CN112011737B - 390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for bridge structure and production method thereof - Google Patents
390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for bridge structure and production method thereof Download PDFInfo
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Abstract
The invention provides 390 MPa-grade minus 20 ℃ resistant hot-rolled angle steel for a bridge structure and a production method thereof, and the steel comprises the following components: c: 0.15-0.18%, Si: 0.20-0.45%, Mn: 1.35-1.45%, P: less than or equal to 0.025 percent, S: less than or equal to 0.025 percent, Cr: 0.020-0.060%, V: 0.030-0.080%, Als: 0.010-0.025%, and the balance of Fe and trace residual elements. Compared with the prior art, the invention integrates multiple processes of converter smelting, deoxidation refining, protective pouring, blank heating, cogging rolling and the like, and realizes the production of the hot-rolled angle steel for the bridge structure with the yield strength of 390MPa grade, low finish rolling compression ratio, low yield ratio and-20 ℃ low-temperature impact power of not less than 65J by utilizing BD cogging rolling, finish rolling and post-rolling controlled cooling processes through reasonable component proportion and production process control.
Description
Technical Field
The invention belongs to the technical field of metal material production, and relates to 390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for a bridge structure and a production method thereof.
Background
With the rapid development of economy, the bridge foundation engineering construction in China also obtains rapid and vigorous development. Particularly, in the last decade, the number of bridges in China is increased by 3 ten thousand every year, the total length of bridges is increased by 5 ten thousand kilometers, a large number of bridge projects of the world level are built, and China becomes a world bridge kingdom. The section steel product has the advantages of being green, energy-saving, simple in section, convenient to use and the like, and is widely applied to bridge construction.
At present, the section steel products for bridges in domestic markets mainly comprise H-shaped steel, but in a steel beam structure, a truss beam usually needs to use a high-strength and high-toughness hot-rolled angle steel product. The main strength of the traditional angle steel for the bridge can meet the use requirement of a steel beam member at 345MPa, but along with the change of bridge engineering environment, particularly in low-temperature areas, the market of the angle steel for the bridge structure starts to take the main development directions of high strength and high and low-temperature toughness, so that the development of the bridge engineering in the low-temperature areas can be greatly promoted by developing hot-rolled angle steel products with high strength and high and low-temperature toughness.
The patent with the publication number of CN 107513665A and the name of Q345-grade hot-rolled weather-resistant large horn steel for the iron tower and the preparation method thereof, which is disclosed on 26.12.7.2017, discloses that the Q345-grade hot-rolled weather-resistant large horn steel for the iron tower contains the following components: c: 0.03 to 0.10 wt%, Si: 0.15 wt% -0.50 wt%, Mn: 0.30-0.90 wt%, P is less than or equal to 0.020 wt%, S is less than or equal to 0.015 wt%, Cr: 0.40 wt% -0.80 wt%, Ni: 0.10 wt% to 0.30 wt%, Cu: 0.20 wt% -0.50 wt%, Als is more than or equal to 0.015 wt%, Ti: 0.01 wt% to 0.05 wt%, V: 0.03 to 0.10 weight percent, and the balance of Fe. The component design scheme of low C, V and Ti composite addition and a proper amount of corrosion resisting elements is adopted. However, the component process strictly controls the continuous casting of the special-shaped blank, particularly, the Ti micro-alloy is adopted to increase refining energy consumption, and the final strength of the product can only reach 345MPa level, so that the requirement of the steel for the bridge structure on the strength cannot be met.
A patent with patent publication number CN106636528A entitled "production method of low temperature impact resistant C-level power angle steel" published 5/10.2017 mainly adopts a converter (end point control of C, P, Ti content) -LF refining (normal furnace soft blowing temperature 1565 + 1575 ℃) -continuous casting (whole protection pouring) -rolling mill (initial rolling temperature 1050 + 1200 ℃, high pressure water descaling, billet blank assembly rolling is not allowed, rolling groove numbers are sequenced from a transmission side to an operation side, synchronous adjustment of guides is noticed after rolled piece adjustment, and simultaneously the left side and the right side of each guide are tightly extruded by wood or other objects). The method has the advantages of complex control process, strict requirements on field operation process, narrow process window, increased investment of field tooling equipment, and capability of only meeting the requirements of C-level (0 ℃) power angle steel on low-temperature impact toughness and failing to realize service conditions at lower temperature (-20 ℃).
The invention discloses a patent with patent publication number CN105543677A, 2016, 5, 4, and name '14 MPa-level hot-rolled angle steel for a power communication tower in a highland and mountainous area and a preparation method thereof', wherein the 345 MPa-level 14-level hot-rolled angle steel for the power communication tower in the highland and mountainous area adopts the following steps: 0.14-0.20%, Si: 0.20-0.30%, Mn: 0.85-1.05%, V: 0.016-0.030%, Ti: 0.015 to 0.030%, Mo: 0.015-0.025%, P not more than 0.020%, S not more than 0.015%, and the balance Fe and inevitable impurities. The method mainly adopts a large amount of V + Ti + Mo composite alloy elements, has complex production process and strict steel-making process requirements, simultaneously increases the production cost due to a large amount of alloy content, and the yield strength of the angle steel product produced by the method is in 345MPa level, and the strength index does not meet the requirements of the angle steel for the bridge structure.
The patent publication No. CN 105734418A published in 2016, 7, 6 and named as 'a low-temperature resistant hot-rolled angle steel and a preparation method thereof' discloses low-temperature resistant angle steel and a production method thereof. The angle steel comprises the following chemical components in percentage by mass: c: 0.10-0.15%, Si: 0.20 to 0.50%, Mn: 1.3-1.7%, V: 0.04-0.06%, Al: 0.005-0.015 percent of N, less than or equal to 0.01 percent of N, less than or equal to 0.006 percent of O, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, and the balance of Fe and inevitable impurities. The production method comprises the working procedures of molten iron pre-desulfurization, converter smelting, LF refining, continuous casting of a square billet continuous casting machine and rolling, and the sulfur content in the molten iron is ensured to be less than or equal to 0.005 wt% after desulfurization. Although the product has higher impact toughness, the whole production process has extremely high requirements on the steelmaking process, the content of elements such as O, N, S and the like is strictly controlled, the steelmaking cost is greatly increased, in addition, the heating temperature is overhigh in the rolling process, the soaking section is 1220-.
The invention provides niobium microalloyed high-strength high-weather-resistant angle steel and a production process thereof, wherein the patent publication No. CN 110699598A published on 27.1.2020 is named as a patent of 'niobium microalloyed high-strength high-weather-resistant angle steel and a production process thereof', and the chemical components of the niobium microalloyed high-strength high-weather-resistant angle steel in percentage by mass are as follows: c: 0.05 to 0.12%, Si: 0.20-0.75%, Mn is less than or equal to 1.00%, Cu: 0.20-0.55%, P: 0.07-0.10%, Cr: 0.30-1.25%, Ni: 0.12-0.65%, Nb: 0.015-0.060%, S is less than or equal to 0.020%, Ceq is less than or equal to 0.44, I is more than or equal to 6, and the balance is Fe and inevitable impurities; the production process comprises continuous casting billet production, angle steel rolling and angle steel straightening. The method mainly adopts a large amount of Cr + Ni + Nb + Cu composite alloy elements, has complex production process and strict steel-making process requirements, and the low-temperature (-20 ℃) impact energy of the product prepared by the method is only more than 34J and is far less than the requirement of angle steel for a bridge structure on low-temperature impact value.
The invention discloses a patent with the publication number of CN 106906411A in 30.6.2017 and the name of Q345FRD fire-resistant anti-seismic hot-rolled angle steel for public steel structure buildings and a preparation method thereof, wherein the preparation method of the fire-resistant anti-seismic hot-rolled angle steel comprises the following components: 0.16 to 0.21 wt%, Si: 0.23 to 0.33 wt%, Mn: 0.85-1.05 wt%, V: 0.017-0.032 wt%, Ti: 0.015 to 0.030 wt%, Mo: 0.080-0.100 wt%, S is less than or equal to 0.015 wt%, P is less than or equal to 0.020 wt%, and the balance of Fe and inevitable impurities, wherein the production process comprises the following steps: A. pretreating and desulfurizing molten iron; B. smelting molten steel; C. deoxidizing and alloying; D. refining the molten steel in an LF furnace; E. casting molten steel; F. heating a steel billet; G. descaling a steel billet high-pressure water tank; H. preforming by a cogging mill; I. continuously rolling by using a universal mill; J. detecting the online shape and size of the angle steel; K. and (6) finishing. The method has strict requirements on the molten iron treatment process (molten iron pretreatment, converter smelting, deoxidation alloying, LF furnace refining, and bloom full-process protection continuous casting), increases the production process and the production cost, and the final angle steel product has the yield strength of 345MPa level and the strength index which does not meet the requirements of the angle steel for the bridge structure.
The patent publication No. CN 109127724A disclosed on 10.4.2020/4 is named as a patent of 'a production process method of high-toughness angle steel', and the technical scheme of the production process method adopted by the invention is as follows: the double heat storage walking beam type heating furnace + I750 two-roller reversible rolling mill rolls 5-7 times (rough rolling) + II 750 two-roller reversible rolling mill rolls 3 times (middle rolling) + pauses for 0.5-3 minutes on a transition roller way between the finishing mill and the II 750 rolling mill, ensures the temperature of entering the finishing mill to be 900 ℃, and then enters the finishing mill for rolling. However, the method is subject to special arrangement of rolling mill equipment, the rolling temperature is limited to 800-. Moreover, the strength grade of the product produced by the technical scheme is grade C, and the D-grade requirement of the steel for the common bridge structure is not met.
In conclusion, the angle steel products have certain technology accumulation in the development aspect, the main application of the angle steel products is concentrated on the aspects of iron tower structures, electric power communication, structural buildings and the like, and the process data of the angle steel products are limited by different equipment conditions of different manufacturers; in addition, most yield strength indexes of angle steel products with different technical processes are concentrated on 355MPa level, low-temperature impact toughness is mainly concentrated on 0 ℃ and-20 ℃ (more than or equal to 34J), the mechanical properties of the angle steel can meet the requirements of the current common structure and members, but for bridge structures, particularly for angle steel used as bridge structural members in low-temperature regions, the low-temperature toughness of the angle steel needs to meet the requirement of D level (-20 ℃), and the impact value is far greater than the 34J requirement value. In addition, in terms of strength indexes, the traditional angle steel of 345MPa level does not meet the matching requirements of modern bridge structural members, so that the strength needs to be improved to ensure the use safety of the angle steel members.
Therefore, for angle steel used in the field of bridge structural engineering, there is an urgent need to develop a hot-rolled angle steel product with low temperature resistance and high strength, which meets the market demand of steel for bridge structures in current low-temperature regions.
Disclosure of Invention
The invention aims to provide 390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for a bridge structure and a production method thereof, which solve the defects of low strength, poor low-temperature-resistant toughness and the like for the bridge structure, and the product has yield strength not lower than 390MPa, elongation not lower than 25%, impact work value at minus 20 ℃ not lower than 65J, yield ratio less than 0.78 and finish rolling compression ratio less than 4.0, and meets the use requirements of angle steel in the field of bridge structures in China.
The specific technical scheme of the invention is as follows:
390 MPa-grade minus 20 ℃ resistant hot-rolled angle steel for bridge structures comprises the following chemical components in percentage by mass: c: 0.15-0.18%, Si: 0.20-0.45%, Mn: 1.35-1.45%, P: less than or equal to 0.025 percent, S: less than or equal to 0.025 percent, Cr: 0.020-0.060%, V: 0.030-0.080%, Als: 0.010-0.025%, and the balance of Fe and trace residual elements.
The specification of the 390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for the bridge structure is less than 80 multiplied by 5-10 minus 125 multiplied by 8-16, unit: mm.
The action and the proportion of each element are as follows:
carbon (C): at present, the carbon content of the low-temperature resistant angle steel is 0.10-0.20%, considering that carbon has an excellent solid solution strengthening effect, in order to obtain higher strength, according to field section bar production experience, in order to ensure that a pearlite structure with the proportion of not less than 25% is obtained to realize higher strength, the lower limit is set to be 0.15 wt%; however, the carbon content is too high, which significantly reduces the ductility and weldability of the material, and the upper limit is set to 0.18 wt%.
Silicon (Si): the steel has a strong solid solution strengthening effect, Si is a non-carbide forming element and exists in a solid solution form in steel, so that ferrite can be obviously strengthened, and the lower limit is set to be 0.20 wt% for obtaining high strength; however, when the Si content is higher than 0.7%, the ductility and toughness of the material are remarkably reduced, the strength of the steel is increased, the ductility and toughness of the steel are remarkably reduced, and the upper limit is set to 0.45 wt%.
Manganese (Mn): within a certain range, the strength and the toughness of the material can be simultaneously improved. The material has the effect of reducing the phase transition temperature, can effectively inhibit the transformation from ferrite to pearlite, and greatly improves the low-temperature toughness of the material. Research shows that when w (Mn) is more than or equal to 1.2 wt%, the strengthening effect of the steel is obvious, and when w (Mn) is more than or equal to 1.5 wt%, the toughness of the steel is reduced, so that the influence of low-temperature toughness is considered while the strengthening effect is ensured, and the Mn content is controlled to be 1.35-1.45 wt%.
Phosphorus (P): segregation is easy to occur in steel grades, the plasticity and toughness of steel are greatly reduced, the surface quality of steel is influenced to a certain extent, and the upper limit is set to be 0.025 wt% in consideration of the P removal difficulty in the steelmaking process.
Sulfur (S): the steel has similar effect with P element, and the steel belongs to impurity element, which has larger influence on the toughness of the steel, and the upper limit is set to be 0.025 wt% considering the P removing difficulty in the steel making process.
Vanadium (V): has obvious precipitation strengthening and fine crystal strengthening effects. Vanadium and nitrogen are easy to form a carbon-nitrogen compound, the compound can effectively recrystallize in the austenite transformation process, prevent grains from excessively growing, promote the transformation from austenite to ferrite, facilitate the precipitation of a soft and tough phase and improve the low-temperature toughness of the material. In addition, during the cooling process after rolling, the carbon-nitrogen compound is precipitated to play a certain strengthening role. According to the production experience of on-site production of Q355D grade steel, the strength is increased by about 10-20 MPa for each 0.01 wt% of V element, and for Q390 grade high-strength required steel, the lower limit of 0.030 wt% is set for the high-strength required steel in consideration of the strengthening effect of vanadium, but the toughness of the steel is difficult to improve with the increase of vanadium content, and the upper limit is set to 0.080 wt%.
Chromium (Cr): the steel has obvious strengthening effect, can obviously improve the strength of steel, and simultaneously, under the condition of not influencing the plasticity and the toughness of the steel, the strength of the material can be effectively improved by adding a certain Cr element, the lower limit is set to be 0.020 wt%, and meanwhile, in order to limit the damage of excessive Cr element to the plasticity and the toughness, the lower limit is set to be 0.060 wt%.
Aluminum (Al): the strong oxidizing element can perform steelmaking deoxidation in steel. In addition, aluminum element and nitrogen element can be separated out in a form of a combination, the function of refining austenite grains can be achieved, and the lower limit is set to be 0.010 wt%; however, the content of aluminum element is too high, the plasticity and the toughness of the material are obviously reduced, and the continuous casting special-shaped blank is easy to form nodules to cause steel leakage to influence the production safety, and the upper limit is set to be 0.025 wt%.
The production method of the 390 MPa-grade minus 20 ℃ resistant hot-rolled angle steel for the bridge structure comprises the following process flows of: molten iron pretreatment → converter smelting → argon blowing refining → LF refining → casting blank pouring → blank heating → BD rolling → finish rolling → air cooling.
Further, the pretreatment of the molten iron is specifically as follows: the time of the molten iron pretreatment procedure is less than or equal to 30 minutes; the visual slag removal bright surface is more than or equal to 70 percent; blowing after slagging-off is finished, and discharging [ S ] is less than or equal to 0.015 percent;
the converter smelting specifically comprises the following steps: the dosage of the molten iron is not less than 60 +/-5 tons; the steelmaking reference process time is 30 +/-5 minutes; the final point pressure gun is more than 20 seconds, and the tapping time is more than 1 minute; the composition target of the primary molten steel after deoxidation and alloying is as follows: c: less than or equal to 0.10 percent, Si: 0.20-0.45%, Mn: 1.31-1.41%, V: 0.020-0.060%; when tapping about 1/5, adding 3-4.5 kg/t (unit: kg/per ton of molten iron) of low-silicon high-alumina premelted refining slag and 3-4.5 kg/t (unit: kg/per ton of molten iron) of lime through an alloy chute; adding 1.0 kg of aluminum and iron per ton of steel, and adding 1.8-2.2 kg/t of silicon, calcium and barium (unit: kg/ton of molten iron) after finishing adding the aluminum and iron; VN was added after all alloys were added.
The argon blowing refining specifically comprises the following steps: the time of the argon blowing station is less than or equal to 10 minutes; and (3) oxygen determination, feeding aluminum wires, and controlling the content of Als at the outlet to be 0.010-0.020% according to the oxygen determination result.
The LF refining is specifically as follows: the LF slagging time is less than or equal to 25 minutes; 300 to 3000NL/m is used3Controlling the argon flow while blowing the large argon flow; the slag melting time is more than or equal to 10 minutes, and the slag is introduced according to the slag conditionProperly adding lime or low-silicon high-alumina premelted refining slag according to 0-200 kg by calculating the alkalinity value of the slag, and adding aluminum particles and calcium carbide every 2-3 minutes to adjust slag components; simultaneously controlling the flow of argon gas, and slagging until white slag is formed; in addition, [ Als ] is adjusted by adding aluminum particles]The components are 0.010-0.025 percent.
The casting blank pouring specifically comprises the following steps: adopting whole-process protective casting; the open pouring time is not more than 30 seconds when each furnace is continuously poured; the tundish adopts argon micro-positive pressure protection, and the depth of the working liquid level of the tundish is more than or equal to 500 mm. The tundish adopts a water gap and stopper rod form; the crystallizer is automatically controlled by adopting an externally-mounted submersed nozzle stopper rod; the immersion type water gap insertion depth is 80-120 mm; the casting period was 35. + -.5 minutes.
The blank heating specifically comprises the following steps: the heating temperature of the beam blank in the heating furnace is 1200-1230 ℃, the furnace time is 90-120 min, and simultaneously, the temperature of the descaled billet is not lower than 1150 ℃ before the discharged blank of the heating furnace is sent to a BD rolling mill for rolling.
The BD rolling specifically comprises the following steps: before rolling by a BD rolling mill, high-pressure water descaling is carried out, the descaling needs to be ensured to be clean, and the descaling pressure is more than or equal to 12 MPa. Further, the rolling temperature of the BD is 1120-1150 ℃, the finishing temperature is not lower than 1050 ℃, the temperature of a cogging BD rolling section is ensured to be higher than the complete recrystallization temperature of austenite, and meanwhile, the austenite grains are ensured not to be too large through the action of large pressure.
The finish rolling specifically comprises the following steps: the initial rolling temperature is 980-1040 ℃, the final rolling temperature of the sixth frame is not higher than 960 ℃, the process mainly ensures rolling large deformation to realize grain refinement in the continuous rolling stage, and the area ratio of the finished product section to the section before initial rolling is not lower than 25% (the finish rolling section ratio) in the whole deformation stage.
The air cooling specifically comprises the following steps: after rolling, the steel is put on a cooling bed for air cooling and is cooled to room temperature, so that the transformation of ferrite and pearlite is realized in the cooling process, and excellent strength and toughness indexes are obtained.
Based on the actual production of hot-rolled angle steel, the invention integrates multiple processes such as converter smelting, deoxidation refining, protective pouring, blank heating, cogging rolling and the like, and realizes the production of the hot-rolled angle steel for the bridge structure with the yield strength of 390MPa grade, low finish rolling compression ratio, low yield ratio and-20 ℃ low-temperature impact power of not less than 65J by utilizing BD cogging rolling, finish rolling and post-rolling controlled cooling processes through reasonable component proportion and production process control.
Compared with the prior art, the invention is based on the production practice, the control requirement on alloy elements in the actual production process is met by reasonably adjusting the distribution ratio, the actual process operation of on-site production is combined, the BD cogging rolling, finish rolling and post-rolling controlled cooling process is realized, the produced hot rolled angle steel product for the bridge structure has the product strength of more than 390MPa level, the elongation of not less than 25 percent, the impact work value at minus 20 ℃ of not less than 65J, the yield ratio of not more than 0.78 and the finish rolling compression ratio of less than 4.0, and meets the use requirement of the angle steel in the field of bridge structures in China. The product of the invention is widely applied to domestic and foreign bridge construction projects at present, and provides a good technical support for promoting the development of angle steel products in the field of bridge structures.
Drawings
FIG. 1 is a metallographic structure diagram of example 1 of the present invention.
FIG. 2 is a metallographic structure diagram of comparative example 2 of the present invention.
Detailed Description
The following describes embodiments of the present invention in further detail by way of description of the embodiments.
Example 1 to example 6
390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for bridge structures comprises the chemical components shown in the table 1 in percentage by mass, and the balance of Fe and inevitable impurities which are not listed in the table 1.
Comparative examples 1 to 2
The hot-rolled angle steel comprises the chemical components shown in the mass percentage in Table 1, and the balance of Fe and inevitable impurities which are not listed in the Table 1.
TABLE 1 chemical composition of examples (unit: wt%)
The production method of the 390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for the bridge structure in the embodiment 1 to the embodiment 6 comprises the following process flows of:
molten iron pretreatment → converter smelting → argon blowing refining → LF refining → casting blank pouring → blank heating → BD rolling → finish rolling → air cooling.
Further, the pretreatment of the molten iron is specifically as follows: the time of the molten iron pretreatment procedure is less than or equal to 30 minutes; the visual slag removal bright surface is more than or equal to 70 percent; blowing after slagging-off is finished, and discharging [ S ] is less than or equal to 0.015 percent;
the converter smelting specifically comprises the following steps: the dosage of the molten iron is 60 +/-5 tons; the steelmaking reference process time is 30 +/-5 minutes; the final point pressure gun is more than 20 seconds, and the tapping time is more than 1 minute. The composition target of the primary molten steel after deoxidation and alloying is as follows: c: less than or equal to 0.10 percent, Si: 0.20-0.45%, Mn: 1.31-1.41%, V: 0.020-0.060%. When about 1/5 steel is tapped, 200 kg of low-silicon high-alumina premelted refining slag and 200 kg of lime are added through an alloy chute; then adding 1.0 kg of aluminum iron per ton of steel, and adding 2.0 kg of silicon, calcium and barium per ton of steel after finishing adding the aluminum iron; VN was added after all alloys were added.
The argon blowing refining specifically comprises the following steps: the time of the argon blowing station is less than or equal to 10 minutes; and (3) oxygen determination, feeding aluminum wires, and controlling the content of Als at the outlet to be 0.010-0.020% according to the oxygen determination result.
The LF refining is specifically as follows: the LF slagging time is less than or equal to 25 minutes; 1000 to 2000NL/m is used3Controlling argon flow while blowing through with large argon flow (strong stirring); the slag melting time is more than or equal to 10 minutes, 200 kg of lime and low-silicon high-alumina premelted refining slag are added properly according to the condition of the slag, and aluminum particles and calcium carbide are added every 2 minutes to adjust the slag components; in addition, [ Als ] is adjusted by adding aluminum particles]The components are 0.010-0.025 percent.
The casting blank pouring specifically comprises the following steps: adopting whole-process protective casting; the open pouring time is not more than 30 seconds when each furnace is continuously poured; the tundish adopts argon micro-positive pressure protection, and the depth of the working liquid level of the tundish is more than or equal to 500 mm. The tundish adopts a water gap and stopper rod form; the crystallizer is automatically controlled by adopting an externally-mounted submersed nozzle stopper rod; the immersion type water gap insertion depth is 80-120 mm; the casting period was 35. + -.5 minutes.
The blank heating specifically comprises the following steps: the heating temperature of the beam blank in the heating furnace is 1200-1230 ℃, the furnace time is 90-120 min, and simultaneously, the temperature of the descaled billet is not lower than 1150 ℃ before the discharged blank of the heating furnace is sent to a BD rolling mill for rolling.
The BD rolling specifically comprises the following steps: before rolling by a BD rolling mill, high-pressure water descaling is carried out, the descaling needs to be ensured to be clean, and the descaling pressure is more than or equal to 12 MPa. Furthermore, the rolling temperature is 1120-1150 ℃, the finishing temperature is not lower than 1050 ℃, the temperature of the rolling section of the cogging BD is ensured to be higher than the complete recrystallization temperature of austenite, and meanwhile, the austenite grains are ensured not to be too coarse through the action of high pressure.
The finish rolling specifically comprises the following steps: the initial rolling temperature is 980-1040 ℃, the final rolling temperature of the sixth frame is not higher than 960 ℃, the process mainly ensures rolling large deformation to realize grain refinement in the continuous rolling stage, and the area ratio of the finished product section to the section before initial rolling is not lower than 25% (the finish rolling section ratio) in the whole finish rolling deformation stage.
The air cooling specifically comprises the following steps: after rolling, the steel is put on a cooling bed for air cooling and is cooled to room temperature, so that the transformation of ferrite and pearlite is realized in the cooling process, and excellent strength and toughness indexes are obtained.
The control parameters of the BD rolling, finish rolling and air cooling production processes in examples 1 to 6 are shown in Table 2.
Comparative examples 1 to 2
The process flow of the hot-rolled corner production is the same as that of the examples 1 to 6, wherein the process flow and parameter control of molten iron pretreatment → converter smelting → argon blowing refining → LF refining → casting blank pouring → blank heating are the same as those of the examples 1 to 6, and the difference is that the control parameters of BD rolling, finish rolling and air cooling are different from those of the comparative examples 1 to 2, specifically:
the BD rolling specifically comprises the following steps: before rolling by a BD rolling mill, high-pressure water descaling is carried out, the descaling needs to be ensured to be clean, and the descaling pressure is more than or equal to 12 MPa. Furthermore, the rolling temperature is 1130-1160 ℃, compared with the rolling reduction of the BD cogging section in the embodiments 1-6, the rolling reduction of the BD cogging section is relatively small, and the temperature of the BD section can be relatively set to be high in order to ensure the subsequent finish rolling rhythm; the finishing temperature is not lower than 1060 ℃.
The finish rolling specifically comprises the following steps: the initial rolling temperature is 1000-1040 ℃, the final rolling temperature of the sixth frame is not higher than 980 ℃, compared with the process of the embodiment 1-6, the relative reduction in the continuous rolling stage is larger, and the rolling temperature can be properly increased for reducing the load of the rolling mill. The whole finish rolling deformation stage meets the condition that the area ratio of the finished product section to the section before the initial rolling is not more than 25 percent (the finish rolling section ratio).
The air cooling specifically comprises the following steps: after rolling, the steel is put on a cooling bed for air cooling and is cooled to room temperature, so that the transformation of ferrite and pearlite is realized in the cooling process, and excellent strength and toughness indexes are obtained.
Control parameters in the BD rolling, finish rolling and air cooling production processes of comparative examples 1 to 2 are shown in Table 2.
Specific process parameters related to the production method of 390MPa grade-20 ℃ resistant hot-rolled angle steel for bridge structures described in examples 1-6 and comparative examples 1-2 are shown in Table 2.
TABLE 2 Main Process parameters for the production of the examples and comparative examples
The metallographic structure obtained by the method is as follows: ferrite and pearlite, and the grain size is 9.0-9.5 grade.
The finish rolling compression ratios of the comparative examples 1 and 2 are both larger than 4.0, which shows that the reduction of the BD segment is relatively small; on the contrary, in examples 1 to 6, the finish rolling reduction ratios are all less than 4.0, which means that the BD stage reduction is relatively large.
Mechanical properties of 390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for bridge structures produced in the above examples 1 to 6 and comparative examples 1 to 2 are shown in the following table 3, wherein a sample sampling method executes GB/T20066 and GB/T2975 standards, and a test method executes GB/T4336, GB/T228.1 and GB/T229 standards.
TABLE 3 mechanical Properties of hot rolled angle steels of examples and comparative examples
| ReL/MPa | Rm/MPa | A/％ | -20℃KV2/J | Yield ratio | |
| Example 1 | 449 | 590 | 28 | 87(97、85、79) | 0.76 |
| Example 2 | 416 | 585 | 25 | 94(49、129、103) | 0.71 |
| Example 3 | 472 | 605 | 28 | 103(78、129、103) | 0.78 |
| Example 4 | 488 | 623 | 28 | 77(80、77、74) | 0.78 |
| Example 5 | 453 | 596 | 26 | 72(70、78、68) | 0.76 |
| Example 6 | 450 | 595 | 27 | 66(75、65、56) | 0.76 |
| Comparative example 1 | 403 | 512 | 25 | 42(51、32、43) | 0.79 |
| Comparative example 2 | 425 | 564 | 23 | 56(52、49、67) | 0.75 |
As shown in the examples in tables 1 to 3, the comparative examples 1 to 2 adopt different production processes, the yield strength of the product is 403 to 425MPa, the tensile strength is 512 to 564MPa, the elongation is 23 to 25 percent, the impact energy at the temperature of minus 20 ℃ is 42 to 56J, the room temperature yield ratio is 0.75 to 0.79, and the finish rolling compression ratio is 4.12 to 4.33.
Examples 1-6 the angle steel products produced by the method of the present invention have yield strength of 416-488MPa, tensile strength of 585-623MPa, elongation of 25% -28%, impact energy of 66J-103J at-20 ℃, room temperature yield ratio of 0.71-0.78, and finish rolling compression ratio of 3.57-4.0, which indicates that the products have good room temperature strength, plasticity and low temperature toughness, and meet the use requirements of the products in the field of bridge structure engineering.
Claims (8)
1. The 390 MPa-grade-20-DEG-resistant hot-rolled angle steel for the bridge structure is characterized by comprising the following chemical components in percentage by mass: c: 0.15-0.18%, Si: 0.20-0.45%, Mn: 1.35-1.45%, P: less than or equal to 0.025 percent, S: less than or equal to 0.025 percent, Cr: 0.020-0.060%, V: 0.030-0.080%, Als: 0.010-0.025 percent, and the balance of Fe and trace residual elements;
the production method of the 390 MPa-grade minus 20 ℃ resistant hot-rolled angle steel for the bridge structure comprises the following process flows of: molten iron pretreatment → converter smelting → argon blowing refining → LF refining → casting blank casting → blank heating → BD rolling → finish rolling → air cooling;
the BD rolling specifically comprises the following steps: the initial rolling temperature is 1120-1150 ℃, and the final rolling temperature is not lower than 1050 ℃;
the 390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for the bridge structure is characterized by comprising the following structures: ferrite and pearlite, and the grain size is 9.0-9.5 grade.
2. The 390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for the bridge structure according to claim 1, characterized in that the initial smelting molten steel after converter smelting and deoxidation alloying has the following composition targets: c: less than or equal to 0.10 percent, Si: 0.20-0.45%, Mn: 1.31-1.41%, V: 0.020-0.060%.
3. The 390MPa grade-20 ℃ resistant hot-rolled angle steel for the bridge structure according to claim 1, characterized in that the molten iron is pretreated, and the standing [ S ] is less than or equal to 0.015%.
4. The 390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for the bridge structure according to claim 1, wherein the argon blowing refining specifically comprises: the time of the argon blowing station is less than or equal to 10 minutes; and (3) oxygen determination, feeding aluminum wires, and controlling the content of Als at the outlet to be 0.010-0.020% according to the oxygen determination result.
5. The 390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for the bridge structure according to claim 1, wherein the LF refining is specifically: the LF slagging time is less than or equal to 25 minutes; 300 to 3000NL/m is used3Controlling argon flow while blowing large argon flow, controlling slag melting time to be more than or equal to 10 minutes, and adjusting by adding aluminum particles [ Als ]]The components are 0.010-0.025 percent.
6. The 390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for the bridge structure according to claim 1, wherein the casting blank casting specifically comprises: adopting whole-process protective casting; the open pouring time is not more than 30 seconds when each furnace is continuously poured; the tundish adopts argon micro-positive pressure protection, and the depth of the working liquid level of the tundish is more than or equal to 500 mm; the tundish adopts a water gap and stopper rod form; the crystallizer is automatically controlled by adopting an externally-mounted submersed nozzle stopper rod; the immersion type water gap insertion depth is 80-120 mm; the casting period was 35. + -.5 minutes.
7. The 390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for the bridge structure according to claim 1, wherein the blank heating specifically comprises: the heating temperature of the beam blank in the heating furnace is 1200-1230 ℃, the furnace time is 90-120 min, and simultaneously, the temperature of the descaled billet is not lower than 1150 ℃ before the discharged blank of the heating furnace is sent to a BD rolling mill for rolling.
8. The 390 MPa-grade-20-DEG C-resistant hot-rolled angle steel for the bridge structure according to claim 1, wherein the finish rolling is specifically: the initial rolling temperature is 980-1040 ℃, the finish rolling temperature of the sixth frame is not higher than 960 ℃, and the finish rolling section accounts for not less than 25%.
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Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102676921A (en) * | 2012-05-04 | 2012-09-19 | 武汉钢铁(集团)公司 | Cold-resistant high-strength hot-rolled angle steel and production method thereof |
| KR20150050702A (en) * | 2013-10-30 | 2015-05-11 | 현대제철 주식회사 | Inverted angle steel and method of manufacturing the same |
| CN105734418A (en) * | 2016-03-11 | 2016-07-06 | 宣化钢铁集团有限责任公司 | Low-temperature-resistant hot-rolled angle steel and preparation method thereof |
| JP2017137576A (en) * | 2016-01-29 | 2017-08-10 | Ｊｆｅスチール株式会社 | Angle steel and production method of angle steel |
| JP2017166064A (en) * | 2016-03-09 | 2017-09-21 | Ｊｆｅスチール株式会社 | Non-refining low yield ratio high tensile thick steel sheet, manufacturing method therefor, shaped steel and structure |
| CN108425066A (en) * | 2018-03-19 | 2018-08-21 | 北京国网富达科技发展有限责任公司 | It a kind of angle steel and its prepares and steel tower of its manufacture |
| CN108517467A (en) * | 2018-05-17 | 2018-09-11 | 常熟市龙腾特种钢有限公司 | A kind of production method of low-temperature high-toughness electric power pylon angle steel |
| CN111411304A (en) * | 2020-04-17 | 2020-07-14 | 南京钢铁股份有限公司 | Q460-grade hot-rolled angle steel and preparation method thereof |
-
2020
- 2020-08-18 CN CN202010832091.0A patent/CN112011737B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102676921A (en) * | 2012-05-04 | 2012-09-19 | 武汉钢铁(集团)公司 | Cold-resistant high-strength hot-rolled angle steel and production method thereof |
| KR20150050702A (en) * | 2013-10-30 | 2015-05-11 | 현대제철 주식회사 | Inverted angle steel and method of manufacturing the same |
| JP2017137576A (en) * | 2016-01-29 | 2017-08-10 | Ｊｆｅスチール株式会社 | Angle steel and production method of angle steel |
| JP2017166064A (en) * | 2016-03-09 | 2017-09-21 | Ｊｆｅスチール株式会社 | Non-refining low yield ratio high tensile thick steel sheet, manufacturing method therefor, shaped steel and structure |
| CN105734418A (en) * | 2016-03-11 | 2016-07-06 | 宣化钢铁集团有限责任公司 | Low-temperature-resistant hot-rolled angle steel and preparation method thereof |
| CN108425066A (en) * | 2018-03-19 | 2018-08-21 | 北京国网富达科技发展有限责任公司 | It a kind of angle steel and its prepares and steel tower of its manufacture |
| CN108517467A (en) * | 2018-05-17 | 2018-09-11 | 常熟市龙腾特种钢有限公司 | A kind of production method of low-temperature high-toughness electric power pylon angle steel |
| CN111411304A (en) * | 2020-04-17 | 2020-07-14 | 南京钢铁股份有限公司 | Q460-grade hot-rolled angle steel and preparation method thereof |
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