Method for improving Z-direction performance of Q390E thick plate with thickness of 50-80mm

Abstract

The invention discloses a method for improving Z-direction performance of a Q390E thick plate with the thickness of 50-80mm. The plate comprises the following chemical components, by weight, 0.07-0.10% of C, 1.4-1.50 % of Mn, 0.15-0.25% of Si, less than or equal to 0.005% of S, less than or equal to 0.015% of P, 0.020-0.04% of Als, 0.025-0.035% of Nb, 0.035-0.045% of Ti, less than or equal to 20PPM of T[O], less than or equal to 50PPM of N and less than or equal to 1.5PPM of H. The thickness of the plate ranges from 50-80mm. The whole process flow comprises the steps of molten iron pre-desulfurization treatment, converter treatment, LF and RH refining, 250mm thick plate blank treatment, heating, controlled rolling and controlled cooling and stack cooling. A converter tapping slag washing process is adopted, high-alkalinity synthetic slag is used, and the synthetic slag comprises the components, more than or equal to 60% and less than or equal to 70% of CaO, 15-20% of BaO, more than 0 and less than or equal to 3.0% of SiO2, more than 0 and less than or equal to 4.5% of Al2O3, more than 2.0% and less than or equal to 4.1% of Na2O, less than or equal to 7.5% of CaF2 and less than or equal to 4% of MgO. Casting powder used in the continuous casting process comprises the specific chemical components, by weight, 4.1-6.5% of C, 25-30% of CaO, 27-32% of SiO2, 5-10% of Na2O, 7-10% of TiC, 3-6% of TiO2, 5-8% of F, 7-15% of B2O3, less than or equal to 3% of Al2O3, 1-1.5% of MgO; less than or equal to 3% of MnO, less than 3% of Fe2O3; and less than 0.5% of H2O.

Description

technical field [0001] The invention relates to compositional design of steelmaking and clean steel control technology, in particular to a method for improving the Z-direction performance of a Q390E thick plate with a thickness of 50-80mm. Background technique [0002] According to the public papers of "Q390E" keyword query of CNKI, there is "Development and Production of Low-alloy High-strength Structural Steel Plate Q390E" (Tianjin Metallurgy, 2008 No. 4), the development thickness is less than 50mm, and Nb / V / Ti composite is used. Enhanced design; "Research and Application of Production Technology Based on 400mm Continuous Casting Billet Development of 120 mmQ390E" (Physical Test, Issue 4, 2018), the thickness of which is 120mmQ390E. [0003] According to the patent information comprehensive service platform "Z-direction performance" keyword query, the published patents are: a production process that guarantees the Z-direction performance pass rate of medium-thick steel pl...

AI Technical Summary

Problems solved by technology

Relevant patents, the use of expensive Ni and Mo alloy design in the thick specification Q390E, or the use of normalizing furnace for normalizing treatment, not only high composition, but also long production cycle, which is not conducive to batch supply of contracts

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