WO2012108027A1 - High-strength steel material for steam piping, and process for production thereof - Google Patents

High-strength steel material for steam piping, and process for production thereof Download PDF

Info

Publication number
WO2012108027A1
WO2012108027A1 PCT/JP2011/052831 JP2011052831W WO2012108027A1 WO 2012108027 A1 WO2012108027 A1 WO 2012108027A1 JP 2011052831 W JP2011052831 W JP 2011052831W WO 2012108027 A1 WO2012108027 A1 WO 2012108027A1
Authority
WO
WIPO (PCT)
Prior art keywords
less
mass
steel material
steel
temperature
Prior art date
Application number
PCT/JP2011/052831
Other languages
French (fr)
Japanese (ja)
Inventor
中村　浩史
岡口　秀治
Original Assignee
住友金属工業株式会社
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by 住友金属工業株式会社 filed Critical 住友金属工業株式会社
Priority to PCT/JP2011/052831 priority Critical patent/WO2012108027A1/en
Priority to JP2012556708A priority patent/JP5447698B2/en
Publication of WO2012108027A1 publication Critical patent/WO2012108027A1/en

Links

Images

Classifications

    • 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
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • C21D9/14—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes wear-resistant or pressure-resistant pipes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese

Definitions

  • the present invention relates to a high-strength steel material for steam piping and a manufacturing method thereof.
  • Oil sand is sandstone containing mineral oil with extremely high viscosity (hereinafter referred to as “bitumen”).
  • bitumen extremely high viscosity
  • steam at a high temperature of about 350 ° C into oil sand for a long period of 20 years or longer.
  • the steel material for steam piping which can send high temperature steam for a long period of time is calculated
  • Patent Document 1 discloses a technique relating to a method for manufacturing a steel sheet for high-strength steam piping that is excellent in the toughness of a welding heat-affected zone (hereinafter referred to as “HAZ”).
  • Patent Document 2 discloses a technique related to a steel plate and a steel pipe for steam transport piping excellent in high-temperature characteristics and a method for producing them. According to the techniques disclosed in Patent Document 1 and Patent Document 2, it is said that a steel material for steam piping having a yield strength of 550 MPa or more can be obtained.
  • the present invention has a yield strength of 700 MPa or more even after being exposed to a high temperature for a long period of time, and also has good toughness and weldability, and is a high-strength steel material for steam piping. And it aims at providing the manufacturing method.
  • simulated heat treatment a heat treatment condition that simulates a use condition of exposure to 350 ° C. for 20 years using the Larson-Miller parameter (hereinafter, this heat treatment is referred to as “simulated heat treatment”).
  • Plm is a parameter for correcting time with temperature, and using this parameter can shorten the experiment time. That is, in Plm, the parameter value of the temperature and period (time) assumed in the use condition of the steel material is approximately the same as the parameter value of the temperature and period (time) in the experiment. Assumed use conditions of steel materials (use conditions for 20 years exposure to 350 ° C.) correspond to, for example, heat treatment at 400 ° C. for 2000 hours, heat treatment at 450 ° C. for 50 hours, and heat treatment at 500 ° C. for 2 hours. Plm at this time is 15700.
  • the present inventors have investigated the conditions for yield strength of 700 MPa or more at room temperature even after the heat treatment with Plm of 15700 for various steel materials, and completed the present invention.
  • the gist of the present invention resides in high strength steel materials for steam piping shown in the following (A) to (D) and high strength steel materials for steam piping shown in (E) to (G) below.
  • Heating, rolling and accelerated cooling are performed under the condition that Fp obtained from the following formula (4) is 86 or more.
  • Method for producing a high-strength steel product for a steam pipe characterized.
  • Pcm C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B
  • Fc 44-165C-34Si-26Mn-12Cu + 85Ni + 12Cr + 73Mo + 13V-77Nb + 9900B
  • Fp (10Fc + Th + 5Tf + 5Ta + Tb) / 100 (4)
  • the element symbols in the formulas (1) and (2) mean the content (mass%) of each element in the steel
  • Fc in the formula (4) is a value obtained from the formula (2)
  • Th is the rolling Previous heating temperature (° C.)
  • Tf means rolling finish temperature (° C.)
  • Ta means accelerated cooling start temperature (° C.)
  • Tb means
  • the high-strength steel material of the present invention has a yield strength of 700 MPa or more even after being exposed to a high temperature of 350 ° C. or longer for a long time, it is suitable as a high-strength steel material for steam piping. Particularly, it is suitable for piping for injecting steam into oil sand, piping for transporting bitumen after injecting water vapor, and the like. Since the high-strength steel material of the present invention is excellent in toughness and weldability, pipe production can be easily performed in the UOE process. According to the manufacturing method of the present invention, the high-strength steel material can be manufactured relatively easily.
  • % of the content of each element in the chemical composition means “mass%”.
  • C is an element necessary for increasing the strength of steel. In order to obtain this effect, the C content is 0.02% or more. However, if the C content exceeds 0.15%, weld cracking is likely to occur. Therefore, the C content is 0.02 to 0.15%. A preferred lower limit is 0.03%. A preferable upper limit is 0.11%, and a more preferable upper limit is 0.07%.
  • Si 0.01 to 0.60%
  • Si is an element having a deoxidizing action. In order to obtain this effect, the Si content is 0.01% or more. However, if the Si content exceeds 0.60%, the toughness of the base material and the HAZ is significantly deteriorated. Therefore, the Si content is set to 0.01 to 0.60%.
  • a preferred lower limit is 0.05%, and a more preferred lower limit is 0.09%.
  • a preferable upper limit is 0.30%.
  • Mn 0.5 to 2.5%
  • Mn has the effect
  • the Mn content is 0.5% or more. However, if the content exceeds 2.5%, weld cracks are likely to occur. Therefore, the Mn content is set to 0.5 to 2.5%.
  • a preferred lower limit is 1.2%, and a more preferred lower limit is 1.4%.
  • a preferable upper limit is 2.0%.
  • Ti 0.005 to 0.05%
  • Ti forms precipitates (TiN) together with N to improve the toughness of HAZ, so 0.005% or more is contained.
  • the Ti content is set to 0.005 to 0.05%.
  • a preferred lower limit is 0.007%.
  • a preferable upper limit is 0.025%, a more preferable upper limit is 0.020%, and a further preferable upper limit is 0.014%.
  • sol. Al 0.005 to 0.090%
  • Al is an element having a deoxidizing action.
  • sol. Al (“acid-soluble Al”) is contained in an amount of 0.005% or more.
  • the Al content is 0.005 to 0.090%.
  • a preferred lower limit is 0.015%.
  • a preferable upper limit is 0.060%, and a more preferable upper limit is 0.045%.
  • N 0.001 to 0.009% N forms a precipitate (TiN) together with Ti to improve the toughness of the HAZ, so 0.001% or more is contained. However, if the content exceeds 0.009%, the toughness of the base material and the HAZ deteriorates. Therefore, the N content is set to 0.001 to 0.009%.
  • a preferred lower limit is 0.002%.
  • a preferable upper limit is 0.005%.
  • the high-strength steel material for steam piping of the present invention contains the above-mentioned elements as basic components, and Cu: 0.1 to 2.0%, Ni: 0.1 to 3.0% in order to improve the strength of the steel material.
  • Cr 0.1-1.0%, Mo: 0.05-1.0%, V: 0.01-0.10%, Nb: 0.005-0.09% and B: 0.0003 Contains one or more selected from ⁇ 0.0050%.
  • Cu 0.1 to 2.0%
  • Cu is an element effective for improving the strength of the steel material. This effect becomes remarkable when Cu is contained by 0.1% or more. However, if the Cu content exceeds 2.0%, the surface properties and toughness of the steel material are deteriorated, and weld cracks are likely to occur. Therefore, the content when Cu is contained is 0.1 to 2.0% or less. A preferred lower limit is 0.2%. A preferable upper limit is 0.60% or less.
  • Ni 0.1-3.0%
  • Ni is an element effective for improving the strength and toughness of a steel material. This effect becomes remarkable when Ni is contained by 0.1% or more. However, when the Ni content exceeds 3.0%, the surface properties of the steel material may be deteriorated. Therefore, when Ni is contained, the content is made 0.1 to 3.0%. A preferred lower limit is 0.2%. A preferable upper limit is 0.60%.
  • Cr 0.1 to 1.0% Cr is an element effective for improving the strength of a steel material. This effect becomes remarkable when Cr is contained by 0.1% or more. However, if the Cr content exceeds 1.0%, weld cracks are likely to occur. Therefore, when Cr is contained, the content is set to 0.1 to 1.0%. A preferred lower limit is 0.2%. A preferable upper limit is 0.60%.
  • Mo 0.05 to 1.0% Mo is an element effective for improving the strength of the steel material. This effect becomes remarkable when 0.05% or more of Mo is contained. However, if the Mo content exceeds 1.0%, weld cracks are likely to occur. Therefore, when Mo is contained, the content is set to 0.05 to 1.0%. A preferred lower limit is 0.1%. A preferable upper limit is 0.60%.
  • V 0.01 to 0.10%
  • V is an element effective for improving the strength of the steel material. This effect becomes remarkable when V is contained by 0.01% or more. However, if the V content exceeds 0.10%, ductility and toughness may be deteriorated. Therefore, when V is contained, the content is made 0.01 to 0.10%.
  • a preferred lower limit is 0.02%.
  • a preferable upper limit is 0.06%.
  • Nb 0.005 to 0.09%
  • Nb has an effect of improving the strength of the steel material, and also has an effect of increasing the base material toughness if appropriate rolling is performed. This effect becomes remarkable when Nb is contained by 0.005% or more.
  • a preferred lower limit is 0.01%.
  • a preferable upper limit is 0.06%, and a more preferable upper limit is 0.04%.
  • B 0.0003 to 0.0050%
  • B is an element effective for improving the strength of the steel material. This effect becomes remarkable when B is contained by 0.0003% or more. However, if the content of B exceeds 0.0050%, weld cracking is likely to occur. Therefore, when B is contained, the content is made 0.0003 to 0.0050%.
  • a preferred lower limit is 0.0006%, and a more preferred lower limit is 0.0010%.
  • a preferred upper limit is 0.0025%.
  • the high-strength steel material for steam piping of the present invention has the above-described chemical composition, and the balance is made of Fe and impurities.
  • An impurity means the component mixed by raw materials and other factors, such as an ore and a scrap, when manufacturing steel materials industrially.
  • P, S and O as impurities is high, there is a possibility of deteriorating the properties of the steel. Therefore, it is necessary to limit the content of these elements to the following ranges.
  • P 0.020% or less P is an element that inevitably exists as an impurity in the steel material and deteriorates toughness. However, the P content is acceptable up to 0.020%. A preferable upper limit is 0.015%. A more preferred upper limit is 0.005%.
  • S 0.010% or less S is an element that inevitably exists as an impurity in the steel material and generates many inclusions harmful to ductility or toughness. However, the S content is acceptable up to 0.010%.
  • a preferred upper limit is 0.004%, a more preferred upper limit is 0.002%, and a further preferred upper limit is 0.001%.
  • O 0.005% or less
  • O (oxygen) is an element that inevitably exists as an impurity in the steel material and adversely affects the base material toughness and ductility.
  • the O content is acceptable up to 0.005%.
  • a preferable upper limit is 0.002%.
  • the high strength steel material for steam piping of the present invention may contain the following elements instead of a part of Fe.
  • Ca and REM are effective elements for controlling the form of sulfide (particularly MnS) and improving low temperature toughness and hydrogen cracking resistance.
  • Ca and / or REM may be included.
  • the content is excessive, inclusions containing Ca and REM become coarse.
  • the cleanliness of the steel is impaired and the weldability may be adversely affected. Therefore, when Ca is contained, the content is 0.01% or less, and when REM is contained, the content is 0.02% or less. The above effect becomes remarkable when Ca is contained in an amount of 0.0005% or more and REM is contained in an amount of 0.001% or more.
  • the Ca content is preferably 0.006% or less from the viewpoint of weldability.
  • REM is a generic name for a total of 17 elements of Sc, Y, and lanthanoid, and can contain one or more selected from these elements.
  • the content of REM means the total amount of the above elements.
  • Mg 0.008% or less Mg forms an oxide finely dispersed, and exhibits the effect of improving the low temperature toughness by suppressing coarsening of the austenite grain size of HAZ.
  • Mg may be contained.
  • the Mg content exceeds 0.008%, a coarse oxide may be generated to deteriorate toughness.
  • the content shall be 0.008% or less. The above effect becomes significant when Mg is contained in an amount of 0.0005% or more.
  • Sn 0.50% or less
  • Sn has a function of suppressing corrosion by dissolving as Sn 2+ . This is because Sn 2+ has an effect of rapidly reducing Fe 3+ having a corrosion promoting action. Sn also has the effect of suppressing the anodic dissolution reaction of steel and improving the corrosion resistance. In order to obtain these effects, Sn may be included. However, when the Sn content exceeds 0.50%, these effects are saturated. Therefore, when it contains Sn, the content shall be 0.50% or less. The above effect becomes remarkable when Sn is contained by 0.03% or more. A preferred lower limit is 0.05%. A preferable upper limit is 0.30%.
  • each element in the steel material has a yield strength of 700 MPa or more and good toughness and weldability when used under severe conditions of being exposed to 350 ° C. for 20 years. It cannot be obtained stably. Therefore, it is necessary to set Pcm obtained from the following equation (1) and Fc obtained from the following equation (2) within a specific range.
  • Pcm 0.15 to 0.29
  • Pcm is an index for maintaining the mechanical performance of the base material and obtaining good weldability.
  • the strength of the base material increases as Pcm increases, and becomes better when the Pcm is 0.15 or more. However, when Pcm exceeds 0.29, weld cracks become prominent. Therefore, Pcm is set to 0.15 to 0.29.
  • the lower limit is preferably set to 0.17.
  • the upper limit is preferably 0.25. A more preferred upper limit is 0.23, and a more preferred upper limit is 0.21.
  • Fc 30 or more
  • the present inventors conducted experiments in which various steel materials were subjected to simulated heat treatment under use conditions that were exposed to 350 ° C. for 20 years based on the Larson-Miller parameter.
  • the element which reduces the mechanical properties of the steel material when exposed to 350 ° C. for 20 years was specified, and the above formula (2) was found in consideration of the influence of each element.
  • the inventors of the present invention if Fc is 30 or more, the decrease in yield strength after the experiment is small, that is, the yield strength of the steel material is maintained at 700 MPa or more even after being exposed to 350 ° C. for 20 years. It was found that it can be done (see FIG. 1).
  • Fc is preferably 50 or more, and more preferably 60 or more.
  • Fc is preferably 80 or more, and more preferably 120 or more.
  • the room temperature yield strength after the heat treatment is 720 MPa or more.
  • the room temperature yield strength after the heat treatment is 740 MPa or more, more preferably 760 MPa or more.
  • the heating temperature before rolling (° C.), the rolling finishing temperature (° C.), the accelerated cooling start temperature (° C.), and the accelerated cooling stop temperature (° C.) may be set so as to satisfy the equation (4). Preferred conditions are shown below.
  • the heating temperature (Th) before rolling is preferably 850 ° C. or higher in order to easily perform hot rolling of the steel material. If heating before rolling is performed at this temperature, effects such as promotion of solid solution of carbonitride are obtained, and strength and toughness are improved. Th is more preferably 1050 ° C. or higher. However, when Th is too high, austenite crystal grains may become coarse and low temperature toughness may deteriorate. Therefore, Th is preferably set to 1200 ° C. or less.
  • Rolling is preferably performed under the condition that the total rolling reduction in a temperature range of 900 ° C. or lower is 50% or more. Thereby, a residual strain can be reliably given to austenite and it becomes easy to ensure favorable toughness.
  • the total rolling reduction in the temperature range of 900 ° C. or less is more preferably 70% or more.
  • “the total rolling reduction in a temperature range of 900 ° C. or lower” is ⁇ (thickness when reaching 900 ° C.) ⁇ (Rolling thickness) ⁇ / (thickness when reaching 900 ° C.) X100 (%) is meant.
  • the rolling finishing temperature (Tf) is preferably 700 to 850 ° C. Thereby, good strength and toughness can be obtained more reliably.
  • Tf is less than 700 ° C.
  • the accelerated cooling start temperature becomes low, the degree of quenching is not sufficient, and the strength of the steel sheet may be insufficient.
  • Tf exceeds 850 ° C., it may be difficult to ensure good toughness.
  • a preferred lower limit is 750 ° C and a preferred upper limit is 800 ° C.
  • Ta Accelerated cooling after rolling is performed in order to obtain good strength and toughness. If this accelerated cooling start temperature (Ta) is too low, the effect of quenching is reduced, so Ta is preferably 600 ° C. or higher, and more preferably 650 ° C. or higher. If Ta is high, good toughness may not be obtained, so Ta is preferably 800 ° C. or lower, more preferably 750 ° C. or lower, and further preferably 700 ° C. or lower.
  • Accelerated cooling stop temperature is preferably 200 ° C. or higher, and more preferably 400 ° C. or higher, in order to suppress the occurrence of hydrogen cracking and changes in characteristics during heat treatment. After the accelerated cooling is stopped, it is preferable to cool or cool slowly.
  • the cooling rate In accelerated cooling, it is preferable to set the cooling rate of 650 to 500 ° C. to 10 ° C./s or more in order to ensure strength.
  • the cooling rate in this temperature range is preferably 20 ° C./s or more in order to obtain good strength, and 70 ° C./s or less is preferable in order to ensure good ductility.
  • the above temperatures refer to the surface temperature at the representative position of the material to be rolled (for example, the center of the steel plate), and the accelerated cooling stop temperature means the maximum temperature reached after reheating.
  • the cooling rate is a value obtained by dividing the difference between the accelerated cooling start temperature and the accelerated cooling stop temperature by the accelerated cooling time.
  • accelerated cooling time means immersion time, when cooling in a water tank, for example.
  • a line pipe can be produced by forming into a tubular shape using the steel plate produced in the present invention, joining the butt portion, and applying a coating for expanding the tube and preventing corrosion as necessary.
  • a steel piece having a chemical composition shown in Table 1 and having a thickness of 140 mm was heated, hot-rolled, and further subjected to accelerated cooling (water cooling) to produce a steel plate.
  • Tables 2 and 3 show the temperature of each step. In addition, it hold
  • hot rolling the total rolling reduction in the temperature range of 900 ° C. or lower was 78%, and the finished plate thickness was 25 mm.
  • the cooling rate at 650 to 500 ° C. was about 35 ° C./s.
  • Each steel plate obtained was subjected to a simulated heat treatment at 500 ° C. for 2 hours, and then subjected to a tensile test and a Charpy impact test at room temperature.
  • the calculated value of Plm in this simulated heat treatment is about 15700, which simulates the use condition of exposure at 350 ° C. for 20 years.
  • ⁇ Tensile test> Using a round bar tensile test piece (parallel part diameter: 8.5 mm, gauge distance: 42.5 mm) taken from the center of the plate thickness so that the axis of the test piece was perpendicular to the rolling direction, A tensile test was performed at room temperature, and YP (0.2% yield strength), TS (tensile strength), and El (total elongation) were determined.
  • ⁇ Charpy impact test> A Charpy impact test was conducted using a V-notch test piece (JIS Z 2242-2005) taken from the center of the plate thickness so that the long side of the test piece was perpendicular to the rolling direction, and vE-40 (- The absorption energy at 40 ° C.) and vTs (fracture surface transition temperature) were determined.
  • test Nos. Satisfying the conditions defined in the present invention. 1 to 3, 5 to 31, 33 to 60, and 62 to 83 have a YP of 700 MPa or more after simulated heat treatment, vTs of ⁇ 10 ° C. or less, and vE-40 of 47 J or more. It had good toughness.
  • Test No. In No. 34 Fp deviated from the range specified in the present invention, so that YP after the simulated heat treatment was 712 MPa, which was a lower level than other examples of the present invention.
  • Fc does not satisfy the conditions defined in the present invention.
  • 32 and 61 YP after heat treatment was less than 700 MPa.
  • the high-strength steel material of the present invention is suitable as a high-strength steel material for steam piping because it has a yield strength of 700 MPa or more even after being exposed to a high temperature of 350 ° C. or longer for a long time. Particularly, it is suitable for piping for injecting steam into oil sand, piping for transporting bitumen after injecting water vapor, and the like. Since the high-strength steel material of the present invention is excellent in toughness and weldability, pipe production can be easily performed in the UOE process. According to the manufacturing method of the present invention, the high-strength steel material can be manufactured relatively easily.

Abstract

A high-strength steel material for steam piping, comprising, in mass%, 0.02-0.15% of C, 0.01-0.60% of Si, 0.5-2.5% of Mn, 0.005-0.05% of Ti, 0.005-0.090% of sol.Al, 0.001-0.009% of N, at least one element selected from Cu in an amount of 0.1-2.0%, Ni in an amount of 0.1-3.0%, Cr in an amount of 0.1-1.0%, Mo in an amount of 0.05-1.0%, V in an amount of 0.01-0.10%, Nb in an amount of 0.005-0.09% and B in an amount of 0.0003-0.0050%, and a remainder made up by Fe and impurities, wherein the content of P is 0.020% or less, the content of S is 0.010% or less, the content of O is 0.005% or less, Pcm (= C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B) is 0.15-0.29, and Fc (= 44-165C-34Si-26Mn-12Cu+85Ni+12Cr+73Mo+13V-77Nb+9900B) is 30 or more.

Description

スチーム配管用高強度鋼材およびその製造方法High-strength steel for steam piping and method for manufacturing the same
　本発明は、スチーム配管用高強度鋼材およびその製造方法に関する。 The present invention relates to a high-strength steel material for steam piping and a manufacturing method thereof.
　石油の類似資源であるオイルサンドの開発がカナダなどで進められている。オイルサンドとは、極めて粘性の高い鉱物油分（以下、「ビチューメン」という。）を含む砂岩のことである。露天掘りが難しい比較的深い位置に存在するオイルサンドの場合、３５０℃程度の高温の水蒸気を２０年以上の長期間オイルサンドに注入することにより、ビチューメンの粘度を下げ、液化したビチューメンを汲み上げることが行われている。このため、高温水蒸気を長期間送ることが可能なスチーム配管用鋼材が求められている。 Development of oil sands, a similar resource of oil, is being promoted in Canada and other countries. Oil sand is sandstone containing mineral oil with extremely high viscosity (hereinafter referred to as “bitumen”). In the case of oil sands that are located in relatively deep positions where it is difficult to dig open-pit, it is possible to lower the viscosity of bitumen and pump up liquefied bitumen by injecting steam at a high temperature of about 350 ° C into oil sand for a long period of 20 years or longer. Has been done. For this reason, the steel material for steam piping which can send high temperature steam for a long period of time is calculated | required.
　スチーム配管用鋼材は、軽量化による敷設コスト低減などの目的で、要求される強度が増加する傾向にある。最近では降伏強度が７００ＭＰａ以上の製品が要望されている。しかしながら、鋼材は、高温に長期間さらされると機械的性能が低下することがある。 鋼 Steam pipe steel tends to increase the required strength for the purpose of reducing laying costs due to weight reduction. Recently, a product having a yield strength of 700 MPa or more has been demanded. However, the mechanical performance of steel materials may deteriorate when exposed to high temperatures for long periods of time.
　従来、スチーム配管用鋼材を高強度化するため、化学組成または製造条件を制御して鋼材の性能を高める技術が開示されている。例えば、特許文献１には、溶接熱影響部（以下、「ＨＡＺ」という。）の靭性に優れた高強度蒸気配管用鋼板の製造方法に関する技術が開示されている。また、特許文献２には、高温特性に優れた蒸気輸送配管用鋼板および鋼管ならびにそれらの製造方法に関する技術が開示されている。特許文献１および特許文献２で開示された技術によれば、降伏強度５５０ＭＰａ以上のスチーム配管用鋼材が得られるとされている。 Conventionally, in order to increase the strength of steel materials for steam piping, a technique for improving the performance of the steel materials by controlling the chemical composition or manufacturing conditions has been disclosed. For example, Patent Document 1 discloses a technique relating to a method for manufacturing a steel sheet for high-strength steam piping that is excellent in the toughness of a welding heat-affected zone (hereinafter referred to as “HAZ”). Patent Document 2 discloses a technique related to a steel plate and a steel pipe for steam transport piping excellent in high-temperature characteristics and a method for producing them. According to the techniques disclosed in Patent Document 1 and Patent Document 2, it is said that a steel material for steam piping having a yield strength of 550 MPa or more can be obtained.
特開２００６－１８３１３３号公報JP 2006-183133 A 特開２００８－１９５９９１号公報JP 2008-195991 A
　特許文献１および特許文献２で開示された技術を用いても、７００ＭＰａ以上の降伏強度を安定的に有する鋼材を得ることが難しい。 Even using the techniques disclosed in Patent Document 1 and Patent Document 2, it is difficult to obtain a steel material having a stable yield strength of 700 MPa or more.
　スチーム配管用鋼材は、ＵＯＥ工程で製管される。このとき、鋼板が冷間加工によって管状に成形され、突合せ部をサブマージアーク溶接などによって接合された後、必要に応じて拡管が行われて鋼管となる。よって、スチーム配管用鋼材には、良好な靱性および溶接性も求められる。 鋼 Steam piping steel is manufactured in the UOE process. At this time, the steel plate is formed into a tubular shape by cold working, and the butt portion is joined by submerged arc welding or the like, and then expanded as necessary to form a steel pipe. Therefore, the steel material for steam piping is also required to have good toughness and weldability.
　本発明は、このような従来技術の問題を解決するため、高温に長期間曝された後にも７００ＭＰａ以上の降伏強度を有するとともに、良好な靱性および溶接性をも有する、スチーム配管用高強度鋼材およびその製造方法を提供することを目的とする。 In order to solve the problems of the prior art, the present invention has a yield strength of 700 MPa or more even after being exposed to a high temperature for a long period of time, and also has good toughness and weldability, and is a high-strength steel material for steam piping. And it aims at providing the manufacturing method.
　高温に長期間曝した後の降伏強度を実際に測定することは不可能である。そこで、本発明者らは、Ｌａｒｓｏｎ－Ｍｉｌｌｅｒパラメータを使用して、３５０℃に２０年間曝される使用条件を模擬した熱処理の条件を見出した（以下、この熱処理を「模擬熱処理」という。）。 It is impossible to actually measure the yield strength after long-term exposure to high temperatures. Accordingly, the present inventors have found a heat treatment condition that simulates a use condition of exposure to 350 ° C. for 20 years using the Larson-Miller parameter (hereinafter, this heat treatment is referred to as “simulated heat treatment”).
　高温に長期間曝された後の降伏強度は、下記（３）式から求められるＬａｒｓｏｎ－Ｍｉｌｌｅｒパラメータ（Ｐｌｍ）により評価することができる。
　Ｐｌｍ＝Ｔ（ｌｏｇ（ｔ）＋２０）・・・（３）
　ただし（３）式中のＴは温度（Ｋ）、ｔは時間（ｈｏｕｒ）、ｌｏｇは常用対数をそれぞれ意味する。 The yield strength after long-term exposure to high temperatures can be evaluated by the Larson-Miller parameter (Plm) obtained from the following equation (3).
Plm = T (log (t) +20) (3)
However, T in the formula (3) means temperature (K), t means time, and log means common logarithm.
　Ｐｌｍは時間を温度で補正するパラメータであり、これを用いることで実験時間を短縮できる。すなわち、Ｐｌｍでは、鋼材の使用条件において想定される温度および期間（時間）のパラメータ値が、実験における温度および期間（時間）のパラメータ値と同程度になる。想定される鋼材の使用条件（３５０℃に２０年間曝される使用条件）は、例えば、４００℃で２０００時間の熱処理、４５０℃で５０時間の熱処理、５００℃で２時間の熱処理に相当する。このときのＰｌｍは１５７００である。 Plm is a parameter for correcting time with temperature, and using this parameter can shorten the experiment time. That is, in Plm, the parameter value of the temperature and period (time) assumed in the use condition of the steel material is approximately the same as the parameter value of the temperature and period (time) in the experiment. Assumed use conditions of steel materials (use conditions for 20 years exposure to 350 ° C.) correspond to, for example, heat treatment at 400 ° C. for 2000 hours, heat treatment at 450 ° C. for 50 hours, and heat treatment at 500 ° C. for 2 hours. Plm at this time is 15700.
　本発明者らは、各種鋼材について、上記Ｐｌｍが１５７００である熱処理をした後でも常温で７００ＭＰａ以上の降伏強度を有する条件を調査し、本発明を完成した。 The present inventors have investigated the conditions for yield strength of 700 MPa or more at room temperature even after the heat treatment with Plm of 15700 for various steel materials, and completed the present invention.
　本発明の要旨は、下記（Ａ）～（Ｄ）に示すスチーム配管用高強度鋼材および下記（Ｅ）～（Ｇ）に示すスチーム配管用高強度鋼材の製造方法にある。 The gist of the present invention resides in high strength steel materials for steam piping shown in the following (A) to (D) and high strength steel materials for steam piping shown in (E) to (G) below.
　（Ａ）質量％で、Ｃ：０．０２～０．１５％、Ｓｉ：０．０１～０．６０％、Ｍｎ：０．５～２．５％、Ｔｉ：０．００５～０．０５％、ｓｏｌ．Ａｌ：０．００５～０．０９０％およびＮ：０．００１～０．００９％と、さらに、Ｃｕ：０．１～２．０％、Ｎｉ：０．１～３．０％、Ｃｒ：０．１～１．０％、Ｍｏ：０．０５～１．０％、Ｖ：０．０１～０．１０％、Ｎｂ：０．００５～０．０９％およびＢ：０．０００３～０．００５０％から選択される１種以上とを含有し、残部はＦｅおよび不純物からなり、不純物としてのＰ、ＳおよびＯが、それぞれＰ：０．０２０％以下、Ｓ：０．０１０％以下およびＯ：０．００５％以下であり、下記の（１）式から求められるＰｃｍが０．１５～０．２９であり、下記の（２）式から求められるＦｃが３０以上であるスチーム配管用高強度鋼材。
　Ｐｃｍ＝Ｃ＋Ｓｉ／３０＋Ｍｎ／２０＋Ｃｕ／２０＋Ｎｉ／６０＋Ｃｒ／２０＋Ｍｏ／１５＋Ｖ／１０＋５Ｂ・・・（１）
　Ｆｃ＝４４－１６５Ｃ－３４Ｓｉ－２６Ｍｎ－１２Ｃｕ＋８５Ｎｉ＋１２Ｃｒ＋７３Ｍｏ＋１３Ｖ－７７Ｎｂ＋９９００Ｂ・・・（２）
　ただし、（１）、（２）式中の元素記号は各元素の鋼中含有量（質量％）を意味する。 (A) By mass%, C: 0.02 to 0.15%, Si: 0.01 to 0.60%, Mn: 0.5 to 2.5%, Ti: 0.005 to 0.05% , Sol. Al: 0.005 to 0.090% and N: 0.001 to 0.009%, Cu: 0.1 to 2.0%, Ni: 0.1 to 3.0%, Cr: 0 0.1-1.0%, Mo: 0.05-1.0%, V: 0.01-0.10%, Nb: 0.005-0.09% and B: 0.0003-0.0050 And the balance consists of Fe and impurities, and P, S and O as impurities are respectively P: 0.020% or less, S: 0.010% or less and O: High-strength steel material for steam pipes of 0.005% or less, Pcm calculated from the following formula (1) is 0.15 to 0.29, and Fc calculated from the following formula (2) is 30 or more. .
Pcm = C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B (1)
Fc = 44-165C-34Si-26Mn-12Cu + 85Ni + 12Cr + 73Mo + 13V-77Nb + 9900B (2)
However, the element symbols in the formulas (1) and (2) mean the content (mass%) of each element in steel.
　（Ｂ）質量％で、Ｃ：０．０２～０．１５％、Ｓｉ：０．０１～０．６０％、Ｍｎ：０．５～２．５％、Ｔｉ：０．００５～０．０５％、ｓｏｌ．Ａｌ：０．００５～０．０９０％およびＮ：０．００１～０．００９％と、さらに、Ｃｕ：０．１～２．０％、Ｎｉ：０．１～３．０％、Ｃｒ：０．１～１．０％、Ｍｏ：０．０５～１．０％、Ｖ：０．０１～０．１０％、Ｎｂ：０．００５～０．０９％およびＢ：０．０００３～０．００５０％から選択される１種以上とを含有し、残部はＦｅおよび不純物からなり、不純物としてのＰ、ＳおよびＯが、それぞれＰ：０．０２０％以下、Ｓ：０．０１０％以下およびＯ：０．００５％以下であり、下記の（１）式から求められるＰｃｍが０．１５～０．２９であり、下記の（３）式から求められるＰｌｍが１５７００を満足する熱処理後に７００ＭＰａ以上の降伏強度を有するスチーム配管用高強度鋼材。
　Ｐｃｍ＝Ｃ＋Ｓｉ／３０＋Ｍｎ／２０＋Ｃｕ／２０＋Ｎｉ／６０＋Ｃｒ／２０＋Ｍｏ／１５＋Ｖ／１０＋５Ｂ・・・（１）
　Ｐｌｍ＝Ｔ（ｌｏｇ（ｔ）＋２０）・・・（３）
　ただし、（１）式中の元素記号は各元素の鋼中含有量（質量％）を意味し、（３）式中のＴは温度（Ｋ）、ｔは時間（ｈｏｕｒ）、ｌｏｇは常用対数をそれぞれ意味する。
　（Ｃ）さらに、質量％で、Ｃａ：０．０１％以下、ＲＥＭ：０．０２％以下およびＭｇ：０．００８％以下から選択される１種以上を含有する上記（Ａ）または（Ｂ）のスチーム配管用高強度鋼材。 (B) By mass, C: 0.02 to 0.15%, Si: 0.01 to 0.60%, Mn: 0.5 to 2.5%, Ti: 0.005 to 0.05% , Sol. Al: 0.005 to 0.090% and N: 0.001 to 0.009%, Cu: 0.1 to 2.0%, Ni: 0.1 to 3.0%, Cr: 0 0.1-1.0%, Mo: 0.05-1.0%, V: 0.01-0.10%, Nb: 0.005-0.09% and B: 0.0003-0.0050 And the balance consists of Fe and impurities, and P, S and O as impurities are respectively P: 0.020% or less, S: 0.010% or less and O: Yield of 700 MPa or more after heat treatment in which Pcm calculated from the following formula (1) is 0.15 to 0.29 and Plm calculated from the following formula (3) satisfies 15700. High-strength steel material for steam piping with strength.
Pcm = C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B (1)
Plm = T (log (t) +20) (3)
However, the element symbol in the formula (1) means the content (mass%) of each element in steel, T in the formula (3) is temperature (K), t is time (hour), and log is a common logarithm. Means each.
(C) Furthermore, the above (A) or (B) containing one or more selected from Ca: 0.01% or less, REM: 0.02% or less, and Mg: 0.008% or less in mass% High strength steel for steam piping.
　（Ｄ）さらに、質量％で、Ｓｎ：０．５％以下を含有する上記（Ａ）～（Ｃ）のいずれかのスチーム配管用高強度鋼材。 (D) The high-strength steel material for steam piping according to any one of the above (A) to (C), further containing, by mass%, Sn: 0.5% or less.
　（Ｅ）質量％で、Ｃ：０．０２～０．１５％、Ｓｉ：０．０１～０．６０％、Ｍｎ：０．５～２．５％、Ｔｉ：０．００５～０．０５％、ｓｏｌ．Ａｌ：０．００５～０．０９０％およびＮ：０．００１～０．００９％と、さらに、Ｃｕ：０．１～２．０％、Ｎｉ：０．１～３．０％、Ｃｒ：０．１～１．０％、Ｍｏ：０．０５～１．０％、Ｖ：０．０１～０．１０％、Ｎｂ：０．００５～０．０９％およびＢ：０．０００３～０．００５０％から選択される１種以上とを含有し、残部はＦｅおよび不純物からなり、不純物としてのＰ、ＳおよびＯが、それぞれＰ：０．０２０％以下、Ｓ：０．０１０％以下およびＯ：０．００５％以下であり、下記の（１）式から求められるＰｃｍが０．１５～０．２９であり、下記の（２）式から求められるＦｃが３０以上である鋼片または鋼塊を、下記の（４）式から求められるＦｐが８６以上となる条件で、加熱、圧延および加速冷却を行うことを特徴とするスチーム配管用高強度鋼材の製造方法。
　Ｐｃｍ＝Ｃ＋Ｓｉ／３０＋Ｍｎ／２０＋Ｃｕ／２０＋Ｎｉ／６０＋Ｃｒ／２０＋Ｍｏ／１５＋Ｖ／１０＋５Ｂ・・・（１）
　Ｆｃ＝４４－１６５Ｃ－３４Ｓｉ－２６Ｍｎ－１２Ｃｕ＋８５Ｎｉ＋１２Ｃｒ＋７３Ｍｏ＋１３Ｖ－７７Ｎｂ＋９９００Ｂ・・・（２）
Ｆｐ＝（１０Ｆｃ＋Ｔｈ＋５Ｔｆ＋５Ｔａ＋Ｔｂ）／１００　・・・（４）
　ただし、（１）、（２）式中の元素記号は各元素の鋼中含有量（質量％）を意味し、（４）式中のＦｃは（２）式から求められる値、Ｔｈは圧延前の加熱温度（℃）、Ｔｆは圧延仕上温度（℃）、Ｔａは加速冷却開始温度（℃）、Ｔｂは加速冷却停止温度（℃）をそれぞれ意味する。 (E) By mass, C: 0.02 to 0.15%, Si: 0.01 to 0.60%, Mn: 0.5 to 2.5%, Ti: 0.005 to 0.05% , Sol. Al: 0.005 to 0.090% and N: 0.001 to 0.009%, Cu: 0.1 to 2.0%, Ni: 0.1 to 3.0%, Cr: 0 0.1-1.0%, Mo: 0.05-1.0%, V: 0.01-0.10%, Nb: 0.005-0.09% and B: 0.0003-0.0050 And the balance consists of Fe and impurities, and P, S and O as impurities are respectively P: 0.020% or less, S: 0.010% or less and O: A steel slab or ingot having a Pcm of 0.005% or less, a Pcm calculated from the following formula (1) of 0.15 to 0.29, and an Fc calculated from the following formula (2) of 30 or more. Heating, rolling and accelerated cooling are performed under the condition that Fp obtained from the following formula (4) is 86 or more. Method for producing a high-strength steel product for a steam pipe, characterized.
Pcm = C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B (1)
Fc = 44-165C-34Si-26Mn-12Cu + 85Ni + 12Cr + 73Mo + 13V-77Nb + 9900B (2)
Fp = (10Fc + Th + 5Tf + 5Ta + Tb) / 100 (4)
However, the element symbols in the formulas (1) and (2) mean the content (mass%) of each element in the steel, Fc in the formula (4) is a value obtained from the formula (2), and Th is the rolling Previous heating temperature (° C.), Tf means rolling finish temperature (° C.), Ta means accelerated cooling start temperature (° C.), and Tb means accelerated cooling stop temperature (° C.).
　（Ｆ）さらに、質量％で、Ｃａ：０．０１％以下、ＲＥＭ：０．０２％以下およびＭｇ：０．００８％以下から選択される１種以上を含有する上記（Ｅ）のスチーム配管用高強度鋼材の製造方法。 (F) Further, for steam piping according to (E) above, which contains at least one selected from Ca: 0.01% or less, REM: 0.02% or less, and Mg: 0.008% or less by mass% Manufacturing method of high strength steel.
　（Ｇ）さらに、質量％で、Ｓｎ：０．５％以下を含有する上記（Ｅ）または（Ｆ）のスチーム配管用高強度鋼材の製造方法。 (G) The method for producing a high-strength steel material for steam piping according to (E) or (F) above, further containing, by mass%, Sn: 0.5% or less.
　本発明の高強度鋼材は、３５０℃以上の高温に長期間さらされた後にも７００ＭＰａ以上の降伏強度を有するため、スチーム配管用高強度鋼材として好適である。特に、オイルサンドにスチームを注入するための配管、水蒸気を注入した後にビチューメンを運搬するための配管などに適している。本発明の高強度鋼材は、靱性および溶接性にも優れているため、ＵＯＥ工程で製管を容易に行うことができる。
　本発明の製造方法によれば、上記の高強度鋼材を比較的容易に製造することができる。 Since the high-strength steel material of the present invention has a yield strength of 700 MPa or more even after being exposed to a high temperature of 350 ° C. or longer for a long time, it is suitable as a high-strength steel material for steam piping. Particularly, it is suitable for piping for injecting steam into oil sand, piping for transporting bitumen after injecting water vapor, and the like. Since the high-strength steel material of the present invention is excellent in toughness and weldability, pipe production can be easily performed in the UOE process.
According to the manufacturing method of the present invention, the high-strength steel material can be manufactured relatively easily.
模擬熱処理後の常温降伏強度とＦｃとの関係Relation between Fc and normal temperature yield strength after simulated heat treatment
　以下、本発明の各要件について詳しく説明する。なお、化学組成における各元素の含有量の「％」は「質量％」を意味する。 Hereinafter, each requirement of the present invention will be described in detail. In addition, “%” of the content of each element in the chemical composition means “mass%”.
　[１]鋼材の化学組成について
　Ｃ：０．０２～０．１５％
　Ｃは、鋼の強度を高めるために必要な元素である。この効果を得るために、Ｃ含有量は０．０２％以上とする。しかし、Ｃの含有量が０．１５％を超えると、溶接割れが起こり易い。よって、Ｃ含有量は０．０２～０．１５％とする。好ましい下限は０．０３％である。好ましい上限は０．１１％であり、より好ましい上限は０．０７％である。 [1] Chemical composition of steel C: 0.02 to 0.15%
C is an element necessary for increasing the strength of steel. In order to obtain this effect, the C content is 0.02% or more. However, if the C content exceeds 0.15%, weld cracking is likely to occur. Therefore, the C content is 0.02 to 0.15%. A preferred lower limit is 0.03%. A preferable upper limit is 0.11%, and a more preferable upper limit is 0.07%.
　Ｓｉ：０．０１～０．６０％
　Ｓｉは、脱酸作用を有する元素である。この効果を得るために、Ｓｉ含有量は０．０１％以上とする。しかし、Ｓｉの含有量が０．６０％を超えると、母材およびＨＡＺの靱性が著しく悪化する。よって、Ｓｉ含有量は０．０１～０．６０％とする。好ましい下限は０．０５％であり、より好ましい下限は０．０９％である。好ましい上限は０．３０％である。 Si: 0.01 to 0.60%
Si is an element having a deoxidizing action. In order to obtain this effect, the Si content is 0.01% or more. However, if the Si content exceeds 0.60%, the toughness of the base material and the HAZ is significantly deteriorated. Therefore, the Si content is set to 0.01 to 0.60%. A preferred lower limit is 0.05%, and a more preferred lower limit is 0.09%. A preferable upper limit is 0.30%.
　Ｍｎ：０．５～２．５％
　Ｍｎは、鋼の強度を高める作用を有する。この効果を得るために、Ｍｎ含有量は０．５％以上とする。しかし、その含有量が２．５％を超えると、溶接割れが起こりやすくなる。このため、Ｍｎの含有量は０．５～２．５％とする。好ましい下限は１．２％であり、より好ましい下限は１．４％である。好ましい上限は２．０％である。 Mn: 0.5 to 2.5%
Mn has the effect | action which raises the intensity | strength of steel. In order to obtain this effect, the Mn content is 0.5% or more. However, if the content exceeds 2.5%, weld cracks are likely to occur. Therefore, the Mn content is set to 0.5 to 2.5%. A preferred lower limit is 1.2%, and a more preferred lower limit is 1.4%. A preferable upper limit is 2.0%.
　Ｔｉ：０．００５～０．０５％
　Ｔｉは、Ｎとともに析出物（ＴｉＮ）を形成してＨＡＺの靱性を改善するので、０．００５％以上含有させる。しかし、その含有量が０．０５％を超えると、母材とＨＡＺの靱性が悪化する。よって、Ｔｉ含有量は０．００５～０．０５％とする。好ましい下限は０．００７％である。好ましい上限は０．０２５％であり、より好ましい上限は０．０２０％であり、さらに好ましい上限は０．０１４％である。 Ti: 0.005 to 0.05%
Ti forms precipitates (TiN) together with N to improve the toughness of HAZ, so 0.005% or more is contained. However, if the content exceeds 0.05%, the toughness of the base material and the HAZ deteriorates. Therefore, the Ti content is set to 0.005 to 0.05%. A preferred lower limit is 0.007%. A preferable upper limit is 0.025%, a more preferable upper limit is 0.020%, and a further preferable upper limit is 0.014%.
　ｓｏｌ．Ａｌ：０．００５～０．０９０％
　Ａｌは、脱酸作用を有する元素である。この効果を得るために、ｓｏｌ．Ａｌ（「酸可溶Ａｌ」）として０．００５％以上含有させる。しかし、ｓｏｌ．Ａｌ含有量が０．０９０％を超えると、ＨＡＺの靱性が悪化する場合がある。よって、ｓｏｌ．Ａｌ含有量は０．００５～０．０９０％とする。好ましい下限は０．０１５％である。好ましい上限は０．０６０％であり、より好ましい上限は０．０４５％である。 sol. Al: 0.005 to 0.090%
Al is an element having a deoxidizing action. In order to obtain this effect, sol. Al (“acid-soluble Al”) is contained in an amount of 0.005% or more. However, sol. If the Al content exceeds 0.090%, the toughness of the HAZ may deteriorate. Therefore, sol. The Al content is 0.005 to 0.090%. A preferred lower limit is 0.015%. A preferable upper limit is 0.060%, and a more preferable upper limit is 0.045%.
　Ｎ：０．００１～０．００９％
　Ｎは、Ｔｉとともに析出物（ＴｉＮ）を形成してＨＡＺの靱性を改善するので、０．００１％以上含有させる。しかし、その含有量が０．００９％を超えると、母材とＨＡＺの靱性が悪化する。よって、Ｎ含有量は０．００１～０．００９％とする。好ましい下限は０．００２％である。好ましい上限は０．００５％である。 N: 0.001 to 0.009%
N forms a precipitate (TiN) together with Ti to improve the toughness of the HAZ, so 0.001% or more is contained. However, if the content exceeds 0.009%, the toughness of the base material and the HAZ deteriorates. Therefore, the N content is set to 0.001 to 0.009%. A preferred lower limit is 0.002%. A preferable upper limit is 0.005%.
　本発明のスチーム配管用高強度鋼材は、上記の各元素を基本成分とし、鋼材の強度を向上させるために、Ｃｕ：０．１～２．０％、Ｎｉ：０．１～３．０％、Ｃｒ：０．１～１．０％、Ｍｏ：０．０５～１．０％、Ｖ：０．０１～０．１０％、Ｎｂ：０．００５～０．０９％およびＢ：０．０００３～０．００５０％から選択される１種以上を含有する。 The high-strength steel material for steam piping of the present invention contains the above-mentioned elements as basic components, and Cu: 0.1 to 2.0%, Ni: 0.1 to 3.0% in order to improve the strength of the steel material. Cr: 0.1-1.0%, Mo: 0.05-1.0%, V: 0.01-0.10%, Nb: 0.005-0.09% and B: 0.0003 Contains one or more selected from ˜0.0050%.
　Ｃｕ：０．１～２．０％
　Ｃｕは、鋼材の強度を向上させるのに有効な元素である。この効果は、Ｃｕを０．１％以上含有させた場合に顕著となる。しかし、Ｃｕ含有量が２．０％を超えると、鋼材の表面性状および靱性が悪化し、溶接割れが起こりやすくなる。よって、Ｃｕを含有させる場合の含有量は０．１～２．０％以下とする。好ましい下限は０．２％である。好ましい上限は０．６０％以下である。 Cu: 0.1 to 2.0%
Cu is an element effective for improving the strength of the steel material. This effect becomes remarkable when Cu is contained by 0.1% or more. However, if the Cu content exceeds 2.0%, the surface properties and toughness of the steel material are deteriorated, and weld cracks are likely to occur. Therefore, the content when Cu is contained is 0.1 to 2.0% or less. A preferred lower limit is 0.2%. A preferable upper limit is 0.60% or less.
　Ｎｉ：０．１～３．０％
　Ｎｉは、鋼材の強度および靱性を向上させるのに有効な元素である。この効果は、Ｎｉを０．１％以上含有させた場合に顕著となる。しかし、Ｎｉ含有量が３．０％を超えると、鋼材の表面性状が悪化することがある。よって、Ｎｉを含有させる場合には、その含有量を０．１～３．０％とする。好ましい下限は０．２％である。好ましい上限は０．６０％である。 Ni: 0.1-3.0%
Ni is an element effective for improving the strength and toughness of a steel material. This effect becomes remarkable when Ni is contained by 0.1% or more. However, when the Ni content exceeds 3.0%, the surface properties of the steel material may be deteriorated. Therefore, when Ni is contained, the content is made 0.1 to 3.0%. A preferred lower limit is 0.2%. A preferable upper limit is 0.60%.
　Ｃｒ：０．１～１．０％
　Ｃｒは、鋼材の強度を向上させるのに有効な元素である。この効果は、Ｃｒを０．１％以上含有させた場合に顕著となる。しかし、Ｃｒ含有量が１．０％を超えると、溶接割れが起こりやすくなる。よって、Ｃｒを含有させる場合には、その含有量を０．１～１．０％とする。好ましい下限は０．２％である。好ましい上限は０．６０％である。 Cr: 0.1 to 1.0%
Cr is an element effective for improving the strength of a steel material. This effect becomes remarkable when Cr is contained by 0.1% or more. However, if the Cr content exceeds 1.0%, weld cracks are likely to occur. Therefore, when Cr is contained, the content is set to 0.1 to 1.0%. A preferred lower limit is 0.2%. A preferable upper limit is 0.60%.
　Ｍｏ：０．０５～１．０％
　Ｍｏは、鋼材の強度を向上させるのに有効な元素である。この効果は、Ｍｏを０．０５％以上含有させた場合に顕著となる。しかし、Ｍｏ含有量が１．０％を超えると、溶接割れが起こりやすくなる。よって、Ｍｏを含有させる場合には、その含有量を０．０５～１．０％とする。好ましい下限は０．１％である。好ましい上限は０．６０％である。 Mo: 0.05 to 1.0%
Mo is an element effective for improving the strength of the steel material. This effect becomes remarkable when 0.05% or more of Mo is contained. However, if the Mo content exceeds 1.0%, weld cracks are likely to occur. Therefore, when Mo is contained, the content is set to 0.05 to 1.0%. A preferred lower limit is 0.1%. A preferable upper limit is 0.60%.
　Ｖ：０．０１～０．１０％
　Ｖは、鋼材の強度を向上させるのに有効な元素である。この効果は、Ｖを０．０１％以上含有させた場合に顕著となる。しかし、Ｖ含有量が０．１０％を超えると、延性および靱性が悪化するおそれがある。よって、Ｖを含有させる場合には、その含有量を０．０１～０．１０％とする。好ましい下限は０．０２％である。好ましい上限は０．０６％である。 V: 0.01 to 0.10%
V is an element effective for improving the strength of the steel material. This effect becomes remarkable when V is contained by 0.01% or more. However, if the V content exceeds 0.10%, ductility and toughness may be deteriorated. Therefore, when V is contained, the content is made 0.01 to 0.10%. A preferred lower limit is 0.02%. A preferable upper limit is 0.06%.
　Ｎｂ：０．００５～０．０９％
　Ｎｂは、鋼材の強度を向上させる効果を有し、また、適切な圧延を行えば、母材靱性を高める作用もある。この効果は、Ｎｂを０．００５％以上含有させた場合に顕著となる。しかし、その含有量が０．０９％を超えると、母材とＨＡＺの靱性が悪化する。よって、Ｎｂを含有させる場合には、その含有量を０．００５～０．０９％とする。好ましい下限は０．０１％である。好ましい上限は０．０６％であり、より好ましい上限は０．０４％である。 Nb: 0.005 to 0.09%
Nb has an effect of improving the strength of the steel material, and also has an effect of increasing the base material toughness if appropriate rolling is performed. This effect becomes remarkable when Nb is contained by 0.005% or more. However, if the content exceeds 0.09%, the toughness of the base material and the HAZ deteriorates. Therefore, when Nb is contained, the content is made 0.005 to 0.09%. A preferred lower limit is 0.01%. A preferable upper limit is 0.06%, and a more preferable upper limit is 0.04%.
　Ｂ：０．０００３～０．００５０％
　Ｂは、鋼材の強度を向上させるのに有効な元素である。この効果は、Ｂを０．０００３％以上含有させた場合に顕著となる。しかし、Ｂの含有量が０．００５０％を超えると、溶接割れが起こりやすくなる。よって、Ｂを含有させる場合には、その含有量を０．０００３～０．００５０％とする。好ましい下限は０．０００６％であり、より好ましい下限は０．００１０％である。好ましい上限は０．００２５％である。 B: 0.0003 to 0.0050%
B is an element effective for improving the strength of the steel material. This effect becomes remarkable when B is contained by 0.0003% or more. However, if the content of B exceeds 0.0050%, weld cracking is likely to occur. Therefore, when B is contained, the content is made 0.0003 to 0.0050%. A preferred lower limit is 0.0006%, and a more preferred lower limit is 0.0010%. A preferred upper limit is 0.0025%.
　本発明のスチーム配管用高強度鋼材は、上記の化学組成を有し、残部はＦｅおよび不純物からなるものである。不純物とは、鋼材を工業的に製造する際に、鉱石、スクラップ等の原料その他の要因により混入する成分を意味する。ただし、Ｐ、ＳおよびＯは、不純物としての含有量が高いと、鋼の特性を悪化させる可能性がある。よって、これらの元素については、その含有量を下記の範囲に制限する必要がある。 The high-strength steel material for steam piping of the present invention has the above-described chemical composition, and the balance is made of Fe and impurities. An impurity means the component mixed by raw materials and other factors, such as an ore and a scrap, when manufacturing steel materials industrially. However, if the content of P, S and O as impurities is high, there is a possibility of deteriorating the properties of the steel. Therefore, it is necessary to limit the content of these elements to the following ranges.
　Ｐ：０．０２０％以下
　Ｐは、鋼材中に不純物として不可避的に存在し、靱性を悪化させる元素である。ただし、Ｐ含有量は０．０２０％まで許容できる。好ましい上限は０．０１５％である。より好ましい上限は０．００５％である。 P: 0.020% or less P is an element that inevitably exists as an impurity in the steel material and deteriorates toughness. However, the P content is acceptable up to 0.020%. A preferable upper limit is 0.015%. A more preferred upper limit is 0.005%.
　Ｓ：０．０１０％以下
　Ｓは、鋼材中に不純物として不可避的に存在し、延性または靱性に有害な介在物を多く生成する元素である。ただし、Ｓ含有量は０．０１０％まで許容できる。好ましい上限は０．００４％であり、より好ましい上限は０．００２％であり、さらに好ましい上限は０．００１％である。 S: 0.010% or less S is an element that inevitably exists as an impurity in the steel material and generates many inclusions harmful to ductility or toughness. However, the S content is acceptable up to 0.010%. A preferred upper limit is 0.004%, a more preferred upper limit is 0.002%, and a further preferred upper limit is 0.001%.
　Ｏ：０．００５％以下
　Ｏ（酸素）は、鋼材中に不純物として不可避的に存在し、母材靱性および延性に悪影響を及ぼす元素である。ただし、Ｏ含有量は０．００５％まで許容できる。好ましい上限は０．００２％である。 O: 0.005% or less O (oxygen) is an element that inevitably exists as an impurity in the steel material and adversely affects the base material toughness and ductility. However, the O content is acceptable up to 0.005%. A preferable upper limit is 0.002%.
　本発明のスチーム配管用高強度鋼材には、Ｆｅの一部に代えて、下記の元素を含有させてもよい。 The high strength steel material for steam piping of the present invention may contain the following elements instead of a part of Fe.
　Ｃａ：０．０１％以下
　ＲＥＭ：０．０２％以下
　ＣａおよびＲＥＭは、硫化物（特にＭｎＳ）の形態を制御し、低温靱性および耐水素割れ性能を向上させるのに有効な元素である。この効果を得るために、Ｃａおよび／またはＲＥＭを含有させてもよい。ただし、含有量が過剰な場合、ＣａおよびＲＥＭを含む介在物が粗大となる。粗大化した介在物がクラスター化すると、鋼の清浄度を害し、溶接性にも悪影響を及ぼすことがある。よって、Ｃａを含有させる場合には、その含有量は０．０１％以下とし、ＲＥＭを含有させる場合には、その含有量は０．０２％以下とする。上記の効果は、Ｃａは０．０００５％以上、ＲＥＭは０．００１％以上含有させた場合に顕著となる。Ｃａ含有量は、溶接性の観点から０．００６％以下にすることが好ましい。ＲＥＭは、Ｓｃ、Ｙおよびランタノイドの合計１７元素の総称であり、これらの元素から選択される１種以上を含有させることができる。ＲＥＭの含有量は上記元素の合計量を意味する。 Ca: 0.01% or less REM: 0.02% or less Ca and REM are effective elements for controlling the form of sulfide (particularly MnS) and improving low temperature toughness and hydrogen cracking resistance. In order to obtain this effect, Ca and / or REM may be included. However, when the content is excessive, inclusions containing Ca and REM become coarse. When the coarse inclusions are clustered, the cleanliness of the steel is impaired and the weldability may be adversely affected. Therefore, when Ca is contained, the content is 0.01% or less, and when REM is contained, the content is 0.02% or less. The above effect becomes remarkable when Ca is contained in an amount of 0.0005% or more and REM is contained in an amount of 0.001% or more. The Ca content is preferably 0.006% or less from the viewpoint of weldability. REM is a generic name for a total of 17 elements of Sc, Y, and lanthanoid, and can contain one or more selected from these elements. The content of REM means the total amount of the above elements.
　Ｍｇ：０．００８％以下
　Ｍｇは、微細に分散した酸化物を形成し、ＨＡＺのオーステナイト粒径の粗大化を抑制して低温靭性を向上させる効果を発揮する。この効果を得るためにＭｇを含有させてもよい。ただし、Ｍｇ含有量が０．００８％を超えると、粗大な酸化物を生成して靭性を劣化させることがある。このため、Ｍｇを含有させる場合には、その含有量は０．００８％以下とする。上記の効果は、Ｍｇを０．０００５％以上含有させた場合に顕著となる。 Mg: 0.008% or less Mg forms an oxide finely dispersed, and exhibits the effect of improving the low temperature toughness by suppressing coarsening of the austenite grain size of HAZ. In order to obtain this effect, Mg may be contained. However, when the Mg content exceeds 0.008%, a coarse oxide may be generated to deteriorate toughness. For this reason, when it contains Mg, the content shall be 0.008% or less. The above effect becomes significant when Mg is contained in an amount of 0.0005% or more.
　Ｓｎ：０．５０％以下
　Ｓｎは、Ｓｎ２＋となって溶解し、腐食を抑制する作用を有する。これは、Ｓｎ２＋が腐食促進作用を有するＦｅ３＋を速やかに還元する効果を有するからである。Ｓｎは鋼のアノード溶解反応を抑制し耐食性を向上させる作用も有する。これらの効果を得るためにＳｎを含有させてもよい。ただし、Ｓｎ含有量が０．５０％を超えると、これらの効果は飽和する。よって、Ｓｎを含有させる場合には、その含有量を０．５０％以下とする。上記の効果は、Ｓｎを０．０３％以上含有させた場合に顕著となる。好ましい下限は０．０５％である。好ましい上限は０．３０％である。 Sn: 0.50% or less Sn has a function of suppressing corrosion by dissolving as Sn 2+ . This is because Sn 2+ has an effect of rapidly reducing Fe 3+ having a corrosion promoting action. Sn also has the effect of suppressing the anodic dissolution reaction of steel and improving the corrosion resistance. In order to obtain these effects, Sn may be included. However, when the Sn content exceeds 0.50%, these effects are saturated. Therefore, when it contains Sn, the content shall be 0.50% or less. The above effect becomes remarkable when Sn is contained by 0.03% or more. A preferred lower limit is 0.05%. A preferable upper limit is 0.30%.
　ここで、鋼材中の各元素をそれぞれ規定するだけでは、３５０℃に２０年間曝されるという過酷な条件で使用された場合に、７００ＭＰａ以上の降伏強度を有するとともに、良好な靱性および溶接性が安定して得られない。そのため、下記（１）式から求められるＰｃｍおよび下記（２）式から求められるＦｃを特定の範囲とする必要がある。
　Ｐｃｍ＝Ｃ＋Ｓｉ／３０＋Ｍｎ／２０＋Ｃｕ／２０＋Ｎｉ／６０＋Ｃｒ／２０＋Ｍｏ／１５＋Ｖ／１０＋５Ｂ・・・（１）
　Ｆｃ＝４４－１６５Ｃ－３４Ｓｉ－２６Ｍｎ－１２Ｃｕ＋８５Ｎｉ＋１２Ｃｒ＋７３Ｍｏ＋１３Ｖ－７７Ｎｂ＋９９００Ｂ・・・（２）
　ただし、（１）、（２）式中の元素記号は各元素の鋼中含有量（質量％）を意味する。 Here, simply defining each element in the steel material has a yield strength of 700 MPa or more and good toughness and weldability when used under severe conditions of being exposed to 350 ° C. for 20 years. It cannot be obtained stably. Therefore, it is necessary to set Pcm obtained from the following equation (1) and Fc obtained from the following equation (2) within a specific range.
Pcm = C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B (1)
Fc = 44-165C-34Si-26Mn-12Cu + 85Ni + 12Cr + 73Mo + 13V-77Nb + 9900B (2)
However, the element symbols in the formulas (1) and (2) mean the content (mass%) of each element in steel.
　Ｐｃｍ：０．１５～０．２９
　Ｐｃｍは、母材の機械的性能を維持し、良好な溶接性を得るための指標となる。母材の強度は、Ｐｃｍが大きいほど向上し、０．１５以上の場合に良好となる。しかし、Ｐｃｍが０．２９を超えると溶接割れが顕著となる。よって、Ｐｃｍは０．１５～０．２９とする。母材の強度をさらに向上させるためには、下限を０．１７とすることが好ましい。溶接割れを抑制するためには、上限は０．２５とするのが好ましい。より好ましい上限は０．２３であり、さらに好ましい上限は０．２１である。 Pcm: 0.15 to 0.29
Pcm is an index for maintaining the mechanical performance of the base material and obtaining good weldability. The strength of the base material increases as Pcm increases, and becomes better when the Pcm is 0.15 or more. However, when Pcm exceeds 0.29, weld cracks become prominent. Therefore, Pcm is set to 0.15 to 0.29. In order to further improve the strength of the base material, the lower limit is preferably set to 0.17. In order to suppress weld cracking, the upper limit is preferably 0.25. A more preferred upper limit is 0.23, and a more preferred upper limit is 0.21.
　Ｆｃ：３０以上
　本発明者らは、Ｌａｒｓｏｎ－Ｍｉｌｌｅｒパラメータに基づいて、３５０℃に２０年間曝される使用条件の模擬熱処理を種々の鋼材に施す実験を行った。その結果、３５０℃に２０年間曝された場合に鋼材の機械的特性を低下させる元素を特定するとともに、各元素の影響を勘案して上記（２）式を見出した。本発明者らはさらに、Ｆｃが３０以上であれば、上記実験後の降伏強度の低下が小さい、すなわち、３５０℃に２０年間曝された後であっても鋼材の降伏強度を７００ＭＰａ以上に維持できることを見出した（図１参照）。Ｆｃは５０以上とすることが好ましく、６０以上とすることがより好ましい。Ｆｃは、さらに８０以上とすることが好ましく、１２０以上とすることが一層好ましい。 Fc: 30 or more The present inventors conducted experiments in which various steel materials were subjected to simulated heat treatment under use conditions that were exposed to 350 ° C. for 20 years based on the Larson-Miller parameter. As a result, the element which reduces the mechanical properties of the steel material when exposed to 350 ° C. for 20 years was specified, and the above formula (2) was found in consideration of the influence of each element. Further, the inventors of the present invention, if Fc is 30 or more, the decrease in yield strength after the experiment is small, that is, the yield strength of the steel material is maintained at 700 MPa or more even after being exposed to 350 ° C. for 20 years. It was found that it can be done (see FIG. 1). Fc is preferably 50 or more, and more preferably 60 or more. Fc is preferably 80 or more, and more preferably 120 or more.
　Ｐｌｍが１５７００である熱処理をした後の常温降伏強度：７００ＭＰａ以上
　ただし、Ｐｌｍは、下記（３）式から求められる値であり、下記（３）式中のＴは温度（Ｋ）、ｔは時間（ｈｏｕｒ）、ｌｏｇは常用対数をそれぞれ意味する。
Ｐｌｍ＝Ｔ（ｌｏｇ（ｔ）＋２０）・・・（３）
　鋼材が３５０℃以上の高温に長期間曝された後の降伏強度を７００ＭＰａ以上にするためには、Ｐｌｍが１５７００である熱処理をした後でも常温で７００ＭＰａ以上の降伏強度を有するものにすることが好ましい。よって、本発明の鋼材は、Ｆｃの規定に代えて、Ｐｌｍが１５７００である熱処理をした後に７００ＭＰａ以上の常温降伏強度を有するものとも表現できる。実際の使用環境における降伏応力の低下を小さくするためには、Ｐｌｍが１５７００である熱処理をした後の常温降伏強度を大きくすることが好ましく、上記熱処理後の常温降伏強度は７２０ＭＰａ以上であることが好ましく、７４０ＭＰａ以上であることがより好ましく、７６０ＭＰａ以上であることがさらに好ましい。 Normal temperature yield strength after heat treatment with Plm of 15700: 700 MPa or more However, Plm is a value obtained from the following equation (3), T in the following equation (3) is temperature (K), and t is time (Hour) and log mean a common logarithm.
Plm = T (log (t) +20) (3)
In order to obtain a yield strength of 700 MPa or more after the steel material has been exposed to a high temperature of 350 ° C. or more for a long time, it should have a yield strength of 700 MPa or more at room temperature even after heat treatment with Plm of 15700. preferable. Therefore, the steel material of the present invention can be expressed as having a room temperature yield strength of 700 MPa or more after heat treatment with Plm of 15700, instead of defining Fc. In order to reduce the decrease in yield stress in the actual use environment, it is preferable to increase the room temperature yield strength after the heat treatment with Plm of 15700, and the room temperature yield strength after the heat treatment is 720 MPa or more. Preferably, it is 740 MPa or more, more preferably 760 MPa or more.
　[２]製造条件について
　上記[１]で説明した化学組成を有する鋼片または鋼塊を用いて、（４）式から求められるＦｐが８６以上となる加熱、圧延および加速冷却を行うことが必要である。
　Ｆｐ＝（１０Ｆｃ＋Ｔｈ＋５Ｔｆ＋５Ｔａ＋Ｔｂ）／１００　・・・（４）
　ただし、（４）式中のＦｃは（２）式から求められる値、Ｔｈは圧延前の加熱温度（℃）、Ｔｆは圧延仕上温度（℃）、Ｔａは加速冷却開始温度（℃）、Ｔｂは加速冷却停止温度（℃）をそれぞれ意味する。
　Ｆｐが８６以上となる加熱、圧延および加速冷却を行えば、炭窒化物の固溶が促進し、焼入れ性が向上する。その結果、降伏強度の高い鋼材が得られるとともに、３５０℃で２０年曝された後でも常温で７００ＭＰａ以上の降伏強度を確実に得ることができる。Ｆｐは９０以上であることが好ましい。 [2] Manufacturing conditions It is necessary to perform heating, rolling, and accelerated cooling with an Fp of 86 or more obtained from the formula (4) using the steel slab or steel ingot having the chemical composition described in [1] above. It is.
Fp = (10Fc + Th + 5Tf + 5Ta + Tb) / 100 (4)
However, Fc in the equation (4) is a value obtained from the equation (2), Th is a heating temperature before rolling (° C.), Tf is a rolling finishing temperature (° C.), Ta is an accelerated cooling start temperature (° C.), Tb Means accelerated cooling stop temperature (° C.).
When heating, rolling, and accelerated cooling with Fp of 86 or more are performed, solid solution of carbonitride is promoted and hardenability is improved. As a result, a steel material having a high yield strength can be obtained, and a yield strength of 700 MPa or more can be reliably obtained at room temperature even after being exposed at 350 ° C. for 20 years. Fp is preferably 90 or more.
　（４）式を満たすように、圧延前の加熱温度（℃）、圧延仕上温度（℃）、加速冷却開始温度（℃）、加速冷却停止温度（℃）を設定すればよいが、各工程の好ましい条件を以下に示す。 (4) The heating temperature before rolling (° C.), the rolling finishing temperature (° C.), the accelerated cooling start temperature (° C.), and the accelerated cooling stop temperature (° C.) may be set so as to satisfy the equation (4). Preferred conditions are shown below.
　圧延前の加熱温度（Ｔｈ）は、鋼材の熱間圧延を容易に行うため、８５０℃以上とするのが好ましい。この温度で圧延前の加熱を行えば、炭窒化物の固溶が促進するなどの効果が得られ、強度および靱性が向上する。Ｔｈは、１０５０℃以上とするのがより好ましい。ただし、Ｔｈが高すぎると、オーステナイト結晶粒が粗大化して低温靱性が劣化することがある。したがって、Ｔｈは１２００℃以下とするのが好ましい。 The heating temperature (Th) before rolling is preferably 850 ° C. or higher in order to easily perform hot rolling of the steel material. If heating before rolling is performed at this temperature, effects such as promotion of solid solution of carbonitride are obtained, and strength and toughness are improved. Th is more preferably 1050 ° C. or higher. However, when Th is too high, austenite crystal grains may become coarse and low temperature toughness may deteriorate. Therefore, Th is preferably set to 1200 ° C. or less.
　圧延は、９００℃以下の温度域における合計圧下率が５０％以上となる条件で行うことが好ましい。これにより、オーステナイトに残留ひずみを確実に与えることができ、良好な靱性を確保することが容易になる。９００℃以下の温度域における合計圧下率は７０％以上とするのがより好ましい。ここで、「９００℃以下の温度域における合計圧下率」とは、｛（９００℃に達した時点の厚さ）－（圧延仕上厚さ）｝／（９００℃に達した時点の厚さ）×１００（％）を意味する。 Rolling is preferably performed under the condition that the total rolling reduction in a temperature range of 900 ° C. or lower is 50% or more. Thereby, a residual strain can be reliably given to austenite and it becomes easy to ensure favorable toughness. The total rolling reduction in the temperature range of 900 ° C. or less is more preferably 70% or more. Here, “the total rolling reduction in a temperature range of 900 ° C. or lower” is {(thickness when reaching 900 ° C.) − (Rolling thickness)} / (thickness when reaching 900 ° C.) X100 (%) is meant.
　さらに、圧延仕上温度（Ｔｆ）は、７００～８５０℃とすることが好ましい。これにより、良好な強度および靱性がより確実に得られる。Ｔｆが７００℃未満の場合には、加速冷却開始温度が低くなり、焼入れの程度が充分でなく、鋼板の強度が不足することがある。一方、Ｔｆが８５０℃を超えると、良好な靱性の確保が難しくなることがある。好ましい下限は７５０℃であり、好ましい上限は８００℃である。 Further, the rolling finishing temperature (Tf) is preferably 700 to 850 ° C. Thereby, good strength and toughness can be obtained more reliably. When Tf is less than 700 ° C., the accelerated cooling start temperature becomes low, the degree of quenching is not sufficient, and the strength of the steel sheet may be insufficient. On the other hand, if Tf exceeds 850 ° C., it may be difficult to ensure good toughness. A preferred lower limit is 750 ° C and a preferred upper limit is 800 ° C.
　圧延後の加速冷却は、良好な強度、および靱性を得るために行うものである。この加速冷却開始温度（Ｔａ）が低すぎると焼入れの効果が小さくなるので、Ｔａは６００℃以上が望ましく、６５０℃以上とすることがより好ましい。Ｔａが高いと良好な靱性が得られない場合があるため、Ｔａは８００℃以下が好ましく、７５０℃以下がより好ましく、７００℃以下とするのがさらに好ましい。 Accelerated cooling after rolling is performed in order to obtain good strength and toughness. If this accelerated cooling start temperature (Ta) is too low, the effect of quenching is reduced, so Ta is preferably 600 ° C. or higher, and more preferably 650 ° C. or higher. If Ta is high, good toughness may not be obtained, so Ta is preferably 800 ° C. or lower, more preferably 750 ° C. or lower, and further preferably 700 ° C. or lower.
　水素割れの発生および熱処理時の特性変化を抑制するために、加速冷却停止温度（Ｔｂ）は２００℃以上とするのが好ましく、４００℃以上とするのがより好ましい。加速冷却停止後は、放冷または徐冷することが好ましい。 Accelerated cooling stop temperature (Tb) is preferably 200 ° C. or higher, and more preferably 400 ° C. or higher, in order to suppress the occurrence of hydrogen cracking and changes in characteristics during heat treatment. After the accelerated cooling is stopped, it is preferable to cool or cool slowly.
　加速冷却においては、強度確保を確実にするため、６５０～５００℃の冷却速度を１０℃／ｓ以上とすることが好ましい。この温度域の冷却速度は、良好な強度を得るために、２０℃／ｓ以上とするのが好ましく、良好な延性を確保するためには、７０℃／ｓ以下とするのが好ましい。 In accelerated cooling, it is preferable to set the cooling rate of 650 to 500 ° C. to 10 ° C./s or more in order to ensure strength. The cooling rate in this temperature range is preferably 20 ° C./s or more in order to obtain good strength, and 70 ° C./s or less is preferable in order to ensure good ductility.
　上記各温度は、被圧延材の代表位置（例えば、鋼板の中央部）における表面温度を指し、加速冷却停止温度とは、復熱後の最大到達温度を意味する。冷却速度は、加速冷却開始温度と加速冷却停止温度との差を加速冷却時間で除した値である。また、加速冷却時間とは、例えば水槽で冷却を行う場合、浸漬時間を意味する。 The above temperatures refer to the surface temperature at the representative position of the material to be rolled (for example, the center of the steel plate), and the accelerated cooling stop temperature means the maximum temperature reached after reheating. The cooling rate is a value obtained by dividing the difference between the accelerated cooling start temperature and the accelerated cooling stop temperature by the accelerated cooling time. Moreover, accelerated cooling time means immersion time, when cooling in a water tank, for example.
　本発明で製造された鋼板を用いて、管状に成形し、突合せ部を接合し、必要に応じて、拡管、防食のためのコーティングを施すことによって、ラインパイプを製造することができる。 A line pipe can be produced by forming into a tubular shape using the steel plate produced in the present invention, joining the butt portion, and applying a coating for expanding the tube and preventing corrosion as necessary.
　以下、実施例によって本発明をより具体的に説明するが、本発明はこれらの実施例に限定されるものではない。 Hereinafter, the present invention will be described more specifically by way of examples. However, the present invention is not limited to these examples.
　表１に示す化学組成を有する厚さ１４０ｍｍの鋼片を、加熱し、熱間圧延し、さらに加速冷却（水冷）を行って、鋼板を作製した。表２および表３に各工程の温度を示す。なお、加熱後にその温度で１時間保持した。熱間圧延において、９００℃以下の温度域における合計圧下率は７８％とし、仕上げ板厚は２５ｍｍとした。加速冷却において、いずれも６５０～５００℃の冷却速度は約３５℃／ｓであった。 A steel piece having a chemical composition shown in Table 1 and having a thickness of 140 mm was heated, hot-rolled, and further subjected to accelerated cooling (water cooling) to produce a steel plate. Tables 2 and 3 show the temperature of each step. In addition, it hold | maintained at the temperature for 1 hour after a heating. In hot rolling, the total rolling reduction in the temperature range of 900 ° C. or lower was 78%, and the finished plate thickness was 25 mm. In the accelerated cooling, the cooling rate at 650 to 500 ° C. was about 35 ° C./s.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　得られた各鋼板に５００℃で２時間の模擬熱処理を行った後、常温で引張試験およびシャルピー衝撃試験を行った。この模擬熱処理におけるＰｌｍの計算値は約１５７００であり、３５０℃で２０年間曝される使用条件を模擬したものである。 Each steel plate obtained was subjected to a simulated heat treatment at 500 ° C. for 2 hours, and then subjected to a tensile test and a Charpy impact test at room temperature. The calculated value of Plm in this simulated heat treatment is about 15700, which simulates the use condition of exposure at 350 ° C. for 20 years.
　＜引張試験＞
　板厚中央部から、試験片の軸が圧延方向に対して垂直になるように採取した丸棒引張試験片（平行部の直径：８．５ｍｍ、標点距離：４２．５ｍｍ）を用いて、室温で引張試験を実施し、ＹＰ（０．２％耐力）、ＴＳ（引張強度）およびＥｌ（全伸び）を求めた。 <Tensile test>
Using a round bar tensile test piece (parallel part diameter: 8.5 mm, gauge distance: 42.5 mm) taken from the center of the plate thickness so that the axis of the test piece was perpendicular to the rolling direction, A tensile test was performed at room temperature, and YP (0.2% yield strength), TS (tensile strength), and El (total elongation) were determined.
　＜シャルピー衝撃試験＞
　板厚中央部から、試験片の長辺が圧延方向に対して垂直になるように採取したＶノッチ試験片（ＪＩＳ　Ｚ　２２４２－２００５）を用いてシャルピー衝撃試験を実施し、ｖＥ－４０（－４０℃での吸収エネルギー）、およびｖＴｓ（破面遷移温度）を求めた。 <Charpy impact test>
A Charpy impact test was conducted using a V-notch test piece (JIS Z 2242-2005) taken from the center of the plate thickness so that the long side of the test piece was perpendicular to the rolling direction, and vE-40 (- The absorption energy at 40 ° C.) and vTs (fracture surface transition temperature) were determined.
　各試験結果を表２および表３に併記した。 Each test result is shown in Table 2 and Table 3.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表２および表３に示すように、本発明で規定される条件を満足する試験Ｎｏ．１～３、５～３１、３３～６０および６２～８３（本発明例）は、模擬熱処理後のＹＰが７００ＭＰａ以上であり、ｖＴｓが－１０℃以下で、ｖＥ－４０が４７Ｊ以上であり、良好な靱性を有していた。ただし、本発明例のうち、試験Ｎｏ．３４は、Ｆｐが本発明で規定される範囲を外れるため、模擬熱処理後のＹＰが７１２ＭＰａと、他の本発明例よりも低い水準にとどまった。一方、Ｆｃが本発明で規定される条件を満しない試験Ｎｏ．４、３２および６１は、熱処理後のＹＰが７００ＭＰａ未満であった。 As shown in Tables 2 and 3, test Nos. Satisfying the conditions defined in the present invention. 1 to 3, 5 to 31, 33 to 60, and 62 to 83 (examples of the present invention) have a YP of 700 MPa or more after simulated heat treatment, vTs of −10 ° C. or less, and vE-40 of 47 J or more. It had good toughness. However, among the examples of the present invention, Test No. In No. 34, Fp deviated from the range specified in the present invention, so that YP after the simulated heat treatment was 712 MPa, which was a lower level than other examples of the present invention. On the other hand, Fc does not satisfy the conditions defined in the present invention. In 4, 32 and 61, YP after heat treatment was less than 700 MPa.
　本発明の高強度鋼材は、３５０℃以上の高温に長期間さらされた後にも７００ＭＰａ以上の降伏強度を有するため、スチーム配管用高強度鋼材として好適である。特に、オイルサンドにスチームを注入するための配管、水蒸気を注入した後にビチューメンを運搬するための配管などに適している。本発明の高強度鋼材は、靱性および溶接性にも優れているため、ＵＯＥ工程で製管を容易に行うことができる。本発明の製造方法によれば、上記の高強度鋼材を比較的容易に製造することができる。 The high-strength steel material of the present invention is suitable as a high-strength steel material for steam piping because it has a yield strength of 700 MPa or more even after being exposed to a high temperature of 350 ° C. or longer for a long time. Particularly, it is suitable for piping for injecting steam into oil sand, piping for transporting bitumen after injecting water vapor, and the like. Since the high-strength steel material of the present invention is excellent in toughness and weldability, pipe production can be easily performed in the UOE process. According to the manufacturing method of the present invention, the high-strength steel material can be manufactured relatively easily.

Claims (7)

  1. 　質量％で、Ｃ：０．０２～０．１５％、Ｓｉ：０．０１～０．６０％、Ｍｎ：０．５～２．５％、Ｔｉ：０．００５～０．０５％、ｓｏｌ．Ａｌ：０．００５～０．０９０％、およびＮ：０．００１～０．００９％と、さらに、
    　Ｃｕ：０．１～２．０％、Ｎｉ：０．１～３．０％、Ｃｒ：０．１～１．０％、Ｍｏ：０．０５～１．０％、Ｖ：０．０１～０．１０％、Ｎｂ：０．００５～０．０９％およびＢ：０．０００３～０．００５０％から選択される１種以上とを含有し、残部はＦｅおよび不純物からなり、
    　不純物としてのＰ、ＳおよびＯが、それぞれＰ：０．０２０％以下、Ｓ：０．０１０％以下およびＯ：０．００５％以下であり、
    　下記の（１）式から求められるＰｃｍが０．１５～０．２９であり、
    　下記の（２）式から求められるＦｃが３０以上であることを特徴とするスチーム配管用高強度鋼材。
    Ｐｃｍ＝Ｃ＋Ｓｉ／３０＋Ｍｎ／２０＋Ｃｕ／２０＋Ｎｉ／６０＋Ｃｒ／２０＋Ｍｏ／１５＋Ｖ／１０＋５Ｂ・・・（１）
    Ｆｃ＝４４－１６５Ｃ－３４Ｓｉ－２６Ｍｎ－１２Ｃｕ＋８５Ｎｉ＋１２Ｃｒ＋７３Ｍｏ＋１３Ｖ－７７Ｎｂ＋９９００Ｂ・・・（２）
    　ただし、（１）、（２）式中の元素記号は各元素の鋼中含有量（質量％）を意味する。     % By mass, C: 0.02 to 0.15%, Si: 0.01 to 0.60%, Mn: 0.5 to 2.5%, Ti: 0.005 to 0.05%, sol. Al: 0.005 to 0.090% and N: 0.001 to 0.009%, and
    Cu: 0.1-2.0%, Ni: 0.1-3.0%, Cr: 0.1-1.0%, Mo: 0.05-1.0%, V: 0.01- 0.10%, Nb: 0.005 to 0.09% and B: one or more selected from 0.0003 to 0.0050%, with the balance consisting of Fe and impurities,
    P, S and O as impurities are respectively P: 0.020% or less, S: 0.010% or less and O: 0.005% or less,
    Pcm calculated from the following formula (1) is 0.15 to 0.29,
    A high-strength steel material for steam piping, wherein Fc calculated from the following formula (2) is 30 or more.
    Pcm = C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B (1)
    Fc = 44-165C-34Si-26Mn-12Cu + 85Ni + 12Cr + 73Mo + 13V-77Nb + 9900B (2)
    However, the element symbols in the formulas (1) and (2) mean the content (mass%) of each element in steel.
  2. 　質量％で、Ｃ：０．０２～０．１５％、Ｓｉ：０．０１～０．６０％、Ｍｎ：０．５～２．５％、Ｔｉ：０．００５～０．０５％、ｓｏｌ．Ａｌ：０．００５～０．０９０％およびＮ：０．００１～０．００９％と、さらに、
    　Ｃｕ：０．１～２．０％、Ｎｉ：０．１～３．０％、Ｃｒ：０．１～１．０％、Ｍｏ：０．０５～１．０％、Ｖ：０．０１～０．１０％、Ｎｂ：０．００５～０．０９％およびＢ：０．０００３～０．００５０％から選択される１種以上とを含有し、残部はＦｅおよび不純物からなり、
    　不純物としてのＰ、ＳおよびＯが、それぞれＰ：０．０２０％以下、Ｓ：０．０１０％以下およびＯ：０．００５％以下であり、
    　下記の（１）式から求められるＰｃｍが０．１５～０．２９であり、
    　下記の（３）式から求められるＰｌｍが１５７００を満足する熱処理後に７００ＭＰａ以上の降伏強度を有することを特徴とするスチーム配管用高強度鋼材。
    Ｐｃｍ＝Ｃ＋Ｓｉ／３０＋Ｍｎ／２０＋Ｃｕ／２０＋Ｎｉ／６０＋Ｃｒ／２０＋Ｍｏ／１５＋Ｖ／１０＋５Ｂ・・・（１）
    Ｐｌｍ＝Ｔ（ｌｏｇ（ｔ）＋２０）・・・（３）
    　ただし、（１）式中の元素記号は各元素の鋼中含有量（質量％）を意味し、（３）式中のＴは温度（Ｋ）、ｔは時間（ｈｏｕｒ）、ｌｏｇは常用対数をそれぞれ意味する。     % By mass, C: 0.02 to 0.15%, Si: 0.01 to 0.60%, Mn: 0.5 to 2.5%, Ti: 0.005 to 0.05%, sol. Al: 0.005-0.090% and N: 0.001-0.009%, and
    Cu: 0.1-2.0%, Ni: 0.1-3.0%, Cr: 0.1-1.0%, Mo: 0.05-1.0%, V: 0.01- 0.10%, Nb: 0.005 to 0.09% and B: one or more selected from 0.0003 to 0.0050%, with the balance consisting of Fe and impurities,
    P, S and O as impurities are respectively P: 0.020% or less, S: 0.010% or less and O: 0.005% or less,
    Pcm calculated from the following formula (1) is 0.15 to 0.29,
    A high-strength steel material for steam pipes, which has a yield strength of 700 MPa or more after heat treatment in which Plm obtained from the following formula (3) satisfies 15700.
    Pcm = C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B (1)
    Plm = T (log (t) +20) (3)
    However, the element symbol in the formula (1) means the content (mass%) of each element in steel, T in the formula (3) is temperature (K), t is time (hour), and log is a common logarithm. Means each.
  3. 　さらに、質量％で、Ｃａ：０．０１％以下、ＲＥＭ：０．０２％以下およびＭｇ：０．００８％以下から選択される１種以上を含有することを特徴とする請求項１または２に記載のスチーム配管用高強度鋼材。 Furthermore, by mass%, it contains 1 or more types selected from Ca: 0.01% or less, REM: 0.02% or less, and Mg: 0.008% or less, The Claim 1 or 2 characterized by the above-mentioned. High-strength steel for steam piping as described.
  4. 　さらに、質量％で、Ｓｎ：０．５％以下を含有することを特徴とする請求項１から３までのいずれかに記載のスチーム配管用高強度鋼材。 The high strength steel material for steam piping according to any one of claims 1 to 3, further comprising Sn: 0.5% or less by mass.
  5. 　質量％で、Ｃ：０．０２～０．１５％、Ｓｉ：０．０１～０．６０％、Ｍｎ：０．５～２．５％、Ｔｉ：０．００５～０．０５％、ｓｏｌ．Ａｌ：０．００５～０．０９０％およびＮ：０．００１～０．００９％と、さらに、
    　Ｃｕ：０．１～２．０％、Ｎｉ：０．１～３．０％、Ｃｒ：０．１～１．０％、Ｍｏ：０．０５～１．０％、Ｖ：０．０１～０．１０％、Ｎｂ：０．００５～０．０９％およびＢ：０．０００３～０．００５０％から選択される１種以上とを含有し、残部はＦｅおよび不純物からなり、
    　不純物としてのＰ、ＳおよびＯが、それぞれＰ：０．０２０％以下、Ｓ：０．０１０％以下およびＯ：０．００５％以下であり、
    　下記の（１）式から求められるＰｃｍが０．１５～０．２９であり、
    　下記の（２）式から求められるＦｃが３０以上である鋼片または鋼塊を、
    　下記の（４）式から求められるＦｐが８６以上となる条件で、加熱、圧延および加速冷却を行うことを特徴とするスチーム配管用高強度鋼材の製造方法。
    Ｐｃｍ＝Ｃ＋Ｓｉ／３０＋Ｍｎ／２０＋Ｃｕ／２０＋Ｎｉ／６０＋Ｃｒ／２０＋Ｍｏ／１５＋Ｖ／１０＋５Ｂ・・・（１）
    Ｆｃ＝４４－１６５Ｃ－３４Ｓｉ－２６Ｍｎ－１２Ｃｕ＋８５Ｎｉ＋１２Ｃｒ＋７３Ｍｏ＋１３Ｖ－７７Ｎｂ＋９９００Ｂ・・・（２）
    Ｆｐ＝（１０Ｆｃ＋Ｔｈ＋５Ｔｆ＋５Ｔａ＋Ｔｂ）／１００・・・（４）
    　ただし、（１）、（２）式中の元素記号は各元素の鋼中含有量（質量％）を意味し、（４）式中のＦｃは（２）式から求められる値、Ｔｈは圧延前の加熱温度（℃）、Ｔｆは圧延仕上温度（℃）、Ｔａは加速冷却開始温度（℃）、Ｔｂは加速冷却停止温度（℃）をそれぞれ意味する。     % By mass, C: 0.02 to 0.15%, Si: 0.01 to 0.60%, Mn: 0.5 to 2.5%, Ti: 0.005 to 0.05%, sol. Al: 0.005-0.090% and N: 0.001-0.009%, and
    Cu: 0.1-2.0%, Ni: 0.1-3.0%, Cr: 0.1-1.0%, Mo: 0.05-1.0%, V: 0.01- 0.10%, Nb: 0.005 to 0.09% and B: one or more selected from 0.0003 to 0.0050%, with the balance consisting of Fe and impurities,
    P, S and O as impurities are respectively P: 0.020% or less, S: 0.010% or less and O: 0.005% or less,
    Pcm calculated from the following formula (1) is 0.15 to 0.29,
    A steel slab or steel ingot whose Fc calculated from the following formula (2) is 30 or more,
    The manufacturing method of the high strength steel material for steam piping characterized by performing heating, rolling, and accelerated cooling on the conditions from which Fp calculated | required from the following (4) formula becomes 86 or more.
    Pcm = C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B (1)
    Fc = 44-165C-34Si-26Mn-12Cu + 85Ni + 12Cr + 73Mo + 13V-77Nb + 9900B (2)
    Fp = (10Fc + Th + 5Tf + 5Ta + Tb) / 100 (4)
    However, the element symbols in the formulas (1) and (2) mean the content (mass%) of each element in the steel, Fc in the formula (4) is a value obtained from the formula (2), and Th is the rolling Previous heating temperature (° C.), Tf means rolling finish temperature (° C.), Ta means accelerated cooling start temperature (° C.), and Tb means accelerated cooling stop temperature (° C.).
  6. 　さらに、質量％で、Ｃａ：０．０１％以下、ＲＥＭ：０．０２％以下およびＭｇ：０．００８％以下から選択される１種以上を含有することを特徴とする請求項５に記載のスチーム配管用高強度鋼材の製造方法。 Furthermore, by mass%, it contains 1 or more types selected from Ca: 0.01% or less, REM: 0.02% or less, and Mg: 0.008% or less. Manufacturing method of high strength steel for steam piping.
  7. 　さらに、質量％で、Ｓｎ：０．５％以下を含有することを特徴とする請求項５または６に記載のスチーム配管用高強度鋼材の製造方法。 Furthermore, it contains Sn: 0.5% or less by mass%, The manufacturing method of the high strength steel materials for steam piping of Claim 5 or 6 characterized by the above-mentioned.
PCT/JP2011/052831 2011-02-10 2011-02-10 High-strength steel material for steam piping, and process for production thereof WO2012108027A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/JP2011/052831 WO2012108027A1 (en) 2011-02-10 2011-02-10 High-strength steel material for steam piping, and process for production thereof
JP2012556708A JP5447698B2 (en) 2011-02-10 2011-02-10 High-strength steel for steam piping and method for manufacturing the same

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2011/052831 WO2012108027A1 (en) 2011-02-10 2011-02-10 High-strength steel material for steam piping, and process for production thereof

Publications (1)

Publication Number Publication Date
WO2012108027A1 true WO2012108027A1 (en) 2012-08-16

Family

ID=46638270

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2011/052831 WO2012108027A1 (en) 2011-02-10 2011-02-10 High-strength steel material for steam piping, and process for production thereof

Country Status (2)

Country Link
JP (1) JP5447698B2 (en)
WO (1) WO2012108027A1 (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102888571A (en) * 2012-10-26 2013-01-23 江苏省沙钢钢铁研究院有限公司 690MPa-level low weld crack sensitive steel and production method thereof
CN103834874A (en) * 2012-11-27 2014-06-04 宝山钢铁股份有限公司 X65-70 subsea pipeline steel with thick wall and high DWTT (drop weight tear test) property and production method
WO2016157856A1 (en) * 2015-03-27 2016-10-06 Ｊｆｅスチール株式会社 High-strength steel, production method therefor, steel pipe, and production method therefor
WO2016157857A1 (en) * 2015-03-27 2016-10-06 Ｊｆｅスチール株式会社 High-strength steel, production method therefor, steel pipe, and production method for steel pipe
US10954576B2 (en) 2015-03-27 2021-03-23 Jfe Steel Corporation High-strength steel, method for manufacturing high-strength steel, steel pipe, and method for manufacturing steel pipe
KR102236850B1 (en) * 2019-11-04 2021-04-06 주식회사 포스코 Hot rolled steel plate having exellent hydrogen induced crack resistance and tensile property at high temperature and method of manufacturing the same

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114959483B (en) * 2022-06-02 2023-06-16 武汉钢铁有限公司 Weather-resistant steel resistant to wet heat and high in salinity marine atmospheric environment and production method thereof

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56166324A (en) * 1980-05-23 1981-12-21 Kawasaki Steel Corp Production of high-strength seamless steel pipe of good weldability for middle temperature region
JP2003313627A (en) * 2002-04-25 2003-11-06 Jfe Steel Kk Low-alloy heat resistant steel superior in high- temperature strength
JP2007169747A (en) * 2005-12-26 2007-07-05 Jfe Steel Kk Method for producing high-strength and high-toughness steel plate excellent in strength and deformability in middle temperature zone
JP2008255468A (en) * 2007-03-09 2008-10-23 Jfe Steel Kk Fatigue crack propagation delayed steel and its manufacturing method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56166324A (en) * 1980-05-23 1981-12-21 Kawasaki Steel Corp Production of high-strength seamless steel pipe of good weldability for middle temperature region
JP2003313627A (en) * 2002-04-25 2003-11-06 Jfe Steel Kk Low-alloy heat resistant steel superior in high- temperature strength
JP2007169747A (en) * 2005-12-26 2007-07-05 Jfe Steel Kk Method for producing high-strength and high-toughness steel plate excellent in strength and deformability in middle temperature zone
JP2008255468A (en) * 2007-03-09 2008-10-23 Jfe Steel Kk Fatigue crack propagation delayed steel and its manufacturing method

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102888571A (en) * 2012-10-26 2013-01-23 江苏省沙钢钢铁研究院有限公司 690MPa-level low weld crack sensitive steel and production method thereof
CN103834874A (en) * 2012-11-27 2014-06-04 宝山钢铁股份有限公司 X65-70 subsea pipeline steel with thick wall and high DWTT (drop weight tear test) property and production method
WO2016157856A1 (en) * 2015-03-27 2016-10-06 Ｊｆｅスチール株式会社 High-strength steel, production method therefor, steel pipe, and production method therefor
WO2016157857A1 (en) * 2015-03-27 2016-10-06 Ｊｆｅスチール株式会社 High-strength steel, production method therefor, steel pipe, and production method for steel pipe
JPWO2016157857A1 (en) * 2015-03-27 2017-06-22 Ｊｆｅスチール株式会社 High strength steel and method for manufacturing the same, steel pipe and method for manufacturing the steel pipe
JPWO2016157856A1 (en) * 2015-03-27 2017-07-13 Ｊｆｅスチール株式会社 High strength steel and method for manufacturing the same, steel pipe and method for manufacturing the same
US10570477B2 (en) 2015-03-27 2020-02-25 Jfe Steel Corporation High-strength steel, method for manufacturing high-strength steel, steel pipe, and method for manufacturing steel pipe
US10954576B2 (en) 2015-03-27 2021-03-23 Jfe Steel Corporation High-strength steel, method for manufacturing high-strength steel, steel pipe, and method for manufacturing steel pipe
KR102236850B1 (en) * 2019-11-04 2021-04-06 주식회사 포스코 Hot rolled steel plate having exellent hydrogen induced crack resistance and tensile property at high temperature and method of manufacturing the same

Also Published As

Publication number Publication date
JPWO2012108027A1 (en) 2014-07-03
JP5447698B2 (en) 2014-03-19

Similar Documents

Publication Publication Date Title
JP4969915B2 (en) Steel tube for high-strength line pipe excellent in strain aging resistance, steel plate for high-strength line pipe, and production method thereof
JP5418662B2 (en) Base material of high toughness clad steel plate excellent in weld zone toughness and method for producing the clad steel plate
JP5447698B2 (en) High-strength steel for steam piping and method for manufacturing the same
CA2980247C (en) Thick steel plate for structural pipes or tubes, method of producing thick steel plate for structural pipes or tubes, and structural pipes and tubes
CA2980424C (en) Thick steel plate for structural pipes or tubes, method of producing thick steel plate for structural pipes or tubes, and structural pipes and tubes
JP4484123B2 (en) High strength and excellent base material for clad steel plate with excellent weld heat affected zone toughness
JP5527455B2 (en) Base material of high toughness clad steel plate and method for producing the clad steel plate
JP6079165B2 (en) High toughness and corrosion resistant Ni alloy clad steel plate with excellent weld toughness and method for producing the same
JP2008030086A (en) Method for producing high-strength clad steel plate
CA2980250A1 (en) Steel plate for structural pipes or tubes, method of producing steel plate for structural pipes or tubes, and structural pipes and tubes
JP6288288B2 (en) Steel plate for line pipe, manufacturing method thereof and steel pipe for line pipe
JP5245921B2 (en) Manufacturing method of steel for line pipe
JP4709632B2 (en) Manufacturing method of high strength steel for welded structure with excellent high temperature strength and low temperature toughness
JP6303628B2 (en) Hot rolled steel sheet for ERW steel pipe with a thickness of 15mm or more
JP5605304B2 (en) Steel materials excellent in fatigue crack growth resistance and low temperature toughness of weld heat affected zone, and manufacturing method thereof
JP4770415B2 (en) High tensile steel plate excellent in weldability and method for producing the same
JP5098207B2 (en) Manufacturing method of high strength steel for welded structure with excellent high temperature strength and low temperature toughness
JP5098317B2 (en) Manufacturing method of welded structural steel with excellent high temperature strength and low temperature toughness
JP2013142197A (en) Ni-ADDED STEEL PLATE HAVING EXCELLENT TOUGHNESS SUCH THAT CHARPY TEST VALUES OF BOTH OF BASE MATERIAL AND WELDING JOINT AT -196°C ARE EACH 100 J OR MORE AND EXCELLENT PRODUCTIVITY, AND METHOD FOR MANUFACTURING THE SAME
JP6398576B2 (en) Steel sheet with excellent toughness and method for producing the same
JP2008188641A (en) High-strength welded steel tube of excellent welding softening resistance and excellent fatigue characteristic
JP2011195856A (en) Steel for line pipe and method for producing the same
JP5020691B2 (en) Steel sheet for high-strength linepipe excellent in low-temperature toughness, high-strength linepipe, and production method thereof
JP2016056425A (en) High strength steel sheet
JP5272878B2 (en) Manufacturing method of welded structural steel with excellent high temperature strength and low temperature toughness

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 11858039

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2012556708

Country of ref document: JP

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 11858039

Country of ref document: EP

Kind code of ref document: A1