Method for improving internal quality of medium plate

Abstract

The invention discloses a method for improving internal quality of a medium plate. According to the invention, by adding Ti to fix N, the vast amounts of generation of AlN is reduced, and manganese segregation is minimized. The method comprises the following steps: 1, after molten steel arrives at the argon station, adding ferrotitanium with the amount of 1-1.5 kg per ton steel; and 2, after adding ferrotitanium, blowing argon for more than 3 min, then adding aluminium wires with the amount of 4-6 m per ton steel. According to the invention, the content of N in steel is reduced, the center segregation of the casting blank is reduced, and the internal quality of the medium plate is improved.

Description

technical field [0001] The invention belongs to the technical field of production and manufacture of medium-thick steel plates, and in particular relates to a method for improving the internal quality of medium-thick steel plates. Background technique [0002] At present, the internal flaw detection quality of steel plates is the bottleneck that restricts the improvement of the qualified rate of medium and thick plates. The steel plates that fail the flaw detection are mainly concentrated in steels with high content of microalloying elements such as Nb, V, and A1, because such steels During this solidification process, a large number of particles such as AlN, Nb(C)N, and VN are precipitated at the austenite grain boundaries. During the rolling process, the internal stress of the steel plate is often too large due to rolling stability control. In addition, the N in the steel If the content is too high, cracks will be generated inside the steel plate during the cooling process...

AI Technical Summary

Problems solved by technology

[0002] At present, the internal flaw detection quality of steel plates is the bottleneck that restricts the improvement of the qualified rate of medium and thick plates. The steel plates that fail the flaw detection are mainly concentrated in steels with high content of microalloying elements such as Nb, V, and A1, because such steels During this solidification process, a large number of particles such as AlN, Nb(C)N, and VN are precipitated at the austenite grain boundaries. During the rolling process, the internal stress of the steel plate is often too large due to rolling stability control. In addition, the N in the steel If the content is too high, cracks will occur inside the steel plate during the cooling process at the end of rolling, and eventually the steel plate will fail to pass the flaw detection

The enrichment of manganese in the center of the slab causes the CCT curve to move to the right in the central area of ​​the steel plate thickness, resulting in abnormal structures in the center. Under the action of structural stress and thermal stress during the rolling process, microcracks are generated in the central area of ​​the steel plate, resulting in Steel plate flaw detection failure