CN112981257B - Economical thick-wall high-strength high-toughness X70M hot-rolled steel plate and manufacturing method thereof - Google Patents
Economical thick-wall high-strength high-toughness X70M hot-rolled steel plate and manufacturing method thereof Download PDFInfo
- Publication number
- CN112981257B CN112981257B CN202110176162.0A CN202110176162A CN112981257B CN 112981257 B CN112981257 B CN 112981257B CN 202110176162 A CN202110176162 A CN 202110176162A CN 112981257 B CN112981257 B CN 112981257B
- Authority
- CN
- China
- Prior art keywords
- rolling
- temperature
- passes
- stage
- less
- 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
- 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
- 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
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
-
- 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
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
-
- 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
- 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
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
-
- 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
- C22C38/04—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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with 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 an economical thick-wall high-strength and high-toughness X70M hot-rolled steel plate and a manufacturing method thereof, wherein the steel plate comprises the following chemical components in percentage by weight: 0.045-0.09% of C, 0.10-0.35% of Si, 1.50-1.85% of Mn, less than or equal to 0.01% of P, less than or equal to 0.015% of S, 0.04-0.09% of Nb, 0.008-0.0250% of Ti, 0.015-0.045% of Al, 0.25-0.5% of Cr, 0.15-0.55% of Cu, 0.02-0.04% of Zr, 0.0041-0.006% of N, and the balance of Fe and inevitable impurities; the steel plate is suitable for manufacturing the steel plate with the pipe diameter of
Description
Technical Field
The invention relates to the technical field of low-carbon microalloyed steel production, in particular to an economical thick-wall high-strength high-toughness X70M hot-rolled steel plate and a manufacturing method thereof.
Background
Pipeline transportation is the most economical, most convenient and most important transportation mode for transporting oil and gas in long distance. The thick-specification pipeline pipe is mainly used in special requirements and severe environment areas such as large-volume oil and gas pipelines and pipelines passing through earthquake zones. With the development requirements of oil and gas resource exploitation from inland to polar region, from land to sea, from shallow sea to deep sea and large transportation volume of pipeline transportation, the thick-wall pipeline pipe with large caliber is widely applied to oil and gas pipeline construction and has good application prospect.
In order to improve the operation safety and the conveying capacity of submarine pipelines and land pipelines and reduce the maintenance cost, a thick-wall high-toughness welded pipe needs to be adopted under the condition of keeping the steel grade unchanged, and the requirements of wide width, thick specification and high toughness are provided for pipeline steel. Therefore, the wide and thick pipeline steel becomes a key product for future application, and the development difficulty of the wide and thick pipeline steel mainly lies in how to ensure the strength and the low-temperature toughness of the wide and full-wall-thickness X70M pipeline steel, especially the DWTT (drop weight tear test) performance.
To be manufactured
The width of the steel plate of the caliber steel pipe is required to be larger than 4465mm, and the width of the steel plate before trimming is not cut is at least ensured to be more than 4605 mm. However, the difficulty of rolling increases greatly with the increase in width and thickness of the X70M steel sheet. Firstly, the load of a rolling mill, the temperature uniformity of a steel plate, the shape control and the like face severe examination; secondly, the improvement of the steel plate performance mainly depends on the contents of impurities such as phosphorus, sulfur and the like in the steel, the contents of alloy elements in the steel and the control of key process parameters in the production processes such as smelting, rolling and the like. The method for solving the problems in the prior art is as follows: the performance of wide and thick pipeline steel is ensured by improving the equipment capacity (such as increasing the thickness of a continuous casting billet and ensuring a large compression ratio), or the uniformity of the performance of a steel plate is improved by processes such as online heat treatment and the like, and the equipment cost input and the production cost are greatly increased. Therefore, how to solve the above problemsThe production problem can be solved, and the production cost of the pipeline steel can be reduced, so that the method is a key for researching and developing the thick and wide X70M pipeline steel science and technology.
Chinese patent with publication number CN104264069B discloses 'extra-thick X70 pipeline steel and a manufacturing method thereof', wherein the thickness of the pipeline steel is 30-32 mm, the chemical components comprise, by mass, 0.03-0.06% of C, 0.1-0.30% of Si, 1.30-1.60% of Mn, less than or equal to 0.010% of P, less than or equal to 0.0050% of S, 0.030-0.050% of Nb, 0.008-0.020% of Ti, 0.10-0.30% of Ni, 0.10-0.30% of Cr and 0.10-0.30% of Cu. In order to provide the steel plate with the pipeline steel with high strength, excellent low-temperature toughness and excellent HIC resistance, the proposal adds noble metal elements such as Ni and Cu in the component design, so the alloy cost is high, and only the X70 pipeline steel with the thickness specification of 30-32 mm is produced, namely, the production thickness specification range is narrow, the production cost is high, and the width of the steel plate is not clear.
Chinese patent with publication No. CN102277530B discloses 'pipeline steel with thickness more than or equal to 25mm for deep sea and manufacturing method thereof', wherein the main elements and contents thereof are C0.025-0.080%, Si 0.05-0.50%, Mn 1.20-1.60%, Mo 0.05-0.30%, Nb 0.03-0.06%, Ni less than or equal to 0.30%, Cr less than or equal to 0.30%, Cu less than or equal to 0.08%, and V less than or equal to 0.05%. In order to enable the steel plate to have the characteristic of high strain, the technical scheme adds noble metal elements such as Mo, Ni and V in the component design, so that the alloy cost is high; two relaxation stages are needed in the production process, so that the process complexity and the production cost are increased, and the characteristic of low cost is not achieved.
Chinese patent with publication number CN103846277B discloses a production method for improving the low-temperature crack arrest toughness of submarine pipeline steel, wherein the thickness specification of the submarine pipeline steel is 25.4-31.8 mm. The method requires that the reduction rate of longitudinal rolling passes of rough rolling is gradually increased, the reduction rate of a single pass is 15-32%, the reduction of the last 2 passes is 25-32%, the load of a rolling mill is large, the cooling of a rolled steel plate adopts an ultra-fast cooling and laminar cooling process, the temperature range of cooling water is required to be controlled to be 10-16 ℃, and the cooling condition is very harsh; and the steel plates after final cooling need to be stacked and slowly cooled for 12-20 h, so that the production efficiency is low, the working procedures are complex, and the production cost is high.
The production width of X70M mentioned in journal paper 'Rolling technology research of ultra-wide pipeline steel X70M' (Wide and Thick plate 2010.1) is 3830mm, DWTT performance is not guaranteed, typical chemical components of the steel usually adopt C-Mn-Mo-Nb system, a gamma phase region is enlarged mainly by adding Mo, the transformation temperature of gamma-alpha is reduced, and the formation of acicular ferrite is promoted. However, Mo is relatively expensive, so that the cost of the pipeline steel produced by adopting the alloy series is high, and meanwhile, Mo has high red hardness and high-temperature deformation resistance, thereby bringing serious examination to the load of a rolling mill. Journal article "development of 36.5mm thick X70 steel plate for deep sea and its large-diameter longitudinal submerged arc welded pipe" (mechanical engineering material 2016.12) discloses the composition, structure and performance of X70 steel plate with specification of 36.5mm and longitudinal submerged arc welded pipe with specification of D1016mm × 36.5 mm. The steel contains precious metal elements such as Mo and Ni, the alloy cost is high, and the technical scheme recorded by the paper is not suitable for producing the steel plate with low cost and large thickness-diameter ratio for the steel pipe.
Although the steel grades disclosed in the above documents achieve high strength and some have excellent HIC resistance, they are generally expensive to produce, and therefore, it is impossible to produce steel plates for thick-gauge, wide-width pipelines at low cost.
Disclosure of Invention
The invention provides an economical thick-wall high-strength and high-toughness X70M hot-rolled steel plate and a manufacturing method thereof, which are suitable for manufacturing a hot-rolled steel plate with a pipe diameter of
The oil and gas conveying straight welded pipe with the wall thickness of 25-38 mm can meet the technical requirements of an ultra-wide X70M steel plate without subsequent off-line heat treatment and stacking slow cooling, the problems of large rolling resistance, large straightening resistance, poor performance uniformity of the steel plate and the like in the production process of the steel plate are solved, and the produced steel plate has high strength, high toughness and good comprehensive performance and can ensure the safety of oil and gas conveying pipeline pipes.
In order to achieve the purpose, the invention adopts the following technical scheme:
an economical thick-wall high-strength-toughness X70M hot-rolled steel plate, wherein the thickness of the steel plate is 25-38 mm; the steel plate comprises the following chemical components in percentage by weight: 0.045 to 0.09 percent of C, 0.10 to 0.35 percent of Si, 1.50 to 1.85 percent of Mn, less than or equal to 0.01 percent of P, less than or equal to 0.015 percent of S, 0.04 to 0.09 percent of Nb, 0.008 to 0.0250 percent of Ti, 0.015 to 0.045 percent of Al, 0.25 to 0.5 percent of Cr, 0.15 to 0.55 percent of Cu, 0.02 to 0.04 percent of Zr, 0.0041 to 0.006 percent of N, and the balance of Fe and inevitable impurities, wherein O in the impurities is less than or equal to 0.0050 percent, and the total amount of other impurity elements is less than 0.05 percent.
An economical manufacturing method of a thick-wall high-strength and high-toughness X70M hot-rolled steel plate comprises the production process steps of molten steel smelting → external refining, degassing → continuous casting → slab reheating → controlled rolling → controlled cooling → air cooling to room temperature; the method comprises the following specific steps:
1) smelting molten steel to a continuous casting process;
pretreating the raw material by KR molten iron, controlling the content of S to be less than or equal to 0.015 percent, and feeding the raw material into a converter after slagging off; removing P by a double-slag method in converter smelting, controlling the content of P to be less than or equal to 0.01%, controlling the content of C to be 0.045-0.09% at the smelting end point of the converter, and blowing argon for 12-20 min during tapping; performing LF refining and RH vacuum degassing treatment, and maintaining RH vacuum for more than 20 min; when the slab is continuously cast, the continuous casting superheat degree is 15-20 ℃, and the continuous casting and blank drawing speed is 1.2-1.7 m/min; putting the continuous casting billet into a horizontal sector section, namely a solidification tail end under heavy reduction, wherein the reduction of the continuous casting billet is 15-22 mm;
2) reheating the plate blank;
feeding the casting blank into a stepping heating furnace for heating, and discharging the casting blank after passing through a preheating section, a heating section and a soaking section in sequence; wherein the temperature of the preheating section is 950-1150 ℃, the temperature of the heating section is 1150-1230 ℃, the temperature of the soaking section is 1140-1210 ℃, and the in-furnace time is 4.5-6.5 hours;
3) controlling the rolling and cooling processes;
before rolling, descaling the discharged casting blank for 1-1.5 min by using high-pressure water, wherein the pressure of a descaling machine is 30-40 MPa; rolling in three stages: the first stage is deformation recrystallization rolling, the final rolling temperature is 1000-1100 ℃, and the number of rolling passes is less than or equal to 7; the second stage is low-temperature austenite deformation rolling, the initial rolling temperature is 970-1000 ℃, the final rolling temperature is 910-940 ℃, and the number of rolling passes is less than or equal to 5 passes; the third stageThe method comprises the steps of carrying out austenite and ferrite two-phase region rolling, wherein the initial rolling temperature is 810-900 ℃, the final rolling temperature is 730-770 ℃, and the number of rolling passes is less than or equal to 8; in the third stage, the rolling speed is increased and is 3-5 m/s; quickly polishing steel after rolling, wherein the steel polishing speed is 4-6.5 m/s; then laminar cooling is adopted, the start cooling temperature is 700-740 ℃, the final cooling temperature is 380-430 ℃, the cooling speed is controlled to be 25-30 ℃/s, the side spraying is started after the steel plate is discharged and controlled to be cooled, the side spraying pressure is 1-3 MPa, and the side spraying water amount is 35-70 m3Per hour, straightening for 4 times by thermal straightening, leading the position of a roller to be-0.8 mm to-2.2 mm, and leading the position of the roller to be-2.5 mm to-3.7 mm;
4) air cooling to room temperature.
The thickness of the casting blank is 250-300 mm.
In the first stage, the pass reduction system is as follows: the reduction rate of at least 1 pass of the first 3 passes is more than 20 percent; in the second stage, the pass reduction system is as follows: the reduction rate of at least 1 pass of the first 2 passes is more than 15%, and the reduction rate of at least 1 pass of the last 3 passes is not less than 10%; in the third stage, the pass reduction system is as follows: the reduction rate of at least 1 pass of the first 2 passes is more than 22%, and the reduction rate of at least 1 pass of the last 3 passes is not less than 10%.
And after the first stage and the second stage of rolling are finished, the thickness of the obtained intermediate blank is 2.7-4 times of that of the finished product.
And in the last 3 passes of the second-stage rolling, descaling water is sprayed in each pass, the descaling time is 1-1.5 min, and the pressure of a descaler is 10-25 MPa.
The metallographic structure of the produced steel plate is a complex phase structure mainly comprising acicular ferrite and granular bainite.
The properties of the produced steel sheet are: the yield strength of transverse stretching is 500-540 MPa, the tensile strength is 590-640 MPa, the yield ratio is 0.8-0.9, and the elongation is more than or equal to 30%; the horizontal Charpy impact work at minus 35 ℃ is more than or equal to 370J, and the horizontal shearing area SA of DWTT at minus 20 ℃ is not less than 85 percent.
Compared with the prior art, the invention has the beneficial effects that:
1) the KR molten iron is pretreated for deep desulfurization and then is completely drossed, a converter adopts a double-slag method for removing P, so that the P, S content of a casting blank is lower, the argon blowing time is controlled, and the RH vacuum degassing time is kept, thereby overcoming the defects of casting blank center segregation, inclusion, excessive H, O content and the like caused by higher Mn content, and being beneficial to improving the plastic toughness of pipeline steel; the superheat degree and the withdrawal rate of the continuous casting billet are reasonably controlled, and heavy reduction is added, so that the steel billet segregation is favorably reduced, austenite grains are refined, and internal structure defects are reduced;
2) the steel has reasonable chemical component design and low alloy addition amount, and the alloy cost is greatly reduced by replacing Mo with Cr and adding a small amount of microalloy elements Nb and Zr; in the process of reheating the casting blank, the temperature of a preheating section is 950-1150 ℃, so that carbides and nitrides of Nb and Zr can be promoted to be rapidly and fully dissolved in a matrix and fully diffused;
3) the three-stage rolling control process is adopted, the pass rolling reduction and the rolling temperature of each rolling stage are respectively controlled, the thickness of an intermediate billet is optimized, the initial rolling temperature of the first stage is increased, the flexible high-pressure water descaling process is adopted, the waiting time of a billet is shortened, excessive growth of crystal grains is inhibited, the grain structure of different stages is refined and pre-deformed to a certain degree through the three-stage rolling, the size of the crystal grains after phase transformation is reduced, and relaxation waiting is not needed after rolling; the final cooling temperature of the steel plate is controlled to be 380-430 ℃ by the technical means of quickly throwing steel after rolling, ensuring the water inlet temperature of the steel plate and the like, and the side spraying investment is beneficial to controlling the shape of the steel plate, improving the performance uniformity of the steel plate, reducing the probability of the shape problems of a buckle head and a buckle tail plate and saving the investment cost of subsequent cold straightening equipment;
4) the invention reduces the alloy cost through simple component design, and simultaneously obtains a pipe diameter suitable for manufacturing by matching with corresponding steelmaking, continuous casting and controlled rolling and controlled cooling processes
The economical X70M ultra-wide steel plate of oil gas conveying straight welded pipe with the wall thickness of 25-38 mm has the advantages that the metallographic structure mainly comprises acicular ferrite and bainite, the steel plate has good low-temperature toughness and DWTT performance, and meanwhile, the shape and the surface quality of the ultra-wide plate are guaranteed.
Detailed Description
The invention provides an economical thick-wall high-strength and high-toughness X70M hot-rolled steel plate, wherein the thickness of the steel plate is 25-38 mm; the steel plate comprises the following chemical components in percentage by weight: 0.045 to 0.09 percent of C, 0.10 to 0.35 percent of Si, 1.50 to 1.85 percent of Mn, less than or equal to 0.01 percent of P, less than or equal to 0.015 percent of S, 0.04 to 0.09 percent of Nb, 0.008 to 0.0250 percent of Ti, 0.015 to 0.045 percent of Al, 0.25 to 0.5 percent of Cr, 0.15 to 0.55 percent of Cu, 0.02 to 0.04 percent of Zr, 0.0041 to 0.006 percent of N, and the balance of Fe and inevitable impurities, wherein O in the impurities is less than or equal to 0.0050 percent, and the total amount of other impurity elements is less than 0.05 percent.
An economical manufacturing method of a thick-wall high-strength and high-toughness X70M hot-rolled steel plate comprises the production process steps of molten steel smelting → external refining, degassing → continuous casting → slab reheating → controlled rolling → controlled cooling → air cooling to room temperature; the specific process is as follows:
1) smelting molten steel to a continuous casting process;
pretreating the raw material by KR molten iron, controlling the content of S to be less than or equal to 0.015 percent, and feeding the raw material into a converter after slagging off; removing P by a double-slag method in converter smelting, controlling the content of P to be less than or equal to 0.01%, controlling the content of C to be 0.045-0.09% at the smelting end point of the converter, and blowing argon for 12-20 min during tapping; performing LF refining and RH vacuum degassing treatment, and maintaining RH vacuum for more than 20 min; when the slab is continuously cast, the continuous casting superheat degree is 15-20 ℃, and the continuous casting and blank drawing speed is 1.2-1.7 m/min; putting the continuous casting billet into a horizontal sector section, namely a solidification tail end under heavy reduction, wherein the reduction of the continuous casting billet is 15-22 mm;
2) reheating the plate blank;
feeding the casting blank into a stepping heating furnace for heating, and discharging the casting blank after passing through a preheating section, a heating section and a soaking section in sequence; wherein the temperature of the preheating section is 950-1150 ℃, the temperature of the heating section is 1150-1230 ℃, the temperature of the soaking section is 1140-1210 ℃, and the in-furnace time is 4.5-6.5 hours;
3) controlling the rolling and cooling processes;
before rolling, descaling the discharged casting blank for 1-1.5 min by using high-pressure water, wherein the pressure of a descaling machine is 30-40 MPa; rolling in three stages: the first stage is deformation recrystallization rolling,the final rolling temperature is 1000-1100 ℃, and the number of rolling passes is less than or equal to 7; the second stage is low-temperature austenite deformation rolling, the initial rolling temperature is 970-1000 ℃, the final rolling temperature is 910-940 ℃, and the number of rolling passes is less than or equal to 5 passes; the third stage is austenite and ferrite two-phase region rolling, the starting rolling temperature is 810-900 ℃, the finishing rolling temperature is 730-770 ℃, and the number of rolling passes is less than or equal to 8 passes; in the third stage, the rolling speed is increased and is 3-5 m/s; quickly polishing steel after rolling, wherein the steel polishing speed is 4-6.5 m/s; then laminar cooling is adopted, the start cooling temperature is 700-740 ℃, the final cooling temperature is 380-430 ℃, the cooling speed is controlled to be 25-30 ℃/s, the side spraying is started after the steel plate is discharged and controlled to be cooled, the side spraying pressure is 1-3 MPa, and the side spraying water amount is 35-70 m3Per hour, straightening for 4 times by thermal straightening, leading the position of a roller to be-0.8 mm to-2.2 mm, and leading the position of the roller to be-2.5 mm to-3.7 mm;
4) air cooling to room temperature.
The thickness of the casting blank is 250-300 mm.
In the first stage, the pass reduction system is as follows: the reduction rate of at least 1 pass of the first 3 passes is more than 20 percent; in the second stage, the pass reduction system is as follows: the reduction rate of at least 1 pass of the first 2 passes is more than 15%, and the reduction rate of at least 1 pass of the last 3 passes is not less than 10%; in the third stage, the pass reduction system is as follows: the reduction rate of at least 1 pass of the first 2 passes is more than 22%, and the reduction rate of at least 1 pass of the last 3 passes is not less than 10%.
And after the first stage and the second stage of rolling are finished, the thickness of the obtained intermediate blank is 2.7-4 times of that of the finished product.
And in the last 3 passes of the second-stage rolling, descaling water is sprayed in each pass, the descaling time is 1-1.5 min, and the pressure of a descaler is 10-25 MPa.
The metallographic structure of the produced steel plate is a complex phase structure mainly comprising acicular ferrite and granular bainite.
The properties of the produced steel sheet are: the yield strength of transverse stretching is 500-540 MPa, the tensile strength is 590-640 MPa, the yield ratio is 0.8-0.9, and the elongation is more than or equal to 30%; the horizontal Charpy impact work at minus 35 ℃ is more than or equal to 370J, and the horizontal shearing area SA of DWTT at minus 20 ℃ is not less than 85 percent.
The economic thick-wall high-strength and high-toughness X70M hot rolled steel plate has the following main elements in chemical components:
c: the most economical and basic strengthening elements in the steel have obvious effect on improving the strength of the steel through solid solution strengthening and precipitation strengthening, but the improvement of the content of C has negative influence on the plasticity, the toughness and the weldability of the steel. Therefore, the content range of C is set to be 0.045-0.09%.
Mn: the strength of the steel is improved by the solid solution strengthening, and the loss of the strength of the steel sheet caused by the reduction of the C content is compensated. In addition, the gamma-alpha phase transformation temperature can be reduced, so that ferrite grains are refined, a fine low-temperature phase transformation product is obtained, and the toughness of the product is improved. However, increasing the Mn content will aggravate the center segregation of the continuous casting slab, which is not favorable for increasing the low temperature toughness of the steel plate, and the uniformity of the structure of the cross section of the steel plate cannot be ensured. Therefore, the Mn content range of the present invention is designed to be 1.50% to 1.85%.
Si: has the functions of steelmaking deoxidization and matrix strength improvement, improves the content of Si, can purify ferrite, reduces the content of pearlite and is beneficial to reducing the Bauschinger effect of matrix materials. However, excessive Si can reduce the toughness of the welding heat affected zone of the base metal; therefore, the Si content is set to 0.10% to 0.35% in the present invention.
Nb: is one of common elements in modern microalloyed pipeline steel, and has good fine grain strengthening and precipitation strengthening effects; austenite recrystallization is also delayed, but excess Nb increases production costs and difficulties in controlling the continuous casting process. The invention selects the Nb content range of 0.04-0.09%, and can obtain a uniform composite phase mainly comprising an acicular ferrite structure by matching with a reasonable TMCP process, so that the steel has good toughness.
N: the N element in the steel has no other obvious effect except that fine TiN grains are formed to refine austenite grains, so that the content of the N element needs to be kept at a lower content level, and the N content range selected by the invention is 0.0041-0.006%.
Ti: is a strong solid N element and exists in the form of TiN in the continuous casting billet. The fine TiN particles can effectively inhibit the growth of austenite grains when the continuous casting slab is reheated, and contribute to improving the solid solubility of Nb in austenite and improving the impact toughness of a welding heat affected zone. When the addition amount of Ti exceeds a certain value, the TiN particles will be coarsened, and the stress concentration level of the particle interface and the matrix is improved. Therefore, the Ti content range is 0.008-0.025 percent.
Al: in general, AlN also has a function of refining the structure when it is formed as a deoxidizer in steel. When the content of Al exceeds 0.045%, excessive alumina inclusions may degrade the cleanliness of the steel. Since deoxidation is insufficient when the Al content is too low and an easily oxidizable element such as Ti forms an oxide, the Al content is set to 0.015% to 0.045% in the present invention.
Cr: the steel plate can effectively improve hardenability, inhibit ferrite formation, promote the formation of main elements of bainite, play an important role in controlling phase transformation structure, promote the formation of acicular ferrite with a large amount of dislocation distribution in crystal in a medium-temperature and low-temperature region, and improve the strength, plasticity and toughness of the steel plate, and the content range of Cr selected by the invention is 0.25-0.5 percent.
Cu: the strength of the steel can be improved through solid solution strengthening, and the corrosion resistance can also be improved, but too high Cu causes hot brittleness and is unfavorable for toughness, so the Cu content is selected to be 0.15-0.55 percent.
Zr: the Zr content is 0.02-0.04% in the invention, because the Zr content is selected to be strong carbide and strong hardenability forming elements, the crystal grains can be obviously refined by adding a small amount of Zr, the low-temperature toughness of the steel is improved, the hardenability of the steel is improved, the strength and the structural uniformity of the steel are further improved, and meanwhile, the hot brittleness of the steel is improved by Zr.
P, S: is an inevitable impurity element in steel, and too high P, S affects drop weight property and weldability of the steel sheet, so that the lower the content, the better. But cannot be lowered without limit in view of the economy of the smelting process. The upper limit of the content of P, S is set to 0.010 percent and 0.015 percent respectively.
The following examples are carried out on the premise of the technical scheme of the invention, and detailed embodiments and specific operation processes are given, but the scope of the invention is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.
[ examples ] A method for producing a compound
In the embodiment, the target thickness of the X70M hot rolled steel plate is 25-38 mm, a billet with the thickness of 250-300 mm is used for production on a medium-thickness plate reciprocating mill, and the quenching medium is water.
As shown in the following table, Table 1 shows the chemical compositions of the steels in the examples, Table 2 shows the smelting process parameters of the steels in the examples, and Table 3 shows the heating system of the casting blank and the high-pressure water descaling process parameters before the continuous casting blank is rolled in the examples; table 4 shows the rolling reduction of each pass of the steel at different rolling stages in each example; table 5 shows the controlled cooling process parameters of the steel plates in the examples; table 6 shows the transverse mechanical properties of the steel sheets in the examples.
TABLE 1 chemical composition of steel (wt%)
Note: the impurity element P in the steel of each embodiment is less than or equal to 0.01 percent; s is less than or equal to 0.015 percent; 0 percent or less than 0.0050 percent and the total amount of other impurity elements is less than 0.05 percent.
TABLE 2 smelting Process parameters of the steels
TABLE 3 heating System of casting blank and high-pressure water descaling Process parameters before rolling of continuous casting blank
TABLE 4 heating and Rolling parameters of the steels
TABLE 5 reduction of the steels at different rolling stages for each pass
TABLE 6 controlled Cooling Process parameters of Steel plates
TABLE 7 transverse mechanical Properties of the Steel sheets
The embodiment proves that compared with the prior art, the ultra-wide and thick-wall X70M pipeline steel produced by the method has simple chemical components, but reaches the strength of X70M steel grade, has excellent mechanical property, moldability and welding performance, and can be used for manufacturing large-caliber pipeline steel
X70M pipeline steel pipe.
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 person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (2)
1. An economical thick-wall high-strength-toughness X70M hot-rolled steel plate is characterized in that the thickness of the steel plate is 25-38 mm; the steel plate comprises the following chemical components in percentage by weight: 0.082-0.09% of C, 0.10-0.12% of Si, 1.50-1.85% of Mn, less than or equal to 0.01% of P, less than or equal to 0.015% of S, 0.083-0.09% of Nb, 0.008-0.012% of Ti, 0.034-0.045% of Al, 0.33-0.5% of Cr, 0.52-0.55% of Cu, 0.028-0.04% of Zr, 0.0041-0.006% of N, and the balance of Fe and inevitable impurities, wherein O in the impurities is less than or equal to 0.0050%, and the total amount of other impurity elements is less than 0.05%;
the metallographic structure of the steel plate is a complex phase structure mainly comprising acicular ferrite and granular bainite; the properties of the steel sheet were: the yield strength of transverse stretching is 500-540 MPa, the tensile strength is 590-640 MPa, the yield ratio is 0.8-0.9, and the elongation is more than or equal to 30%; the horizontal Charpy impact work at minus 35 ℃ is more than or equal to 370J, and the horizontal shearing area SA of DWTT at minus 20 ℃ is not less than 85 percent;
the production process of the steel plate comprises the steps of molten steel smelting → external refining, degassing → continuous casting → slab reheating → controlled rolling → controlled cooling → air cooling to room temperature; the method comprises the following specific steps:
1) smelting molten steel to a continuous casting process;
pretreating the raw material by KR molten iron, controlling the content of S to be less than or equal to 0.015 percent, and feeding the raw material into a converter after slagging off; the converter smelting adopts a double-slag method to remove P, the content of P is controlled to be less than or equal to 0.01 percent, the content of C is controlled to be 0.082-0.09 percent at the smelting end point of the converter, and argon is blown for 12-20 min during tapping; performing LF refining and RH vacuum degassing treatment, and maintaining RH vacuum for more than 20 min; when the slab is continuously cast, the continuous casting superheat degree is 15-20 ℃, and the continuous casting and blank drawing speed is 1.4-1.7 m/min; putting the continuous casting billet into a horizontal sector section, namely a solidification tail end under heavy reduction, wherein the reduction of the continuous casting billet is 15-22 mm; the thickness of the casting blank is 250-300 mm;
2) reheating the plate blank;
feeding the casting blank into a stepping heating furnace for heating, and discharging the casting blank after passing through a preheating section, a heating section and a soaking section in sequence; wherein the temperature of the preheating section is 950-1150 ℃, the temperature of the heating section is 1150-1230 ℃, the temperature of the soaking section is 1140-1210 ℃, and the in-furnace time is 4.5-6.5 hours;
3) controlling the rolling and cooling processes;
before rolling, descaling the discharged casting blank for 1-1.5 min by using high-pressure water, wherein the pressure of a descaling machine is 30-40 MPa; rolling in three stages: the first stage is deformation recrystallization rolling, the final rolling temperature is 1000-1100 ℃, and the number of rolling passes is less than or equal to 7; in the first stage, the pass reduction system is as follows: the reduction rate of at least 1 pass of the first 3 passes is more than 20 percent;
the second stage is low-temperature austenite deformation rolling, the initial rolling temperature is 970-1000 ℃, the final rolling temperature is 910-940 ℃, and the number of rolling passes is less than or equal to 5 passes; in the second stage, the pass reduction system is as follows: the reduction rate of at least 1 pass of the first 2 passes is more than 15%, and the reduction rate of at least 1 pass of the last 3 passes is not less than 10%; in the last 3 passes of the second-stage rolling, descaling water is sprayed in each pass, the descaling time is 1-1.5 min, and the pressure of a descaler is 10-25 MPa;
after the first stage and the second stage of rolling are finished, the thickness of the obtained intermediate blank is 2.7-4 times of that of a finished product;
the third stage is austenite and ferrite two-phase region rolling, the starting rolling temperature is 810-900 ℃, the finishing rolling temperature is 730-770 ℃, and the number of rolling passes is less than or equal to 8 passes; in the third stage, the rolling speed is increased and is 3-5 m/s; in the third stage, the pass reduction system is as follows: the reduction rate of at least 1 pass of the first 2 passes is more than 22%, and the reduction rate of at least 1 pass of the last 3 passes is not less than 10%;
quickly polishing steel after rolling, wherein the steel polishing speed is 4-6.5 m/s; then laminar cooling is adopted, the start cooling temperature is 700-740 ℃, the final cooling temperature is 380-430 ℃, the cooling speed is controlled to be 25-30 ℃/s, the side spraying is started after the steel plate is discharged and controlled to be cooled, the side spraying pressure is 1-3 MPa, and the side spraying water amount is 35-70 m3Per hour, straightening for 4 times by thermal straightening, leading the position of a roller to be-0.8 mm to-2.2 mm, and leading the position of the roller to be-2.5 mm to-3.7 mm;
4) air cooling to room temperature.
2. The method for manufacturing the economical thick-walled high-strength and high-toughness X70M hot-rolled steel plate according to claim 1, wherein the production process comprises the steps of molten steel smelting → external refining, degassing → continuous casting → slab reheating → controlled rolling → controlled cooling → air cooling to room temperature; the method comprises the following specific steps:
1) smelting molten steel to a continuous casting process;
pretreating the raw material by KR molten iron, controlling the content of S to be less than or equal to 0.015 percent, and feeding the raw material into a converter after slagging off; the converter smelting adopts a double-slag method to remove P, the content of P is controlled to be less than or equal to 0.01 percent, the content of C is controlled to be 0.082-0.09 percent at the smelting end point of the converter, and argon is blown for 12-20 min during tapping; performing LF refining and RH vacuum degassing treatment, and maintaining RH vacuum for more than 20 min; when the slab is continuously cast, the continuous casting superheat degree is 15-20 ℃, and the continuous casting and blank drawing speed is 1.4-1.7 m/min; putting the continuous casting billet into a horizontal sector section, namely a solidification tail end under heavy reduction, wherein the reduction of the continuous casting billet is 15-22 mm; the thickness of the casting blank is 250-300 mm;
2) reheating the plate blank;
feeding the casting blank into a stepping heating furnace for heating, and discharging the casting blank after passing through a preheating section, a heating section and a soaking section in sequence; wherein the temperature of the preheating section is 950-1150 ℃, the temperature of the heating section is 1150-1230 ℃, the temperature of the soaking section is 1140-1210 ℃, and the in-furnace time is 4.5-6.5 hours;
3) controlling the rolling and cooling processes;
before rolling, descaling the discharged casting blank for 1-1.5 min by using high-pressure water, wherein the pressure of a descaling machine is 30-40 MPa; rolling in three stages: the first stage is deformation recrystallization rolling, the final rolling temperature is 1000-1100 ℃, and the number of rolling passes is less than or equal to 7; in the first stage, the pass reduction system is as follows: the reduction rate of at least 1 pass of the first 3 passes is more than 20 percent;
the second stage is low-temperature austenite deformation rolling, the initial rolling temperature is 970-1000 ℃, the final rolling temperature is 910-940 ℃, and the number of rolling passes is less than or equal to 5 passes; in the second stage, the pass reduction system is as follows: the reduction rate of at least 1 pass of the first 2 passes is more than 15%, and the reduction rate of at least 1 pass of the last 3 passes is not less than 10%; in the last 3 passes of the second-stage rolling, descaling water is sprayed in each pass, the descaling time is 1-1.5 min, and the pressure of a descaler is 10-25 MPa;
after the first stage and the second stage of rolling are finished, the thickness of the obtained intermediate blank is 2.7-4 times of that of a finished product;
the third stage is austenite and ferrite two-phase region rolling, the starting rolling temperature is 810-900 ℃, the finishing rolling temperature is 730-770 ℃, and the number of rolling passes is less than or equal to 8 passes; in the third stage, the rolling speed is increased and is 3-5 m/s; in the third stage, the pass reduction system is as follows: the reduction rate of at least 1 pass of the first 2 passes is more than 22%, and the reduction rate of at least 1 pass of the last 3 passes is not less than 10%;
quickly polishing steel after rolling, wherein the steel polishing speed is 4-6.5 m/s; then adopting laminar coolingHowever, the start cooling temperature is 700-740 ℃, the final cooling temperature is 380-430 ℃, the cooling speed is controlled to be 25-30 ℃/s, the side spraying is started after the steel plate is discharged and controlled to be cooled, the side spraying pressure is 1-3 MPa, and the side spraying water amount is 35-70 m3Per hour, straightening for 4 times by thermal straightening, leading the position of a roller to be-0.8 mm to-2.2 mm, and leading the position of the roller to be-2.5 mm to-3.7 mm;
4) air cooling to room temperature.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110176162.0A CN112981257B (en) | 2021-02-09 | 2021-02-09 | Economical thick-wall high-strength high-toughness X70M hot-rolled steel plate and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110176162.0A CN112981257B (en) | 2021-02-09 | 2021-02-09 | Economical thick-wall high-strength high-toughness X70M hot-rolled steel plate and manufacturing method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112981257A CN112981257A (en) | 2021-06-18 |
| CN112981257B true CN112981257B (en) | 2022-03-22 |
Family
ID=76392605
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110176162.0A Active CN112981257B (en) | 2021-02-09 | 2021-02-09 | Economical thick-wall high-strength high-toughness X70M hot-rolled steel plate and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112981257B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113549824A (en) * | 2021-06-29 | 2021-10-26 | 武汉钢铁有限公司 | Hot continuous rolling limit thickness specification high-strength pipeline steel plate coil and manufacturing method thereof |
| CN114737109B (en) * | 2022-02-28 | 2023-03-17 | 鞍钢股份有限公司 | Steel for X52 straight welded pipe for thick-wall HIC-resistant oil and gas pipeline and manufacturing method thereof |
| CN114774770B (en) * | 2022-02-28 | 2023-04-14 | 鞍钢股份有限公司 | Low-cost anti-HIC (hydrogen induced cracking) L290 hot rolled steel plate for oil and gas pipelines and manufacturing method thereof |
| CN115323268B (en) * | 2022-07-20 | 2023-09-22 | 江阴兴澄特种钢铁有限公司 | Gear steel with high strength and high toughness and capable of being used for induction quenching and manufacturing method thereof |
| CN115652211B (en) * | 2022-11-08 | 2023-11-10 | 鞍钢股份有限公司 | Economical 420 MPa-level steel plate cooling uniformity control method for engineering structure |
| CN115679216B (en) * | 2022-11-08 | 2023-11-10 | 鞍钢股份有限公司 | Economical 345MPa grade steel plate cooling uniformity control method for engineering structure |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013147741A (en) * | 2011-12-22 | 2013-08-01 | Jfe Steel Corp | High-strength steel sheet for heavy heat input welding excellent in material uniformity within the steel sheet and method for producing the same |
| CN104264069A (en) * | 2014-09-30 | 2015-01-07 | 江阴兴澄特种钢铁有限公司 | Super-thick X70 pipeline steel and manufacturing method thereof |
| CN105039870A (en) * | 2015-08-31 | 2015-11-11 | 山东钢铁股份有限公司 | X80M pipeline steel resistant to low temperature and large in strain and manufacturing method and application of X80M pipeline steel |
| CN105088096A (en) * | 2015-08-31 | 2015-11-25 | 山东钢铁股份有限公司 | X80 pipeline steel with high stress ratio and high arrest toughness and preparation method and application of X80 pipeline steel |
| CN107385324A (en) * | 2017-06-08 | 2017-11-24 | 江阴兴澄特种钢铁有限公司 | A kind of big thickness Q500GJCD high-strength buildings structural steel plate and its manufacture method |
-
2021
- 2021-02-09 CN CN202110176162.0A patent/CN112981257B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2013147741A (en) * | 2011-12-22 | 2013-08-01 | Jfe Steel Corp | High-strength steel sheet for heavy heat input welding excellent in material uniformity within the steel sheet and method for producing the same |
| CN104264069A (en) * | 2014-09-30 | 2015-01-07 | 江阴兴澄特种钢铁有限公司 | Super-thick X70 pipeline steel and manufacturing method thereof |
| CN105039870A (en) * | 2015-08-31 | 2015-11-11 | 山东钢铁股份有限公司 | X80M pipeline steel resistant to low temperature and large in strain and manufacturing method and application of X80M pipeline steel |
| CN105088096A (en) * | 2015-08-31 | 2015-11-25 | 山东钢铁股份有限公司 | X80 pipeline steel with high stress ratio and high arrest toughness and preparation method and application of X80 pipeline steel |
| CN107385324A (en) * | 2017-06-08 | 2017-11-24 | 江阴兴澄特种钢铁有限公司 | A kind of big thickness Q500GJCD high-strength buildings structural steel plate and its manufacture method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112981257A (en) | 2021-06-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112981257B (en) | Economical thick-wall high-strength high-toughness X70M hot-rolled steel plate and manufacturing method thereof | |
| CN108467993B (en) | Ultra-wide high-toughness hot-rolled thick plate for low-temperature pipeline and production method thereof | |
| CN110295320B (en) | Large-wall-thickness X52MS acid-resistant pipeline steel plate produced by LF-RH refining process and manufacturing method thereof | |
| CN112981254B (en) | Wide high-strength high-toughness thick-wall X80M pipeline steel plate and manufacturing method thereof | |
| CN109957713B (en) | Hot rolled steel plate for ultra-wide thick-wall X80-grade pipeline and production method thereof | |
| CN109536846B (en) | High-toughness hot-rolled steel plate with yield strength of 700MPa and manufacturing method thereof | |
| CN100430506C (en) | Nickel-free micro-alloy low-temperature pressure vessel steel and manufacturing method thereof | |
| CN114774770B (en) | Low-cost anti-HIC (hydrogen induced cracking) L290 hot rolled steel plate for oil and gas pipelines and manufacturing method thereof | |
| CN116162863A (en) | 550 MPa-grade steel plate with excellent low-temperature ductility and manufacturing method thereof | |
| CN115572912B (en) | Economical 460 MPa-level steel plate cooling uniformity control method for engineering structure | |
| CN114737109B (en) | Steel for X52 straight welded pipe for thick-wall HIC-resistant oil and gas pipeline and manufacturing method thereof | |
| CN110629001A (en) | Manufacturing method of steel plate for extra-thick pipeline steel | |
| CN116397162A (en) | Marine high-strength steel plate with excellent low-temperature ductility and manufacturing method thereof | |
| CN113930684B (en) | Economical aging-resistant high-strain precipitation-strengthened pipeline steel and production method thereof | |
| CN113699462B (en) | Hot-rolled steel strip for 750 MPa-grade continuous oil pipe and manufacturing method thereof | |
| CN115558851A (en) | Hot rolled steel plate for 370 MPa-level engineering structure and manufacturing method thereof | |
| CN113151740B (en) | VL4-4L steel plate with good low-temperature toughness for ship and manufacturing method thereof | |
| CN112375997B (en) | Manufacturing method of X70M pipeline steel plate used under low-cost and ultralow-temperature conditions | |
| CN112981258B (en) | X70M hot-rolled steel plate for thin-specification gas transmission straight welded pipe and manufacturing method | |
| CN115838902B (en) | TMCP (thermal mechanical control process) extra-thick steel plate and production method thereof | |
| CN111270162B (en) | Medium-thickness low-temperature high-core impact A537CL2 container steel plate and production method thereof | |
| CN114737110B (en) | Steel for X52 straight welded pipe for HIC-resistant oil and gas pipeline and manufacturing method thereof | |
| CN113151739B (en) | 540 MPa-grade VL4-4MOD ship steel plate and manufacturing method thereof | |
| CN115558850A (en) | Hot rolled steel plate for 420 MPa-level engineering structure and manufacturing method thereof | |
| CN117070851A (en) | Economical 355 MPa-grade hot rolled steel plate and elongation stable control 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 | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |