Method for preparing Q235B casting blank from high-sulfur low-manganese vanadium-titanium molten iron

Abstract

The invention discloses a method for preparing a Q235B casting blank from high-sulfur low-manganese vanadium-titanium molten iron. The method comprises three steps of molten iron desulfurization pretreatment, converter steelmaking and continuous casting, the sulfur content S in the desulfurized molten iron is controlled to be less than 0.020%, and the weight percentages of molten steel components at the end point of a converter are controlled as follows: C is 0.05-0.12%, P is less than or equal to 0.030%, and S is less than or equal to 0.025%. Low superheat degree casting is adopted, the superheat degree of a tundish is controlled according to 15-25 DEG C, a crystallizer is a copper pipe crystallizer, the casting pulling speed is controlled to be less than or equal to 2.5 m / min, the primary cooling water amount is controlled according to 140-150 m < 3 > / h, and the secondary cooling water amount is controlled according to 28-40 m < 3 > / h. According to the method, the problems of quality defects such as surface bulging, surface corrosion points and center penetrating cracks existing in preparation of the Q235B casting blank from existing high-sulfur low-manganese vanadium-titanium molten iron are solved.

Description

technical field [0001] The invention relates to a production method of casting slabs, in particular to a method for preparing Q235B casting slabs from high-sulfur, low-manganese, vanadium-titanium molten iron, which belongs to the technical field of iron and steel smelting and casting. Background technique [0002] Q235B is one of the common steel materials. It has certain elongation, strength, good toughness and castability. It is easy to stamp and weld. It is widely used in the manufacture of general mechanical parts, mainly used in construction and bridge engineering with high quality requirements. Welded structural parts. Q235B steel is a carbon structural steel for special purposes, such as bridge steel, marine steel, bridge tunnel support and various civil uses, etc. It needs to be tested for impact toughness at room temperature (20°C), and the impact toughness test uses Charpy V-notch specimens . For grades B, C, and D steels, Akv≥27J is required under their respect...

AI Technical Summary

Problems solved by technology

[0004] In view of this, aiming at the deficiencies of the above-mentioned prior art, the present invention provides a method for preparing Q235B cast slabs from high-sulfur, low-manganese, vanadium-titanium hot metals, so as to solve the problems existing in the preparation of Q235B cast slabs from existing high-sulfur, low-manganese, vanadium-titanium hot metals. Problems with quality defects such as bulging, surface rust spots, and center through cracks

Images