CN104233075A - Chromium-containing niobium microalloyed 400MPa-grade reinforcing bar steel and production method thereof - Google Patents
Chromium-containing niobium microalloyed 400MPa-grade reinforcing bar steel and production method thereof Download PDFInfo
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- CN104233075A CN104233075A CN201310566665.4A CN201310566665A CN104233075A CN 104233075 A CN104233075 A CN 104233075A CN 201310566665 A CN201310566665 A CN 201310566665A CN 104233075 A CN104233075 A CN 104233075A
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Abstract
The invention discloses chromium-containing niobium microalloyed 400MPa-grade reinforcing bar steel, which is composed of the following elements: 0.15-0.25% of C, 0.30-0.80% of Si, 0.40-1.20% of Mn, 0.31-0.60% of Cr, equal to or less than 0.045% of P and S, and 0.010-0.035% of Nb. The production method comprises processes of smelting, continuous casting and rolling, wherein heating temperature is 1050-1220 DEG C, and rolling is completed at temperature more than 950 DEG C; after rolling, a rolled piece is rapidly cooled, and a cooling rate of the rolled piece is equal to or more than 150 DEG C/s after being delivered out of a finishing mill, the surface temperature of reinforcing bar on a cooling bed is controlled at Ac3-Ac3+100 DEG C or 800-890 DEG C, and the reinforcing bar is naturally cooled on the cooling bed. A mechanical property of the reinforcing bar can meet a demand on a 400MPa-grade reinforcing bar, and rusting time in an indoor environment is obviously delayed compare to niobium microalloyed 400MPa-grade control-cooled reinforcing bar free from chromium.
Description
Technical field
The invention belongs to Steel Concrete hot-rolled reinforced bar, especially relate to 400MPa level reinforcing bar and production method thereof.
Background technology
Hot rolled ribbed steel bar is the important materials for building concrete structure.The standard that current China hot rolled ribbed steel bar product performs is GB1499.2-2007 " concrete reinforcement steel second section: hot rolled ribbed steel bar ", and product has 335 MPa levels, 400 MPa levels and 500 MPa level 3 strength grades.Development trend progressively eliminates 335 MPa level low strength reinforcing bars, actively popularization 400 MPa levels and 500 MPa grade high-strength reinforcing bars, research and development application 600 MPa level and higher level high strength cast iron.
Along with the fast development of construction business, the output of 400 MPa level hot rolled ribbed steel bars increases considerably, also more and more higher to the specification of quality of product.Current 400 MPa level reinforcing bars mainly adopt 20MnSi steel to add vanadium, vanadium nitrogen, niobium, titanium microalloying explained hereafter.In order to the prerequisite decline lower production cost of ensuring the quality of products, after rolling, weak water management of wearing generally all is adopted to cool.
Patent of invention " trace niobium-containing steel for cooling-control reinforced bar and production method thereof " (CN100465321C) proposes a kind of trace niobium-containing steel for cooling-control reinforced bar, be made up of following elements by weight percentage: 0.15-0.25%C, 0.30-0.80%Si, 1.00-1.60%Mn, ≤ 0.045%P, S, 0.005-0.020%Nb ,≤0.0080%N, all the other are Fe and impurity element.Production technique is: steel-making, by the element of specifying and content, adopts conventional smelting process, and in converter or electric furnace, smelting, continuous casting become steel billet; Merchant bar mill rolling, during rolling, billet heating temperature controls, 1050-1220 DEG C of scope, to complete rolling more than more than 950 DEG C; Controlled cooling model, roll rear rolled piece and cool fast, on reinforcing bar, the temperature of cold bed controls at 800-1050 DEG C; After naturally cooling, shearing, bundling, warehouse-in.Reinforcing bar content of niobium reduces, functional, and solves production technique that current Nb-microalloying reinforcing bar exists well and the problem such as unstable properties, billet heating temperature are too high, Cracks In Continuous Cast Billets occurrence probability is high, reduces production cost.But cool fast owing to rolling rear rolled piece, water coolant makes reinforcing bar easily produce serious corrosion in storage, transportation, directly affects sale.
Patent of invention " a kind of cooling controlling and rolling controlling process of hot rolled ribbed steel bar " (CN101367093) and patent of invention " a kind of combined control rolling process for hot-rolled steel bar with rib " (CN101367094) propose the novel process of producing hot rolled ribbed steel bar, all have employed and after rolled piece goes out finishing mill, to enter the technique that water cooler carries out cooling fast, on rolled piece during cold bed surface temperature control at A
c3~ A
c3+ 50 DEG C.When ensure mechanical property meet or higher than Standard, the content of Mn, Si and micro alloying element in steel can be reduced significantly, even can not use micro alloying element, and surface of reinforced bar is without tempered structure.But same water coolant makes reinforcing bar easily produce serious corrosion in storage, transportation.
Summary of the invention
For overcoming the shortcoming of prior art, the present invention proposes a kind of Nb-microalloying 400MPa level reinforcing bar steel containing chromium and production technique thereof.Under the qualified stable prerequisite of guarantee reinforcement property, obviously can alleviate and adopt the corrosion phenomena of the 400MPa level reinforcing bar of weak Water cooling explained hereafter in storage, transportation.
For solving the problems of the technologies described above, the invention provides a kind of Nb-microalloying 400MPa level reinforcing bar steel containing chromium, be made up of following elements by weight percentage: 0.15-0.25%C, 0.30-0.80%Si, 0.40-1.20%Mn, 0.31-0.60%Cr ,≤0.045%P, S, 0.010-0.035%Nb, all the other are Fe and impurity element.
Containing a Nb-microalloying 400MPa level reinforcing bar steel for chromium, its preferred weight percent is made up of following elements: 0.18-0.24%C, 0.50-0.70%Si, 0.90-1.10%Mn, 0.31-0.40%Cr ,≤0.045%P, S, 0.015-0.030%Nb, all the other are Fe and impurity element.
Containing a Nb-microalloying 400MPa level reinforcing bar steel for chromium, the weight percent of its optimum is made up of following elements: 0.20-0.24%C, 0.50-0.65%Si, 0.95-1.10%Mn, 0.31-0.35%Cr ,≤0.045%P, S, 0.020-0.028%Nb, all the other are Fe and impurity element.
The present invention also provides the production method of the Nb-microalloying 400MPa level reinforcing bar containing chromium, comprises the steps: to smelt, and by designed element and content, adopt conventional smelting process, converter or electric furnace are smelted, and continuous pouring becomes steel billet; Merchant bar mill rolling, during rolling, billet heating temperature controls, 1050-1220 DEG C of scope, more than 950 DEG C, to complete rolling; Roll rear rolled piece to cool fast, rolled piece goes out speed of cooling>=150 after finishing mill DEG C/s, on reinforcing bar during cold bed surface temperature control at A
c3~ A
c3+ 100 DEG C or 800-890 DEG C, reinforcing bar is naturally cooling on cold bed.
Illustrate the content of technical scheme below.
Carbon of the present invention, silicone content and existing yield strength 400MPa level reinforcing bar are substantially suitable, and the requirement of phosphorus, sulphur impurity element is also suitable.The effect adding a small amount of chromium in steel mainly improves the erosion resistance of steel, and chromium is also improved oxidation-resistance, improves the intensity of steel and the effect of hardness, hot strength and hardening capacity in steel.Can intensity be improved owing to adding chromium, so a part of manganese can be substituted, Fe content suitably be reduced.The present invention adopts niobium as micro alloying element, and the strengthening effect main manifestations of niobium to reinforcing bar is grain refining, precipitation strength and phase transformation strengthening, and adding of niobium is necessary, present invention employs 0.010-0.035% content of niobium.
During rolling, billet heating temperature is by 1050-1220 DEG C of general scope control.Complete rolling more than more than 950 DEG C and basic complete rolling in austenite recrystallization district be to realize recrystallization softening, and existing steel rolling equipment and technique easily realize.Rolling temperature easily produces mixed crystal in partial, re-crystallization district, has a negative impact to performance.Rolling temperature is difficult to realize at the then existing steel rolling equipment of Unhydrated cement and technique.Suitable accelerating cooling is conducive to preventing Austenite Grain Growth, also be conducive to suppressing the carbon of niobium, nitride in the precipitation of middle warm area and growing up, and increase precipitation nucleation rate, increase the effect that it stops recrystal grain to be grown up, before phase transformation, Austenite Grain Refinement result in the structure refinement of the finished product.Accelerating cooling also helps carbon, nitride is separated out in cold zone.The refined crystalline strengthening increased and precipitation strength improve the intensity of reinforcing bar.But the temperature on cooling table of reinforcing bar must control at A
c3~ A
c3+ 100 DEG C or 800-890 DEG C, too low, can occur the low temperature phase change products such as too much bainite appear in tempered structure and reinforcing bar section at surface of reinforced bar, the effect of too high then cooling reinforcing is bad.
Compared with prior art, the present invention has following technique effect: the Nb-microalloying 400MPa level reinforcing bar containing chromium that (1) the present invention produces, and its mechanical performance index reaches: R
eL(R
p0.2)=400-520MPa, R
m>=570MPa, R
m/ R
eL(R
p0.2)>=1.25, A
gt>=7.5%; (2) the corrosion imagination adopting the 400MPa level reinforcing bar of weak Water cooling explained hereafter in storage, transportation is obviously alleviated; (3) ensure that the smooth enforcement of reinforcing bar low cost weak Water cooling technique, thus alloy resource, reduction production cost can be saved.
Embodiment
The present invention is further illustrated below by embodiment.Adopt conventional smelting process, the element of specifying by each specification of table 1 and content are smelted in converter, and continuous casting becomes 150mm square billet; Adopt general continuous merchant bar mill, strict control billet heating temperature 1050-1250 DEG C, more than 950 DEG C, rolling completes; Roll rear rolled piece to cool fast, rolled piece goes out speed of cooling>=150 after finishing mill DEG C/s, on reinforcing bar during cold bed surface temperature control at A
c3~ A
c3+ 100 DEG C or 800-890 DEG C, reinforcing bar is naturally cooling on cold bed, then shearing, bundling, warehouse-in.Its processing parameter, mechanical property and rolling start the number of days (D of corrosion under being placed on indoor environment
corrosion) list in table 2.
Table 1, table 2 have also listed file names with the number of days (D starting corrosion under the composition of Nb-microalloying 400MPa level controlled cooling reinforcing bar, processing parameter, mechanical property and rolling are placed on indoor environment
corrosion).
For the corrosion test under above-mentioned all reinforcing bar indoor environments, the reinforcing bar of same specification is all produce on the same day, and be all be placed in same test point to start test simultaneously, there is relatively meaning, the time starting corrosion is that reinforcing bar cross rib root border is covered closed day by new rust completely, calculates the number of days D starting to occur corrosion accordingly
corrosion.
Table 1: the chemical composition of reinforcing bar
Table 2: the processing parameter of reinforcing bar, mechanical property, corrosion resisting property
As seen from Table 2, the mechanical property containing the Nb-microalloying 400MPa level reinforcing bar of chromium all reaches index request: R
eL(R
p0.2)=400-520MPa, R
m>=570MPa, R
m/ R
eL(R
p0.2)>=1.25, A
gt>=7.5%.The time of corrosion is started than obviously not delaying containing chromium Nb-microalloying 400MPa level controlled cooling reinforcing bar under its indoor environment.
Claims (4)
1. the Nb-microalloying 400MPa level reinforcing bar steel containing chromium, it is characterized in that: be made up of following elements by weight percentage: 0.15-0.25%C, 0.30-0.80%Si, 0.40-1.20%Mn, 0.31-0.60%Cr, 0.010-0.035%Nb, P≤0.045%, S≤0.045%, all the other are Fe and impurity element.
2. the Nb-microalloying 400MPa level reinforcing bar steel containing chromium as claimed in claim 1, it is characterized in that: be made up of following elements by weight percentage: 0.18-0.24%C, 0.50-0.70%Si, 0.90-1.10%Mn, 0.31-0.40%Cr, 0.015-0.030%Nb, P≤0.045%, S≤0.045%, all the other are Fe and impurity unit
Element.
3. the Nb-microalloying 400MPa level reinforcing bar steel containing chromium as claimed in claim 1, it is characterized in that: be made up of following elements by weight percentage: 0.20-0.24%C, 0.50-0.65%Si, 0.95-1.10%Mn, 0.31-0.35%Cr, 0.020-0.028%Nb, P≤0.045%, S≤0.045%, all the other are Fe and impurity element.
4. one kind contains the production method of the Nb-microalloying 400MPa level reinforcing bar of chromium as claimed in claim 1, comprise smelting, continuous casting, rolling, cooling step, it is characterized in that: during rolling, billet heating temperature controls at 1050-1220 DEG C, more than 950 DEG C, complete rolling; Roll rear rolled piece to cool fast, rolled piece goes out speed of cooling>=150 after finishing mill DEG C/s, on reinforcing bar during cold bed surface temperature control at A
c3~ A
c3+ 100 DEG C or 800-890 DEG C, reinforcing bar is naturally cooling on cold bed.
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| CN201310566665.4A CN104233075A (en) | 2013-11-13 | 2013-11-13 | Chromium-containing niobium microalloyed 400MPa-grade reinforcing bar steel and production method thereof |
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|---|---|---|---|
| CN201310566665.4A CN104233075A (en) | 2013-11-13 | 2013-11-13 | Chromium-containing niobium microalloyed 400MPa-grade reinforcing bar steel and production method thereof |
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ID=52221961
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107747048A (en) * | 2017-11-30 | 2018-03-02 | 攀钢集团攀枝花钢铁研究院有限公司 | Steel wire rod and its production method are built containing V, Nb, Ti, Cr microalloy |
| CN107815526A (en) * | 2017-11-30 | 2018-03-20 | 攀钢集团攀枝花钢铁研究院有限公司 | Microalloy containing Nb builds Steel Bar and its production method |
| CN107815601A (en) * | 2017-11-30 | 2018-03-20 | 攀钢集团攀枝花钢铁研究院有限公司 | Steel wire rod and its LF stove production methods are built containing Nb, Cr microalloy |
| CN111621718A (en) * | 2020-06-28 | 2020-09-04 | 马鞍山钢铁股份有限公司 | Steel for high-ductility cold-rolled steel bar for welded mesh and production method thereof |
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| JPH04176845A (en) * | 1990-11-09 | 1992-06-24 | Daido Steel Co Ltd | Manufacture of non-thermal refining wire rod |
| CN1730705A (en) * | 2005-08-08 | 2006-02-08 | 宣化钢铁集团有限责任公司 | Microalloyed reinforcing steel bar containing chromium and niobium, and its production process |
| CN1952198A (en) * | 2005-10-17 | 2007-04-25 | 马鞍山钢铁股份有限公司 | Trace niobium -containing steel for cooling-control reinforced bar and method for producing same |
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2013
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Patent Citations (3)
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| JPH04176845A (en) * | 1990-11-09 | 1992-06-24 | Daido Steel Co Ltd | Manufacture of non-thermal refining wire rod |
| CN1730705A (en) * | 2005-08-08 | 2006-02-08 | 宣化钢铁集团有限责任公司 | Microalloyed reinforcing steel bar containing chromium and niobium, and its production process |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107747048A (en) * | 2017-11-30 | 2018-03-02 | 攀钢集团攀枝花钢铁研究院有限公司 | Steel wire rod and its production method are built containing V, Nb, Ti, Cr microalloy |
| CN107815526A (en) * | 2017-11-30 | 2018-03-20 | 攀钢集团攀枝花钢铁研究院有限公司 | Microalloy containing Nb builds Steel Bar and its production method |
| CN107815601A (en) * | 2017-11-30 | 2018-03-20 | 攀钢集团攀枝花钢铁研究院有限公司 | Steel wire rod and its LF stove production methods are built containing Nb, Cr microalloy |
| CN107815601B (en) * | 2017-11-30 | 2020-02-04 | 攀钢集团攀枝花钢铁研究院有限公司 | Microalloy construction steel wire rod containing Nb and Cr and LF furnace production method thereof |
| CN111621718A (en) * | 2020-06-28 | 2020-09-04 | 马鞍山钢铁股份有限公司 | Steel for high-ductility cold-rolled steel bar for welded mesh and production method thereof |
| CN111621718B (en) * | 2020-06-28 | 2021-12-14 | 马鞍山钢铁股份有限公司 | Steel for high-ductility cold-rolled steel bar for welded mesh and production method thereof |
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Application publication date: 20141224 |