CN102644032B - Cooling after rolling method for high-weather fastness hot-rolled H-steel with yield strength up to 550MPa - Google Patents
Cooling after rolling method for high-weather fastness hot-rolled H-steel with yield strength up to 550MPa Download PDFInfo
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- 238000001816 cooling Methods 0.000 title claims abstract description 127
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 87
- 239000010959 steel Substances 0.000 title claims abstract description 87
- 238000005096 rolling process Methods 0.000 title claims abstract description 79
- 238000000034 method Methods 0.000 title claims abstract description 75
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000010438 heat treatment Methods 0.000 claims abstract description 10
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 4
- 229910052804 chromium Inorganic materials 0.000 claims abstract 3
- 229910052802 copper Inorganic materials 0.000 claims abstract 3
- 229910052759 nickel Inorganic materials 0.000 claims abstract 3
- 230000008569 process Effects 0.000 claims description 38
- 229910052742 iron Inorganic materials 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 abstract description 15
- 238000005728 strengthening Methods 0.000 abstract description 11
- 229910001563 bainite Inorganic materials 0.000 abstract description 10
- 238000005275 alloying Methods 0.000 abstract description 6
- 230000007246 mechanism Effects 0.000 abstract description 5
- 238000003466 welding Methods 0.000 abstract description 5
- 238000005098 hot rolling Methods 0.000 abstract description 3
- 229910052748 manganese Inorganic materials 0.000 abstract description 3
- 238000001556 precipitation Methods 0.000 abstract description 3
- 239000000654 additive Substances 0.000 abstract 1
- 230000000996 additive effect Effects 0.000 abstract 1
- 229910052799 carbon Inorganic materials 0.000 abstract 1
- 238000005266 casting Methods 0.000 abstract 1
- 229910052757 nitrogen Inorganic materials 0.000 abstract 1
- 229910052698 phosphorus Inorganic materials 0.000 abstract 1
- 239000002344 surface layer Substances 0.000 abstract 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 38
- 229910001566 austenite Inorganic materials 0.000 description 11
- 230000003628 erosive effect Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 230000009466 transformation Effects 0.000 description 6
- 235000019362 perlite Nutrition 0.000 description 5
- 239000010451 perlite Substances 0.000 description 5
- 229910000859 α-Fe Inorganic materials 0.000 description 5
- 239000000498 cooling water Substances 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 239000002826 coolant Substances 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- 238000001953 recrystallisation Methods 0.000 description 3
- 230000003068 static effect Effects 0.000 description 3
- 239000013078 crystal Substances 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000003801 milling Methods 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
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- 238000011084 recovery Methods 0.000 description 1
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Abstract
The invention discloses a cooling after rolling method for high-weather fastness hot-rolled H-steel with yield strength up to 550MPa. The high-weather fastness hot-rolled H-steel with the yield strength up to 550MPa comprises the following components in weight percentage: 0.06-0.12 percent of C, 0.30-0.60 percent of Si, 1.25-1.50 percent of Mn, 0.010-0.030 percent of P, 0.001-0.015 percent of S, 0.20-0.35 percent of Cu, 0.20-0.40 percent of Cr, 0.15-0.30 percent of Ni, 0.10-0.12 percent of V, 0.008-0.014 percent of N, 0.003-0.030 percent of Als and the balance of ferrum and residual trace impurities. An H-steel rolling process comprises the following steps of: heating a casting blank in a heating furnace, rolling by a roughing mill, rolling by a universal rolling mill, and performing two-stage rapid cooling after rolling is ended. According to the cooling after rolling method for the high-weather fastness hot-rolled H-steel with the yield strength up to 550MPa, through adopting a two-stage rapid cooling method after hot rolling is performed on the H-steel and by utilizing a refined crystalline strengthening mechanism, a precipitation strengthening mechanism and a phase change strengthening mechanism, an H-steel texture which is provided with single-phase bainite on the surface layer, is of a multiphase structure inside and has fine grains is obtained, thereby, the additive amount of alloying elements is reduced, the production cost is obviously reduced, the welding performance of the steel is improved, and the production efficiency is increased.
Description
Technical field
The present invention relates to low alloy steel field, relate in particular to method of cooling after a kind of yield strength 550MPa level high-weatherability rolling of hot-rolled H-shaped steel.
Background technology
Hot rolled H-shaped is a kind of economic section section bar, has good mechanical property and superior use properties, can be widely used in construction industry, communications and transportation, the fields such as electric power, water conservancy, the energy, chemical industry and production.Wherein, weather-proof H shaped steel is mainly used in the manufacture of high-speed train railway carriage, bridge etc., at loss of weight, increase the service life, raise speed, increase volume of freight traffic and reduce aspect logistics cost and all play an important role.Particularly, along with the fast development of national economy, Railway Transport Industry strides forward to high speed, heavy loading, long service life direction, hot rolled H-shaped in the urgent need to high-weatherability, high strength, high tenacity.Because high-weatherability H shaped steel is when requiring high weathering resistance, also require high intensity, good low-temperature impact toughness and welding property, therefore to metallurgical technology process and device control level, require very high.
The H shaped steel manufacturing enterprise of China has developed yield strength 345MPa, other weather-proof H shaped steel of 420MPa grade at present, for guaranteeing that the indexs such as intensity of steel reach standard-required, be all to adopt to add compared with the hot-rolling method of high alloy element nb, V, Mn to produce, its rolling technology is: strand process furnace heating → bloomer rolling → Rolling With Universal Mill.As yield strength be the hot rolled H-shaped V content of Q420NQR1 of 420MPa level up to 0.10~0.14wt%, Mn content, up to 1.40~1.60wt%, causes production cost to improve; And because it is organized as ferrite+perlite, the homogeneity of tissue is poor, cause its weathering resistance poor, compare with common Q 345B steel, erosion rate can only reach 50~55% relatively; Because alloying element content is higher, welding property worsens simultaneously.As adopt the method to produce the weather-proof H shaped steel of 550MPa level, and its alloying element content will higher, cause production cost very high, and welding property worsens, and its weathering resistance and hot rolled H-shaped suitable of Q420NQR1.In addition, for obtaining good impelling strength, require very low finishing temperature, both increased load and the energy consumption of milling train, reduced again production efficiency.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, provide a kind of and can significantly reduce alloying element consumption, meet method of cooling after the yield strength 550MPa level high-weatherability rolling of hot-rolled H-shaped steel of high-weatherability performance requriements; Further aim of the present invention is to provide production technique simpler and easy, energy-conservation, efficient, and production cost is low, method of cooling after the high low-alloy high-strength yield strength 550MPa level high-weatherability rolling of hot-rolled H-shaped steel of production efficiency.
To achieve these goals, the technical solution used in the present invention is:
Described yield strength 550MPa level high-weatherability is hot rolled H-shaped rolls rear method of cooling, yield strength 550MPa level high-weatherability is hot rolled H-shaped, according to weight percent meter (wt%), composition is: C:0.06~0.12, Si:0.30~0.60, Mn:1.25~1.50, P:0.010~0.030, S:0.001~0.015, Cu:0.20~0.35, Cr:0.20~0.40, Ni:0.15~0.30, V:0.10~0.12, N:0.008~0.014, Als:0.003~0.030, all the other are iron and remaining trace impurity;
This H section rolling technique is: strand process furnace heating → bloomer rolling → Rolling With Universal Mill → roll rear two-part is cooling fast; Be specially:
Strand is heated to 1200~1250 ℃ through process furnace; Bloomer rolling sequence start rolling temperature is 1100~1150 ℃, and finishing temperature is 980~1020 ℃; The start rolling temperature of universal mill is 900~950 ℃, and finishing temperature is 860~900 ℃; Roll rear employing two-part cooling fast, the quick process for cooling parameter of first paragraph is: when H section steel flange and web begin to cool down, temperature is 850~890 ℃, and during cooling end, temperature is 650~700 ℃, and speed of cooling is 75~150 ℃/s; After first paragraph is fast cooling, carry out immediately second segment cooling fast, the quick process for cooling parameter of second segment is: when H section steel flange and web begin to cool down, temperature is 650~700 ℃, and during cooling end, temperature is 500~600 ℃, and speed of cooling is 20~45 ℃/s; Strand is carried out to two-part quick when cooling, H section steel flange and web are adopted to the water-cooled type of cooling of spray normal temperature, water coolant is sprayed onto on H section steel flange and web by nozzle; During actually operating, according to H shaped steel specification, at H section steel flange and web outside, one or more groups nozzle is set, with water pump, controls cooling water pressure and the flow from nozzle ejection, and then control quick speed of cooling when cooling of two-part.
Method of cooling after described yield strength 550MPa level high-weatherability rolling of hot-rolled H-shaped steel, the technical scheme of employing, has the following advantages:
First, method of cooling after described yield strength 550MPa level high-weatherability rolling of hot-rolled H-shaped steel, by adopt two-part method for rapid cooling after the hot rolling of H shaped steel, can be cooled to suitable temperature by the H shaped steel with comparatively high temps within a short period of time; This method of cooling is utilized refined crystalline strengthening, precipitation strength and phase transformation strengthening mechanism, obtains top layer and is single-phase bainite, innerly for heterogeneous structure has the H shaped steel structural state of small grains, obviously reduced the addition of alloying element, can significantly reduce production costs;
Secondly, the H shaped steel that after described yield strength 550MPa level high-weatherability rolling of hot-rolled H-shaped steel, method of cooling is manufactured, top layer is even single-phase bainite structure, can significantly improve its weathering resistance;
Again secondly, the H shaped steel that after described yield strength 550MPa level high-weatherability rolling of hot-rolled H-shaped steel, method of cooling is manufactured, because alloying element content is lower, has improved the welding property of steel;
Finally, method of cooling after described yield strength 550MPa level high-weatherability rolling of hot-rolled H-shaped steel, finishing temperature is higher, has both reduced load and the energy consumption of milling train, has improved again production efficiency.
Embodiment
Description below by optimum embodiment, is described in further detail the specific embodiment of the present invention.
Embodiment 1
Described yield strength 550MPa level high-weatherability is hot rolled H-shaped rolls rear method of cooling, and yield strength 550MPa level high-weatherability is hot rolled H-shaped, according to weight percent meter, composition is: C:0.06, Si:0.42, Mn:1.46, P:0.030, S:0.014, Cu:0.22, Cr:0.28, Ni:0.15, V:0.12, N:0.014, Als:0.006, all the other are iron and remaining trace impurity;
This H section rolling technique is: strand process furnace heating → bloomer rolling → Rolling With Universal Mill → roll rear two-part is cooling fast; Be specially:
Strand is heated to 1235 ℃ through process furnace; 1125 ℃ of bloomer rolling sequence start rolling temperatures, 1005 ℃ of finishing temperatures; 925 ℃ of the start rolling temperatures of universal mill, 880 ℃ of finishing temperatures; After rolling, adopt immediately two-part rapid water cooling, the quick process for cooling parameter of first paragraph is: when H section steel flange and web begin to cool down, temperature is 870 ℃, and during cooling end, temperature is 670 ℃, and controlling water cooling speed is 100 ℃/s; After first paragraph rapid water is cooling, carry out immediately second segment rapid water cooling, second segment rapid water process for cooling parameter is: when H section steel flange and web begin to cool down, temperature is 670 ℃, and during cooling end, temperature is 560 ℃, and controlling water cooling speed is 35 ℃/s.
H shaped steel (specification is 600mm * 200mm * 11mm * 17mm) performance index are: R
eLfor 580MPa, R
mfor 690MPa, A is that 20% ,-40 ℃ of impacts of collision absorb energy KV
2for 131J.Compare with common Q 345B steel, erosion rate can reach 45.5% relatively.
Embodiment 2
Yield strength 550MPa level high-weatherability is hot rolled H-shaped rolls rear method of cooling, and yield strength 550MPa level high-weatherability is hot rolled H-shaped, according to weight percent meter, composition is: C:0.12, Si:0.38, Mn:1.27, P:0.015, S:0.004, Cu:0.34, Cr:0.21, Ni:0.27, V:0.10, N:0.011, Als:0.024, all the other are iron and remaining trace impurity;
This H section rolling technique is: strand process furnace heating → bloomer rolling → Rolling With Universal Mill → roll rear two-part is cooling fast; Be specially:
Strand is heated to 1210 ℃ through process furnace; 1105 ℃ of bloomer rolling sequence start rolling temperatures, 985 ℃ of finishing temperatures; 910 ℃ of the start rolling temperatures of universal mill, 860 ℃ of finishing temperatures; After rolling, adopt immediately two-part rapid water cooling, the quick process for cooling parameter of first paragraph is: when H section steel flange and web begin to cool down, temperature is 850 ℃, and during cooling end, temperature is 650 ℃, and controlling water cooling speed is 80 ℃/s; After first paragraph rapid water is cooling, carry out immediately second segment rapid water cooling, second segment rapid water process for cooling parameter is: when H section steel flange and web begin to cool down, temperature is 650 ℃, and during cooling end, temperature is 570 ℃, and controlling water cooling speed is 20 ℃/s.
H shaped steel (specification is 600mm * 200mm * 11mm * 17mm) performance index are: R
eLfor 575MPa, R
mfor 695MPa, A is that 21% ,-40 ℃ of impacts of collision absorb energy KV
2for 140J.Compare with common Q 345B steel, erosion rate can reach 48% relatively.
Embodiment 3
Yield strength 550MPa level high-weatherability is hot rolled H-shaped rolls rear method of cooling, and yield strength 550MPa level high-weatherability is hot rolled H-shaped, according to weight percent meter, composition is: C:0.10, Si:0.31, Mn:1.38, P:0.020, S:0.009, Cu:0.27, Cr:0.38, Ni:0.20, V:0.11, N:0.012, Als:0.016, all the other are iron and remaining trace impurity;
This H section rolling technique is: strand process furnace heating → bloomer rolling → Rolling With Universal Mill → roll rear two-part is cooling fast; Be specially:
Strand is heated to 1240 ℃ through process furnace; 1140 ℃ of bloomer rolling sequence start rolling temperatures, 1015 ℃ of finishing temperatures; 950 ℃ of the start rolling temperatures of universal mill, 900 ℃ of finishing temperatures; After rolling, adopt immediately two-part rapid water cooling, the quick process for cooling parameter of first paragraph is: when H section steel flange and web begin to cool down, temperature is 895 ℃, and during cooling end, temperature is 650 ℃, and controlling water cooling speed is 125 ℃/s; After first paragraph rapid water is cooling, carry out immediately second segment rapid water cooling, second segment rapid water process for cooling parameter is: when H section steel flange and web begin to cool down, temperature is 650 ℃, and during cooling end, temperature is 500 ℃, and controlling water cooling speed is 30 ℃/s.
H shaped steel (specification is 600mm * 200mm * 11mm * 17mm) performance index are: R
eLfor 565MPa, R
mfor 675MPa, A is that 23% ,-40 ℃ of impacts of collision absorb energy KV
2for 115J.Compare with common Q 345B steel, erosion rate can reach 47% relatively.
Embodiment 4
Yield strength 550MPa level high-weatherability is hot rolled H-shaped rolls rear method of cooling, and yield strength 550MPa level high-weatherability is hot rolled H-shaped, according to weight percent meter, composition is: C:0.08, Si:0.30, Mn:1.50, P:0.010, S:0.015, Cu:0.35, Cr:0.4, Ni:0.30, V:0.12, N:0.008, Als:0.030, all the other are iron and remaining trace impurity;
This H section rolling technique is: strand process furnace heating → bloomer rolling → Rolling With Universal Mill → roll rear two-part is cooling fast; Be specially:
Strand is heated to 1200 ℃ through process furnace; 1100 ℃ of bloomer rolling sequence start rolling temperatures, 980 ℃ of finishing temperatures; 900 ℃ of the start rolling temperatures of universal mill, 865 ℃ of finishing temperatures; After rolling, adopt immediately two-part rapid water cooling, the quick process for cooling parameter of first paragraph is: when H section steel flange and web begin to cool down, temperature is 850 ℃, and during cooling end, temperature is 700 ℃, and controlling water cooling speed is 75 ℃/s; After first paragraph rapid water is cooling, carry out immediately second segment rapid water cooling, second segment rapid water process for cooling parameter is: when H section steel flange and web begin to cool down, temperature is 700 ℃, and during cooling end, temperature is 600 ℃, and controlling water cooling speed is 40 ℃/s.
H shaped steel (specification is 600mm * 200mm * 11mm * 17mm) performance index are: R
eLfor 560MPa, R
mfor 655MPa, A is that 22.5% ,-40 ℃ of impacts of collision absorb energy KV
2for 105J.Compare with common Q 345B steel, erosion rate can reach 46.5% relatively.
Embodiment 5
Yield strength 550MPa level high-weatherability is hot rolled H-shaped rolls rear method of cooling, and yield strength 550MPa level high-weatherability is hot rolled H-shaped, according to weight percent meter, composition is: C:0.11, Si:0.60, Mn:1.25, P:0.015, S:0.001, Cu:0.20, Cr:0.20, Ni:0.28, V:0.11, N:0.012, Als:0.018, all the other are iron and remaining trace impurity;
This H section rolling technique is: strand process furnace heating → bloomer rolling → Rolling With Universal Mill → roll rear two-part is cooling fast; Be specially:
Strand is heated to 1250 ℃ through process furnace; 1150 ℃ of bloomer rolling sequence start rolling temperatures, 1020 ℃ of finishing temperatures; 950 ℃ of the start rolling temperatures of universal mill, 890 ℃ of finishing temperatures; After rolling, adopt immediately two-part rapid water cooling, the quick process for cooling parameter of first paragraph is: when H section steel flange and web begin to cool down, temperature is 880 ℃, and during cooling end, temperature is 680 ℃, and controlling water cooling speed is 100 ℃/s; After first paragraph rapid water is cooling, carry out immediately second segment rapid water cooling, second segment rapid water process for cooling parameter is: when H section steel flange and web begin to cool down, temperature is 680 ℃, and during cooling end, temperature is 590 ℃, and controlling water cooling speed is 45 ℃/s.
H shaped steel (specification is 600mm * 200mm * 11mm * 17mm) performance index are: R
eLfor 585MPa, R
mfor 675MPa, A is that 23.5% ,-40 ℃ of impacts of collision absorb energy KV
2for 125J.Compare with common Q 345B steel, erosion rate can reach 47.5% relatively.
In embodiment 1 to embodiment 5, yield strength 550MPa level high-weatherability is hot rolled H-shaped rolls rear method of cooling, roll rear employing two-part rapid water cooling, H section steel flange and web are adopted to the water-cooled type of cooling of spray normal temperature, the normal-temperature water type of cooling can additionally not increase production cost, and water coolant is sprayed onto on H section steel flange and web by nozzle; During actually operating, according to H shaped steel specification, in H section steel flange part and web outside, one or more groups nozzle is set, with water pump, controls from cooling water pressure and the flow of nozzle ejection, and then control quick speed of cooling when cooling of two-part; As the specification H shaped steel that is 600mm * 200mm * 11mm * 17mm, when speed of cooling is 75~150 ℃/s, in H section steel flange part and web both sides, two groups of nozzles are respectively set, every group of nozzle ejection cooling water pressure is 1.0~1.5MPa, and flow is 500~1000L/min; When speed of cooling is 20~45 ℃/s, in H section steel flange part and web both sides, one group of nozzle is respectively set, cooling water pressure is 1.0~1.5MPa, and flow is 300~800L/min.
Principle of the present invention is: (1) utilizes the metallic particles of indissoluble to control original austenite grains size, the required critical strain amount of high temperature austenite Static Recrystallization is reduced, recrystallize more easily carries out, also make the austenite crystal after recrystallize be difficult for growing up, reduced the separate out amount of V (CN) in high temperature austenite district simultaneously; By the distortion of austenite low-temperature range, V (CN) is analyzed at low temperature austenite middle part, thereby in deformed austenite, form a large amount of deformed belts and high density dislocation.
(2) after H shape steel rolling, carry out immediately first paragraph cooling fast, because Quench is to carry out immediately after steel finish to gauge, therefore deformed austenite Static Recrystallization is suppressed, thereby in the deformed austenite of non-recrystallization, retain more dislocation and static recovery subgrain boundary etc., make it to become the cenotype forming core place of Cooling Austenite Transformation; Quench also can stop the front Austenite Grain Growth of phase transformation.Meanwhile, in steel surface Quench process, because water coolant is taken away amount of heat, therefore make steel surface and core produce larger condensate depression, thereby the crystal boundary forming core free energy of ferritic transformation is reduced, promote its forming core, realize structure refinement, and increased V (CN) and separate out motivating force.Thereby the effect of the refined crystalline strengthening of giving full play to and precipitation strength.
(3) first paragraph is fast cooling finishes before the bainitic transformation of steel, immediately carries out second segment supper-fast cooling, and by supper-fast cooling, perlite sheet spacing reduces, and plays certain strengthening effect; Meanwhile, now suitably reduce rate of cooling, can guarantee to form bainite structure appropriate, refinement, avoid forming the thick bainite structure of the toughness plasticity have a strong impact on steel etc., played certain phase transformation strengthening effect, its toughness still can meet the demands, and to the over-all properties of steel, is favourable.Thereby in the present invention, effectively utilize various strengthening mechanisms, adopting under lower alloy content condition, reach the mechanical property requirements of yield strength 550MPa level H shaped steel.
The present invention provides a kind of new structural state to yield strength 550MPa level high-weatherability H shaped steel, and top layer is the thin bainite structure that 1.0-2.0mm is thick, and heart portion is the heterogeneous structure of polygonal ferrite, perlite, acicular ferrite and a small amount of bainite; And the tissue that the conventional mode of production forms is ferrite and pearlite tissue; Because top layer is even single-phase bainite structure, its homogeneity of structure is better than pearlite-ferrite steel, the difference in Electrode Potential of each several part is less, thereby resistance to corrosion is stronger, compare with common Q 345B steel, erosion rate can reach 45~49% relatively, the weather-proof H shaped steel of Q420NQR1 of producing far above ordinary process.
Top layer adopt single-phase bainite structure according to being: homogeneity of structure improves, and can significantly improve its weathering resistance.Heart portion adopt heterogeneous structure according to being: Polygons and acicular ferrite grain-size are little, and matrix dislocation desity is high, have good strengthening effect; In perlite, cemetite lamellae interlamellar spacing is little, and occurs degradation phenomena, and perlite strengthening effect is strengthened; A small amount of bainite has certain effect to the raising of intensity, does not significantly reduce impelling strength and the extension property of steel simultaneously.
Above the present invention is exemplarily described; obviously specific implementation of the present invention is not subject to the restrictions described above; as long as adopted the improvement of the various unsubstantialities that method of the present invention design and technical scheme carry out; or without improving, design of the present invention and technical scheme are directly applied to other occasion, all within protection scope of the present invention.
Claims (5)
1. method of cooling after a yield strength 550MPa level high-weatherability rolling of hot-rolled H-shaped steel, yield strength 550MPa level high-weatherability is hot rolled H-shaped, according to weight percent meter, composition is: C:0.06~0.12, Si:0.30~0.60, Mn:1.25~1.50, P:0.010~0.030, S:0.001~0.015, Cu:0.20~0.35, Cr:0.20~0.40, Ni:0.15~0.30, V:0.10~0.12, N:0.008~0.014, Als:0.003~0.030, all the other are iron and remaining trace impurity;
This H section rolling technique is: strand process furnace heating → bloomer rolling → Rolling With Universal Mill → roll rear two-part is cooling fast; Be specially:
Strand is heated to 1200~1250 ℃ through process furnace; Bloomer rolling sequence start rolling temperature is 1100~1150 ℃, and finishing temperature is 980~1020 ℃; The start rolling temperature of universal mill is 900~950 ℃, and finishing temperature is 860~900 ℃; Roll rear employing two-part cooling fast, the quick process for cooling parameter of first paragraph is: when H section steel flange and web begin to cool down, temperature is 850~890 ℃, and during cooling end, temperature is 650~700 ℃, and speed of cooling is 75~150 ℃/s; After first paragraph is fast cooling, carry out immediately second segment cooling fast, the quick process for cooling parameter of second segment is: when H section steel flange and web begin to cool down, temperature is 650~700 ℃, and during cooling end, temperature is 500~600 ℃, and speed of cooling is 20~45 ℃/s.
2. according to method of cooling after yield strength 550MPa level high-weatherability rolling of hot-rolled H-shaped steel claimed in claim 1, it is characterized in that: wherein, strand is heated to 1210~1240 ℃ through process furnace; 1100~1140 ℃ of bloomer rolling sequence start rolling temperatures, 1005~1015 ℃ of finishing temperatures; 900~925 ℃ of the start rolling temperatures of universal mill, 860~880 ℃ of finishing temperatures; The quick process for cooling parameter of first paragraph is: when H section steel flange and web begin to cool down, temperature is 850~880 ℃, and during cooling end, temperature is 650~680 ℃, and speed of cooling is 75~125 ℃/s; The quick process for cooling parameter of second segment is: when H section steel flange and web begin to cool down, temperature is 650~680 ℃, and during cooling end, temperature is 540~560 ℃, and speed of cooling is 20~40 ℃/s.
3. according to method of cooling after yield strength 550MPa level high-weatherability rolling of hot-rolled H-shaped steel claimed in claim 1, it is characterized in that: wherein, strand is heated to 1200~1235 ℃ through process furnace; 1105~1125 ℃ of bloomer rolling sequence start rolling temperatures, 985~1005 ℃ of finishing temperatures; 925~950 ℃ of the start rolling temperatures of universal mill, 865~880 ℃ of finishing temperatures; The quick process for cooling parameter of first paragraph is: when H section steel flange and web begin to cool down, temperature is 850~870 ℃, and during cooling end, temperature is 650~670 ℃, and speed of cooling is 80~100 ℃/s; The quick process for cooling parameter of second segment is: when H section steel flange and web begin to cool down, temperature is 650~670 ℃, and during cooling end, temperature is 540~570 ℃, and speed of cooling is 30~45 ℃/s.
4. according to method of cooling after the yield strength 550MPa level high-weatherability rolling of hot-rolled H-shaped steel described in claim 1 or 2 or 3, it is characterized in that: the content of the hot rolled H-shaped middle Mn of yield strength 550MPa level high-weatherability, Cu, Cr, Ni and V, be by mass percentage: Mn:1.25~1.38, Cu:0.20~0.27, Cr:0.21~0.28, Ni:0.15~0.20, V:0.10~0.11.
5. according to method of cooling after the yield strength 550MPa level high-weatherability rolling of hot-rolled H-shaped steel described in claim 1 or 2 or 3, it is characterized in that: the content of the hot rolled H-shaped middle Mn of yield strength 550MPa level high-weatherability, Cu, Cr, Ni and V, be by mass percentage: Mn:1.38~1.46, Cu:0.27~0.35, Cr:0.28~0.38, Ni:0.20~0.28, V:0.11~0.12.
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