CN109735699B - Production method for preventing niobium-containing hot-rolled ribbed steel bar from having no obvious yield point - Google Patents
Production method for preventing niobium-containing hot-rolled ribbed steel bar from having no obvious yield point Download PDFInfo
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- CN109735699B CN109735699B CN201811549673.7A CN201811549673A CN109735699B CN 109735699 B CN109735699 B CN 109735699B CN 201811549673 A CN201811549673 A CN 201811549673A CN 109735699 B CN109735699 B CN 109735699B
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 72
- 239000010959 steel Substances 0.000 title claims abstract description 72
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 title claims abstract description 37
- 229910052758 niobium Inorganic materials 0.000 title claims abstract description 36
- 239000010955 niobium Substances 0.000 title claims abstract description 36
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 22
- 238000005096 rolling process Methods 0.000 claims abstract description 43
- 238000001816 cooling Methods 0.000 claims abstract description 33
- 238000000034 method Methods 0.000 claims abstract description 27
- 238000010438 heat treatment Methods 0.000 claims abstract description 22
- 238000002791 soaking Methods 0.000 claims abstract description 5
- 230000008569 process Effects 0.000 claims description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 229910001562 pearlite Inorganic materials 0.000 claims description 9
- 229910000859 α-Fe Inorganic materials 0.000 claims description 9
- 230000006872 improvement Effects 0.000 abstract description 2
- 229910001566 austenite Inorganic materials 0.000 description 7
- 238000005728 strengthening Methods 0.000 description 7
- 229910001563 bainite Inorganic materials 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 6
- 239000010410 layer Substances 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 229910000628 Ferrovanadium Inorganic materials 0.000 description 3
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- PNXOJQQRXBVKEX-UHFFFAOYSA-N iron vanadium Chemical compound [V].[Fe] PNXOJQQRXBVKEX-UHFFFAOYSA-N 0.000 description 3
- 229910000734 martensite Inorganic materials 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- 229910000756 V alloy Inorganic materials 0.000 description 2
- SKKMWRVAJNPLFY-UHFFFAOYSA-N azanylidynevanadium Chemical compound [V]#N SKKMWRVAJNPLFY-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910000742 Microalloyed steel Inorganic materials 0.000 description 1
- 229910001199 N alloy Inorganic materials 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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Abstract
The invention discloses a production method for preventing niobium-containing hot-rolled ribbed steel bars from having no obvious yield point, which comprises the working procedures of heating, rolling and cooling; the improvement is as follows: the heating temperature is 1050-1250 ℃, the soaking temperature is 1100-1250 ℃, and the initial rolling temperature is 1000-1150 ℃; when the initial rolling temperature is 1000-; when the rolling temperature is more than 1000 ℃ and less than or equal to 1150 ℃, after rolling by 3 rolling mills, the rolled blank is cooled to 940-980 ℃ by a roller way, and then is continuously rolled, and the temperature of an upper cooling bed is controlled to 920-980 ℃. The niobium-containing hot-rolled ribbed steel bar produced by the method can completely prevent the niobium-containing steel bar from having no obvious yield phenomenon.
Description
Technical Field
The invention belongs to the field of metal pressure processing, and particularly relates to a production method for preventing niobium-containing hot-rolled ribbed steel bars from having no obvious yield point.
Background
For a long time, the hot-rolled ribbed steel bar of 400Mpa grade and above produced in China mainly adopts ferrovanadium or vanadium-nitrogen alloy micro-alloying process, and the microstructure of the steel bar produced by the process from the surface to the core of the steel bar is ferrite and pearlite structure. In addition to the vanadium microalloying process, in order to reduce the cost, some enterprises do not add microalloying elements but adopt a strong water penetration process to produce hot-rolled steel bars, the outermost layer of the steel bars produced by the process is tempered martensite, and the interior of the steel bars is ferrite and pearlite structures. With the establishment and implementation of the national standard GB/T1499.2-2018, the periphery of the section of the steel bar is definitely required to be not allowed to have rings different from internal contrast in the standard, and the microstructures of the steel bar from the surface to the core are required to be ferrite and pearlite structures, so that the steel bar produced by different processes is differentiated from the structure of the standard, the production of the hot-rolled steel bar by the water penetration process is limited, and the confusion of the steel bar market is prevented; the implementation of the new standard enables steel bar production enterprises to start to adopt a large amount of traditional vanadium microalloy process production, so that the demand of ferrovanadium is greatly increased; on the other hand, with the enhancement of national environmental protection regulation, the supply of vanadium alloy resources is short, and the vanadium alloy price is rapidly increased due to various reasons, so that the production cost of the traditional ferrovanadium or vanadium-nitrogen microalloying process steel bar is greatly increased.
In order to reduce the production cost, production enterprises in China begin to produce niobium-containing microalloyed steel bars, but the alloy steel bars often have the phenomenon of unobvious yield point, and although the yield point is not obvious as specified in the standard, an extensometer can be used as Rp0.2But users generally do not have the ability to measure Rp0.2When the yield of the steel bar is not obvious, the bainite and martensite contents in the structure are high, the plasticity of the steel bar is poor, and therefore, the quality complaints are high; in addition, if the reinforcing steel bar has no obvious yield point, the safety early warning function of the reinforcing steel bar is greatly reduced, and the anti-seismic performance is reduced, so that the reinforcing steel bar without the obvious yield point is not practically approved by building departments and markets. Measures must be taken to prevent the niobium-containing hot-rolled ribbed bars from yielding.
In order to enable the niobium-containing steel bar to have an obvious yield point, the patent application with the publication number of CN 101255492A discloses a production method for preventing the niobium microalloying hot-rolled ribbed steel bar from having no obvious yield point, wherein temperature ranges are respectively given for the heating temperature and the upper cooling bed temperature according to different environmental temperatures, but the heating temperature is lower than 1040-1120 ℃, the low heating temperature is not beneficial to the solid solution of niobium, the full utilization of microalloy elements is influenced, and the requirement on the capacity of rolling mill equipment is higher. In addition, in order to enable the steel bar to have an obvious yield point, the temperature of an upper cooling bed is controlled to be 820-910 ℃ lower, and the water cooling strength is high after rolling, so that a fine grain layer appears on the outermost layer of the steel bar, and the uniformity of the steel bar structure is poor. In addition, the probability that the yield point of the steel bar is not obvious is less than 1 percent by adopting the patent, and the phenomenon that the steel bar has no obvious yield point can not be completely avoided.
Disclosure of Invention
The invention aims to solve the technical problem of providing a production method which can completely put an end to the unobvious yield point of the niobium-containing steel bar, and an obvious yield platform can be obtained by reasonably controlling the heating temperature, the soaking temperature, the rolling temperature and the temperature of an upper cooling bed.
The technical scheme for solving the technical problems is as follows:
the production method for preventing the niobium-containing hot-rolled ribbed steel bar from having no obvious yield point mainly comprises the working procedures of heating, rolling and cooling; the improvement is as follows: in the heating procedure, the heating temperature is 1050-1250 ℃, and the soaking temperature is 1100-1250 ℃; the initial rolling temperature of the rolling procedure is 1000-1150 ℃; the temperature of an upper cooling bed in the cooling process is 920-980 ℃.
According to the production method for preventing the niobium-containing hot-rolled ribbed steel bar from having no obvious yield point, when the initial rolling temperature is 1000-1100 ℃, a rolled blank is continuously rolled into the steel bar, and then the steel bar is cooled by water, and the temperature of the steel bar on a cooling bed is controlled to be 920-980 ℃; when the rolling temperature is more than 1100 ℃ and less than or equal to 1150 ℃, rolling the rolled blank by 3 rolling mills, then cooling the rolled blank to 940-980 ℃ by a roller way, then continuously rolling the rolled blank into a steel bar, and then cooling the steel bar by water, wherein the temperature of an upper cooling bed is controlled to be 920-980 ℃.
According to the production method for preventing the niobium-containing hot-rolled ribbed steel bar from having no obvious yield point, the niobium content of the hot-rolled ribbed steel bar is 0.01-0.04 wt%.
According to the production method for preventing the niobium-containing hot-rolled ribbed steel bar from having no obvious yield point, the hot-rolled ribbed steel bar is a straight bar with the diameter of 20-36 mm.
According to the production method for preventing the niobium-containing hot-rolled ribbed steel bar from having no obvious yield point, after the rolled blank is rolled by 3 rolling mills, the rolling blank roller way is cooled in a reciprocating motion on the roller way, so that the temperature of the rolled blank is reduced to 940-980 ℃, and then continuous rolling is carried out.
According to the production method for preventing the niobium-containing hot-rolled ribbed steel bar from having no obvious yield point, the microstructure of the hot-rolled ribbed steel bar mainly comprises ferrite and pearlite, and the area percentage of the ferrite and the pearlite in the microstructure is more than or equal to 98%.
The theoretical analysis of the invention is as follows:
the main reason why the yield point of the hot-rolled ribbed steel bar is not obvious is that the content of super-cooled structures such as bainite, martensite and the like in the structure is high. In the steel bar containing niobium, niobium mainly has the functions of grain refinement, precipitation strengthening and phase change strengthening, and the phase change strengthening is mainly that niobium increases the stability of austenite and is easy to obtain undercooled structures such as bainite; in order to enable the hot-rolled steel bar to have an obvious yield point, a ferrite + pearlite structure with a high volume fraction needs to be obtained, and meanwhile, the content of a supercooled structure such as bainite needs to be reduced as much as possible, so that the beneficial effects of niobium grain refinement and precipitation strengthening need to be exerted as much as possible, the phase transformation strengthening effect of niobium is weakened, and the occurrence of a bainite structure is avoided or reduced, so that the hot-rolled steel bar has an obvious yield point.
In order to fully exert the beneficial effects of grain refinement and precipitation strengthening of the niobium element, the heating temperature, the temperature of an upper cooling bed and the like need to be controlled in a key way; if the heating temperature is too low, the content of niobium dissolved in austenite is reduced during heating, which is not beneficial to exerting the grain refining and precipitation strengthening effects of the niobium during rolling and cooling, and the niobium can be ensured to be dissolved only by requiring higher heating temperature along with the increase of the content of niobium; if the heating temperature is too high, the undissolved carbonitride of niobium which hinders the growth of austenite grains is reduced, the austenite grains are coarsened, and the refinement of the structure is not facilitated finally; on the other hand, the heating temperature is too high, so that the content of the solid solution niobium is increased, the stability of austenite is enhanced by the increase of the solid solution niobium, the formation of low-temperature phase change products such as bainite is promoted, the yield of a tensile curve is not obvious, and therefore, the reasonable heating temperature must be ensured; the size of austenite grains is represented by the temperature of the upper cooling bed, and fine austenite grains can be obtained by the lower temperature of the upper cooling bed, so that the function of grain refinement is achieved. According to the invention, through mass production tests, key process parameters such as reasonable heating temperature, upper cooling bed temperature and the like are finally determined.
The invention has the beneficial effects that:
the production method can completely avoid the phenomenon that the tensile curve of the niobium-containing hot-rolled ribbed steel bar has no yield point, and is suitable for stably producing the niobium-containing hot-rolled ribbed steel bar in a large scale. Meanwhile, compared with the prior art, the invention does not consider the environment temperature, has strong process adaptability and higher heating temperature, can roll at high temperature, reduces the load of a rolling mill and is beneficial to improving the production efficiency; in addition, if the load of rough rolling equipment is small, the initial rolling temperature can be controlled according to high temperature, after rough rolling, a rolling blank is cooled to a reasonable range through reciprocating motion in a roller way and then is continuously rolled, after rolling, water is not needed to be rapidly cooled to refine grains, the requirement on the capacity of the cooling equipment is low, a fine grain layer does not exist on the surface layer, the structure is ferrite plus pearlite, and the uniformity of the structure is good.
Drawings
FIG. 1 is a metallographic structure (200 times) of hot rolled ribbed steel bar of example 1;
FIG. 2 is a metallographic structure (200 times) of hot rolled ribbed steel bar of example 2;
FIG. 3 is a metallographic structure (200 times) of hot rolled ribbed steel bar of example 3;
FIG. 4 is a metallographic structure (200 times) of hot rolled ribbed steel bar of example 4;
FIG. 5 is a metallographic structure (200 times) of hot rolled ribbed steel bar of example 5;
FIG. 6 is a metallographic structure (200 times) of hot-rolled ribbed steel bar of example 6.
Detailed Description
The present invention will be described in further detail with reference to specific examples 1 to 6.
The niobium-containing steel billets obtained in the embodiments 1 to 6 are rolled by a bar heating furnace at a temperature of 1050 to 1250 ℃ and a soaking temperature of 1100 to 1250 ℃, and at a starting temperature of 1000 to 1150 ℃; when the initial rolling temperature is 1000-1100 ℃, continuously rolling the steel bar into a steel bar with the diameter of 20-36 mm, and then cooling the steel bar by water to control the temperature of an upper cooling bed to be 920-980 ℃; when the rolling temperature is more than 1000 ℃ and less than or equal to 1150 ℃, rolling the rolled blank by the first 3 rolling mills, cooling the rolled blank to 940-980 ℃ by a roller way, continuously rolling the rolled blank to form a steel bar with the thickness of 20-36 mm, and then cooling the steel bar by water to control the temperature of an upper cooling bed to 920-980 ℃. And (4) naturally cooling the steel bars after the steel bars are put into a cooling bed, and then shearing, bundling and warehousing.
The process parameters and tensile curve statistics for examples 1-6 are listed in Table 1.
TABLE 1 statistical conditions of the Process parameters and the tensile curves
Claims (3)
1. The production method for preventing the niobium-containing hot-rolled ribbed steel bar from having no obvious yield point mainly comprises the working procedures of heating, rolling and cooling; the method is characterized in that: in the heating procedure, the heating temperature is 1120-1250 ℃, and the soaking temperature is 1100-1250 ℃; the initial rolling temperature of the rolling procedure is 1000-1150 ℃; the temperature of an upper cooling bed in the cooling process is 920-980 ℃; in the rolling procedure, when the initial rolling temperature is 1000-1100 ℃, a rolled blank is continuously rolled into a steel bar, and then is cooled by water, and the temperature of an upper cooling bed is controlled to be 920-980 ℃; when the initial rolling temperature is more than 1100 ℃ and less than or equal to 1150 ℃, rolling the rolled blank by 3 rolling mills, and then cooling the rolled blank by a rolling mill roller way in a reciprocating motion manner on the roller way, wherein the temperature of the rolled blank is reduced to 940-980 ℃ by the roller way, then continuously rolling the rolled blank into a steel bar, cooling the steel bar by water, and controlling the temperature of an upper cooling bed to be 920-980 ℃; the microstructure of the hot-rolled ribbed steel bar is mainly ferrite and pearlite, and the area percentage of the ferrite and the pearlite in the microstructure is more than or equal to 98%.
2. The method of claim 1, wherein the hot rolled ribbed steel bar comprises no significant yield point, and wherein: the niobium content of the hot-rolled ribbed steel bar is 0.01-0.04 wt%.
3. The method of claim 1 or 2, wherein the hot rolled ribbed steel bar comprises no significant yield point, and wherein: the hot-rolled ribbed steel bar is a straight bar with the diameter of 20-36 mm.
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| CN110684931B (en) * | 2019-10-24 | 2020-11-27 | 柳州钢铁股份有限公司 | Control method for non-yield phenomenon of niobium microalloyed HRB400E hot-rolled ribbed steel bar |
| CN111014287B (en) * | 2019-12-23 | 2021-10-01 | 新疆八一钢铁股份有限公司 | Production method of niobium-containing ribbed steel bar |
| CN113385533A (en) * | 2021-05-21 | 2021-09-14 | 山东莱钢永锋钢铁有限公司 | Controlled rolling and controlled cooling production method for green small-specification HRB500E steel bars |
| CN116103576B (en) * | 2023-02-21 | 2024-05-24 | 北京科技大学 | Hot rolled ribbed straight bar with yield strength of 500MPa and manufacturing method thereof |
| CN117144253B (en) * | 2023-09-07 | 2024-04-30 | 中信金属股份有限公司 | Niobium microalloyed hot rolled ribbed steel bar and production method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101255492A (en) * | 2008-01-02 | 2008-09-03 | 马鞍山钢铁股份有限公司 | Production method for preventing no remarkable yield point of niobium micro-alloyed hot-rolled rib steel bar |
| CN108342641A (en) * | 2018-01-11 | 2018-07-31 | 河钢股份有限公司承德分公司 | A kind of 630MPa grades of hot rolling high-strength quake-proof reinforcing steel bar and its production method |
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| CN101185938A (en) * | 2006-11-09 | 2008-05-28 | 钢铁研究总院 | Method for producing steel bar with rib |
| CN102732787B (en) * | 2012-07-20 | 2013-12-25 | 江苏省沙钢钢铁研究院有限公司 | 600 MPa-level anti-seismic twisted steel and manufacturing method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101255492A (en) * | 2008-01-02 | 2008-09-03 | 马鞍山钢铁股份有限公司 | Production method for preventing no remarkable yield point of niobium micro-alloyed hot-rolled rib steel bar |
| CN108342641A (en) * | 2018-01-11 | 2018-07-31 | 河钢股份有限公司承德分公司 | A kind of 630MPa grades of hot rolling high-strength quake-proof reinforcing steel bar and its production method |
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