CN111154962B

CN111154962B - Anti-seismic corrosion-resistant refractory steel and preparation method thereof

Info

Publication number: CN111154962B
Application number: CN202010054478.8A
Authority: CN
Inventors: 李昭东; 王鑫; 曹燕光; 杨忠民; 陈颖; 王慧敏; 沈俊昶
Original assignee: Zhonglian Advanced Steel Technology Co ltd; Central Iron and Steel Research Institute
Current assignee: Zhonglian Advanced Steel Technology Co ltd; Central Iron and Steel Research Institute
Priority date: 2020-01-17
Filing date: 2020-01-17
Publication date: 2021-03-30
Anticipated expiration: 2040-01-17
Also published as: CN111154962A

Abstract

The invention discloses anti-seismic, corrosion-resistant and fire-resistant steel and a preparation method thereof, and belongs to the technical field of steel for building structures. The problems of complex preparation process and high process control difficulty of the anti-seismic, corrosion-resistant and fire-resistant steel in the prior art are solved. The anti-seismic corrosion-resistant refractory steel comprises the following chemical components in percentage by mass: c: 0.06% -0.10%, Si: 0.65% -1.00%, Mn: 0.80% -1.20%, Mo: 0.50% -0.60%, Ni: 1.00-1.50%, Cr: 0.72% -1.00%, Cu: 0.25-0.40%, Ti: 0.01% -0.03%, Nb: 0.05-0.10%, V: 0.03-0.10%, Al: 0.015% -0.055%, P: < 0.015%, S: < 0.005%, O < 0.003%, N < 0.005%, and the balance Fe and unavoidable impurities. The preparation method comprises the following steps: smelting and casting; two-stage controlled rolling is carried out. The preparation method is simple and easy to control, and the prepared anti-seismic, corrosion-resistant and fire-resistant steel has good comprehensive performance.

Description

Anti-seismic corrosion-resistant refractory steel and preparation method thereof

Technical Field

The invention belongs to the technical field of steel for building structures, and particularly relates to anti-seismic, corrosion-resistant and fire-resistant steel and a preparation method thereof.

Background

The steel for the ultra-high strength building structure simultaneously meets the conditions that the yield strength is more than or equal to 690MPa, the yield ratio is less than or equal to 0.85, and the elongation after fracture is more than or equal to 18 percent, so that the technical difficulty is higher. But the critical heat treatment temperature window of the two-phase region is within 10-20 ℃, so that the process control difficulty is very high.

Disclosure of Invention

In view of the above analysis, the present invention aims to provide a shock-resistant, corrosion-resistant and fire-resistant steel and a preparation method thereof, which can solve at least one of the following technical problems: (1) the existing anti-seismic corrosion-resistant refractory steel has complex preparation process; (2) the difficulty of process control is high; (3) the corrosion resistance is poor.

The purpose of the invention is mainly realized by the following technical scheme:

the invention provides anti-seismic corrosion-resistant fire-resistant steel which comprises the following chemical components in percentage by mass: c: 0.06% -0.10%, Si: 0.65% -1.00%, Mn: 0.80% -1.20%, Mo: 0.50% -0.60%, Ni: 1.00-1.50%, Cr: 0.72% -1.00%, Cu: 0.25-0.40%, Ti: 0.01% -0.03%, Nb: 0.05-0.10%, V: 0.03-0.10%, Al: 0.015% -0.055%, P: < 0.015%, S: < 0.005%, O < 0.003%, N < 0.005%, and the balance Fe and unavoidable impurities.

Furthermore, the atmospheric corrosion resistance index I of the anti-seismic corrosion-resistant refractory steel is more than or equal to 4.9.

Further, the anti-seismic, corrosion-resistant and fire-resistant steel comprises the following components in percentage by mass: c: 0.066% -0.095%, Si: 0.66% -0.95%, Mn: 0.85% -1.18%, Mo: 0.51% -0.60%, Ni: 1.01% -1.47%, Cr: 0.72% -0.93%, Cu: 0.28% -0.38%, Ti: 0.015% -0.028%, Nb: 0.058% -0.096%, V: 0.033 to 0.096%, Al: 0.018-0.052%, P: less than or equal to 0.008 percent, S: less than or equal to 0.003 percent, and the balance of Fe and inevitable impurities.

Furthermore, the structure of the shock-resistant, corrosion-resistant and fire-resistant steel is carbide-free bainite, martensite, residual austenite and MC microalloy carbide.

The invention also provides a preparation method of the anti-seismic, corrosion-resistant and fire-resistant steel, which comprises the following steps:

step S1: smelting and casting;

step S2: two-stage controlled rolling is carried out.

Further, step S2 includes the steps of:

s21, placing the continuous casting slab or the cast ingot into a heating furnace after cogging, heating to T1, and preserving heat;

s22, performing two-stage controlled rolling, wherein the rough rolling is performed for 3-5 times, and the finish rolling is performed for 5-10 times;

and S23, tempering at medium and low temperature after rolling.

Further, T1 is 1200-1250 ℃.

Further, in S22, the rough rolling start temperature is 1150 + -30 ℃, and the rough rolling finish temperature is 950 + -30 ℃.

Further, in S22, the finish rolling temperature was 830. + -. 20 ℃.

Further, the post-rolling medium-low temperature tempering step in S23 is as follows: and charging the rolled steel plate at room temperature, heating the furnace to 350-450 ℃, preserving the heat for 30-90 min, and then air-cooling to room temperature.

Compared with the prior art, the invention has the following beneficial effects:

1) the anti-seismic corrosion-resistant refractory steel (MnCrNiCuMoSi system) provided by the invention adopts a low-carbon design on the component design, and Mn, Cr, Ni, Cu, Mo and the like are added to improve the hardenability, wherein the atmospheric corrosion resistance is improved by Cr, Ni, Cu, Mo and the like, and the Mo and Cr are beneficial to improving the high-temperature strength, so that the refractory performance is ensured, and the Ni also plays a role in ensuring the low-temperature toughness.

2) The addition of Nb and V elements, in cooperation with the function of Mo for refining the size of the microalloy carbide, can precipitate a large amount of MC type microalloy nano carbide (M represents Nb, V and Mo) when meeting fire, further improve the high-temperature strength, and compared with VC, the solid solubility of NbC in steel is lower, and Nb is more easily precipitated when the addition amount of the same mass is equal. Therefore, compared with single Nb microalloying, the compound addition of V and Nb can not remarkably improve the solid solution heating temperature, and can also remarkably improve the total precipitation amount of MC; the synergistic addition of Mo can increase the total precipitation amount of MC as in the case of V composite addition, and more importantly, the size of MC type carbide is refined, the ratio of MC particles with the diameter of less than 20nm is controlled to be more than 50%, and the strengthening increment is improved.

3) The addition of Si with higher content not only has strong solid solution effect, but also more importantly inhibits the formation of cementite in the air cooling process, thereby obtaining the structure of carbide-free (carbide refers to cementite) bainite + martensite + retained austenite + MC type microalloy carbide. Si inhibits the precipitation of cementite, reduces the conversion process from cementite to MC type microalloy carbide, and provides beneficial preparation for rapidly precipitating more MC type microalloy carbide when the steel plate is in service and encounters fire.

4) According to the preparation method of the anti-seismic, corrosion-resistant and fire-resistant steel, provided by the invention, through optimizing the content of alloy elements, the rolling is controlled by adopting two stages of recrystallization and non-recrystallization for promoting austenite refining and flattening, so that fine and flat austenite grains are obtained, and a fine-grained phase change structure is favorably obtained, thereby improving the yield strength and improving the low-temperature impact toughness; carrying out air cooling after hot rolling, carrying out medium-temperature and low-temperature tempering after air cooling to obtain a structure of carbide-free (carbide refers to cementite) bainite, martensite, residual austenite and MC microalloy carbide, and under the premise of ensuring that the steel has enough yield strength (the yield strength is more than or equal to 690MPa, the yield ratio is less than or equal to 0.85 and the elongation after fracture is more than or equal to 18 percent), because a small amount of MC microalloy carbide is precipitated in the rolling and cooling processes of Nb, V, Mo and the like, the MC microalloy carbide is precipitated in the heating process when meeting fire, and the tensile yield strength at 600 ℃ is not lower than 2/3 required by the room-temperature yield strength standard after the temperature of 600 ℃ is; meanwhile, the corrosion resistance is improved, the preparation method is simple, the process window is wide, and the steel can be widely applied to steel for building structures.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

FIG. 1 is a photograph of a microstructure of example 1 of the present invention;

FIG. 2 is an SEM photograph of example 1 of the present invention.

Detailed Description

An anti-seismic, corrosion-resistant and fire-resistant steel and a method for manufacturing the same will be described in further detail with reference to specific examples and comparative examples, which are provided for purposes of comparison and explanation only, and the present invention is not limited to these examples.

The chemical components of the anti-seismic, corrosion-resistant and fire-resistant steel provided by the invention are as follows by mass percent: c: 0.06% -0.10%, Si: 0.65% -1.00%, Mn: 0.80% -1.20%, Mo: 0.50% -0.60%, Ni: 1.00-1.50%, Cr: 0.72% -1.00%, Cu: 0.25-0.40%, Ti: 0.01% -0.03%, Nb: 0.05-0.10%, V: 0.03-0.10%, Al: 0.015% -0.055%, P: < 0.015%, S: < 0.005%, O < 0.003%, N < 0.005%, and the balance Fe and unavoidable impurities; wherein the atmospheric corrosion resistance index I is more than or equal to 4.9.

Compared with the prior art, the MnCrNiCuMoSi series anti-seismic corrosion-resistant refractory steel provided by the invention adopts a low-carbon design on the aspect of component design, and improves the hardenability by adding Mn, Cr, Ni, Cu, Mo and the like, wherein the atmospheric corrosion resistance is improved by Cr, Ni, Cu, Mo and the like, and the Mo and Cr are beneficial to improving the high-temperature strength, so that the refractory performance is ensured, and Ni also plays a role in ensuring the low-temperature toughness; nb and V elements are added to cooperate with the function of Mo to refine the size of the microalloy carbide, so that a large amount of nano carbide is separated out when the microalloy carbide meets fire, and the high-temperature strength is further improved; adding a certain content of Si not only plays a strong solid solution role, but also more importantly inhibits the formation of cementite in the air cooling process, thereby obtaining a structure of carbide-free (carbide refers to cementite here) bainite + martensite + residual austenite + MC microalloy carbide; on the premise of ensuring that the steel has enough yield strength (meeting the requirements that the yield strength is more than or equal to 690MPa, the yield ratio is less than or equal to 0.85 and the elongation after fracture is more than or equal to 18 percent), because a small amount of MC type microalloy carbide is precipitated in the rolling and cooling processes of Nb, V, Mo and the like and a large amount of MC type microalloy carbide is precipitated in the heating process in case of fire, the high-temperature tensile yield strength after the heat preservation for 3 hours at 600 ℃ is not lower than 2/3 required by the room-temperature yield strength.

Specifically, the atmospheric corrosion resistance index I satisfies the following formula:

I＝26.01(Cu)+3.88(Ni)+1.20(Cr)+1.49(Si)+17.28(P)-7.29(Cu)(Ni)-9.10(Ni)(P)-33.39(Cu)²。

the steel of the invention is designed based on the following principles:

carbon: carbon can directly influence the mechanical properties of the steel such as strength, toughness and the like, has obvious gap replacement solid solution strengthening effect, improves the hardenability of steel, and is also a necessary element for forming the nano-scale MC type second phase, so that the room temperature strength cannot be ensured due to low carbon content, and sufficient nano-scale MC type second phase is difficult to form at high temperature; with the increase of the carbon content, the plasticity and the impact toughness of steel are reduced, the corrosion resistance is reduced, the hardenability of a welding heat affected zone is high, and the tendency of generating cold cracks is aggravated; in combination with the above considerations, the carbon content in the steel of the present invention is controlled to be in the range of 0.06% to 0.10%.

Silicon: one of deoxidizing elements in the steel has a strong solid solution strengthening effect, and the corrosion resistance of the steel can be improved; the precipitation of cementite in steel can be inhibited, the formation of a carbide-free bainite + martensite + residual austenite structure in the air cooling process is promoted, and the steel plays an important role in room-temperature stretching and simultaneously meeting the requirements that the yield strength is more than or equal to 690MPa, the yield ratio is less than or equal to 0.85 and the elongation after fracture is more than or equal to 18 percent; however, excessive Si deteriorates the toughness and weldability of the steel. In combination with the above considerations, the silicon content in the steel of the present invention is controlled to be in the range of 0.65% to 1.00%.

Manganese: the austenite stabilizing element can obviously improve hardenability, has a certain solid solution strengthening effect, is an important strong toughness element, and has low price; in order to achieve a good balance between corrosion resistance, the steel of the present invention will contain a certain amount of elements such as Cr, Ni, Cu, etc., which also improve hardenability and carbon equivalent. In combination with the above considerations, the manganese content of the steel of the present invention is controlled to be in the range of 0.80% to 1.20%.

Molybdenum: the hardenability of the steel is obviously improved, and the temper brittleness is reduced; the activity of carbon in austenite is reduced, the bainite is promoted to be incompletely transformed, namely, in a bainite transformation temperature range, particularly a bainite transformation temperature of a higher temperature, the supercooled austenite cannot completely generate bainite transformation, and in addition, the precipitation of cementite is also inhibited by adopting the addition of Si with higher content. Therefore, the untransformed austenite is gradually enriched with elements such as C, Mn and the like to become more stable, and undergoes martensite phase transformation or remains to room temperature when the air cooling is reduced to a lower temperature, and finally a soft and hard multiphase structure without carbide (carbide refers to cementite) bainite, martensite and retained austenite is obtained, so that the yield ratio of the steel is reduced, and the anti-seismic performance is improved; molybdenum is also an important element for improving the high-temperature strength of steel, and the molybdenum inhibits the coarsening of crystal grains and the disappearance of dislocation through the action mechanisms of solid solution strengthening of a ferrite matrix, segregation strengthening of a grain boundary and the like, so that the high-temperature stability of the structure is improved, and the high-temperature strength is improved. On the aspect of nano carbide, the synergistic addition of Mo participates in the precipitation of MC type microalloy carbide on one hand and increases the total precipitation amount on the other hand, more importantly, the high-temperature coarsening tendency of the MC type carbide is reduced, the size of the MC type carbide is refined, the proportion of MC particles with the diameter of less than 20nm can be controlled to be more than 50%, the strengthening increment is improved, and the high-temperature strength is further ensured. If the content of molybdenum is too low, the effect is limited, and if the content is too high, the effect is saturated, even the effect of improving the high-temperature performance is excessive, and the alloy and tempering heat treatment process cost of the steel is increased. Therefore, the content range of the molybdenum in the steel is controlled to be 0.50-0.60%.

Nickel: austenite stabilizing elements exist in gamma phase and alpha phase in the steel in an infinite mutual solubility mode with iron, Fe and Ni are in an infinite mutual solubility mode, Fe-Ni alloys are solid solutions, namely Ni atoms replace the positions of Fe atoms in Fe lattices, or Fe atoms replace the effects of Ni atoms, no other intermetallic compounds are generated, nickel can promote the implementation of cross sliding, the resistance of dislocation motion is reduced, stress is relaxed, and the plasticity and toughness of the steel are improved; in addition, the carbon equivalent coefficient of the nickel element is only 1/15 which is low, so that the welding performance is facilitated; but its price is high. Therefore, the content range of nickel in the steel is controlled to be 1.00-1.50%.

Chromium: the activity of carbon in austenite is reduced, and the transformation of bainite is incomplete; the strength and the atmospheric corrosion resistance of the steel are improved, the hardenability is obviously improved, but the welding performance is not good due to the high Cr content, the toughness of a base metal and a heat affected zone is reduced, and the temper brittleness of the steel can be obviously improved, so that the chromium content range in the steel is controlled to be 0.72-1.00 percent.

Copper: copper can improve the corrosion resistance of steel, and the copper is enriched at the cracks of the rust layer, so that a channel for a corrosive medium to contact with a matrix is blocked, and the corrosion resistance is improved; the addition of copper also promotes gamma-Fe₂O₃Conversion of/γ -FeOOH to the stable rust phase α -FeOOH; however, Cu-containing steels tend to suffer from hot shortness due to surface selective oxidation and should not be contained in too high a content. Therefore, the Cu content in the steel of the present invention is controlled to be in the range of 0.25% to 0.40%.

Titanium: during micro Ti treatment, Ti is mainly combined with N and precipitated from solid steel to form TiN particles with nano-scale sizes, and the main function of the method is to refine austenite grains in the heating process of casting blanks. However, too much Ti tends to form coarse liquated TiN, and seriously deteriorates the toughness and plasticity of the steel. Therefore, the Ti content in the steel is controlled to be 0.01-0.03%.

Niobium: has the functions of refining grains and improving strength; solid solution of Nb can increase the nucleation point of gamma/alpha phase transformation, and austenite coarsening is inhibited in the cooling process, so that the effect of refining grains to strengthen is achieved; the Nb element has strong affinity with C, N to form fine and dispersed Nb (C, N), and Nb (C, N) is precipitated through solid solution of Nb and deformation induction, so that strong inhibition effect on austenite recrystallization is achieved, unrecrystallized austenite with high defect density is obtained, subsequent phase transformation nucleation rate is improved, and the structure after phase transformation is refined, and precipitation strengthening effect is achieved. The niobium carbide particles separated out independently when meeting fire or separated out by compounding with vanadium and molybdenum improve the high-temperature strength. If the Nb content is less than 0.05%, the above effect is not significant, and the effect of further refining the microstructure with excessively high Nb becomes insignificant and the cost increases. Therefore, the content of niobium in the steel is controlled to be 0.05-0.10%.

Vanadium: the solid solubility product of V carbonitride in austenite is relatively maximum, and hardenability and recrystallization temperature are obviously improved; the action of the alloy is similar to that of Nb when encountering fire, and V (C, N) particles are separated out independently or are compounded with Nb and Mo, so that the high-temperature strength is improved; compared with single Nb microalloying, the compound addition of V and Nb can not remarkably improve the solid solution heating temperature, but also can remarkably improve the total precipitation amount of MC. Too high a V content significantly deteriorates the low-temperature toughness of steel, particularly the toughness of the weld heat affected zone, and is relatively costly. Therefore, the vanadium content in the steel is controlled to be 0.03-0.10%.

Aluminum: the aluminum is a strong deoxidizing element, and the content range of the aluminum in the steel is controlled to be 0.015-0.055%.

Phosphorus and sulfur: the impurity elements in the steel obviously reduce the plasticity and the welding performance, and the content of the impurity elements is as low as possible without obviously increasing the cost, so that the content of the impurity elements is controlled to be below 0.015 percent and below 0.005 percent respectively.

Oxygen and nitrogen: gaseous impurity elements in steel. The higher the oxygen content, the more oxide-type inclusions; the grain size refinement of TiN and the like which is unfavorable for controlling the grain size of the heated austenite before rolling due to the excessively high nitrogen content. Therefore, the oxygen and nitrogen contents are controlled to be 0.003% and 0.005% or less, respectively.

In order to further improve the comprehensive performance of the anti-seismic, corrosion-resistant and fire-resistant steel, the composition of the anti-seismic, corrosion-resistant and fire-resistant steel can be further adjusted. Illustratively, the composition comprises the following components in percentage by mass: c: 0.066% -0.095%, Si: 0.66% -0.95%, Mn: 0.85% -1.18%, Mo: 0.51% -0.60%, Ni: 1.01% -1.47%, Cr: 0.72% -0.93%, Cu: 0.28% -0.38%, Ti: 0.015% -0.028%, Nb: 0.058% -0.096%, V: 0.033 to 0.096%, Al: 0.018-0.052%, P: less than or equal to 0.008 percent, S: less than or equal to 0.003 percent, and the balance of Fe and inevitable impurities;

on the other hand, the invention also provides a preparation method of the anti-seismic, corrosion-resistant and fire-resistant steel, which comprises the following steps:

step S1: smelting and casting;

step S2: and (4) carrying out recrystallization and non-recrystallization two-stage controlled rolling by adopting a heavy and medium plate mill.

Specifically, in step S1, molten steel is smelted in a converter or an electric furnace, and continuous casting is used for casting.

Specifically, step S2 includes the following steps:

s21, placing the continuous casting slab or the cast ingot into a heating furnace after cogging, heating to T1, and preserving heat for T1 time;

specifically, in S21, T1 is 1200-1250 ℃, because when T1 is too high, austenite grains of a casting blank are too coarse, energy cost is increased, and when T1 is too low, elements such as Nb and C are difficult to be fully dissolved in a solid state, so that subsequent precipitation and structure control are influenced.

Specifically, in S21, the time t1 is too long, energy cost is increased, production efficiency is not facilitated, the time t1 is too short, and uniformity of thickness and temperature of a casting blank is difficult to guarantee. Therefore, t1 is controlled to be 0.5-3 hours.

S22, carrying out recrystallization and non-recrystallization two-stage controlled rolling: the rough rolling is carried out for 3-5 times, the finish rolling is carried out for 5-10 times, the initial rolling temperature of the rough rolling is 1150 +/-30 ℃, the first secondary rolling reduction is 20-25%, the final rolling temperature of the rough rolling is controlled to be 950 +/-30 ℃ in the secondary time of the rough rolling, the initial rolling temperature of the finish rolling is below 900 ℃, the final rolling temperature of the finish rolling is 830 +/-20 ℃, and the air cooling is carried out to the room temperature after the rolling. The key points of obtaining fine-grained and flat austenite grains are controlling lower rough rolling finishing temperature and finishing rolling temperature and ensuring that the finishing rolling compression ratio is not less than 2.5, so that fine-grained air-cooled phase change structures can be obtained, the room-temperature yield strength is improved, and the low-temperature impact toughness is improved. The rough rolling initial rolling temperature is controlled to be higher and larger in deformation amount to obtain uniform and fine isometric austenite grains which are recrystallized at high temperature, then the temperature is waited for the next time in a rough rolling channel, and the rough rolling temperature is controlled to be properly low, so that the flattening of the austenite grains is controlled at the later stage of the rough rolling. The finish rolling temperature is controlled to be lower than 900 ℃, the finish rolling compression ratio is more than or equal to 2.5, and the austenite grains are promoted to be remarkably flattened.

Specifically, the initial rolling temperature of rough rolling is 1130-1156 ℃; the rough rolling and final rolling temperature is 921-962 ℃; the precision rolling initial rolling temperature is 881-890 ℃; and the finish rolling temperature is 812-846 ℃.

S23, medium and low temperature tempering after rolling: and charging the rolled steel plate at room temperature, heating the furnace to 350-450 ℃, preserving the heat for 30-90 min, and then air-cooling to room temperature.

In the prior art, the anti-seismic corrosion-resistant refractory steel is generally processed by adopting a process mode of hot rolling direct quenching and two-phase region critical heat treatment, hot rolling direct quenching is used for obtaining a structure mainly containing martensite, a high-temperature state is subjected to heat treatment to obtain nanometer second-phase pre-precipitation enhanced high-temperature tempered martensite and a certain amount of reverse transformed austenite, one part of the reverse transformed austenite is subjected to phase transformation in a cooling process to form high-hardness bainite/martensite, the high-temperature tempered secondary martensite and the high-hardness primary bainite/martensite are matched to ensure high yield strength and low yield ratio, and the other part of the reverse transformed austenite is kept to room temperature in the form of residual austenite to improve plasticity. But the critical heat treatment temperature window of the two-phase region is within 10-20 ℃, so that the process control difficulty is very high. The anti-seismic corrosion-resistant refractory steel can obtain a structure of carbide-free (carbide refers to cementite here), bainite, martensite, retained austenite and MC type microalloy carbide through comprehensive control of components, controlled rolling in two stages of recrystallization and non-recrystallization and medium-low temperature tempering; on the premise of ensuring that the steel has enough yield strength (meeting the requirements that the yield strength is more than or equal to 690MPa, the yield ratio is less than or equal to 0.85 and the elongation after fracture is more than or equal to 18 percent), because a small amount of MC type microalloy carbide is precipitated in the rolling and cooling processes of Nb, V, Mo and the like, a large amount of MC type microalloy carbide is precipitated in the heating process in case of fire, and the tensile yield strength at 600 ℃ is not lower than 2/3 required by the room-temperature yield strength standard after the steel is kept warm for 3 hours. For example, the tensile strength of the steel plate is more than 990MPa (such as 999-1030 MPa) at room temperature; the yield strength of the steel plate is more than 750MPa (e.g. 767-828 MPa); elongation of the steel sheet > 18% (e.g. 18.5-20%); the yield ratio of the steel plate is less than 0.83 (such as 0.77-0.82); after the heat preservation is carried out for 3 hours at the temperature of 600 ℃, the tensile strength of the steel plate is more than or equal to 590MPa (such as 590-619 MPa); the yield strength of the steel plate is greater than 480MPa (such as 485-503 MPa); the elongation of the steel plate is more than or equal to 18 percent (for example, 18.0 to 19.5 percent); the impact energy of the steel plate at-40 ℃ is more than or equal to 35J (for example, 35-45J).

The chemical compositions of the steel sheets of examples 1 to 3 of the present invention and comparative example 1 are shown in table 1 below. The examples 1 to 3 and the comparative example 1 are smelted by a converter, and are prepared into a steel plate with the plate thickness of 20mm by smelting, refining, continuous casting and two-stage rolling, and then are tempered at a medium and low temperature and air-cooled to room temperature; the process parameters of examples 1-3 and comparative example 1 are shown in Table 2.

Table 1 chemical composition (wt.%) of steel sheets of examples 1 to 3 and comparative example 1

TABLE 2 preparation Process parameters of examples 1-3 and comparative example 1

The performance results of the steel sheets of examples 1-3 and comparative example 1 are shown in Table 3, and it can be seen from Table 3 that the tensile strength of the steel sheet in the above examples is 999-1030 MPa at room temperature; the yield strength of the steel plate is 767-828 MPa; the elongation of the steel plate is 18.5-20%; the yield ratio of the steel plate is 0.77-0.82; the atmospheric corrosion resistance I index is 8.6-9.2; after the heat preservation is carried out for 3 hours at the temperature of 600 ℃, the tensile strength of the steel plate is 590-619 MPa; the yield strength of the steel plate is 485-503 MPa; the elongation of the steel plate is 18.0-19.5%; the impact energy of the steel plate at-40 ℃ is 35-45J. Tensile strength 943MPa for comparative example 1 at room temperature; yield strength 716 MPa; the impact work at-40 ℃ is 33J; after the heat preservation is carried out for 3 hours at the temperature of 600 ℃, the tensile strength is 589 MPa; the yield strength is 455 MPa; therefore, the steel plate in the embodiment of the application has the advantages of good yield strength, tensile strength and low-temperature impact toughness, low yield ratio, good performance after heat preservation at 600 ℃ for 3 hours, and good fire resistance.

TABLE 3 Properties of Steel sheets of examples 1 to 3 and comparative example 1

The metallographic structure results of comparative example 1 and examples 1 to 3 are shown in Table 4, and FIG. 1 is a photograph of the microstructure of example 1 of the present invention; FIG. 2 is an SEM photograph of example 1. As can be seen, the structures of examples 1 to 3 are all structures without carbide (carbide here means cementite) bainite + martensite + residual austenite + a small amount of MC type microalloy carbide precipitated; wherein the average thickness of austenite grains is less than or equal to 20 μm (such as 17-20 μm), the volume fraction of bainite is 40-55% (such as 43-52%), the volume fraction of martensite is 30-50% (such as 37-45%), and the volume fraction of retained austenite is 5-20% (such as 8-11%); the uniform and fine austenite structure is combined with a certain proportion of non-carbide (carbide refers to cementite) bainite, martensite and MC type microalloy carbide, so that the yield strength of the steel can be improved, the low-temperature impact toughness can be improved, and the fire resistance can be obviously improved.

TABLE 4 metallographic structure of steel sheets of examples 1 to 3 and comparative example 1

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims

1. The anti-seismic corrosion-resistant refractory steel is characterized by comprising the following chemical components in percentage by mass: c: 0.06% -0.10%, Si: 0.65% -1.00%, Mn: 0.80% -1.20%, Mo: 0.51% -0.60%, Ni: 1.01% -1.50%, Cr: 0.72% -1.00%, Cu: 0.25-0.40%, Ti: 0.01% -0.03%, Nb: 0.05-0.10%, V: 0.03-0.10%, Al: 0.015% -0.055%, P: < 0.015%, S: < 0.005%, O < 0.003%, N < 0.005%, and the balance Fe and unavoidable impurities; the atmospheric corrosion resistance index I of the anti-seismic corrosion-resistant refractory steel is not less than 4.9; the structure of the shock-resistant, corrosion-resistant and fire-resistant steel is carbide-free bainite, martensite, residual austenite and MC microalloy carbide, wherein the volume fraction of the bainite is 40-55%, the volume fraction of the martensite is 30-50%, the volume fraction of the residual austenite is 5-20%, and the proportion of MC particles with the diameter of less than 20nm is more than 50%.

2. The anti-seismic, corrosion-resistant and fire-resistant steel according to claim 1, wherein the anti-seismic, corrosion-resistant and fire-resistant steel comprises the following components in percentage by mass: c: 0.066% -0.095%, Si: 0.66% -0.95%, Mn: 0.85% -1.18%, Mo: 0.51% -0.60%, Ni: 1.01% -1.47%, Cr: 0.72% -0.93%, Cu: 0.28% -0.38%, Ti: 0.015% -0.028%, Nb: 0.058% -0.096%, V: 0.033 to 0.096%, Al: 0.018-0.052%, P: less than or equal to 0.008 percent, S: less than or equal to 0.003 percent, and the balance of Fe and inevitable impurities.

3. A method of manufacturing a shock resistant, corrosion resistant and fire resistant steel according to claim 1 or 2, characterized in that the method of manufacturing comprises the steps of:

step S1: smelting and casting;

step S2: two-stage controlled rolling is carried out.

4. The method for preparing the shock-resistant, corrosion-resistant and fire-resistant steel according to claim 3, wherein the step S2 comprises the steps of:

and S23, tempering at medium and low temperature after rolling.

5. The method for preparing the anti-seismic, corrosion-resistant and fire-resistant steel according to claim 4, wherein the T1 is 1200-1250 ℃.

6. The method for preparing the anti-seismic, corrosion-resistant and fire-resistant steel according to claim 5, wherein in S22, the rough rolling start rolling temperature is 1150 +/-30 ℃, and the rough rolling finish rolling temperature is 950 +/-30 ℃.

7. The method for preparing earthquake-resistant, corrosion-resistant and fire-resistant steel according to claim 6, wherein the finish rolling temperature in S22 is 830 +/-20 ℃.

8. The method for preparing the shock-resistant, corrosion-resistant and fire-resistant steel according to any one of claims 4 to 7, wherein the post-rolling medium-low temperature tempering step in S23 is as follows: and charging the rolled steel plate at room temperature, heating the furnace to 350-450 ℃, preserving the heat for 30-90 min, and then air-cooling to room temperature.