Method for eliminating transverse cracks at corners of cold-rolled matrix casting blank

Abstract

The invention provides a method for eliminating transverse cracks at corners of a cold-rolled matrix casting blank. According to the method, the cooling modes of the casting blank at all stages in theaustenite transformation process are determined. Particularly, a, the strong cooling mode is adopted when the casting blank is in a crystallizer and foot roller section, so that MnS is dissolved in austenite before being separated out; b, the strong cooling mode is adopted when the casting blank enters a bent section, so that flake membranaceous ferrite is prevented from being separated out, andthe width of the membranaceous ferrite is controlled to be smaller than or equal to 100 [mu]n; and c, the weak cooling mode is adopted when the casting blank enters a third sectorial section, a fourthsectorial section, a fifth sectorial section and a sixth sectorial section. According to the method for eliminating the transverse cracks at the corners of the cold-rolled matrix casting blank, an empirical equation under different drawing speeds of a continuous casting machine and under different cooling water quantities at different positions is obtained according to the evolvement rule of thesolidification process of the casting blank based on linear analysis of a large quantity of field data. By adoption of the method, the optimal condition can be provided for transforming austenite intoferrite, the membranaceous ferrite is prevented from being separated out, rapid solid solution of second-phase particles MnS is achieved, the precipitation quantity is reduced, and the transverse cracks at the corners of the cold-rolled matrix casting blank are eliminated.

Description

technical field [0001] The invention relates to a method for iron and steel smelting, in particular to a method for eliminating transverse cracks at the corners of a cast slab of a cold-rolled base material. Background technique [0002] The cold-rolled base material is aluminum-killed steel, and the Al content in the steel is 0.020-0.060%, which can ensure that 〔O〕≤20ppm in the steel, but because Al is easily combined with N to form AlN, AlN is brittle in austenite crystallization Grain boundaries increase the crack susceptibility of the steel. At present, there are many studies on the formation mechanism and solutions of slab transverse cracks at home and abroad. There are two traditional measures to solve the transverse cracks at the corners of slabs: one is to increase the surface temperature of the slab in the bending or straightening area, so that It is higher than the upper limit of 700-900°C in the brittle trough area; the second is to reduce the surface temperature...

AI Technical Summary

Problems solved by technology

This conventional method of "specific water volume" controls the water distribution of the secondary cooling. The problem is that it can only distribute the water volume within a given casting speed range, and the cooling intensity above the fan-shaped section is low. The cooling intensity is high, and the cooling water volume becomes smaller from the fifth and sixth fan-shaped sections. This cooling mode is not conducive to eliminating the transverse cracks at the corners of the slab, and cannot adjust the water volume when the casting speed fluctuates. It is not suitable for the casting slab when the casting speed fluctuates. Quality Control

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