Method of controlling the net crack of high-nitrogen continuous-casting slab of high strength weathering steel containing vanadium

Abstract

The invention discloses a net-shaped crack control method of high nitrogen and high strength weathering steel continuous casting billet containing vanadium, the method can not only effectively eliminate net-shaped crack of the continuous casting billet, but also can eliminate the continuous casting billet surface longitudinal crack and surface transverse crack defect. The method synthetically applies following technique measures: presetting cooling water amount of the mold wide face to 2485-2515 L / min, the narrow face cooling water amount is set to 304-306 L / min; the casting pulling rate is stabilized in 0.8-1.0 m / min, the billet casing surface temperature of the casting billet out of the mold lower end is increased to 1050-1120 DEG C, the vibration frequency is 110-130 Hz; reducing Cao mixing amount in the casting powder, the alkalinity of the casting powder is 0.95-1.20, the melting point is 1080-1120 DEG C, when at 1300 DEG C, the viscosity is 0.2-0.5 Pa.s; reducing the second cool segment casting billet cooling water amount, and controlling the continuous casting ratio water amount in 0.60-0.65 L / kg by static or dynamic adjusting method.

Description

technical field [0001] The invention relates to a quality control method of continuous casting slabs, in particular to a method for controlling the surface quality of continuous casting slabs of vanadium-containing high-nitrogen high-strength weathering steel. Background technique [0002] The content of Cu, Cr, Ni, Al, V, N elements in the composition of vanadium-containing high-nitrogen high-strength weathering steel is relatively high, and the carbon content is located in the peritectic reaction zone. When continuous casting produces steel with carbon content located in the peritectic reaction zone, the slab is prone to surface cracks, and the addition of Cu, Cr, Ni and other components in the steel makes the crack sensitivity of the steel stronger, and the addition of Al at the same time , V, N and other components in the continuous casting production process, because Al and V in solid solution at high temperature are dynamically precipitated or statically precipitated a...

AI Technical Summary

Problems solved by technology

In addition, its process of "optimizing suitable continuous casting mold flux, improving the heat transfer of primary cooling and secondary cooling" is not combined with the control of continuous casting casting speed, but factors that affect the heat transfer of the crystallizer, such as continuous casting casting speed, crystallizer Mold slag and mold cooling system are interrelated, and the three must be compatible with the composition of the continuous casting steel to achieve the effect of uniform heat transfer of the slab in the mold and improve the surface quality of the slab. Therefore, only It is difficult to eliminate longitudinal crack defects on the surface of weathering steel slabs from the aspects of optimizing continuous casting mold flux, improving heat transfer of primary cooling and secondary cooling

At the same time, the above two types of steel do not contain vanadium, and the nitrogen content and aluminum content are also low. Another major technical problem encountered in the continuous casting of high nitrogen steel containing vanadium and aluminum is AlN, V (CN) and other precipitates are precipitated at the austenite grain boundary to induce slab network cracks and transverse crack defects, and the technology to solve the vanadium-containing high-nitrogen high-strength weathering steel slab network cracks and surface transverse crack defects has not been reported.

It can be seen from the above research that the surface quality control of weathering steel slabs currently studied is limited to the longitudinal cracks on the surface of low nitrogen steel slabs that do not contain vanadium. In terms of control, it is difficult to play a greater role