CN111979482A - CrMn spring steel bloom and one-step-firing material preparation method thereof - Google Patents
CrMn spring steel bloom and one-step-firing material preparation method thereof Download PDFInfo
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- CN111979482A CN111979482A CN202010748708.0A CN202010748708A CN111979482A CN 111979482 A CN111979482 A CN 111979482A CN 202010748708 A CN202010748708 A CN 202010748708A CN 111979482 A CN111979482 A CN 111979482A
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- 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
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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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- 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
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- 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
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Abstract
The invention discloses a CrMn spring steel bloom and a preparation method of a hot finished product thereof, wherein the bloom comprises the following chemical components: 0.52 to 0.64 percent of C, less than or equal to 0.50 percent of Si, 0.65 to 1.0 percent of Mn, 0.65 to 0.95 percent of Cr, and the balance of Fe and inevitable impurities, and provides a one-shot material preparation method of the bloom. The spring steel has uniform and compact structure, the spring steel has low decarburization depth and low decarburization ferrite content, and the decarburization control requirement of the spring steel for the stabilizer bar is met; the surface of the spring steel is good; the preparation method combines proper heating and rolling rhythm with gas control, and the depth of the decarburization layer of the finished spring steel is well controlled.
Description
Technical Field
The invention relates to a spring steel bloom and a method for preparing a hot formed material thereof, in particular to a CrMn spring steel bloom and a method for preparing a hot formed material thereof.
Background
The automobile stabilizer bar is one of important parts of an automobile chassis system, and the main stabilizer bar materials are Si-Mn series, CrMn series, SiCrV series spring steel bars and alloy structural steel pipes which are emerged in recent years. The main specification of the spring steel bar for the automobile stabilizer bar is phi 15-27mm, and the current main production process comprises two processes of large square billet two-fire forming (electric furnace/converter smelting, external furnace refining, vacuum treatment, large square billet continuous casting, cogging, blank finishing and coping, hot rolling forming), small square billet one-fire forming (electric furnace/converter smelting, external furnace refining, vacuum treatment, continuous casting (the blank shape is generally less than 240mm square), blank finishing and coping, hot rolling forming).
The two processes have advantages and disadvantages respectively. The secondary heating forming has the advantages that the compression ratio is large, the secondary heating is favorable for ensuring the uniformity and the compactness of the material, and the surface quality is better; the disadvantages are high cost and unfavorable control of spring steel decarburization by secondary heating. The advantages of the small square billet and the one-step firing are short process, high-efficiency production is facilitated, the cost is low, and the rolling heating temperature is low, so that decarburization control is facilitated; the defect is that the compression ratio is small, so that the tissue uniformity and compactness are not controlled.
The automobile stabilizer bar is one of important parts of an automobile chassis system, and the main stabilizer bar materials are Si-Mn series, CrMn series, SiCrV series spring steel bars and alloy structural steel pipes which are emerged in recent years. The automobile stabilizer bar is a key part of an automobile chassis system, is related to the comfort and the stability of an automobile, has high requirement on fatigue life (the fatigue life is usually more than or equal to 20 ten thousand times), and is made of a material for the automobile stabilizer bar, so that the material has high internal and surface quality. The spring steel used for the automobile stabilizer bar is generally formed by a big square billet and a small square billet through one heating process. The secondary heating forming has the advantages that the compression ratio is large, and the twice heating is beneficial to ensuring the uniformity and compactness of the material; the disadvantages are high cost and unfavorable control of spring steel decarburization caused by two times of heating. The advantages of the small square billet and the one-step firing are short process, high-efficiency production is facilitated, the cost is low, and the rolling heating temperature is low, so that decarburization control is facilitated; the defect is that the compression ratio is small, so that the tissue uniformity and compactness are not controlled.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a CrMn spring steel bloom with low cost and high quality, and aims to provide a one-step material preparation method of the CrMn spring steel bloom.
The technical scheme is as follows: the CrMn spring steel bloom comprises the following chemical components: 0.52 to 0.64 percent of C, less than or equal to 0.50 percent of Si, 0.65 to 1.0 percent of Mn, 0.65 to 0.95 percent of Cr, and the balance of Fe and inevitable impurities.
The preparation method of the CrMn spring steel bloom comprises the following steps: smelting, refining, vacuum treatment, bloom continuous casting, heating, rolling, primary cooling, pre-finish rolling, secondary cooling, finish rolling, final cooling temperature control, inspection and flaw detection.
Further, five sections of heating are adopted for heating.
Preferably, the temperature of the preheating section of the five-section heating is less than or equal to 800 ℃, the temperature of the heating section of the five-section heating is less than or equal to 930 ℃, the temperature of the heating section of the five-section heating is 1010-.
The smelting uses an electric furnace or a converter. Refining is LF refining. The vacuum treatment is VD or RH vacuum treatment. The heating adopts a stepping continuous heating furnace. And the finish rolling is finish rolling of a KOCKS rolling mill. The heating uses gas as the mixed gas of blast furnace gas and high coke-to-mixed gas. The compression ratio of the large square billet is 130-450.
Has the advantages that: compared with the prior art, the invention has the following remarkable advantages:
(1) the spring steel has uniform and compact structure, and the comprehensive performance is close to that of a second fire material and superior to that of a first fire material of a small square billet;
(2) the spring steel has low decarburization depth and low ferrite content of a decarburized layer, and the decarburization control requirement of the spring steel for the stabilizer bar is met; the surface of the spring steel is good;
(3) the preparation method combines the proper heating and rolling rhythm with gas control, and the depth of the decarburized layer of the finished spring steel is well controlled;
(4) the large-compression-ratio rolling improves the influence of the original surface of a casting blank on the surface of a finished product, improves the surface quality of the finished product spring steel, fully crushes dendritic structures in the steel, has fine and uniform structures and good density, and is beneficial to the control of strong materials and toughness;
(5) the method integrates the advantages of two-heating forming and one-heating forming, avoids the defects of the two, adopts bloom and one-heating forming, and is a method for producing the CrMn stabilizer bar spring steel material with high efficiency, low cost and high quality.
Drawings
FIG. 1 shows that the finished product of SUP9D is decarburized 0.05 mm;
FIG. 2 shows that the decarbonization of the 55Cr3 finished product is 0.10 mm;
FIG. 3 is the longitudinal structure of the finished product;
FIG. 4 is a transverse microstructure of the finished product;
FIG. 5 is a finished austenite grain size;
FIG. 6 is a photograph of the acid pickling of the final product.
Detailed Description
The technical solution of the present invention is further illustrated by the following examples.
Example 1
Rolling the square billet into a continuous casting square billet with the diameter of 250mm by 300mm spring steel SUP9DZL
The SUP9D spring round steel process flow of specification is: BOF converter smelting, LF refining furnace, RH treatment, bloom continuous casting, heap cooling, heating by a stepping continuous heating furnace (preheating section temperature: 650-Gas mixing), 20-pass rolling (10-pass primary rolling and 10-pass intermediate rolling), 4-pass pre-finish rolling, 4-pass KOCKS rolling mill finish rolling, inspection, flaw detection (UT + ET), inspection, packaging, metering and warehousing.
The physical and chemical detection performance of the finished product material produced by the process is excellent, the surface state is good, and the compression ratio of the bloom is 130: 1 times lower
2. Depth of decarburized layer
| Standard requirements | Decarburization of less than or equal to 1.0% of ferrite D: 0; less than or equal to 0.20mm |
| Test results | 0.05mm, 0.10mm, ferrite decarburization: 0 |
3. Grain size
Heat treatment temperature and heat preservation time: keeping the temperature at 860 ℃ for 60min
| Standard requirements | Grade not less than 6 |
| Test results | Stage 8.0 |
4. Mechanical properties
5. Nondestructive testing
| Total number of counts | Number of qualified counts | Flaw detection grade | Percent of pass | |
| Surface magnetic flux leakage flaw detection | 807 | 780 | GB/T32547 grade N-0.15 | 96.65％ |
| Ultrasonic flaw detection | 807 | 807 | GB/T4162-2008A grade | 100 |
Example 2
The steel is continuously cast into square billets by using 250mm 300mm spring steel 55Cr3ZL and is rolled into the diameter
The 55Cr3 spring round steel process flow with the specification is as follows: converter smelting, an LF refining furnace, RH treatment, bloom continuous casting, dump cooling, heating by a stepping continuous heating furnace (the temperature of a preheating section is 780-800 ℃, the temperature of a heating section is 920-930 ℃, the temperature of a heating section is 1060-1080 ℃, the temperature of a soaking section is 1090-1100 ℃, the temperature of a soaking section is 1110-1120 ℃, the temperature of final rolling is 860 ℃, the total heating time is 215-228min, fuel gas is blast furnace gas and high-coke-conversion mixed gas), 20-pass rolling (10-pass initial rolling + 10-pass intermediate rolling), 4-pass pre-rolling, 4-pass CKS rolling mill finish rolling, inspection, finish rolling (UT + ET), inspection, packaging, metering and warehousing.
The physical and chemical detection performance of the finished product material produced by the process is excellent, the surface state is good, and the compression ratio of the bloom is 450:
1. low power
2. Depth of decarburized layer
| Standard requirements | Decarbonizing ferrite with the mass percent of less than or equal to 1.0% and D (less than or equal to 0.258 mm): 0 |
| Test results | 0.11mm/0.10 mm; full decarburization 0 |
3. Austenite grain size
Heat treatment temperature and heat preservation time: keeping the temperature at 860 ℃ for 60min
| Standard requirements | Grade not less than 6 |
| Test results | Stage 8.0 |
4. Mechanical properties
5. Nondestructive testing
| Total number of counts | Number of qualified counts | Flaw detection grade | Percent of pass | |
| Surface magnetic flux leakage flaw detection | 1022 | 991 | GB/T32547 grade N-0.20 | 96.97 |
| Ultrasonic flaw detection | 1022 | 1022 | GB/T4162-2008A grade | 100 |
The spring steel for the CrMn stabilizer bar produced according to the invention comprises the following components: the depth of the decarburized layer is small (see figures 1 and 2: 0.051-0.10 mm); the structure is pearlite and a small amount of ferrite, and the transverse direction and the longitudinal direction both have good equiaxed crystal characteristics (see fig. 3 and 4); the finished product sample is subjected to heat preservation at 860 ℃ for 60min to form austenite, and the crystal grains are fine (see figure 5); the finished product is low-density and has no obvious defect (see figure 6).
Claims (10)
1. A CrMn spring steel bloom is characterized by comprising the following chemical components: 0.52 to 0.64 percent of C, less than or equal to 0.50 percent of Si, 0.65 to 1.0 percent of Mn, 0.65 to 0.95 percent of Cr, and the balance of Fe and inevitable impurities.
2. A method for producing a CrMn spring steel bloom in one go, according to claim 1, characterized by comprising the steps of: smelting, refining, vacuum treatment, bloom continuous casting, heating, rolling, primary cooling, pre-finish rolling, secondary cooling, finish rolling, final cooling temperature control, inspection and flaw detection.
3. The method for preparing the CrMn spring steel bloom through one-step hot briquetting according to claim 2, characterized in that: the heating adopts five-section heating.
4. The method for preparing the CrMn spring steel bloom through one-step hot briquetting according to claim 3, characterized by comprising the following steps: the temperature of the preheating section of the five-section heating is less than or equal to 800 ℃, the temperature of the heating section of the five-section heating is less than or equal to 930 ℃, the temperature of the heating section of the five-section heating is 1010-.
5. The method for preparing the CrMn spring steel bloom through one-step hot briquetting according to claim 2, characterized in that: the smelting is carried out by using an electric furnace or a converter.
6. The method for preparing the CrMn spring steel bloom through one-step hot briquetting according to claim 2, characterized in that: the refining is LF refining.
7. The method for preparing the CrMn spring steel bloom through one-step hot briquetting according to claim 2, characterized in that: the vacuum treatment is VD or RH vacuum treatment.
8. The method for preparing the CrMn spring steel bloom through one-step hot briquetting according to claim 2, characterized in that: the heating adopts a stepping continuous heating furnace.
9. The method for preparing the CrMn spring steel bloom through one-step hot briquetting according to claim 2, characterized in that: the heating gas is the mixed gas of blast furnace gas and high coke-to-mixed gas.
10. The method for preparing the CrMn spring steel bloom through one-step hot briquetting according to claim 2, characterized in that: the compression ratio of the bloom is 130-450.
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| CN202010748708.0A CN111979482B (en) | 2020-07-30 | 2020-07-30 | CrMn spring steel bloom and one-step-firing material preparation method thereof |
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| CN202010748708.0A CN111979482B (en) | 2020-07-30 | 2020-07-30 | CrMn spring steel bloom and one-step-firing material preparation method thereof |
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| CN111979482A true CN111979482A (en) | 2020-11-24 |
| CN111979482B CN111979482B (en) | 2022-03-22 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115229152A (en) * | 2022-07-28 | 2022-10-25 | 江苏联峰实业有限公司 | Production control process of 55Cr3 spring steel bar with high surface quality |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102151693A (en) * | 2010-12-02 | 2011-08-17 | 大冶特殊钢股份有限公司 | Method for rolling low-hardness small-sized spring steel |
| CN102560046A (en) * | 2012-02-21 | 2012-07-11 | 南京钢铁股份有限公司 | Method for controlling surface decarburization of spring steel wires |
| CN110331264A (en) * | 2019-07-22 | 2019-10-15 | 南京钢铁股份有限公司 | A kind of heating Decarburization Control method of spring steel blank |
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2020
- 2020-07-30 CN CN202010748708.0A patent/CN111979482B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102151693A (en) * | 2010-12-02 | 2011-08-17 | 大冶特殊钢股份有限公司 | Method for rolling low-hardness small-sized spring steel |
| CN102560046A (en) * | 2012-02-21 | 2012-07-11 | 南京钢铁股份有限公司 | Method for controlling surface decarburization of spring steel wires |
| CN110331264A (en) * | 2019-07-22 | 2019-10-15 | 南京钢铁股份有限公司 | A kind of heating Decarburization Control method of spring steel blank |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115229152A (en) * | 2022-07-28 | 2022-10-25 | 江苏联峰实业有限公司 | Production control process of 55Cr3 spring steel bar with high surface quality |
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