CN110592484B - 460 MPa-level low-welding-crack-sensitivity refractory steel with excellent low-temperature toughness and production method thereof - Google Patents
460 MPa-level low-welding-crack-sensitivity refractory steel with excellent low-temperature toughness and production method thereof Download PDFInfo
- Publication number
- CN110592484B CN110592484B CN201910983370.4A CN201910983370A CN110592484B CN 110592484 B CN110592484 B CN 110592484B CN 201910983370 A CN201910983370 A CN 201910983370A CN 110592484 B CN110592484 B CN 110592484B
- Authority
- CN
- China
- Prior art keywords
- equal
- less
- percent
- steel
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
The invention relates to 460 MPa-grade low-welding crack sensitivity refractory steel with excellent low-temperature toughness and a production method thereof, wherein the steel contains the following chemical components in percentage by mass: c: 0.020-0.055%, Si: 0.10 to 0.25%, Mn: 1.75-2.25%, P is less than or equal to 0.005%, S is less than or equal to 0.001%, Mo: 0.12-0.24%, W: 0.08-0.20%, Ni: 0.15 to 0.32%, Nb: 0.015-0.045%, Ti: 0.005-0.020%, Zr: 0.0020-0.0045%, Hf: 0.0045 to 0.0075%, [ O ]: 0.0035-0.0075%, [ N ]: 0.0020-0.0040%, and the balance of Fe and inevitable impurities, and the chemical components also need to satisfy the following requirements: firstly, 2Mo +3W is more than or equal to 0.68 percent and less than or equal to 0.86 percent, secondly, 2.01 is more than or equal to (2 Zr + Hf)/[ O ] is more than or equal to 2.36 percent, and thirdly, C, Si/30, Mn/20 and Mo/15 are more than or equal to 0.15 percent and less than or equal to 0.17 percent; the steel has excellent metallurgical quality, and the product produced by the controlled rolling process has high strength, high elongation, low yield ratio, low welding crack sensitivity, excellent low-temperature toughness, excellent fireproof performance and excellent lamellar tearing resistance, and meanwhile, the manufacturing process is simple, the production cost is low, and the large-scale production is easy.
Description
Technical Field
The invention relates to the technical field of steel materials, in particular to 460 MPa-level low-welding crack sensitivity refractory steel with excellent low-temperature toughness and a production method thereof.
Background
With the continuous progress of metallurgical technology, the technical requirements of large engineering projects such as buildings, bridges and the like on high-strength steel are higher and higher, and the requirements on the traditional indexes such as strength, toughness, plasticity and the like are improved, and higher requirements on the seismic performance (low yield ratio), the fire resistance and the welding performance of the steel are also provided. Yield ratio is an ability to resist deformation from yielding to plastically unstable, and low yield ratio is an important characteristic of steel structures from the viewpoint of safety; the fireproof performance is that the yield strength of the steel is required to be not lower than 2/3 of the standard required yield strength value at room temperature at the high temperature of 600 ℃, and the steel with the fireproof performance is adopted, so that the thickness of the fireproof coating can be greatly reduced, and the construction cost and the maintenance cost are reduced. However, the high-strength steel produced by the traditional quenching and tempering process ensures high strength, the yield ratio of the high-strength steel is increased (more than 0.90), the welding performance is poor, the high-strength steel does not have the fire resistance, and obviously, the high-strength steel cannot meet the strict requirements of modern large-scale engineering on the yield ratio, the welding performance and the fire resistance. At present, a large amount of structural steel with high strength, lower yield ratio and fire resistance is needed for the construction of the vigorously developed infrastructure in China, so the construction of large-scale steel structure engineering will gradually increase along with the continuous high-speed development of economy in China, and the development of the structural high-strength steel with fire resistance is one of the development directions.
Prior to the present application, Chinese patent No. 200910061106.1 discloses a high strength low yield ratio welded structural steel and a method for producing the same, wherein the steel must contain high content of noble alloying elements such as Cu, Cr and Ni. The Chinese invention patent with the patent number of 201010599469.3 discloses an 800 MPa-level low-yield-ratio structural steel plate and a production method thereof, the steel must contain more Cu and Ni elements, the alloy cost is high, the elongation rate is low due to the addition of B element, and the yield strength of the steel plate after tempering is low. The invention patent with the patent number OF EP20010930007 discloses 'THICK STEEL PLATE best EXCELLENT IN CTOD CHARACTERISTIC IN WELDING HEAT AFFECTED ZONE AND HAVING YIELD STRENGTH OF 460MPa OR MORE', the steel is produced by adopting a direct quenching and tempering OR TMCP process route, but the strength OF the invented steel is lower. The invention patent number 201310649811.X discloses a low-carbon bainite construction steel with a yield ratio less than 0.8 and a production method thereof, the steel is produced by adopting a TMCP process without heat treatment, but the steel needs to accurately control the ferrite area percentage content in a tissue to be 12-25%, and the production difficulty is high. In addition, the invention patent with the patent number of 201310498628.4 discloses a low-cost high-strength steel plate and a production method thereof, the invention adopts TMCP + tempering process for production, but the yield ratio of the product of the invention is higher than 0.80. Meanwhile, the invention patents do not have fire resistance.
The Chinese invention patents with patent numbers 201110080774.6, 201110247615.0 and 200910045146.7 respectively disclose a low-cost high-strength high-toughness anti-seismic fire-resistant steel and a preparation process thereof, a fire-resistant anti-seismic construction steel, a high-strength high-toughness low-yield-ratio fire-resistant steel and a manufacturing method thereof, but the three invention patents have lower strength level and only require 0 ℃ impact toughness; the invention patent No. 200910011963 discloses a high-performance fire-resistant steel plate for building structure and its manufacturing method, the steel of the invention has the characteristics of simple components, low yield ratio, good fire resistance and the like, but the strength grade is lower.
Therefore, at present, no structural steel which has high strength, high elongation, low yield ratio and fire resistance exists at home and abroad, so that a steel product with the above properties is developed to fill the gap, and the problem to be solved in the industry is urgently needed.
Disclosure of Invention
The invention provides 460 MPa-grade low-welding crack sensitivity refractory steel with excellent low-temperature toughness and a production method thereof, aiming at the problem that no structural steel with high strength, high elongation, low yield ratio and fire resistance exists at home and abroad at present. The steel has excellent metallurgical quality, and the product produced by the controlled rolling process has high strength, high elongation, low yield ratio, low welding crack sensitivity, excellent low-temperature toughness, excellent fireproof performance and excellent lamellar tearing resistance, and meanwhile, the manufacturing process is simple, the production cost is low, and the large-scale production is easy.
The 460 MPa-grade low-welding crack sensitivity refractory steel with excellent low-temperature toughness contains the following chemical components in percentage by mass: c: 0.020-0.055%, Si: 0.10 to 0.25%, Mn: 1.75-2.25%, P is less than or equal to 0.005%, S is less than or equal to 0.001%, Mo: 0.12-0.24%, W: 0.08-0.20%, Ni: 0.15 to 0.32%, Nb: 0.015-0.045%, Ti: 0.005-0.020%, Zr: 0.0020-0.0045%, Hf: 0.0045 to 0.0075%, [ O ]: 0.0035-0.0075%, [ N ]: 0.0020-0.0040%, and the balance of Fe and inevitable impurities, and the chemical components also need to satisfy the following requirements: firstly, 2Mo +3W is more than or equal to 0.68 percent and less than or equal to 0.86 percent, secondly, 2.01 is more than or equal to (2 Zr + Hf)/[ O ] is more than or equal to 2.36 percent, and thirdly, C, Si/30, Mn/20 and Mo/15 are more than or equal to 0.15 percent and less than or equal to 0.17 percent.
Preferably, the 460 MPa-grade low-welding crack sensitivity refractory steel with excellent low-temperature toughness contains the following chemical components in percentage by mass: c: 0.028-0.048%, Si: 0.12 to 0.23%, Mn: 1.87-2.20%, P is less than or equal to 0.005%, S is less than or equal to 0.001%, Mo: 0.14 to 0.22%, W: 0.10 to 0.18%, Ni: 0.18-0.30%, Nb: 0.019-0.041%, Ti: 0.007-0.018%, Zr: 0.0023-0.0043%, Hf: 0.0048-0.0071%, [ O ]: 0.0041 to 0.0071%, [ N ]: 0.0022-0.0038%, and the balance of Fe and inevitable impurities, wherein the chemical components also need to satisfy the following requirements: 0.75 percent to less than or equal to 2Mo +3W to less than or equal to 0.82 percent, 2.211 percent to less than or equal to (2 Zr + Hf)/[ O ] to less than or equal to 2.292 percent, and 0.154 percent to less than or equal to C + Si/30+ Mn/20+ Mo/15 to less than or equal to 0.159 percent.
Most preferably, the 460 MPa-grade low-welding crack sensitivity refractory steel with excellent low-temperature toughness contains the following chemical components in percentage by mass: c: 0.040%, Si: 0.20%, Mn: 1.93%, P is less than or equal to 0.0006%, S is less than or equal to 0.0007%, Mo: 0.18%, W: 0.16%, Ni: 0.24%, Nb: 0.028%, Ti: 0.014%, Zr: 0.0035%, Hf: 0.0062%, [ O ]: 0.0061%, [ N ]: 0.0032 percent, and the balance of Fe and inevitable impurities, and the chemical components also have the following requirements: (iii) 2Mo +3W =0.84%, (2 Zr + Hf)/[ O ] =2.164, and (C + Si/30+ Mn/20+ Mo/15= 0.159%.
The steel plate yield strength R in the inventioneL490 to 540MPa, tensile strength Rm620 to 700MPa, and a yield ratio ReL/Rm0.72-0.78, and 30.0-38.0% of elongation A; yield strength R at 600 DEG CP0.2380-430 MPa, yield strength R at 600 DEG CP0.2And normal temperature yield strength ReLThe ratio of (A) to (B) is 0.75-0.86 KV at-60 deg.C2≥280J。
The invention relates to a production method of 460 MPa-level low-welding crack sensitivity refractory steel with excellent low-temperature toughness, which comprises the following steps: the process comprises the following main process steps of converter smelting, RH vacuum treatment, continuous casting, casting blank heating, controlled rolling and laminar cooling, wherein the process comprises the following steps:
(1) smelting in a converter: and C, smelting end point control: 0.05-0.08 percent of P and less than or equal to 0.010 percent of P;
(2) RH vacuum treatment: adding Zr and Hf alloy, controlling Zr: 0.0020-0.0045%, Hf: 0.0045-0.0075%, and meets the requirements that (2 Zr + Hf)/[ O ] is less than or equal to 2.36, and the vacuum treatment time is 20-30 min;
(3) heating a casting blank: heating the casting blank to 1220-1250 ℃ at a heating rate of 9-11 min/cm, and preserving heat for 25-35 min within the range of 1200-1230 ℃, wherein the tapping temperature is controlled to 1120-1150 ℃;
(4) controlling rolling: the rolling comprises I-stage rough rolling and II-stage finish rolling, wherein the initial rolling temperature of the I-stage rough rolling is controlled to be 1050-1100 ℃, the single-pass reduction rate is controlled to be 12-20%, the total reduction rate is controlled to be 60-70%, the termination temperature is controlled to be 1020-1050 ℃, and then the rolling is air-cooled to the initial rolling temperature of the II-stage finish rolling; the initial rolling temperature of the finish rolling in the stage II is 1000-2.5h, the final rolling temperature is 880-h/2℃, the cumulative reduction rate of the last three times is 35-45%, and the reduction rate of the last time is controlled to be 10-15%. Wherein h is the finished product thickness value in mm;
(5) laminar cooling: and carrying out laminar cooling on the steel plate, controlling the cooling starting temperature to be (780 + h/2) ° C, controlling the cooling speed to be 5-10 ℃/s, controlling the cooling re-reddening temperature to be 450-570 ℃, and finally carrying out air cooling to the room temperature, wherein h is the thickness value of the finished product in mm.
The reason for limiting the amount of each chemical component in the present invention is as follows:
the content of C is selected to be 0.020-0.055%, and C is one of essential elements for ensuring the strength. However, too high C content tends to cause carbon segregation, improve low weld crack sensitivity, deteriorate low temperature toughness and weldability of steel, and affect cold and hot workability of steel. The C content is too low, which leads to insufficient strength and improved yield ratio of the steel, so that the C content is limited to 0.020-0.055%.
The Si content is selected to be 0.10-0.25%, the Si mainly plays roles of solid solution strengthening and deoxidation, but is not beneficial to low-temperature toughness and welding performance, so the Si content is limited to be 0.10-0.25%.
The Mn content of the invention is selected to be 1.75-2.25%, and a proper amount of Mn can refine the structure, improve the strength and improve the low-temperature toughness. When the Mn content is less than 1.75%, the strength of the steel is insufficient; when the Mn content is higher than 2.25%, the binding force of iron atoms is weakened during heating, the self-diffusion of the iron atoms is accelerated, and the growth of austenite grains is promoted, which are not favorable for low-temperature toughness and welding performance, so that the Mn content is limited to 1.75-2.25%.
P is less than or equal to 0.005 percent, S is less than or equal to 0.001 percent, and P, S is a harmful impurity element in steel. P is easy to cause segregation, influences the uniformity of the structure and reduces the low-temperature toughness; and S and Mn are easy to form coarse MnS inclusions, which are very unfavorable for low-temperature toughness.
The content of Mo is selected to be 0.12-0.24%, a proper amount of Mo has remarkable effects of solid solution strengthening and yield ratio reduction, the proper amount of Mo not only promotes formation of high-density dislocation substructure bainite to generate structure strengthening, but also can form carbide to improve room temperature and high temperature strength, and can promote precipitation of fine Nb carbonitrides, and the carbonitrides have higher stability at high temperature, so that the refractory performance is improved. However, the Mo content is limited to 0.08-0.25% because the martensite is easily obtained in the processes of rapid laminar cooling and welding cooling after rolling, the low welding crack sensitivity is increased, and the welding crack generation tendency is improved.
The content of W in the invention is selected to be 0.08-0.20%, and the main effect of W is solid solution strengthening effect as same as Mo. W in the steel can exist in a carbide form, and the high-temperature stability of the steel is better, so that the high-temperature performance is improved. However, too high W is not favorable for low-temperature toughness and weldability, so the W content is limited to 0.08 to 0.20%.
The Ni content of the invention is selected to be 0.15-0.32%, and Ni is not obvious to improve the strength of steel, but can obviously improve the low-temperature toughness and heat resistance. However, since the Ni content is too high, scale which is not easily peeled off is easily generated on the surface of the steel sheet, and the surface quality of the steel is seriously deteriorated, the Ni content is limited to 0.15 to 0.32%.
The content of Nb is selected to be 0.015-0.045%, Nb belongs to a strong carbide forming element, carbonitride particles of Nb can effectively inhibit austenite grains from growing large, grains are refined through pinning, and toughness and ductility are improved. In the invention, another important function of Nb is to promote the precipitation of Nb carbonitride with better high-temperature stability by the combined action of Nb and Mo, thereby improving the refractory property. Nb can also obviously improve the austenite recrystallization temperature, expand the rolling process range, ensure that the invention can roll at higher temperature without mixed crystals and ensure good toughness matching of steel. When the content of Nb is less than 0.015%, the above-mentioned effects of Nb cannot be guaranteed, and when the content of Nb is more than 0.045%, not only is the yield ratio easily increased, but also M/a islands in the welding heat affected zone are easily caused, which is not favorable for welding performance.
The Ti is selected to be 0.005-0.020%, and is also a strong carbonitride forming element, so that the fine grain strengthening and precipitation strengthening effects are achieved. The TiN nitride particles of Ti can separate out nano-scale composite particles by taking superfine HfO2 particles as cores, effectively prevent austenite grains from growing in the heating and welding processes, and improve the toughness. However, when the Ti content is more than 0.020%, the size of the precipitated composite particles is only in the micron order, the effect of improving the toughness is not obvious, and when the Ti content is less than 0.005%, the number of particles in a unit area is insufficient, the effect cannot be achieved, so that the Ti content is limited to 0.005-0.020%.
The Zr content of the invention is controlled to be 0.0020-0.0045%. Zr is one of important elements in the invention, besides modifying and spheroidizing MnS inclusion to improve low-temperature toughness and HAZ toughness, a proper amount of Zr has important functions in the invention to combine with [ O ] and [ N ] to form Zr oxide and nitride, so as to play roles of grain refinement and precipitation strengthening, reduce low welding crack sensitivity, improve toughness and improve welding performance. Therefore, the Zr content should not be less than 0.0020%; when the Zr content exceeds 0.0045%, large-sized Zr-containing oxide and sulfide complex inclusions are formed, which are not favorable for impact toughness of the base material and the heat affected zone.
The Hf content of the catalyst is controlled to be 0.0045-0.0075%. Hf element is also important element in the present invention, and can form superfine oxide HfO with O2The particles not only have the function of high temperature resistance, but also have the function of metamorphism and spheroidization for MnS inclusions so as to improve the low-temperature toughness and HAZ toughness, and simultaneously can be used as nucleation cores of TiN and acicular ferrite to refine the grain size, improve the low-temperature toughness and improve the welding performance. Therefore, in order to ensure the above-mentioned function of Hf, if the content of Hf is not less than 0.0045%, and if the content of Hf exceeds 0.0075%, Hf-containing complex oxide-based inclusions with a large size are formed, which is disadvantageous for improvement of ductility and workability. Therefore, the Hf content is limited to 0.0045 to 0.0075%.
The content of O in the steel is selected to be 0.0035-0.0075%, and in general, O belongs to harmful gas in steel, and the content of O needs to be strictly limited to a lower level in order to ensure the purity of steel and the total amount of oxide impurities in the steel. However, when the O content is less than 0.0035%, the number of fine Zr and Hf oxide particles having a nucleation core per unit area in the steel is insufficient. In order to avoid the occurrence of excessive oxide-type large-size composite inclusions in the steel, the upper limit of the content of O in the steel is limited to be within 0.0075%.
The content of N is selected to be 0.0020-0.0040%, and N forms nitride or carbonitride with Nb, Ti, C and other elements in steel, and is an important element for refining the grains of a steel base material structure and a welding structure. If the N content is less than 0.0020%, the number of nitride particles formed by N and Ti and Zr in the steel is insufficient, and the base material and the welded structure cannot be effectively refined. When the content of N is more than 0.0040%, the amount of N dissolved in steel increases, which is not favorable for toughness and surface quality of steel billets.
Meanwhile, the chemical components also have to meet the following requirements: firstly, 2Mo +3W is more than or equal to 0.68 percent and less than or equal to 0.86 percent, secondly, 2.01 is more than or equal to (2 Zr + Hf)/[ O ] is more than or equal to 2.36 percent, and thirdly, C, Si/30, Mn/20 and Mo/15 are more than or equal to 0.15 percent and less than or equal to 0.17 percent.
In the steel, when the 2Mo +3W is less than 0.68%, the room temperature and high temperature strength of the steel cannot be guaranteed, and when the 2Mo +3W is more than 0.86%, the low temperature toughness of the steel can be deteriorated; when (2 Zr + Hf)/[ O ] < 2.01, the metamorphic spheroidization of MnS inclusion by Zr and Hf is not obvious, the number of fine oxide particles of Zr and Hf which are taken as nucleation cores in unit area is not enough, and when (2 Zr + Hf)/[ O ] > 2.36, a large amount of oxide and sulfide composite inclusion with larger size can be formed, thus being not beneficial to the performance of steel; in order to ensure the strength and the welding performance, the alloy also needs to meet the requirement that C is more than or equal to 0.15 percent and less than or equal to 0.17 percent and more than or equal to 30 percent and Mn is more than or equal to 20 percent and Mo is less than or equal to 15 percent.
The steel of the present invention contains the above chemical components, and the balance of Fe and inevitable impurities.
In the production method, various process parameters in the process steps are obtained by combining a large amount of experimental research with performance analysis, repeatedly adjusting and testing and verifying, wherein:
in order to accurately control the Zr content and the Hf content and ensure that the Zr content and the Hf content can play an important role, the Zr content and the Hf content are added into an RH furnace, and the Zr content: 0.0020-0.0045%, Hf: 0.0045-0.0075%, and satisfies (2 Zr + Hf)/[ O ] less than or equal to 2.01 and less than or equal to 2.36, and simultaneously, the vacuum treatment time is controlled within 20-30 min in order to ensure the performances of steel purity, low-temperature toughness, lamellar tearing resistance and the like.
In order to promote the Mo, W and other alloys to be fully dissolved in austenite, ensure that the temperature of each part of a billet is fully uniform, and take the problems of energy consumption, production rhythm and the like into consideration, the heating rate, the heating temperature, the heat preservation temperature and the heat preservation time of a casting blank into consideration, and under the process parameters, the Zr and Hf fine oxide particles can be promoted to be fully separated out so as to play the role of preventing the austenite grains from growing as much as possible.
The rolling process requires that the process parameters such as rolling pass reduction, initial rolling temperature, termination temperature, initial cooling temperature, cooling rate and the like of each stage are limited. The invention has a two-phase structure of bainite and (quasi-) polygonal ferrite with proper proportion, and can ensure excellent toughness matching and low yield ratio. Therefore, the invention is particularly important for controlling the laminar cooling starting temperature and the re-reddening temperature of finished products with different thicknesses, otherwise, a bainite and ferrite dual-phase structure with a reasonable proportion cannot be obtained. More importantly, under the cooling process parameters, uniformly distributed M/A islands with the equivalent size of nanometer level can be obtained, the interface strength of the small-sized M/A islands and the matrix is very high, the separation of the M/A islands and the matrix is delayed strongly during cold deformation, and the lower yield ratio and the excellent plastic property (elongation rate) are ensured.
The invention has the following advantages:
1. the steel has high strength and toughness, high extensibility, low yield ratio and excellent fire resistance;
2. the steel has lower welding crack sensitivity, and does not need preheating and heat treatment after welding, thereby greatly improving the welding efficiency;
3. the steel has the advantages of low cost, simple manufacturing procedure and the like, and can be implemented in various metallurgical enterprises.
Detailed Description
In order to better explain the technical solution of the present invention, the technical solution of the present invention is further described below with reference to specific examples, which are only exemplary to illustrate the technical solution of the present invention and do not limit the present invention in any way.
The following table 1 is a list of chemical components contained in the steel plates according to the examples of the present invention in percentage by mass;
the following table 2 is a value list of main process parameters of the steel plate according to each embodiment of the invention;
table 3 below shows the mechanical property test results of the examples of the present invention.
The following examples are 9 batches of steel which are smelted and rolled according to the requirements of the chemical components and the production process of the steel of the invention, and respectively correspond to examples 1 to 9, wherein the thicknesses of examples 1 to 3 are 24mm, the thicknesses of examples 4 to 6 are 48mm, and the thicknesses of examples 7 to 9 are 72 mm.
The invention relates to a production method of 460 MPa-level low-welding crack sensitivity refractory steel with excellent low-temperature toughness, which comprises the following steps: the process comprises the following main process steps of converter smelting, RH vacuum treatment, continuous casting, casting blank heating, controlled rolling and laminar cooling, wherein the process comprises the following steps:
(1) smelting in a converter: and C, smelting end point control: 0.05-0.08 percent of P and less than or equal to 0.010 percent of P;
(2) RH vacuum treatment: adding Zr and Hf alloy, controlling Zr: 0.0020-0.0045%, Hf: 0.0045-0.0075%, and meets the requirements that (2 Zr + Hf)/[ O ] is less than or equal to 2.36, and the vacuum treatment time is 20-30 min;
(3) heating a casting blank: heating the casting blank to 1220-1250 ℃ at a heating rate of 9-11 min/cm, and preserving heat for 25-35 min within the range of 1200-1230 ℃, wherein the tapping temperature is controlled to 1120-1150 ℃;
(4) controlling rolling: the rolling comprises I-stage rough rolling and II-stage finish rolling, wherein the initial rolling temperature of the I-stage rough rolling is controlled to be 1050-1100 ℃, the single-pass reduction rate is controlled to be 12-20%, the total reduction rate is controlled to be 60-70%, the termination temperature is controlled to be 1020-1050 ℃, and then the rolling is air-cooled to the initial rolling temperature of the II-stage finish rolling; the initial rolling temperature of the finish rolling in the stage II is 1000-2.5h, the final rolling temperature is 880-h/2℃, the cumulative reduction rate of the last three times is 35-45%, and the reduction rate of the last time is controlled to be 10-15%. Wherein h is the finished product thickness value in mm;
(5) laminar cooling: and carrying out laminar cooling on the steel plate, controlling the cooling starting temperature to be (780 + h/2) ° C, controlling the cooling speed to be 5-10 ℃/s, controlling the cooling re-reddening temperature to be 450-570 ℃, and finally carrying out air cooling to the room temperature, wherein h is the thickness value of the finished product in mm.
TABLE 1 tabulation of the mass percentage of chemical components contained in steel sheets of each example of the present invention
Table 2 list of values of main process parameters of steel plates according to various embodiments of the present invention
TABLE 3 mechanical Property test results of the examples of the present invention
(Note: Steel grade fire resistance is evaluated by 2/3 having a yield strength of 600 ℃ C. not lower than room temperature.)
As can be seen from Table 3 above, the results of the room temperature and high temperature tensile properties-60 ℃ impact property tests on the steel sheet of the present invention show: examples 1 to 9 of the present invention yield Strength ReL501-515 MPa, tensile strength Rm652 to 682MPa, and a yield ratio ReL/Rm0.745-0.776, elongation A of 32.5-35.0%, and yield strength R at 600 deg.CP0.2Is 401 to 412MPa, and has a yield strength R at 600 DEG CP0.2And normal temperature yield strength ReLThe ratio of (A) to (B) is 0.796-0.827 KV at-60 deg.C2300-321J, it can be seen that the steel of the present invention has high strength, high ductility and toughness, low yield ratio and excellent fire resistance, and through a large number of test verifications and production tests, in combination with the test results of Table 1, Table 2 and Table 3, example 6 is the best example of the present invention.
Claims (4)
1. A460 MPa-grade low-welding crack sensitivity refractory steel with excellent low-temperature toughness is characterized in that: the steel comprises the following chemical components in percentage by mass: c: 0.020-0.055%, Si: 0.10 to 0.25%, Mn: 1.75-2.25%, P is less than or equal to 0.005%, S is less than or equal to 0.001%, Mo: 0.12-0.24%, W: 0.08-0.20%, Ni: 0.15 to 0.32%, Nb: 0.015-0.045%, Ti: 0.005-0.020%, Zr: 0.0027-0.0045%, Hf: 0.0045-0.0075%, [ O ]]：0.0035～0.0075%，[N]: 0.0020-0.0040%, and the balance of Fe and inevitable impurities, and the chemical components also need to satisfy the following requirements: 0.68 percent to less than or equal to 2Mo +3W to less than or equal to 0.86 percent, 2.01 percent to less than or equal to (2 Zr + Hf)/[ O ]]Not more than 2.36 percent, and not more than 0.15 percent and not more than 0.17 percent of C, Si/30, Mn/20 and Mo/15; yield strength R of the steeleL490 to 540MPa, tensile strength Rm620 to 700MPa, and a yield ratio ReL/Rm0.72-0.78, and 30.0-38.0% of elongation A; yield strength R at 600 DEG CP0.2380-430 MPa, yield strength R at 600 DEG CP0.2And normal temperature yield strength ReLThe ratio of (A) to (B) is 0.75-0.86 KV at-60 deg.C2≥280J。
2. The 460MPa grade low weld crack sensitivity refractory steel with excellent low temperature toughness according to claim 1, characterized in that: the steel comprises the following chemical components in percentage by mass: c: 0.028-0.048%, Si: 0.12 to 0.23%, Mn: 1.87-2.20%, P is less than or equal to 0.005%, S is less than or equal to 0.001%, Mo: 0.14 to 0.22%, W: 0.10 to 0.18%, Ni: 0.18-0.30%, Nb: 0.019-0.041%, Ti: 0.007-0.018%, Zr: 0.0027-0.0043%, Hf: 0.0048-0.0071%, [ O ]: 0.0041 to 0.0071%, [ N ]: 0.0022-0.0038%, and the balance of Fe and inevitable impurities, wherein the chemical components also need to satisfy the following requirements: 0.75 percent to less than or equal to 2Mo +3W to less than or equal to 0.82 percent, 2.211 percent to less than or equal to (2 Zr + Hf)/[ O ] to less than or equal to 2.292 percent, and 0.154 percent to less than or equal to C + Si/30+ Mn/20+ Mo/15 to less than or equal to 0.159 percent.
3. The 460MPa grade low weld crack sensitivity refractory steel with excellent low temperature toughness according to claim 1, characterized in that: the steel comprises the following chemical components in percentage by mass: c: 0.040%, Si: 0.20%, Mn: 1.93%, P is less than or equal to 0.0006%, S is less than or equal to 0.0007%, Mo: 0.18%, W: 0.16%, Ni: 0.24%, Nb: 0.028%, Ti: 0.014%, Zr: 0.0035%, Hf: 0.0062%, [ O ]: 0.0061%, [ N ]: 0.0032 percent, and the balance of Fe and inevitable impurities, and the chemical components also have the following requirements: (iii) 2Mo +3W =0.84%, (2 Zr + Hf)/[ O ] =2.164, and (C + Si/30+ Mn/20+ Mo/15= 0.155%.
4. A method for producing a 460MPa grade low weld crack susceptibility refractory steel excellent in low temperature toughness as claimed in claim 1, 2 or 3, comprising: the converter smelting-RH vacuum treatment-continuous casting-casting blank heating-controlled rolling-laminar cooling process is characterized in that:
(1) smelting in a converter: and C, smelting end point control: 0.05-0.08 percent of P and less than or equal to 0.010 percent of P;
(2) RH vacuum treatment: adding Zr and Hf alloy, controlling Zr: 0.0020-0.0045%, Hf: 0.0045-0.0075%, and meets the requirements that (2 Zr + Hf)/[ O ] is less than or equal to 2.36, and the vacuum treatment time is 20-30 min;
(3) heating a casting blank: heating the casting blank to 1220-1250 ℃ at a heating rate of 9-11 min/cm, and preserving heat for 25-35 min at 1200-1230 ℃, wherein the tapping temperature is controlled at 1120-1145 ℃;
(4) controlling rolling: the rolling comprises I-stage rough rolling and II-stage finish rolling, wherein the initial rolling temperature of the I-stage rough rolling is controlled to be 1050-1090 ℃, the single-pass reduction rate is controlled to be 12-20%, the total reduction rate is controlled to be 60-70%, the termination temperature is controlled to be 1020-1050 ℃, and then the rolling is air-cooled to the initial rolling temperature of the II-stage finish rolling; the initial rolling temperature of the finish rolling in the stage II is (1000-2.5 h) ° C, the final rolling temperature is (880-h/2) ° C, the cumulative reduction rate of the last three times is 35-45%, and the reduction rate of the last time is controlled to be 10-15%, wherein h is the thickness value of the finished product in mm;
(5) laminar cooling: and carrying out laminar cooling on the steel plate, controlling the cooling starting temperature to be (780 + h/2) ° C, controlling the cooling speed to be 5-10 ℃/s, controlling the cooling re-reddening temperature to be 450-570 ℃, and finally carrying out air cooling to the room temperature, wherein h is the thickness value of the finished product in mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910983370.4A CN110592484B (en) | 2019-10-16 | 2019-10-16 | 460 MPa-level low-welding-crack-sensitivity refractory steel with excellent low-temperature toughness and production method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910983370.4A CN110592484B (en) | 2019-10-16 | 2019-10-16 | 460 MPa-level low-welding-crack-sensitivity refractory steel with excellent low-temperature toughness and production method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110592484A CN110592484A (en) | 2019-12-20 |
| CN110592484B true CN110592484B (en) | 2021-02-26 |
Family
ID=68867572
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910983370.4A Active CN110592484B (en) | 2019-10-16 | 2019-10-16 | 460 MPa-level low-welding-crack-sensitivity refractory steel with excellent low-temperature toughness and production method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110592484B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115094326B (en) * | 2022-07-05 | 2023-08-11 | 马鞍山钢铁股份有限公司 | High-resistance Wen Lengdui steel and heat treatment method, production method and application thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013224460A (en) * | 2012-04-20 | 2013-10-31 | Nippon Steel & Sumitomo Metal Corp | Fire-resistant steel material and method for producing the same |
| CN104775078A (en) * | 2015-03-13 | 2015-07-15 | 武汉钢铁(集团)公司 | Low yield ratio steel (Rel>620MPa) for fireproof structure and production method thereof |
| CN106854732A (en) * | 2016-12-13 | 2017-06-16 | 武汉钢铁股份有限公司 | The high tenacity low-yield-ratio fire resistant weathering steel and its production method of tensile strength >=600MPa |
| CN109055858A (en) * | 2018-08-31 | 2018-12-21 | 武汉钢铁有限公司 | A kind of the welding structure fire-resistant and weather-resistant steel and its production method of yield strength >=620MPa |
| CN110306114A (en) * | 2019-07-26 | 2019-10-08 | 武汉钢铁有限公司 | A kind of yield strength is 460MPa grades of anti-corrosion fireproof construction steel and production method |
-
2019
- 2019-10-16 CN CN201910983370.4A patent/CN110592484B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013224460A (en) * | 2012-04-20 | 2013-10-31 | Nippon Steel & Sumitomo Metal Corp | Fire-resistant steel material and method for producing the same |
| CN104775078A (en) * | 2015-03-13 | 2015-07-15 | 武汉钢铁(集团)公司 | Low yield ratio steel (Rel>620MPa) for fireproof structure and production method thereof |
| CN106854732A (en) * | 2016-12-13 | 2017-06-16 | 武汉钢铁股份有限公司 | The high tenacity low-yield-ratio fire resistant weathering steel and its production method of tensile strength >=600MPa |
| CN109055858A (en) * | 2018-08-31 | 2018-12-21 | 武汉钢铁有限公司 | A kind of the welding structure fire-resistant and weather-resistant steel and its production method of yield strength >=620MPa |
| CN110306114A (en) * | 2019-07-26 | 2019-10-08 | 武汉钢铁有限公司 | A kind of yield strength is 460MPa grades of anti-corrosion fireproof construction steel and production method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110592484A (en) | 2019-12-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109628836B (en) | High-strength anti-seismic fire-resistant steel for building structure and preparation method thereof | |
| CN106854732B (en) | The high tenacity low-yield-ratio fire resistant weathering steel and its production method of tensile strength >=600MPa | |
| CN110306114B (en) | Corrosion-resistant and fire-resistant structural steel with yield strength of 460MPa and production method thereof | |
| CN113234995B (en) | Ultra-thick hot-rolled H-shaped steel with yield strength of 600MPa and production method thereof | |
| CN109536846B (en) | High-toughness hot-rolled steel plate with yield strength of 700MPa and manufacturing method thereof | |
| CN110306111A (en) | A kind of thick steel plates and its manufacturing method | |
| WO2014015822A1 (en) | Glass-enameling high-strength steel plate and manufacturing method therefor | |
| CN107964624A (en) | A kind of yield strength 500MPa level structure steel and preparation method thereof | |
| CN107686943B (en) | 370 MPa-yield-strength rare earth weather-resistant bridge steel plate and preparation method thereof | |
| CN104178697B (en) | A kind of high-temperature resistant anti-shock reinforcing bar and production method thereof | |
| CN108796370A (en) | A kind of the welding structure fire-resistant and weather-resistant steel and its production method of yield strength >=690MPa | |
| CN106756567A (en) | A kind of preparation method of the hot rolling low density steel of strength and ductility product >=40GPa% | |
| CN114807772B (en) | Aging-strengthened high-strength high-toughness light steel and manufacturing method thereof | |
| CN110592491B (en) | High-wear-resistance martensite/austenite dual-phase wear-resistant steel plate and manufacturing method thereof | |
| JP2017197787A (en) | High tensile strength thick steel sheet excellent in ductility and manufacturing method therefor | |
| CN108754335B (en) | A kind of the welding structure fire-resistant and weather-resistant steel and production method of yield strength >=550MPa | |
| CN108914005B (en) | Super-thick corrosion-resistant steel plate with yield strength larger than 460MPa and excellent low-temperature toughness and production method thereof | |
| CN104775078B (en) | The low-yield-ratio fire resistant structural steel and production method of a kind of Rel ＞ 620MPa | |
| CN109943771B (en) | High-toughness weldable steel plate with fine grain structure and production method thereof | |
| CN110592484B (en) | 460 MPa-level low-welding-crack-sensitivity refractory steel with excellent low-temperature toughness and production method thereof | |
| CN105112810B (en) | Steel for high heat input resisting welding and preparation method thereof | |
| CN104451445B (en) | High-strength non-hardened and non-tempered steel for welded structures and production technology thereof | |
| CN111321340A (en) | Hot rolled steel plate with yield strength of 450MPa and manufacturing method thereof | |
| CN109055858A (en) | A kind of the welding structure fire-resistant and weather-resistant steel and its production method of yield strength >=620MPa | |
| CN112593155B (en) | Anti-seismic, fire-resistant and weather-resistant steel plate for high-strength building structure and preparation method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| CB02 | Change of applicant information |
Address after: No. 215, Wuchang Avenue, Hubei, Ezhou, Hubei Applicant after: Baowu group Echeng Iron and Steel Co., Ltd Address before: No. 215, Wuchang Avenue, Hubei, Ezhou, Hubei Applicant before: WUHAN IRON AND STEEL GROUP ECHENG IRON AND STEEL Co.,Ltd. |
|
| CB02 | Change of applicant information | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |