surface carbon concentration and carburized layer depth is detected, to monitor carburizing process and adjustment in real time
Carburization process, the sample are defined as sample before carburizer.
Since through hardening performance is splendid, martensitic traoformation easily occurs 18CrNiMo7-6 materials in air for sample, can not obtain
Obtain pearlite+ferritic structure of equilibrium state.Its surface center portion obtains quenched martensite, lower bainite, troostite etc. after slow cooling
Non-equilibrium microstructure, as shown in Fig. 1 and 2, the type tissue influences greatly surface carbon concentration detection, on the basis of this class loading,
The extremely difficult observation of grain boundary carbide, and since core obtains the non-equilibrium microstructures such as martensite, granular bainite, carburized layer depth detection
Data do not have any practical directive significance.
It using full annealing technique, is made annealing treatment in electric furnace, surface can obtain clearly statenchyma, but when annealing
Between be up to a few hours, the uncontrollability of carburizing will be increased, is unable to meet production demand.
Using being interrupted after the sample water quenching of stokehold, the method that metallographic method detects carburized layer depth, accuracy of detection is not relatively high, and can not
Surface carbon concentration is accurately detected.
Invention content
Invention broadly provides the methods that sample before a kind of 18CrNiMo7-6 carburizers is annealed, after annealed processing, carburizing
Steel surface and center portion obtain statenchyma, are conducive to accurately detect surface carbon concentration and layer depth index.Its technical solution
It is as follows：
A kind of method that sample is annealed before 18CrNiMo7-6 carburizers, includes the following steps：
(1) by equipped with cast-iron scrap sample box and sample be placed in trial furnace and be heated to 890-910 DEG C；
(2) by sample it is rapid it is buried enter sample box in, and in trial furnace inside holding 9-11min；
(3) stop heating after keeping the temperature, open fire door natural cooling；
(4) fire door and Heat preservation 9-11min are closed when furnace temperature is cooled to 640-660 DEG C；
(5) sample is taken out out of sample box air-cooled.
Preferably, the addition of iron filings accounts for 2/3 in sample box in step (1).
Preferably, the time that furnace temperature naturally cools to 640-660 DEG C by 890-910 DEG C is 25-35min.
Preferably, sample annealing all times are 45-55min before carburizer.
Using the above scheme, the present invention has the following advantages：
The purpose of present invention process cast-iron scrap is to prevent stokehold sample from generating obviously in austenitizing and isothermal annealing process
Decarburization and influence surface carbon concentration detection；Austenitizing temperature is necessary >=and 820 DEG C, consider sample transfer operation process contact air
Heat loss and temperature height be conducive to the efficiency of heating surface raising, 900 DEG C of practical choice can ensure that annealing before do not enter 730-
820 DEG C of two-phase sections, while can ensure that sample is rapidly completed austenitizing transformation and does not generate apparent decarburization.Since stokehold sample is set
In in the sample box of cast-iron scrap, when blow-on door furnace cooling, stokehold sample can quickly with air heat exchange, simultaneously as overall thermal
Capacity is relatively large without will produce excessive drop temperature situation, can be accurately controlled in 650 DEG C of realization isothermal processes conditions.When operation
Between short, whole 50min, it is efficient for full annealing technique a few hours, it is accurate for fractography method.Table
Face and the transformation of center portion statenchyma, surface carbon concentration and carburized layer depth Indexs measure precision are high.
Description of the drawings
Fig. 1 is specimen surface non-equilibrium microstructure metallograph in prior art；
Fig. 2 is sample center portion non-equilibrium microstructure metallograph in prior art；
Fig. 3 is 18CrNiMo7-6 carburizing steel CCT curve figures；
Fig. 4 is carburizing steel annealing process temperature profile in embodiment 1；
Fig. 5 is 1 process pilot sample surface balance tissue metallograph of embodiment；
Fig. 6 is 1 process pilot sample center portion statenchyma metallograph of embodiment.
Specific implementation mode
Experimental method in following embodiment is conventional method unless otherwise required, involved experiment reagent and material
Material is conventional biochemical reagent and material unless otherwise required.
Embodiment 1
A kind of method that sample is annealed before 18CrNiMo7-6 carburizers, includes the following steps：
(1) cast-iron scrap situation in 100 × 100 × 150cm gauge coupons boxes is checked, it is ensured that cast-iron scrap is filled 2/3 and do not gone out
Sample box and stokehold sample are placed in trial furnace and are heated to 900 DEG C by now serious caking phenomenon；
(2) will in stove take out 25 × 25 specifications of Φ stokehold sample, with vice will bind stokehold sample iron wire cut and it is fast
Speed by stokehold sample it is buried enter 900 DEG C of sample box iron filings in, and in trial furnace inside holding 10min；
(3) stop heating after keeping the temperature, open fire door, close electric furnace heating, natural cooling；
(4) fire door and Heat preservation 10min are closed when furnace temperature cools down about 30min to 650 DEG C；
(5) sample is taken out out of sample box air-cooled.
Above-mentioned annealing process temperature change is as shown in figure 4, this technological principle is：18CrNiMo7-6 material center portion AC3 lines are
820 DEG C, it is achieved that the heating temperature of complete austenitizing it is necessary >=820 DEG C.CCT curve as shown in Figure 3, annealed state obtain
The isothermal temperature of statenchyma F+P (ferrite+pearlite) is at 640-680 DEG C, and the cooling velocity above and below this temperature range is not
Statenchyma is influenced to generate.After isothermal processes, stokehold sample surface will obtain pearlite+carbide morphology, center portion obtain pearlite+
Ferritic structure, surface and center portion obtain statenchyma, are conducive to accurately detect surface carbon concentration and layer depth index.Figure
5 and Fig. 6 is specimen surface and center portion statenchyma metallograph after annealing, and as seen from the figure, carburizing steel surface and center portion are equal
Obtain statenchyma.
Embodiment 2
A kind of method that sample is annealed before 18CrNiMo7-6 carburizers, includes the following steps：
(1) cast-iron scrap situation in 100 × 100 × 150cm gauge coupons boxes is checked, it is ensured that cast-iron scrap is filled 2/3 and do not gone out
Sample box and sample are placed in trial furnace and are heated to 890 DEG C by now serious caking phenomenon；
(2) will in stove take out 25 × 25 specifications of Φ stokehold sample, with vice will bind stokehold sample iron wire cut and it is fast
Speed by stokehold sample it is buried enter 890 DEG C of sample box iron filings in, and in trial furnace inside holding 11min；
(3) stop heating after keeping the temperature, open fire door, close electric furnace heating, natural cooling；
(4) fire door and Heat preservation 9min are closed when furnace temperature cools down about 30min to 660 DEG C；
(5) sample is taken out out of sample box air-cooled.
It will be apparent to those skilled in the art that technical solution that can be as described above and design, make various other
Corresponding change and deformation, and all these changes and deformation should all belong to the protection domain of the claims in the present invention
Within.
Claims (4)
1. a kind of method that sample is annealed before 18CrNiMo7-6 carburizers, it is characterised in that：Include the following steps：
(1) by equipped with cast-iron scrap sample box and sample be placed in trial furnace and be heated to 890-910 DEG C；
(2) by sample it is rapid it is buried enter sample box in, and in trial furnace inside holding 9-11min；
(3) stop heating after keeping the temperature, open fire door natural cooling；
(4) fire door and Heat preservation 9-11min are closed when furnace temperature is cooled to 640-660 DEG C；
(5) sample is taken out out of sample box air-cooled.
2. the method that sample is annealed before 18CrNiMo7-6 carburizers according to claim 1, it is characterised in that：In step (1)
The addition of iron filings accounts for 2/3 in sample box.
3. the method that sample is annealed before 18CrNiMo7-6 carburizers according to claim 1, it is characterised in that：Furnace temperature by
The 890-910 DEG C of time for naturally cooling to 640-660 DEG C is 25-35min.
4. the method that sample is annealed before 18CrNiMo7-6 carburizers according to claim 1, it is characterised in that：Before carburizer
Sample anneals all times as 45-55min.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810184503.7A CN108285955A (en) | 2018-03-06 | 2018-03-06 | A kind of method that sample is annealed before 18CrNiMo7-6 carburizers |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810184503.7A CN108285955A (en) | 2018-03-06 | 2018-03-06 | A kind of method that sample is annealed before 18CrNiMo7-6 carburizers |
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| CN108285955A true CN108285955A (en) | 2018-07-17 |
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| CN201810184503.7A Pending CN108285955A (en) | 2018-03-06 | 2018-03-06 | A kind of method that sample is annealed before 18CrNiMo7-6 carburizers |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111518996A (en) * | 2020-04-15 | 2020-08-11 | 大冶特殊钢有限公司 | Heat treatment method of 18CrNiMo7-6 steel |
Citations (5)
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|---|---|---|---|---|
| CN1693490A (en) * | 2005-05-23 | 2005-11-09 | 建设工业(集团)有限责任公司 | Method of preventing decarbon of iron and steel parts during heat treatment in air medium |
| CN102721600A (en) * | 2012-06-26 | 2012-10-10 | 山西太钢不锈钢股份有限公司 | Pure iron test sample annealing protection method |
| CN105296902A (en) * | 2014-07-16 | 2016-02-03 | 刘振宇 | Copper cylinder anaerobic annealing process |
| CN106011431A (en) * | 2016-07-05 | 2016-10-12 | 苏州市虎丘区浒墅关弹簧厂 | Spring heat treatment technology capable of preventing decarbonization |
| CN106001379A (en) * | 2016-05-23 | 2016-10-12 | 辽宁银捷装备科技股份有限公司 | Forging process for bearing rings made of M50 steel |
-
2018
- 2018-03-06 CN CN201810184503.7A patent/CN108285955A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1693490A (en) * | 2005-05-23 | 2005-11-09 | 建设工业(集团)有限责任公司 | Method of preventing decarbon of iron and steel parts during heat treatment in air medium |
| CN102721600A (en) * | 2012-06-26 | 2012-10-10 | 山西太钢不锈钢股份有限公司 | Pure iron test sample annealing protection method |
| CN105296902A (en) * | 2014-07-16 | 2016-02-03 | 刘振宇 | Copper cylinder anaerobic annealing process |
| CN106001379A (en) * | 2016-05-23 | 2016-10-12 | 辽宁银捷装备科技股份有限公司 | Forging process for bearing rings made of M50 steel |
| CN106011431A (en) * | 2016-07-05 | 2016-10-12 | 苏州市虎丘区浒墅关弹簧厂 | Spring heat treatment technology capable of preventing decarbonization |
Non-Patent Citations (1)
| Title |
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| 沈桂琴: "《光学金相技术》", 30 November 1983, 国防工业出版社 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111518996A (en) * | 2020-04-15 | 2020-08-11 | 大冶特殊钢有限公司 | Heat treatment method of 18CrNiMo7-6 steel |
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Application publication date: 20180717 |