31results about How to "Excellent HAZ toughness" patented technology

The invention provides a high tensile steel sheet having a low yield ratio in spite of its tensile strength of >=780 MPa, and having low acoustic anisotropy and excellent weldability, and to provide its production method. The steel sheet has a composition comprising, by mass, 0.010 to 0.080% C, 0.02 to 0.50% Si, 1.10 to 3.00% Mn, <=1.60% Cu, 0.40 to 2.50% Ni, <=0.030% P, <=0.010% S, <=0.200% Al, <=0.0100% N, 0.30 to 2.00% Cr, 0.10 to 1.10% Mo and 0.002 to 0.030% Ti, and the balance Fe with impurities. Further, regarding the following AS and DL, AS>=4.00 and DL<=2.80 are satisfied, the structure in the part of 1 / 4 in the sheet thickness is essentially composed of bainitic ferrite including MA by <=10 area% (excluding 0%), also, the average value of the major axis / manor axis of old austenite grains is 1.0 to 3.0, and further, the hardness ratio of the MA to the bainitic ferrite is >=1.10: AS=[Mn]+[Ni]+2*[Cu], and DL=2.5*[Mo]+30*[Nb]+10*[V]; [X] denotes the content (mass%) of the element X.

Disclosed is a thick steel plate excellent in HAZ toughness even when welding with high heat energy, containing C: 0.03 to 0.12%, Si: 0.2% or less (including 0%), Mn: 1.0 to 2.0%, and P: 0.03% Below (excluding 0%), S: below 0.015% (excluding 0%), Al: below 0.10% (excluding 0%), Ti: 0.015-0.08%, N: 0.0060-0.0120% and B: 0.0010- 0.0050%, in addition to containing Nb: 0.005-0.020% and / or Zr: 0.0001-0.050%, and satisfying the relationship of formula (1), and calculated as 0.05μm or less in circle equivalent diameter, there are 5.0 Ti-containing nitrides per 1mm2 ×106 or more. [Ti]×16[Si]×(12-40[C])<0.38(%)...(1), where [Ti], [Si] and [C] represent the content of Ti, Si and C respectively ( quality%).

Provided is a steel plate capable of full playing excellent HAZ toughness when implementing superrelevation hot input soldering with above 60 kJ / mm of welding heat energy, moreover even though implementing soldering with larger heat energy such as above 15kJ / mm of welding heat energy. The steel plate of the present invention controls chemical constituent composition suitably and meets the relations as follows: 1.0 <= [Ti] / [N] <= 2.5......(1) wherein [Ti] and [N] represent content of Ti and N (by weight) separately; 2.0 <= 1000 * ([Ca] + 2 * [S] + 3 * [O]) <= 10.0...... (2) wherein [Ca], [S] and [O] represent the content of Ca, S and O (by weight) separately, 0.1 <= [1000 * ([Ca] + 2 * [S] + 3 * [O]) / (solidification cooling speed) <= 100.0...... (3), wherein the solidification cooling speed represents average cooling speed (DEG C / s) when the steel plate solidifying.

In a steel sheet, an A value is 4.5% or less, a Pcm value is 0.25% or less, a yield strength is 460 N / mm 2 to 580 N / mm 2 , a tensile strength is 550 N / mm 2 to 670 N / mm2, a difference between a hardness at 1 / 8t, which is a 1 / 8 thickness position from a surface of the steel plate in a through-thickness direction, and a hardness at 1 / 2t, which is a 1 / 2 thickness position from the surface of the steel plate in the through-thickness direction, is 20 or less by Vickers hardness, and an average grain size at 1 / 8t is 35 µm or less.

A plate steel that displays great HAZ toughness under high heat input weld and has excellent shearing property without shear fissure even if it is cut by a shearing press. The plate steel of the invention adjusts chemical components properly and meets formulae (1) and (2) and has tissue with bainite ratio that is above 95 area%. Average diameter of equivalent circle of a block size of the bainite is below 40 microns and a difference of a maximal diameter of equivalent circle of a block size of the bainite and the average diameter of equivalent circle is below 40 microns. [Ti] / [N] is more than or equal to 1.5 but less than or equal to 4.0 (1); X is more than or equal to 40 but less than or equal to 160 (2), X=500[C]+32[Si]+8[Mn]-9[Nb]+14[Cu]+17[Ni]-5[Cr]-25[Mo]-34[V], (in the formula, [] represents content (mass%) of each element.

The invention provides a thick steel plate, which has excellent HAZ toughness even in extra large heat input welding and excellent low temperature base metal toughness. The steel contains: C, 0.030-0.10%; Si, less than 1.0%; Mn, 0.8-2.0%; P, less than 0.03%; S, less than 0.01%; Al, 0.01-0.10%; Nb, 0.015-0.035%; Ti, 0.015-0.03%; B, 0.0015-0.0035%; N, 0.0055-0.01%; Cu, less than 2.0%; Ni, less than 2.0%; Cr, less than 1%; Mo, less than 0.5%; V, less than 0.1%; and other component is Fe and inevitable impurities. The components meet the requirement of: [Ti] / [N] is 2-4, and 500[C]+32[Si]+8[Mn]-9[Nb]+14[Cu]+17[Ni]-5[Cr]-25[Mo]-34[V] not less than 40.

A thick steel plate, the chemical composition of which comprises, in mass%, C in the amount of 0.01-0.20%, Si in the amount of 0.10-0.25%, Mn in the amount of 1.30-2.50%, P in the amount of 0.01% or less, S in the amount of 0.0010-0.0100%, Ti in the amount of 0.005-0.030%, Al in the amount of 0.003% or less, O in the amount of 0.0010-0.0050%, N in the amount of 0.0100% or less, Cu in the amount of0-0.50%, Ni in the amount of 0-1.50%, Cr in the amount of 0-0.50%, Mo in the amount of 0-0.50%, V in the amount of 0-0.10%, and Nb in the amount of 0-0.05%, with the remainder constituting Fe and impurities, wherein the steel also contains a composite inclusion in which MnS is present around a Ti oxide. The surface area ratio of MnS in a cross-section of the composite inclusion is at least 10% and less than 90%, the proportion which MnS constitutes along the peripheral length of the composite inclusion is at least 10%, and the number density of composite inclusions that have a particle diameter of 0.5-5.0 [mu]m is 10-100 / mm<2>. This thick steel plate exhibits excellent HAZ low-temperature properties during high heat input welding.

A thick steel plate for tanks which contains given components and satisfies the relationship (Ti content [Ti])X(N content [N])is equal to or bigger than 0.000085 and in which the nonmetallic particles having a size of 1 [miu] or larger in terms of equivalent circular diameter have a specific average composition and the Ti-containing nitrides satisfy specific average number densities.

The invention provides a high tensile steel sheet having a low yield ratio in spite of its tensile strength of >=780 MPa, and having low acoustic anisotropy and excellent weldability, and to provide its production method. The steel sheet has a composition comprising, by mass, 0.010 to 0.080% C, 0.02 to 0.50% Si, 1.10 to 3.00% Mn, <=1.60% Cu, 0.40 to 2.50% Ni, <=0.030% P, <=0.010% S, <=0.200% Al, <=0.0100% N, 0.30 to 2.00% Cr, 0.10 to 1.10% Mo and 0.002 to 0.030% Ti, and the balance Fe with impurities. Further, regarding the following AS and DL, AS>=4.00 and DL<=2.80 are satisfied, the structure in the part of 1 / 4 in the sheet thickness is essentially composed of bainitic ferrite including MA by <=10 area% (excluding 0%), also, the average value of the major axis / manor axis of old austenite grains is 1.0 to 3.0, and further, the hardness ratio of the MA to the bainitic ferrite is >=1.10: AS=[Mn]+[Ni]+2*[Cu], and DL=2.5*[Mo]+30*[Nb]+10*[V]; [X] denotes the content (mass%) of the element X.

The present invention provides a steel plate which still exhibits excellent HAZ toughness and remarkable brittle cracking propagation cessation characteristic even under high thermal input welding. The inventive thick steel plate is formed by properly regulating chemical ingredients and meets the thick steel plates of the following formulae (1) and (2), and includes an organization having an organization with more than 95 area % of bainite fraction, and dislocation density of the bainite (rho<1 / 2>) is 1.0*10<6> to 5.0*10<7> (m<-1>). [Ti] / [N] is not less than 1.5 but not more than 4.0 ... (1), X value is not less than 40 but not more than 160 ... (2), X value = 500[C]+32[Si]+8[Mn]-9[Nb]+14[Cu]+17[Ni]-5[Cr]- 25[Mo]-34[V], in the formula, [] represents contents of each element (mass%).

A thick steel plate whose chemical composition in mass % is C: 0.01-0.20%, Si: 0.10-0.25%, Mn: 1.30-2.50%, P: less than 0.01%, S: 0.0010-0.0100%, Ti: 0.005 ~0.030%, Al: 0.003% or less, O: 0.0010~0.0050%, N: 0.0100% or less, Cu: 0~0.50%, Ni: 0~1.50%, Cr: 0~0.50%, Mo: 0~0.50% , V: 0 to 0.10%, Nb: 0 to 0.05%, and the balance: Fe and impurities, and the steel contains composite inclusions in which MnS exists around Ti oxides. The area ratio of MnS in the cross section of the composite inclusion is 10% or more and less than 90%, the ratio of MnS to the perimeter of the composite inclusion is 10% or more, and the number density of composite inclusions with a particle size of 0.5 to 5.0 μm 10~100 pieces / mm 2 . This thick steel plate is excellent in the low-temperature characteristics of the HAZ during high heat input welding.

The invention provides a high-tension hick steel plate for welding having excellent toughness for welding heat affected zone in high heat input welding. The hick steel plate comprises 0.02-0.12% of C, 0-0.40% OF Si, 1.0-2.0% of Mn, 0-0.03% of P, 0-0.015% of S, 0-0.050% of Al, 0.005-0.100% of Ti, 0.0002-0.0500% of REM and / or 0.0003-0.0100% of Zr, 0.0020-0.0300% of Nm 0.0005-0.0100% of O, the rest being Fe and unavoidable impurity. There are more than 500 mm<2> of oxide with diameter of equivalent circle being less than 2 um existed in steel, and there are 5 mm<2> of oxide with diameter of equivalent circle being more than 5 um; according to the viscosity of Mn, REM, Ca forming compounds in steel, the value of X defined by formula (1) is less than 10.0; wherein, [insol Mn], [insol REM], [insol Ca] respectively expresses viscosity (5) of Mn, REM, Ca forming compounds in steel; wherein, X=100 x[insol Mn] / ([insol REM]+[insol Ca]+0.

The invention provides a high-tension plate steel with excellent HAZ toughness. In respect of quality percent, the chemical composition thereof contains 0.02-0.12 percent of C, 0-0.40 percent of Si, 1.0-2.0 percent of Mn, 0-0.030 percent of P, 0.001-0.025 percent of S, 0-0.050 percent of Al, 0.005-0.100 percent of Ti, 0.0001-0.0500 percent of REM, 0.0001-0.0500 percent of Zr, 0.0020-0.0300 percent of N, and 0.0005-0.0100 percent of O; remnant parts are Fe and inevitable impurities; when content of oxide with a circle diameter measured to be less than 2 [mu]m is 500 / mm<2>, content of oxysulfide with a circle diameter measured to be more than 2 [mu]m is 40-1000 / cm<2>, and when REM and Mn and the like specified oxide for forming oxysulfide with a circle diameter measured to be more than 2 [mu]m are respectively REM2O3 and MnO2, etc., conversion value of oxide of REM, conversion value of oxide of Mn, oxide conversion value of each specified oxide conversion value calculated according to concentration of S relative to average concentration of each element forming the xoysulfide, and proportion of total value of mean concentration of S in oxysulfide are: oxide equivalent value of REM is over 10 percent; oxide equivalent value of Mn is less than 20 percent; oxide equivalent value of S is 3-20 percent.

The invention provides a thick steel plate. The thick steel plate has a great HAZ toughness in the low heat energy input welding and super high heat energy input welding; and the parent material also has a great toughness. The thick steel plate contains C: 0.030-0.10%, Si: below 0.8-2.0%, P: below 0.03%, S: below 0.01%, Al: 0.01-0.10%, Nb: 0.005-0.035%, Ti: 0.015-0.03%, B: 0.0010-0.0035% and N: 0.0050-0.01%; the grain diameter of the old austenite crystal is below 120 um; the island-shaped martensite (MA) is below 3%; in addition, the invention satisfies the following formulas (1) (2): [Ti] / [N] is more than or equal to 1.5 and less than or equal to 4 (1); X value is more than or equal to 40 and less than or equal to 160 (2); the X value=500[C]+32[Si]+8[Mn]-9[Nb]+14[Cu]+17[Ni]-5[Cr]-25[Mo]-34[V].

In a steel sheet, an A value is 4.5% or less, a Pcm value is 0.25% or less, a yield strength is 460 N / mm 2 to 580 N / mm 2 , a tensile strength is 550 N / mm 2 to 670 N / mm2, a difference between a hardness at 1 / 8t, which is a 1 / 8 thickness position from a surface of the steel plate in a through-thickness direction, and a hardness at 1 / 2t, which is a 1 / 2 thickness position from the surface of the steel plate in the through-thickness direction, is 20 or less by Vickers hardness, and an average grain size at 1 / 8t is 35 µm or less.

The invention provides a thick steel plate, which has excellent HAZ toughness even in extra large heat input welding and excellent low temperature base metal toughness. The steel contains: C, 0.030-0.10%; Si, less than 1.0%; Mn, 0.8-2.0%; P, less than 0.03%; S, less than 0.01%; Al, 0.01-0.10%; Nb, 0.015-0.035%; Ti, 0.015-0.03%; B, 0.0015-0.0035%; N, 0.0055-0.01%; Cu, less than 2.0%; Ni, less than 2.0%; Cr, less than 1%; Mo, less than 0.5%; V, less than 0.1%; and other component is Fe and inevitable impurities. The components meet the requirement of: [Ti] / [N] is 2-4, and 500[C]+32[Si]+8[Mn]-9[Nb]+14[Cu]+17[Ni]-5[Cr]-25[Mo]-34[V] not less than 40.

The invention provides a Bainite high-tension steel plate with excellent weldability over than 590 MPa grade capable of ensuring excellent HAZ toughness even welding in the wide heat energy input range from low heat energy input welding to high heat energy input welding. The high tensile strength steel plate has a prescribed chemical componential composition, and in which BP value and Pcm prescribed by prescribed relational formulae satisfy 120 to 300 (mass%) and <=0.20 (mass%), respectively, also, Ti-containing nitrides with the circle equivalent diameter of <=0.05 [mu]m are present by >=5.0*10<6> pieces per 1 mm<2>, and, therein, the number of the Ti-containing nitrides with the circle equivalent diameter of 0.01 to 0.03 [mu]m occupies >=75% to the number of all the Ti-containing nitrides.

The invention provides a thick steel plate, which is excellent in HAZ toughness during the large energy welding process. The characteristics of the thick steel plate satisfy the following chemical composition by mass% except oxygen constituent elements: Ti> 10%, A1<20%, 5 % <ca<40 % and 5 % <REM<50 %, 5 %<zr<40 % of at least any one of oxide, which satisfies the following formula (1) and (2). (1)Measured by an equivalent circle diameter gauge, the number of the oxide below 2 mu m is 200 / mm < 2 > or more. (2) Measured by an equivalent circle diameter, the number of the oxide over 2 mu m is 100 / mm < 2 > or less.