CN111511950A - Thick steel plate having excellent low-temperature toughness and method for producing same - Google Patents
Thick steel plate having excellent low-temperature toughness and method for producing same Download PDFInfo
- Publication number
- CN111511950A CN111511950A CN201880082930.2A CN201880082930A CN111511950A CN 111511950 A CN111511950 A CN 111511950A CN 201880082930 A CN201880082930 A CN 201880082930A CN 111511950 A CN111511950 A CN 111511950A
- Authority
- CN
- China
- Prior art keywords
- steel plate
- thick steel
- low
- temperature toughness
- relational expression
- 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.)
- Pending
Links
Images
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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
-
- 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
-
- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
-
- 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
-
- 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
- C22C38/02—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
- C22C38/06—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
- C22C38/08—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
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/003—Cementite
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
Abstract
According to an aspect of the present invention, a thick steel plate excellent in low-temperature toughness includes, in wt%, C: 0.03-0.06%, Si: 0.1-0.2%, Mn: 1.0-2.0%, Al: 0.01-0.035%, Nb: 0.015-0.03%, Ti: 0.001-0.02%, Ni: 0.1-0.2%, N: 0.002-0.006%, P: 0.01% or less (not including 0%), S: 0.003% or less, and the balance Fe and other unavoidable impurities, and satisfies the following relational expressions 1 and 2, the fine structure contains 50 to 70% by area of polygonal ferrite and 30 to 50% by area of acicular ferrite, and the average grain size of the ferrite may be 20 μm or less. [ relation 1]0.23 ≦ C ] + [ Si ] +10 ≦ Al 0.61 in the relation 1, [ C ], [ Si ] and [ Al ] indicate contents (wt%) of respective alloy compositions, [ relation 2]1.35 ≦ Mn ] +2 [ Ni ] +10 [ Nb ] ≦ 2.7 in the relation 2, [ Mn ], [ Ni ] and [ Nb ] indicate contents (wt%) of respective alloy compositions.
Description
Technical Field
The present invention relates to a thick steel plate used for offshore wind single-pole steel and structural steel for the infrastructure industry such as construction, and more particularly, to a thick steel plate having high rigidity and excellent low-temperature impact toughness and a method for manufacturing the same.
Background
Since the 2000 s, attention has been focused on environmental issues and new renewable energy sources for reducing greenhouse gases. The new renewable energy is a term collectively called new energy (hydrogen, fuel cell, etc.) and renewable energy (solar energy, wind energy, biology, etc.), and among them, wind power generation, which is the next generation energy, has been the focus of attention, and it is an environment-friendly power generation method, without generating waste and pollution.
In wind power generation, the wind force on land installed on land is limited by noise and an optimal wind formation space, and recently, the wind force on sea installed on the sea (offset wind) is rapidly increasing in europe.
Although these offshore winds are started later than the land winds, the relative advantages of offshore winds over land winds are increasing as the state of the art increases due to the strong wind speeds, the low concerns about noise generation and the various advantages of being able to ensure large areas.
The structure of offshore wind power is divided into a monopole (monopole) section inserted into the sea floor, a transition piece section (transition piece) connecting the monopole and tower (tower) sections, and a tower section supporting the power generation equipment. Wherein the monopole and the transition piece are parts supporting offshore wind power, and a thick steel plate capable of securing extremely thick, low temperature toughness is used. More specifically, the impact toughness at a maximum thickness of 120mm and-50 ℃ should be ensured, and a steel material having a yield strength of 350MPa should be satisfied.
(patent document 1) Korean laid-open patent publication No. 2017-0075867
Disclosure of Invention
Problems to be solved by the invention
A preferred aspect of the present invention is to provide a thick steel plate having high rigidity and excellent low-temperature impact toughness.
It is another preferred aspect of the present invention to provide a method for manufacturing a thick steel plate having high rigidity and excellent low-temperature impact toughness.
Means for solving the problems
According to an aspect of the invention, comprises, in weight%: 0.03-0.06%, Si: 0.1-0.2%, Mn: 1.0-2.0%, Al: 0.01-0.035%, Nb: 0.015-0.03%, Ti: 0.001-0.02%, Ni: 0.1-0.2%, N: 0.002-0.006%, P: 0.01% or less (not including 0%), S: 0.003% or less, and the balance Fe and other unavoidable impurities, and satisfies the following relational expressions 1 and 2, the fine structure contains 50 to 70% by area of polygonal ferrite and 30 to 50% by area of acicular ferrite, and the average grain size of the ferrite may be 20 μm or less.
[ relational expression 1]
0.23≤[C]+[Si]+10*[Al]≤0.61
In the relational expression 1, [ C ], [ Si ] and [ Al ] represent the contents (wt%) of the respective alloy compositions.
[ relational expression 2]
1.35≤[Mn]+2*[Ni]+10*[Nb]≤2.7
In the relational expression 2, [ Mn ], [ Ni ], and [ Nb ] represent the contents (wt%) of the respective alloy compositions.
The fine structure may further include one or both of a cementite and an MA phase, and the fraction of the one or both of the cementite and the MA phase is 5 area% or less (including 0%) by area fraction.
The thick steel plate may have a yield strength of 355Mpa or more and an impact toughness of 100J or more at-50 ℃.
The tensile strength of the thick steel plate may be 450Mpa or more.
The method for manufacturing a thick steel plate excellent in low-temperature toughness according to an aspect of the present invention may include: heating a steel billet at 1020-1100 ℃, wherein the steel billet comprises C: 0.03-0.06%, Si: 0.1-0.2%, Mn: 1.0-2.0%, Al: 0.01-0.035%, Nb: 0.015-0.03%, Ti: 0.001-0.02%, Ni: 0.1-0.2%, N: 0.002-0.006%, P: 0.01% or less (not including 0%), S: 0.003% or less, and the balance of Fe and other unavoidable impurities, and satisfying the following relational expressions 1 and 2, a step of hot rolling the thus heated slab to obtain a hot rolled steel, and a step of cooling the hot rolled steel at a cooling completion temperature of 450 ℃ or lower; the hot rolling includes recrystallization rolling and non-recrystallization rolling.
[ relational expression 1]
0.23≤[C]+[Si]+10*[Al]≤0.61
In the relational expression 1, [ C ], [ Si ] and [ Al ] represent the contents (wt%) of the respective alloy compositions.
[ relational expression 2]
1.35≤[Mn]+2*[Ni]+10*[Nb]≤2.7
In the relational expression 2, [ Mn ], [ Ni ], and [ Nb ] represent the contents (wt%) of the respective alloy compositions.
The recrystallization rolling can be performed at a temperature of 900 ℃ or higher in the last two passes at a reduction ratio of 15 to 20% respectively.
The unrecrystallized rolling may be done at 750 ℃ or more.
The cumulative reduction rate of the unrecrystallized rolling may be 30 to 40%.
The cooling end temperature may be 300 ℃ or less.
The cooling speed of the cooling can be 1-8 ℃/s.
The cooling speed of the cooling can be 2-4 ℃/s.
Said means for solving the technical problem do not fully list the features of the present invention, various features of the present invention and advantages and effects according to these features can be understood in more detail with reference to the following specific embodiments.
Effects of the invention
According to an aspect of the present invention, it is possible to provide a thick steel plate having a thickness of 120mm and capable of securing excellent low-temperature toughness characteristics and a yield strength of 350Mpa or more, and a method for manufacturing the same.
According to an aspect of the present invention, it is possible to provide a thick steel plate particularly suitable for offshore wind industry and a method of manufacturing the same, by improving resistance to deformation and damage of a structure by continuous waves and impact of fish, tides, ships, and the like.
The application of the steel material according to an aspect of the present invention can effectively contribute to securing the stability of the offshore structure and increasing the life thereof.
Drawings
Fig. 1 is a photograph for observing the microstructure of invention example 1, which was taken at a magnification of 200 times using an optical microscope.
Best mode for carrying out the invention
The present invention relates to a thick steel plate excellent in low-temperature toughness and a method for manufacturing the same, and preferred embodiments of the present invention will be described below. The embodiments of the present invention may be modified in various forms and the scope of the present invention should not be construed as being limited to the embodiments described below. The present embodiment is provided to explain the present invention in more detail to those skilled in the art to which the present invention pertains.
Hereinafter, the composition of the steel will be described in further detail. Hereinafter, unless otherwise specified, it means% of the content of each element on a weight basis.
According to an aspect of the present invention, a thick steel plate excellent in low-temperature toughness includes, in wt%, carbon (C): 0.03 to 0.06%, silicon (Si): 0.1 to 0.2%, manganese (Mn): 1.0-2.0%, soluble aluminum (sol. A1): 0.01-0.035%, niobium (Nb): 0.015 to 0.03%, titanium (Ti): 0.001 to 0.02%, nickel (Ni): 0.1 to 0.2%, nitrogen (N): 0.002-0.006%, phosphorus (P): 0.01% or less (excluding 0%), sulfur (S): 0.003% or less, and the balance of Fe and other unavoidable impurities, and satisfies the following relational expressions 1 and 2.
[ relational expression 1]
0.23≤[C]+[Si]+10*[Al]≤0.61
In the relational expression 1, [ C ], [ Si ] and [ Al ] represent the contents (wt%) of the respective alloy compositions.
[ relational expression 2]
1.35≤[Mn]+2*[Ni]+10*[Nb]≤2.7
In the relational expression 2, [ Mn ], [ Ni ], and [ Nb ] represent the contents (wt%) of the respective alloy compositions.
Carbon (C): 0.03 to 0.06 percent
In the present invention, carbon (C) causes solid solution strengthening and is an element added to ensure tensile strength in the form of carbonitride together with niobium (Nb) and the like, and therefore the present invention can limit the lower limit of the content of carbon (C) to 0.03%. However, since the addition of too much carbon (C) not only promotes the generation of MA but also generates pearlite to deteriorate the impact characteristics at temperature, the present invention can limit the upper limit of the carbon (C) content to 0.06%. Therefore, the carbon (C) content of the present invention may be in the range of 0.03 to 0.06%. The preferable carbon (C) content may be in the range of 0.032 to 0.06%, and the more preferable carbon (C) content may be in the range of 0.032 to 0.058%.
Silicon (Si): 0.1 to 0.2 percent
Since silicon (Si) plays a role of assisting aluminum (Al) in deoxidizing molten steel and is an essential element for securing yield strength and tensile strength, the lower limit of the content of silicon (Si) may be limited to 0.1% in the present invention. However, when silicon (Si) is excessively added, diffusion of carbon (C) is hindered to promote formation of MA, and thus it is difficult to secure impact characteristics at low temperature, so the present invention may limit the upper limit of the content of silicon (Si) to 0.2%. Therefore, the content of silicon (Si) in the present invention may be in the range of 0.1 to 0.2%. The preferable content of silicon (Si) may be in the range of 0.1 to 0.18%, and the more preferable content of silicon (Si) may be in the range of 0.12 to 0.18%.
Manganese (Mn): 1.0 to 2.0%
Manganese (Mn) Mn is an element contributing to increase in strength by solid solution strengthening, and the lower limit of the manganese (Mn) content may be limited to 1.0% in order to achieve the effects described above. However, when manganese (Mn) is excessively added, MnS inclusions may be formed and toughness may be reduced due to center segregation, so the present invention may limit the upper limit of the manganese (Mn) content to 2.0%. Therefore, the manganese (Mn) content of the present invention may be in the range of 1.0 to 2.0%. The preferable manganese (Mn) content may be in the range of 1.2 to 1.8%, and the more preferable manganese (Mn) content may be in the range of 1.4 to 1.8%.
Aluminum (Al): 0.01 to 0.035%
In the present invention, aluminum (Al) is a main deoxidizer of steel, and therefore 0.01% or more is required to be added based on the dissolved state. However, when aluminum (Al) is excessively added, Al may be caused2O3The fraction and size of inclusions increase to cause a decrease in low-temperature toughness, and may be a cause of a decrease in low-temperature toughness by promoting the generation of MA phase in the base material and the welding heat affected zone, similarly to silicon (Si), so the present invention limits the content of aluminum (Al) to 0.035% or less based on the dissolved state. Therefore, the content of aluminum (Al) in the present invention may be in the range of 0.01 to 0.035%. The preferable content of aluminum (Al) may be in the range of 0.02 to 0.035%, and the more preferable content of aluminum (A1) may be in the range of 0.02 to 0.03%.
Niobium (Nb): 0.015 to 0.03 percent
Niobium (Nb) is an element that refines the structure and improves the rigidity by precipitating solid solution or carbonitride to suppress recrystallization in rolling or cooling. In the present invention, in order to achieve such an effect, the lower limit of the niobium (Nb) content may be limited to 0.015%. However, when the niobium (Nb) is excessively added, the concentration of the carbon (C) is induced by the affinity with the carbon (C) to promote the formation of the MA phase, and thus there is a possibility that the toughness and fracture characteristics at low temperatures are reduced, and the upper limit of the content of the niobium (Nb) may be limited to 0.03% in the present invention. Therefore, the niobium (Nb) content of the present invention may be in the range of 0.015 to 0.03%. The preferable niobium (Nb) content may be in the range of 0.018 to 0.03%, and the more preferable niobium (Nb) content may be in the range of 0.018 to 0.025%.
Titanium (Ti): 0.001 to 0.02 percent
Titanium (Ti) combines with oxygen (O) or nitrogen (N) to form precipitates, and these precipitates suppress coarsening of the structure, thereby playing a role in making the structure finer and improving the toughness. In the present invention, in order to achieve the above-described effects, the lower limit of the titanium (Ti) content may be limited to 0.001%. However, when titanium (Ti) is excessively added, the titanium (Ti) -based precipitates may be coarsened to cause material damage, so the upper limit of the content of titanium (Ti) may be limited to 0.02% in the present invention. Therefore, the content of titanium (Ti) in the present invention may be in the range of 0.001 to 0.02%. The preferable content of titanium (Ti) may be in the range of 0.005 to 0.02%, and the more preferable content of titanium (Ti) may be in the range of 0.005 to 0.015%.
Nickel (Ni): 0.1 to 0.2 percent
Nickel (Ni) is an effective element for improving stiffness without lowering impact toughness. Nickel (Ni) is also an element that promotes the formation of acicular ferrite. In the present invention, in order to achieve the above-described effects, the lower limit of the nickel (Ni) content may be limited to 0.1%. However, when nickel (Ni) is excessively added, Ar can be reduced3Temperature to form bainite, and therefore, the present invention may limit the upper limit of the nickel (Ni) content to 0.2%. This is because, when bainite is formed, there is a risk that impact toughness in an extremely thick material is lowered. Therefore, the content of nickel (Ni) in the present invention may be in the range of 0.1 to 0.2%. The preferable content of nickel (Ni) may be in the range of 0.11 to 0.2%, and the more preferable content of nickel (Ni) may be in the range of 0.11 to 0.19%.
Nitrogen (N): 0.002-0.006%
Nitrogen (N) is an element contributing to improvement of rigidity and toughness by forming precipitates together with titanium (Ti), niobium (Nb), and aluminum (Al) to refine an austenite structure upon reheating. In the present invention, in order to achieve such an effect, the lower limit of the nitrogen (N) content may be limited to 0.002%. However, when nitrogen (N) is excessively added, surface cracks are caused at high temperature, and precipitates are formed and the remaining N exists in an atomic state to lower toughness, and thus, the present invention can limit the upper limit of the content of nitrogen (N) to 0.006%. Therefore, the nitrogen (N) content of the present invention may be in the range of 0.002 to 0.006%. The preferable content of nitrogen (N) may be in the range of 0.003 to 0.006%, and the more preferable content of nitrogen (N) may be in the range of 0.003 to 0.005%.
Phosphorus (P): 0.01% or less (not including 0%)
Since phosphorus (P) is an element that embrittles steel by intergranular segregation, the upper limit of the content of phosphorus (P) can be limited to 0.01% in the present invention. However, phosphorus (P) is a representative impurity element flowing from a steel making process, and complete removal of phosphorus (P) from steel is not preferable in terms of cost and time. Therefore, the present invention may exclude 0% in the lower limit of the phosphorus (P) content.
Sulfur (S): 0.003% or less (not including 0%)
Sulfur (S) mainly combines with manganese (Mn) to form MnS inclusions that hinder low temperature toughness, and therefore, the present invention limits the upper limit of the sulfur (S) content to 0.003% to ensure low temperature toughness and low temperature fatigue characteristics. However, sulfur (S) is also a representative impurity element flowing from the steel making process, and complete removal of sulfur (S) from steel is not preferable in terms of cost and time. Therefore, the present invention may exclude 0% in the lower limit of the sulfur (S) content.
Copper (Cu), chromium (Cr), molybdenum (Mo)
Copper (Cu) is a component that does not significantly reduce impact characteristics, and is not a component that significantly contributes to improving the rigidity of steel. In addition, when copper (Cu) is excessively added, surface cracks due to thermal shock are generated, and therefore, the present invention is a low cost component and can exclude the addition of Cu.
Chromium (Cr) and molybdenum (Mo) are components that can easily increase the rigidity by forming carbide. However, in the case of an extremely thick steel material, chromium (Cr) and molybdenum (Mo) form coarse carbides depending on the cooling rate of the sheet, and thus impact toughness is hindered, so that the present invention can exclude the addition of chromium (Cr) and molybdenum (Mo).
[ relational expression 1]
0.23≤[C]+[Si]+10*[A1]≤0.61
In the relational expression 1, [ C ], [ Si ] and [ Al ] represent the contents (wt%) of the respective alloy compositions.
When the value calculated by the above-mentioned relational expression 1 is less than 0.23, the yield strength of the steel material does not reach 350MPa, and when the value calculated by the above-mentioned relational expression 1 exceeds 0.61, the formation of MA is promoted and the MA fraction is several percent, so that the impact characteristics may be degraded. Therefore, the present invention can coordinate the relative content ranges of carbon (C), silicon (Si), and aluminum (Al) so that the value calculated by the relational expression 1 satisfies the range of 0.23 to 0.61.
[ relational expression 2]
1.35≤[Mn]+2*[Ni]+10*[Nb]≤2.7
In the relational expression 2, [ Mn ], [ Ni ], and [ Nb ] represent the contents (wt%) of the respective alloy compositions.
Relation 2 relates to fraction assurance useful for ensuring acicular ferrite. That is, in the present invention, in order to secure 30 to 50 area% of acicular ferrite, the relative content ranges of manganese (Mn), nickel (Ni), and niobium (Nb) may be coordinated so that the value calculated by relational expression 2 satisfies the range of 1.35 to 2.7.
In the present invention, the balance may be Fe and inevitable impurities in addition to the above steel composition. Unavoidable impurities can be inadvertently mixed in a typical steel making process and cannot be completely excluded, and their meaning can be easily understood by those skilled in the steel making industry. In addition, the present invention does not completely exclude the addition of compositions other than the above steel compositions.
The microstructure of the present invention will be described in further detail below.
The thick steel plate excellent in low-temperature toughness according to an aspect of the present invention may include 50 to 70% of polygonal ferrite and 30 to 50% of acicular ferrite as a fine structure by area fraction.
In order to achieve center impact toughness at-50 ℃ and fatigue characteristics at-60 ℃ in the extremely thick steel material of the present invention, it is important that the grain size of ferrite, dislocation density, and the like are minimized, and it is important to minimize MA and cementite. The fine polygonal ferrite improves impact toughness absorption energy, while the acicular ferrite improves rigidity, so the combination of the two fine structures is an important factor for securing impact toughness as well as rigidity.
When the fraction of polygonal ferrite is less than 50 area%, it may be difficult to secure impact toughness at-50 ℃ due to the increase in the fraction of acicular ferrite and hard second phase. In addition, when the fraction of polygonal ferrite exceeds 70 area%, the fraction of acicular ferrite decreases, and the securing of rigidity may be impaired.
On the other hand, if the fraction of acicular ferrite is less than 30 area%, there is a problem that the desired level of rigidity cannot be secured. In addition, if the fraction of acicular ferrite exceeds 50 area%, there is a problem that the low temperature toughness of the target level cannot be secured.
The fraction of one or both of the cementite and MA phases may be 5% or less (including 0%) by area. Cementite and MA phase are not favorable for securing low-temperature impact toughness, and the present invention is to positively suppress their formation. Preferably, the fraction of one or both of the cementite and MA phases may be 3% or less (including 0%) by area, and more preferably, the fraction of one or both of the cementite and MA phases may be 1% or less (including 0%) by area.
The ferrite may have an average grain size of 20 μm or less. This is because, when the average grain size of ferrite exceeds 20 μm, the rigidity and low-temperature toughness are simultaneously lowered due to grain growth.
The thick steel plate excellent in low-temperature toughness according to an aspect of the present invention may have a thickness of 20 to 120 mm. In addition, the thick steel plate excellent in low temperature toughness according to an aspect of the present invention may have a yield strength of 355Mpa or more and an impact toughness of 100J or more at-50 ℃, and may have a tensile strength of 450Mpa or more.
The production method of the present invention is described in further detail below.
The method for manufacturing a thick steel plate excellent in low-temperature toughness according to an aspect of the present invention may include: heating a steel billet at 1020-1100 ℃, wherein the steel billet comprises by weight percent: carbon (C): 0.03 to 0.06%, silicon (Si): 0.1 to 0.2%, manganese (Mn): 1.0-2.0%, soluble aluminum (sol. al): 0.01-0.035%, niobium (Nb): 0.015 to 0.03%, titanium (Ti): 0.001 to 0.02%, nickel (Ni): 0.1 to 0.2%, nitrogen (N): 0.002-0.006%, phosphorus (P): 0.01% or less (excluding 0%), sulfur (S): 0.003% or less, and the balance of Fe and other unavoidable impurities, and satisfying the following relational expressions 1 and 2, a step of hot rolling the thus heated slab to obtain a hot rolled steel, and a step of cooling the hot rolled steel at a cooling finish temperature of 450 ℃ or less; the hot rolling includes recrystallization rolling and non-recrystallization rolling.
[ relational expression 1]
0.23≤[C]+[Si]+10*[Al]≤0.61
In the relational expression 1, [ C ], [ Si ] and [ Al ] represent the contents (wt%) of the respective alloy compositions.
[ relational expression 2]
1.35≤[Mn]+2*[Ni]+10*[Nb]≤2.7
In the relational expression 2, [ Mn ], [ Ni ], and [ Nb ] represent the contents (wt%) of the respective alloy compositions.
Billet heating step
The billet having the above composition is heated at 1020 to 1100 ℃. The billet alloy composition of the present invention corresponds to the alloy composition of the thick steel plate described above, and therefore the description of the billet alloy composition of the present invention is replaced with the description of the alloy composition of the thick steel plate described above.
When the heating temperature during heating of the billet is too high, austenite grains are coarsened and a bainite structure is formed by increasing the hardening energy, thereby lowering the toughness, and when the heating temperature is too low, the solid solution of titanium (Ti) and niobium (Nb) may become insufficient, possibly resulting in lowering the rigidity. Therefore, the invention can limit the heating temperature of the billet steel within the range of 1020-1100 ℃.
Step of obtaining a Hot rolled Steel product
The slab heated as described above is hot-rolled to obtain a hot-rolled steel. The hot rolling may include recrystallization rolling and non-recrystallization rolling.
The recrystallization rolling may be performed at a temperature of 900 to 1050 ℃. In the hot rolling, it is preferable that the reduction ratio of recrystallization rolling in the last two passes at 900 ℃ or higher is 15 to 20%. This is to completely recrystallize austenite and to suppress refinement and growth of austenite.
Rolling at 830-Ar without recrystallization3Starting at temperature, preferably Ar3Above the temperature, at a temperature above about 750 ℃. In the case of non-recrystallization rolling, for example, a thick steel material having a thickness of 100 to 120mm preferably has a cumulative rolling reduction of 30 to 40%.
The thickness of the hot rolled steel after hot rolling may be 20 to 120 mm.
Step of cooling hot rolled steel
The hot-rolled steel material obtained by hot rolling as described above is cooled at a cooling finish temperature of 450 ℃ or lower.
The hot rolled steel material may be cooled by water cooling in order to achieve the rigidity and microstructure of the final steel material. For example, the hot rolled steel material may be cooled to a cooling completion temperature of 450 ℃ or lower at a cooling rate of 1 to 8 ℃/sec. This is to suppress the difference in physical properties due to the difference in cooling rate between the surface and the central portion, and when the cooling end temperature is higher than 450 ℃, the formation of MA is promoted, which results in the deterioration of impact toughness. The more preferable cooling end temperature may be 300 ℃ or less, and the more preferable cooling rate may be 2 to 4 ℃/sec. The hot rolled steel can be cooled to normal temperature.
The thick steel sheet produced by the production method according to one aspect of the present invention may contain 50 to 70 area% of polygonal ferrite and 30 to 50 area% of acicular ferrite as a fine structure, and may further contain 5 area% or less (including 0%) of cementite and one or both of MA phases. In this case, the ferrite-side average crystal grain size may be 20 μm or less.
The thick steel plate manufactured by the manufacturing method of an aspect of the present invention may have a yield strength of 355Mpa or more and an impact toughness of 100J or more at-50 ℃, and may have a tensile strength of 450Mpa or more.
Detailed Description
Hereinafter, the present invention will be described in more detail by examples. It should be noted, however, that the embodiments described below are only intended to be more embodied by illustrating the present invention, and are not intended to limit the scope of the claims of the present invention.
After preparing molten steels having the composition shown in table 1 below and having the composition relation shown in table 3, billets were prepared by continuous casting. The slabs were hot-rolled and cooled under the manufacturing conditions in table 2 below to manufacture hot-rolled steel.
In table 1 below, the unit of the content of each element is wt%. The invention steels A to C are steels satisfying the composition ranges specified in the present invention, and the comparative steels D to G are steels not satisfying the composition ranges specified in the present invention. Comparative steel D did not reach [ C ] + [ Si ] +10 ] Al content, comparative steel E exceeded [ C ] + [ Si ] +10 ] Al content, comparative steel F did not reach [ Mn ] +2 [ Ni ] +10 ] Nb content, and comparative steel G was a steel exceeding [ Mn ] +2 [ Ni ] +10 ] Nb content.
In the process conditions, hot rolling is carried out under conditions in which the reduction ratio of the last two passes of recrystallization rolling at 900 ℃ or higher is 19% and the cumulative reduction ratio of non-recrystallization rolling is 37%. The microstructure and physical properties of the hot-rolled steel material produced as described above were measured, and the results are shown in table 3 below. On the other hand, the microstructure of invention example 1 was observed, and the results are shown in fig. 1.
[ TABLE 1]
[ TABLE 2]
[ TABLE 3 ]
As shown in tables 1 to 3, it is understood that the invention examples 1 to 3, which all satisfy the alloy composition and the production conditions disclosed in the present invention, can secure a yield strength of 350MPa and a tensile strength of 450MPa or more, and an impact toughness of 100J or more at-50 ℃. In addition, as shown in fig. 1, in inventive example 1, it was confirmed that the average grain size was 20 μm (micrometer) or less, and polygonal ferrite and acicular ferrite were uniformly distributed at an appropriate ratio. It can be seen that this is an important factor in ensuring the stiffness and toughness of extremely thick materials which the present invention is intended to address.
On the one hand, with comparative example 1, although the alloy composition disclosed in the present invention was satisfied, the cooling end temperature in the production conditions could not be satisfied, which indicates that the impact characteristics at-50 ℃ were poor, which was judged to be due to the large amount of MA produced.
In comparative examples 2, 3, 4 and 5, it is understood that the production conditions disclosed in the present invention were satisfied, but the alloy composition was not satisfied, and the rigidity and sufficient impact toughness property could not be secured.
Specifically, in comparative example 2, the fraction of acicular ferrite was decreased due to the missing content of [ C ] + [ Si ] +10 × a1], which showed a result of decrease in rigidity. In comparative example 3, since the formation of MA was promoted over the range of [ C ] + [ Si ] + 10X [ A1], the MA fraction increased, resulting in poor impact toughness. In comparative examples 4 and 5, it is understood that strength is lowered when the strength is not reached or exceeds the range of [ Mn ] +2 + Ni ] +10 + Nb ], and impact toughness is lowered when the strength is exceeded due to an increase in acicular ferrite.
Although the description has been made with reference to the above embodiments, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the invention as set forth in the claims.
Claims (11)
1. A thick steel plate having excellent low-temperature toughness, wherein,
comprises C: 0.03-0.06%, Si: 0.1-0.2%, Mn: 1.0-2.0%, Al: 0.01-0.035%, Nb: 0.015-0.03%, Ti: 0.001-0.02%, Ni: 0.1-0.2%, N: 0.002-0.006%, P: 0.01% or less and not including 0%, S: 0.003% or less, and the balance Fe and other inevitable impurities, and satisfies the following relational expressions 1 and 2,
the fine structure comprises 50 to 70% by area of polygonal ferrite and 30 to 50% by area of acicular ferrite,
the ferrite has an average grain size of 20 μm or less,
[ relational expression 1]
0.23≤[C]+[Si]+10*[Al]≤0.61
In the relational expression 1, [ C ], [ Si ] and [ Al ] represent the contents in wt% of each alloy composition,
[ relational expression 2]
1.35≤[Mn]+2*[Ni]+10*[Nb]≤2.7
In the relational expression 2, [ Mn ], [ Ni ], and [ Nb ] represent the contents of the respective alloy compositions in wt%.
2. The thick steel plate excellent in low-temperature toughness according to claim 1,
the fine structure further contains one or both of cementite and MA phase,
the fraction of one or both of the cementite and MA phases is 5% or less by area and does not contain 0%.
3. The thick steel plate excellent in low-temperature toughness according to claim 1,
the thick steel plate has a yield strength of 355MPa or more,
the impact toughness of the thick steel plate at-50 ℃ is 100J or more.
4. The thick steel plate excellent in low-temperature toughness according to claim 1,
the tensile strength of the thick steel plate is above 450 MPa.
5. A method for manufacturing a thick steel plate having excellent low-temperature toughness, comprising:
heating a steel billet at 1020-1100 ℃, wherein the steel billet comprises C: 0.03-0.06%, Si: 0.1-0.2%, Mn: 1.0-2.0%, Al: 0.01-0.035%, Nb: 0.015-0.03%, Ti: 0.001-0.02%, Ni: 0.1-0.2%, N: 0.002-0.006%, P: 0.01% or less and not including 0%, S: 0.003% or less, and the balance Fe and other inevitable impurities, and satisfies the following relational expressions 1 and 2,
a step of hot rolling the slab heated as described above to obtain a hot rolled steel, and
cooling the hot-rolled steel at a cooling completion temperature of 450 ℃ or lower;
the hot rolling includes recrystallization rolling and non-recrystallization rolling,
[ relational expression 1]
0.23≤[C]+[Si]+10*[Al]≤0.61
In the relational expression 1, [ C ], [ Si ] and [ Al ] represent the contents in wt% of each alloy composition,
[ relational expression 2]
1.35≤[Mn]+2*[Ni]+10*[Nb]≤2.7
In the relational expression 2, [ Mn ], [ Ni ], and [ Nb ] represent the contents of the respective alloy compositions in wt%.
6. The method for manufacturing a thick steel plate excellent in low-temperature toughness according to claim 5,
the recrystallization rolling is carried out at a temperature of 900 ℃ or higher in the last two passes at a reduction ratio of 15 to 20% respectively.
7. The method for manufacturing a thick steel plate excellent in low-temperature toughness according to claim 5,
the non-recrystallization rolling is completed at 750 ℃ or higher.
8. The method for manufacturing a thick steel plate excellent in low-temperature toughness according to claim 5,
the cumulative reduction rate of the unrecrystallized rolling is 30 to 40%.
9. The method for manufacturing a thick steel plate excellent in low-temperature toughness according to claim 5,
the cooling end temperature is 300 ℃ or lower.
10. The method for manufacturing a thick steel plate excellent in low-temperature toughness according to claim 5,
the cooling speed of the cooling is 1-8 ℃/s.
11. The method for manufacturing a thick steel plate excellent in low-temperature toughness according to claim 10,
the cooling speed of the cooling is 2-4 ℃/s.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020170178949A KR101999018B1 (en) | 2017-12-24 | 2017-12-24 | Thick steel plate with excellent low-temperature toughness and method for manufacturing the same |
| KR10-2017-0178949 | 2017-12-24 | ||
| PCT/KR2018/015950 WO2019124890A1 (en) | 2017-12-24 | 2018-12-14 | Thick steel plate having excellent low-temperature toughness and manufacturing method therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111511950A true CN111511950A (en) | 2020-08-07 |
Family
ID=66994972
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201880082930.2A Pending CN111511950A (en) | 2017-12-24 | 2018-12-14 | Thick steel plate having excellent low-temperature toughness and method for producing same |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP3730640A1 (en) |
| JP (1) | JP7064597B2 (en) |
| KR (1) | KR101999018B1 (en) |
| CN (1) | CN111511950A (en) |
| WO (1) | WO2019124890A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113201691A (en) * | 2021-04-28 | 2021-08-03 | 攀钢集团攀枝花钢铁研究院有限公司 | Hot rolled steel plate for 590 MPa-level hydraulic bulging and preparation method thereof |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR102218423B1 (en) * | 2019-08-23 | 2021-02-19 | 주식회사 포스코 | Thin steel plate having excellent low-temperature toughness and ctod properties, and method for manufacturing thereof |
| CN114686776B (en) * | 2022-03-31 | 2022-10-18 | 鞍钢股份有限公司 | 460 MPa-grade high-toughness extra-thick plate and manufacturing method thereof |
| CN116162855B (en) * | 2023-02-28 | 2024-01-30 | 马鞍山钢铁股份有限公司 | 600 MPa-level thick-specification phosphorus-containing hot-rolled weather-resistant steel plate and manufacturing method thereof |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101705439A (en) * | 2009-12-18 | 2010-05-12 | 江苏省沙钢钢铁研究院有限公司 | Low-temperature high-toughness F460 grade super strength steel plate for building ship and manufacturing method thereof |
| CN104169444A (en) * | 2012-03-30 | 2014-11-26 | 奥钢联钢铁有限责任公司 | High strength cold rolled steel sheet and method of producing such steel sheet |
| KR20160078562A (en) * | 2014-12-24 | 2016-07-05 | 주식회사 포스코 | Steel plate having excellent fracture resistance and yield ratio, and method for manufacturing the same |
| CN107502821A (en) * | 2017-08-29 | 2017-12-22 | 江阴兴澄特种钢铁有限公司 | The economical X 70 pipeline steel plate and its manufacture method used under a kind of special think gauge ultra-low temperature surroundings |
Family Cites Families (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0649898B2 (en) * | 1986-01-24 | 1994-06-29 | 株式会社神戸製鋼所 | Method for producing low yielding high yield point steel with excellent toughness in the heat affected zone |
| JPS62256916A (en) * | 1986-04-28 | 1987-11-09 | Kobe Steel Ltd | Production of low-temperature extra-thick steel plate having excellent uniformity in thickness direction |
| KR100660230B1 (en) * | 2005-12-26 | 2006-12-21 | 주식회사 포스코 | Thick steel plate for welded structure having high strength and excellent toughness at the center of thickness and method of producing the same |
| JP4976749B2 (en) | 2006-06-02 | 2012-07-18 | 株式会社神戸製鋼所 | Steel sheet with excellent fatigue crack growth resistance |
| KR100957970B1 (en) * | 2007-12-27 | 2010-05-17 | 주식회사 포스코 | High-strength and high-toughness thick steel plate and method for producing the same |
| KR101185336B1 (en) * | 2010-07-28 | 2012-09-21 | 현대제철 주식회사 | STEEL PLATE WITH HIGH STRENGTH OF 500MPa GRADE AND LOW TEMPERATURE TOUGHNESS AND METHOD FOR MANUFACTURING THE SAME |
| JP5423737B2 (en) * | 2010-08-10 | 2014-02-19 | Ｊｆｅスチール株式会社 | High-strength hot-rolled steel sheet excellent in workability and manufacturing method thereof |
| JP5612532B2 (en) | 2011-04-26 | 2014-10-22 | 株式会社神戸製鋼所 | Steel sheet excellent in low temperature toughness and weld joint fracture toughness and method for producing the same |
| KR101403224B1 (en) * | 2011-12-28 | 2014-06-02 | 주식회사 포스코 | Thick steel plate having excellent low yield ratio property and low temperature toughness and method for manufacturing the steel plate |
| JP5833964B2 (en) | 2012-03-29 | 2015-12-16 | 株式会社神戸製鋼所 | Steel sheet excellent in bending workability, impact property and tensile property, and method for producing the same |
| JP5811032B2 (en) | 2012-05-23 | 2015-11-11 | 新日鐵住金株式会社 | Steel sheet for LPG tank |
| KR20150002956A (en) * | 2013-06-27 | 2015-01-08 | 현대제철 주식회사 | Steel sheet for line pipe and method of manufacturing the same |
| KR20160078624A (en) * | 2014-12-24 | 2016-07-05 | 주식회사 포스코 | Hot rolled steel sheet for steel pipe having excellent low-temperature toughness and strength and method for manufacturing the same |
| JP6763141B2 (en) | 2015-02-10 | 2020-09-30 | 日本製鉄株式会社 | Manufacturing method of steel plate for LPG tank |
| KR20160147153A (en) * | 2015-06-12 | 2016-12-22 | 동국제강주식회사 | Manufacturing method of high strength steel plate for line pipe and high strength steel plate for line pipe |
| KR20160150190A (en) * | 2015-06-18 | 2016-12-29 | 현대제철 주식회사 | Manufacturing mehtod for thick steel plate and thick steel plate thereof |
| KR101786258B1 (en) | 2015-12-23 | 2017-10-18 | 주식회사 포스코 | The steel sheet having high-strength and excellent heat affected zone toughness and method for manufacturing the same |
| KR101767778B1 (en) * | 2015-12-23 | 2017-08-14 | 주식회사 포스코 | Low yield ratio high strength steel having excellent resistance for stress corrosion cracking and low temperature toughness, and method for manufacturing the same |
| KR101758520B1 (en) * | 2015-12-23 | 2017-07-17 | 주식회사 포스코 | High strength structural steel sheet having excellent heat treatment resistance and method of manufacturing the same |
-
2017
- 2017-12-24 KR KR1020170178949A patent/KR101999018B1/en active IP Right Grant
-
2018
- 2018-12-14 CN CN201880082930.2A patent/CN111511950A/en active Pending
- 2018-12-14 JP JP2020534887A patent/JP7064597B2/en active Active
- 2018-12-14 WO PCT/KR2018/015950 patent/WO2019124890A1/en unknown
- 2018-12-14 EP EP18890536.8A patent/EP3730640A1/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101705439A (en) * | 2009-12-18 | 2010-05-12 | 江苏省沙钢钢铁研究院有限公司 | Low-temperature high-toughness F460 grade super strength steel plate for building ship and manufacturing method thereof |
| CN104169444A (en) * | 2012-03-30 | 2014-11-26 | 奥钢联钢铁有限责任公司 | High strength cold rolled steel sheet and method of producing such steel sheet |
| KR20160078562A (en) * | 2014-12-24 | 2016-07-05 | 주식회사 포스코 | Steel plate having excellent fracture resistance and yield ratio, and method for manufacturing the same |
| CN107502821A (en) * | 2017-08-29 | 2017-12-22 | 江阴兴澄特种钢铁有限公司 | The economical X 70 pipeline steel plate and its manufacture method used under a kind of special think gauge ultra-low temperature surroundings |
Non-Patent Citations (2)
| Title |
|---|
| 张继明等: "《X90/X100管线钢与钢管显微组织鉴定图谱》", 30 November 2017, 陕西新华出版传媒集团 陕西科学技术出版社 * |
| 王有铭等: "《钢材的控制轧制和控制冷却》", 31 March 2009, 冶金工业出版社 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113201691A (en) * | 2021-04-28 | 2021-08-03 | 攀钢集团攀枝花钢铁研究院有限公司 | Hot rolled steel plate for 590 MPa-level hydraulic bulging and preparation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JP7064597B2 (en) | 2022-05-10 |
| JP2021507118A (en) | 2021-02-22 |
| EP3730640A4 (en) | 2020-10-28 |
| WO2019124890A1 (en) | 2019-06-27 |
| KR101999018B1 (en) | 2019-07-10 |
| KR20190077196A (en) | 2019-07-03 |
| EP3730640A1 (en) | 2020-10-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101253890B1 (en) | Ultra thick steel sheet for pressure vessel having excellent central properties and hydrogen induced cracking resistance, and method for manufacturing the same | |
| JP4660250B2 (en) | Thick high-strength steel sheet with excellent low-temperature toughness in the heat affected zone by high heat input welding | |
| JP5397363B2 (en) | Thick high-strength steel sheet with excellent low-temperature toughness in the heat affected zone by high heat input welding | |
| CN110114491B (en) | High manganese steel having excellent low-temperature toughness and yield strength, and method for producing same | |
| CN111511950A (en) | Thick steel plate having excellent low-temperature toughness and method for producing same | |
| KR101205144B1 (en) | H-steel for building structure and method for producing the same | |
| KR20160078669A (en) | Steel plate for pressure vessel having excellent strength and toughness after post weld heat treatment and method for manufacturing the same | |
| JP4878219B2 (en) | Steel sheet with excellent HAZ toughness and small reduction in strength due to heat treatment after welding | |
| KR101465088B1 (en) | Low carbon high strength steel plates with good low temperature toughness and manufacturing method for the same | |
| CN111225987B (en) | Thick steel sheet having excellent low-temperature strain aging impact characteristics and method for producing same | |
| JP4514150B2 (en) | High strength steel plate and manufacturing method thereof | |
| KR101070132B1 (en) | Steel with Excellent Low-Temperature Toughness for Construction and Manufacturing Method Thereof | |
| KR101964247B1 (en) | High-strength thick steel sheet and method for manufacturing same | |
| KR101359082B1 (en) | Thick steel sheet with excellent low temperature dwtt property and method for producing same | |
| KR100957961B1 (en) | High strength steel plate having excellent welded zone toughness for linepipe and the method for manufacturing the same | |
| US20220403479A1 (en) | Normalizing heat-treated steel sheet having good low-temperature impact toughness and method for manufacturing same | |
| KR101403062B1 (en) | Thick Steel Plate for Offshore Structure Having Ultra-High Strength And Method for Manufacturing the Steel Plate | |
| KR101543915B1 (en) | Austenitic steels for low temperature services having excellent strength and method for manufacturing the same | |
| KR20200076799A (en) | Ultra thick steel plate having excellent toughness at the center of thickness and manufacturing method for the same | |
| KR20200075964A (en) | Ultra-high strength and high toughness steel plate and method for manufacturing the same | |
| KR20230094381A (en) | Steel plate having high strength and excellent impact toughness after deformation and method for manufacturing the same | |
| KR20230094375A (en) | Steel plate having high strength and excellent low temperature impact toughness and method for manufacturing the same | |
| CN111566248B (en) | Hot-rolled steel sheet and steel pipe having excellent low-temperature toughness, and method for producing same | |
| KR101989251B1 (en) | Structural steel and method of manufacturing the same | |
| CN117795115A (en) | Steel sheet having excellent toughness in heat affected zone and method for producing same |
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 | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20200807 |
|
| WD01 | Invention patent application deemed withdrawn after publication |