CN1108387C - Method for producing low carbon steel twisted steel - Google Patents
Method for producing low carbon steel twisted steel Download PDFInfo
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- CN1108387C CN1108387C CN00109495A CN00109495A CN1108387C CN 1108387 C CN1108387 C CN 1108387C CN 00109495 A CN00109495 A CN 00109495A CN 00109495 A CN00109495 A CN 00109495A CN 1108387 C CN1108387 C CN 1108387C
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Abstract
The present invention belongs to the metal rolling field, and mainly relates to the rolling of screw steel bars. The method for producing low-carbon screw steel bars in the present invention is characterized in that the final finish rolling of steel billets is carried out at the temperature interval of Ae3 and Ar3 of steel, namely that the final finish rolling is carried out in the sub stable austenite area. After rolling, water penetration and cooling are carried out; the cooling speed is not smaller than 20 DEG C /S, and after the steel billets are cooled to be from 300 to 600 DEG C by water, the steel billets are cooled by air. The same type of steel is rolled by adopting the method of the present invention, and the yield strength of the steel bars can be obviously increased.
Description
Technical field
The invention belongs to metal rolled field.Relate generally to the rolling of Twisted Steel.
Background technology
Twisted Steel is widely used in the reinforcing mat and the net defence in airport, motorway, tunnel etc., and cement prefab of covil construction, cassette ceiling stringer structural part, concrete duct etc.Under identical working conditions, improve the Twisted Steel yield strength, the one, can reduce the diameter of reinforcing bar, save steel, reduce cost; The 2nd, under identical member, with the minimizing of bar diameter, cement grouting will be more unobstructed, can enhance productivity.
Be to improve the rank of building bar, for example with the yield strength σ of reinforcing bar
sBring up to 400MPa (III level) from 335MPa (II grade reinforcing steel), currently used technical measures can reduce following some: 1) improve the carbon content (upper limit of carbon content brings up to 0.25% by 0.18) of soft steel (as the Q235 steel) and carry out alloying (Si, Mn content bring up to 0.8% and 1.6% from 0.4%t and 0.8% respectively) and microalloying (add≤0.1% Nb, V, Ti).As 20MnSiV steel etc.The essence of this measure is to borrow solution strengthening, precipitation strength and structure refinement to reach raising reinforcement yielding intensity σ
sPurpose.2) on the basis of aforementioned increase carbon content and alloying (as the 20MnSi steel) adopts and rolls back immediate quenching technology.Its strengthening mechanism is returned to one's native place to help and is rolled to quench in back (single-phase austenitic area) and self-tempering acquisition part tempered martensite has increased the effect of phase transformation strengthening except that solution strengthening and structure refinement.More than the hot rolling technology and the traditional technology of two kinds of measures do not have obvious difference: all be to carry out finish to gauge, but because of increasing Si, Mn content and/or adding the cost that microalloy elements such as power Nb, V, Ti have improved reinforcing bar in stable single-phase austenitic area.
Summary of the invention
That the object of the present invention is to provide that a kind of technology is simple, cost is low and can guarantee to improve the production method of the low carbon steel twisted steel of yield strength.
Characteristics of the present invention are to use ordinary low-carbon steel (as the Q235 steel) to carry out final finish rolling in the metastable austenite district, by distortion to promotion and the response facilitation effect and the ferrite recrystallize of phase transformation and roll the tiny ferrite+pearlitic structure of fast cold acquisition afterwards, be main highly malleablized means promptly, make the III grade reinforcing steel with the soft steel of simple composition with structure refinement.
Its concrete technical scheme is as follows:
Steel billet is after heating, at the Ae of this steel
3And Ar
3Temperature range is carried out final finish rolling, promptly carries out final finish rolling in the metastable austenite district, and total deformation 〉=50% of final finish rolling rolls the back and cools off with the cooling rate of speed of cooling 〉=20 ℃/S.
In many highly malleablized means, have structure refinement only and can improve intensity and toughness simultaneously.In practice in the past, austenite recrystallization and the district's controlled rolling of austenite non-recrystallization and corresponding cooling control technology have been extensive use of, to reach the purpose of structure refinement.Yet, for ordinary low-carbon steel (Mn content≤0.8%), because the grain growth tendency is very strong, and austenite non-recrystallization temperature province is very narrow, be difficult under big working condition, realize aforementioned two kinds of controlled rolling process, cause its ferrite crystal grain mean sizes often more than 15 μ m.Simultaneously, lower C, Mn content make the hardening capacity of this steel grade extremely low, can't carry out phase transformation strengthening with immediate quenching and self-tempering after aforementioned the rolling.More than two aspect factors make all and produce Twisted Steel that the raising of its yield strength is very limited with soft steel.
Be positioned at Ae
3(austenite/ferrite equilibrium temperature) and Ar
3Single-phase austenite between (austenite-ferrite transformation begins temperature when cooling off continuously) is metastable austenite or supercooled austenite, if on this temperature range and contiguous temperature thereof, it is applied viscous deformation, intensive strain promotion will be arranged and bring out cholesteric-nematic transition, its phase-change product-ferrite will be very tiny.If it is rolling to carry out multi-pass, then also can obtain tiny ferrite crystal grain because of ferritic dynamic and static recrystallize; If be aided with higher speed of cooling and control final cooling temperature after the deformation, then can suppress ferrite crystal grain and grow up, at room temperature obtain the ferrite crystal grain and the perlite of tiny (as 5 μ m), thereby improve yield strength and guarantee essential plasticity.
Adopt the production method of low carbon steel twisted steel of the present invention, produce low carbon steel twisted steel and can significantly improve yield strength.As can be with the yield strength of Q235 steel Twisted Steel by σ with this method
s≤ 335MPa (II grade reinforcing steel) brings up to more than the 400MPa, its elongation δ
5〉=17%, satisfy III grade reinforcing steel (σ
s〉=400MPa, δ
5〉=17%) requirement.
Compared with prior art, advantage of the present invention is needn't improve C, Mn, Si content and carry out microalloying, and cost is low.Simultaneously, since this production method at Ae
3And Ar
3Interval rolling, rolling temperature is low, thereby can reduce the Heating temperature of blank, reduces heating energy consumption and oxidization burning loss.So remarkable in economical benefits.
Embodiment
Adopt the production method of low carbon steel twisted steel of the present invention, produced three batches of low carbon steel twisted steels, three grades of steel that lot number adopted and chemical ingredients are as shown in table 1.Billet heating temperature and rolling temperature, total deformation and to roll postcooling speed as shown in table 2 when rolling.Rolling and the cooling after, sampling and measuring tensile property and ferrite grain size, its result is as shown in table 3.
The yield strength σ of conventional Q235 steel Twisted Steel
s≤ 335MPa, after employing the inventive method is rolling, the yield strength σ of Q235 steel Twisted Steel
s≤ 400MPa (seeing Table 3) promptly reaches the requirement of III level Twisted Steel.
The chemical ingredients (wt%) of table 1 embodiment low carbon steel twisted steel
| Lot number | Steel grade | Chemical ingredients (wt%) | ||||
| C | Si | Mn | P | S | ||
| 1 | Q235-1 | 0.18 | 0.21 | 0.60 | 0.020 | 0.016 |
| 2 | Q235-2 | 0.14 | 0.25 | 0.58 | 0.026 | 0.015 |
| 3 | Q235-3 | 0.14 | 0.19 | 0.51 | 0.032 | 0.024 |
Table 2 embodiment rolling parameter and roll the postcooling parameter
| Lot number | The Ae of steel grade 3、 Ar 3Temperature (℃) | Billet heating temperature (℃) | The start rolling temperature scope (℃) | Final final rolling temperature scope (℃) | Cooling rate after rolling (〉=℃/S) | Temperature before the air cooling (℃) | Total deformation (%) | |
| Ae 3 | Ar 3 | |||||||
| 1 | 850 | 780-800 | 900 | 850- 780 | 540 | |||
| 2 | 850 | 780-800 | 1100 | 950- 1000 | 820- 780 | 20 | 530 | 62 |
| 3 | 850 | 780-800 | 1150 | 1150- 800 | 850- 780 | 20 | 520 | 65 |
Annotate: the Ar of Q235 steel
3Temperature: when speed of cooling is 5 ℃/S, Ar
3It is 780 ℃; When speed of cooling is 1 ℃/S, Ar
3It is 800 ℃.
The tensile property and the grain-size of table 3 embodiment low carbon steel twisted steel
| Lot number | Ferrite grain size μ m | σ s MPa | σ b MPa | δ 5 ％ |
| 1 | 5.0 | 510 | 600 | 17 |
| 2 | 6.0 | 430 | 505 | 36 |
| 3 | 6.6 | 405 | 500 | 34 |
Claims (2)
1, a kind of production method of low carbon steel twisted steel is characterized in that the Ae at this steel
3And Ar
3Temperature range is carried out final finish rolling, promptly carries out final finish rolling in the metastable austenite district.
2, the production method of low carbon steel twisted steel according to claim 1 is characterized in that total deformation 〉=50% of final finish rolling, rolls the back and cools off with the cooling rate of speed of cooling 〉=20 ℃/S.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN00109495A CN1108387C (en) | 2000-07-06 | 2000-07-06 | Method for producing low carbon steel twisted steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN00109495A CN1108387C (en) | 2000-07-06 | 2000-07-06 | Method for producing low carbon steel twisted steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1278013A CN1278013A (en) | 2000-12-27 |
| CN1108387C true CN1108387C (en) | 2003-05-14 |
Family
ID=4579676
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN00109495A Expired - Fee Related CN1108387C (en) | 2000-07-06 | 2000-07-06 | Method for producing low carbon steel twisted steel |
Country Status (1)
| Country | Link |
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| CN (1) | CN1108387C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100434557C (en) * | 2004-02-10 | 2008-11-19 | 鞍山钢铁集团公司 | Production process of low-carbon high-strength composite reinforced superfine grain hot-rolled wire |
| CN1327008C (en) * | 2005-07-07 | 2007-07-18 | 东北大学 | Post rolling fast cooling-production technology of high strength ribbed reinforced bar |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1097659A (en) * | 1994-05-25 | 1995-01-25 | 冶金工业部钢铁研究总院 | The warm rolling method of spiral |
-
2000
- 2000-07-06 CN CN00109495A patent/CN1108387C/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1097659A (en) * | 1994-05-25 | 1995-01-25 | 冶金工业部钢铁研究总院 | The warm rolling method of spiral |
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|---|---|
| CN1278013A (en) | 2000-12-27 |
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Granted publication date: 20030514 Termination date: 20110706 |