33results about How to "Fully refined grains" patented technology

The invention discloses a method for producing an iron-zinc alloy coated steel plate with the yield strength being equal to or higher than 220 MPa. The method comprises the steps that molten iron desulphurization, smelting through a converter and continuous casting are conducted, so that a billet is formed; hot rolling is conducted; rolling is conducted; cold rolling is conducted till the billet reaches the required thickness; continuous hot galvanizing is conducted; rapid cooling is conducted; aerial fog is used for cooling after zinc and iron are alloyed; finishing is conducted; oiling treatment is conducted; and sampling, performance testing and subsequence procedure treatment are conducted. According to the method for producing the iron-zinc alloy coated steel plate with the yield strength being equal to or higher than 220 MPa, on the premise that the yield strength ranges from 220 MPa to 260 MPa, the tensile strength ranges from 300 MPa to 380 MPa, and the elongation is equal to or higher than 43%, grains on the surface of a zinc-iron alloy coating are fine and are even in size distribution, the area ratio of holes in the surface of the coating is equal to or smaller than 5%, no microcrack exists on the surface, and the phenomena of pulverization and falling of the coating are unlikely to occur during stamping forming, namely the 90-degree V bending test grade reaches the level 2.

The invention discloses low-temperature X80HD (High Density) large-deformation pipeline steel with great wall thickness and a production method thereof, belonging to the technical field of medium-thickness plate production and longitudinal submerged arc welded tube production. A steel plate comprises the following chemical components in percentage by mass: not less than 0.04% and not greater than 0.09% of C, not greater than 0.35% of Si, not less than 1.5% and not greater than 1.85% of Mn, not greater than 0.012% of P, not greater than 0.004% of S, not less than 0.02% and not greater than 0.05% of Nb, not less than 0.008% and not greater than 0.025% of Ti, not less than 0.10% and not greater than 0.50% of Ni, not less than 0.10% and not greater than 0.45% of Cr, not less than 0.10% and not greater than 0.30% of Cu, not less than 0.10% and not greater than 0.35% of Mo, not less than 0.020% and not greater than 0.070% of Alt, not greater than 0.0005% of B, not greater than 0.0050% of Ca, and the balance of Fe and inevitable impurities. A preparation method of the steel plate comprises the processes such as converter smelting, external refining, continuous casting, heating, controlled rolling, relaxation phase change control and quick cooling; a texture of the rolled steel plate is ferrite, bainite and a little M / A (Martensite / Austenite), wherein ferrite content is 60%-85%, and bainite and M / A content is 15%-40%. The obtained X80HD large-deformation pipeline steel has high strength and toughness, a high work-hardening index, high uniform ductility, a low yield ratio and good deformation resistance.

The invention discloses a microalloying method capable of improving performance of steel for large heat input welding. The specific flow process of the production method comprises a converter steelmaking process, an LF refining process and a continuous casting process; according to the kind and the adding sequence of a deoxidizing agent in the LF refining process, Mo, Mn, Si, Nb, Al, Ca, Mg and Ti are included; the Al is adopted for final deoxidation, Mo-Nb-Mg-Ti alloying is carried out, the dispersive action of the MgO on Al2O3 and Ti2O3 serves as the foundation, dispersed, rich and small refractory oxides are formed to serve as cores, and generation of acicular ferrite in austenitic crystalline grains is promoted; on the other hand, a certain amount of Mo and Nb improve toughness of the steel while the grains are refined, and forming of pro-eutectoid ferrite of the grain boundary is restrained; in addition, part of small inclusion particles and carbon nitrogen carry out pinning on the austenite grain boundary, through several-aspect joint action, heat affected zone grains are fully refined, and the toughness of the steel is obviously improved; and the method is simple in control and low in production cost, and the steel for large heat input welding can be subject to large-scale production in an industrialization manner.