31results about How to "Improve high heat input welding performance" patented technology

The invention discloses a thick steel plate with a low carbon equivalent and excellent welding heat affected zone toughness and a manufacturing method of the same. The manufacturing method comprises the following steps: 1) smelting, refining and continuously casting the ingredients in the following percentage by mass: 0.045-0.075% of C, 0.10-0.30% of Si, 1.3-1.6% of Mn, not greater than 0.015% of P, 0.001-0.01% of S, 0.20-0.40% of Ni, 0.005-0.03% of Ti, 0.003-0.08% of Al, 0.0005-0.005% of Ca, not greater than 0.02% of REM, not greater than 0.02% of Zr, 0.0005-0.005% of B, 0.001-0.006% of N, 0.32-0.36% of Ceq, 0.0005-0.005% of Bef, and the balance of Fe and inevitable impurities; 2) rolling; and 3) cooling. According to the manufacturing method disclosed by the invention, inclusions with fine dispersed distribution can be formed, and by controlling the surface density of the micron inclusions with diameters of not less than 1 micron, Ca / Al ratio, the length-width ratio of the inclusions and the surface density of the submicron inclusions with diameters of less than 1 micron, the tensile strength of the base material is not less than 510 MPa, the weld heat input is 200-400 kJ / cm, and the average Charpy impact energy of a welding heat affected zone at minus 40 DEG C is greater than 100 J, therefore, excellent impact toughness is achieved.

The invention discloses a method for improving the high heat input welding performance of thick steel plates. The method comprises the following steps of: 1) smelting and casting to obtain an ingot, wherein deoxidants are added in the deoxidation process of molten steel, the adding sequence of the deoxidants is Mn and Si, Al, Ti, and Ca, a Mg deoxidant is added in the casting process of the molten steel, and the initial oxygen potential during the deoxidation of Mg is accurately controlled by adding Fe2O3 powder into a casting ingot mould; and 2) rolling and cooling. In the method, microfine dispersive distribution and Mg-containing inclusions, which are formed by adding the deoxidants in the deoxidation process of the molten steel and adding the Fe2O3 powder into the casting ingot mould to accurately control the oxygen potential during the deoxidation of the Mg, can inhibit the growth of austenite grains in a welding heat affected zone, and promotes the growth of ferrite in the grains, so that the high heat input welding performance of the thick steel plates is greatly improved.

The invention relates to a control method of inclusions in a thick steel plate used for high heat input welding, which is characterized by adding a deoxidizing agent during steel liquid pouring, wherein the components and adding order of the deoxidizing agent are as follows: Mn and Si, Al, Ti, Ca and Mg; the Mg content is 0.0005-0.007%, when Mg is added for deoxidizing, the oxygen content in steel liquid needs to be adjusted and precisely controlled through adding Fe2O3 powder to a casting ingot mold, and the adding amount of the Fe2O3 powder is such that the oxygen content in the steel liquid is maintained at 0.001-0.008%; the Al content in steel is lower than 0.006%; the ratio of the inclusions with size smaller than 3mu m in the steel liquid is not lower than 80%, and the surface density of the inclusions is not smaller than 300 inclusions / mm<2>; the main components in the center of the inclusions are MgO or MgO and Ti2O3, and the main component on the external surface of the inclusions is MnS. The inclusions formed by using the method provided by the invention can favorably inhibit the growth of austenite crystal in a welding heat-affected zone and promote the growth of intracrystalline ferrite, thus improving the high heat input welding performance of the thick plate.

The invention relates to an HT690 steel plate capable of being subjected to high heat inputwelding and a manufacturing method thereof. A component system treated by low C-high Mn-(Nb+V+B) microalloying-ultramicro Ti is adopted, the acid-soluble Als content in steel is properly improved, the Als is not less than (Mn equivalent / C)*(Ntotal-0.292Ti), (Mn equivalent) / C is between 20 and 40, Pcm is notmore than 0.205 percent, the Ti / N is between 2.0 and 4.0, (Cu+Ni+Mo+Cr) is alloyed and Ni / Cu is not less than 1.0, the Ca is treated and the Ca / S ratio is between 0.80 and 3.00 and the F*DI index is controlled to be not less than 0.80*finished steel plate thickness, a TMCP (Thermo-Mechanical Control Process) and a tempering process are optimized to ensure that the microscopic structure of a finished steel plate is fine tempering bainite, and the average crystal cluster size is below 25mum. The steel plate can bear high heat input welding at the same time of obtaining the properties of uniformand excellent obdurability and strong plasticity matching, is especially suitable for large steel structures of a hydroelectric pressure water pipe, a vortex, a sea platform and the like, and can realize low-cost and stable batch industrialized production.

The invention discloses a method for raising large heat input weldability of a thick steel plate, comprising the following steps: 1) smelting and casting to form a steel plate: adding deoxidizers in the deoxidation process of the liquid steel according to the following types and order: Mn, Si, Al, Ti, and Ca and / or Mg, controlling the initial oxygen place in the liquid steel when Mn deoxidation is carried out in casting, adding Fe2O3 powder to let the oxygen content in the liquid steel be 0.001-0.008 wt%, wherein, the steel plate comprises 0.05-0.09 wt% of C, 0.10-0.30 wt% of Si, 1.3-1.7 wt% of Mn, 0.005-0.02 wt% of Ti, no larger than 0.015 wt% of P, no larger than 0.01 wt% of S, no larger than 0.006 wt% of N, no larger than 0.004 wt% of Ca, and the balance consisting of Fe; in the steel, the volumn density of TiN deposition with the particle size of less than 500 nm is larger than 9.0*107 PCs / mm<3>, the average particle size is less than 80 nm, and the proportion of the deposition with the particle size of less than 100 nm is larger than 75 %; 2) rolling and cooling. The large amount of nano TiN deposition with dispersive distribution formed by the invention can inhibit the growth of austenite crystals in the heat affected zone, and greatly raise the large heat input weldability of the thick steel plate.

The invention provides a thick steel plate capable of being welded at a large heat input and a manufacturing method thereof. The manufacturing method comprises the following steps: (1) smelting and casting, wherein the thick steel plate is prepared from the following components in percent by weight: 0.05-0.09% of C, 0.10-0.30% of Si, 1.2-1.6% of Mn, not greater than 0.02% of P, 0.001-0.006% of S, 0.2-0.4% of Ni, 0.15-0.3% of Cu, 0.005-0.03% of Ti, 0.0005-0.01% of Mg, 0.001-0.006% of N, not greater than 0.05% of Al, not greater than 0.005% of Ca, not greater than 0.02% of REM, and not greater than 0.003% of B and the balance of Fe and unavoidable impurities, and Ti / N is no less than 1 and is not greater than 6, and Mg / (Al+Ti) is no less than 0.02; (2) rolling; (3) cooling. According to the thick steel plate capable of being welded at the large heat input and the manufacturing method thereof, tiny dispersion-distribution inclusion can be formed; by controlling the (Mg+Ca) / (Al+Ti) ratio and the surface density of micron inclusion with the diameter of no less than 1 micrometer and the (Mg+Ca) / (Al+Ti) ratio and the surface density of sub-micron inclusion with the diameter of 0.1-1 micrometer, a base metal with the tensile strength of no less than 510 MPa is obtained; when the welding heat input is 200-400 kJ / cm, the average charpy impact energy of the steel plate at -40 DEG C is more than 50 J.

The invention relates to a low-carbon-equivalent large heat input welding thick steel plate and a preparation method thereof. The preparation method comprises the following steps: 1) smelting and casting, wherein the steel plate comprises the following components in percentage by weight: 0.045-0.07% of C, 0.10-0.30% of Si, 1.3-1.6% of Mn, less than or equal to 0.015% of P, 0.001-0.01% of S, 0.2-0.4% of Ni, 0.005-0.035% of Ti, 0.0005-0.01% of Mg, 0.001-0.01% of N, 0.0005-0.005% of B, less than or equal to 0.05% of Al, less than or equal to 0.05% of Ca, less than or equal to 0.02% of REM and the balance of Fe and inevitable impurities and further comprises more than one of less than or equal to 0.03% of Nb or less than or equal to 0.2% of Cr; Ti / N is greater than or equal to 2 but less than or equal to 6, Mg / (Al+Ti) is greater than or equal to 0.024, Ceq is 0.32-0.36% and Bef is 0.0005-0.005%; 2) rolling; 3) cooling. By controlling the (Mg+Ca) / (Al+Ti) ratio and areal density of micron inclusions with the diameter which is greater than or equal to 1 micron as well as the (Mg+Ca) / (Al+Ti) ratio and areal density of submicron inclusions with the diameter which is 0.1-1 micron, for the steel plates with the thickness being 50-70 mm and the base material tensile strength being greater than or equal to 510 MPa, the steel plates are welded with the weld heat input of 200-400kJ / cm, and the average Charpy impact energy of a welding heat affected zone at -40 DEG C reaches 100J above.

The invention belongs to the field of steel material preparation, and particularly relates to a low-yield-ratio marine steel plate with good welding performance and a manufacturing method thereof. Thelow-yield-ratio marine steel plate comprises the following components of, by weight, 0.05%-0.09% of C, 0.1%-0.4% of Si, 1.0%-1.5% of Mn, less than or equal to 0.02% of P, less than or equal to 0.02%of S, 0.005%-0.03% of Als, 0%-0.6% of Ni, 0%-0.3% of Cu, 0.008%-0.05% of Nb, 0.005%-0.03% of Ti, 0.002%-0.01% of N, 0.02%-0.08% of V, 0%-0.3% of Mo, and the balance Fe and inevitable impurities, wherein the yield ratio of the steel plate is less than or equal to 0.80, the carbon equivalent Ceq is less than or equal to 0.41, and Pcm is less than or equal to 0.21. According to the low-yield-ratio marine steel plate with the good welding performance and the manufacturing method thereof, a certain content of N element is added, and second phase dispersion precipitation of V, Ti element is matched,so that the high-heat input welding performance and the low-temperature impact toughness of the steel plate are improved; and chemical components and the processes of high finish rolling temperature,low water inlet high red returning temperature and low cooling speed are combined, so that the high service safety with the yield ratio being less than or equal to 0.8 can be obtained, and a corresponding production process is formed while the high-service safety steel plate which is easy to weld with high heat input is obtained.

The invention discloses a control method for a nano-scaled precipitate in a thick steel plate for high heat input welding. Deoxidizers are added during smelting and casting of molten steel, wherein the types and the adding sequence for the deoxidizers are that: (Mn+Si), Al, Ti and (Ca+Mg); Mg content is 0.0005-0.007 percent; oxygen level in the molten steel is required to be adjusted during Mg deoxidization; accurate control is performed by adding Fe2O3 powder into a cast ingot casting mould; the amount of added Fe2O3 powder is 0.001-0.008 percent of oxygen content in the molten steel; the volume density of the precipitates of less than 500nm in steel is more than 9.0*107 per cubic millimeter; the average particle size is less than 80.0nm; and the proportion of the precipitates of less than 100nm is more than 75 percent. A large number of nano-scaled precipitates with small sizes are formed by the method and are finely dispersed and distributed in the steel; suppression of austenite grain growth of a welding heat affected zone is facilitated; and the high heat input welding performance of the thick plate is improved.