Method of preventing transverse corner cracks of microalloyed steel continuous casting sheet billet

Abstract

The invention relates to the technical field of metallurgy steelmaking sheet billet continuous casting, in particular to a method of preventing transverse corner cracks of a microalloyed steel continuous casting sheet billet. After the method is applied in a ladle furnace smelting technology and a continuous casting technology, the mass percent of Ti in microalloyed steel is controlled at 0.018-0.025%, and a specific water flow of secondary cooling water of a continuous casting machine is adjusted to 0.42L/kg. According to the method, the problem of the transverse corner cracks of microalloyed steel continuous casting sheet billet is mainly solved by adopting a technological means; through molten steel micro-Ti treatment, the grain boundary precipitation of NbN and VN in the microalloyed steel and the grain boundary strength are reduced and weakened, a third high-temperature brittleness area of steel is avoided from a cooling procedure, and the stress strain of corners of the casting billet during straightening is reduced; no additional equipment transformation or investment is required; no strict requirement is made on whether electromagnetic stirring equipment is equipped; and the method is low in investment and wide in application range, and has few restrictions.

Description

technical field [0001] The invention relates to the technical field of metallurgical steelmaking slab continuous casting, in particular to a method for preventing transverse cracks at corners of microalloyed steel continuous casting slabs. Background technique [0002] Microalloyed steel refers to the steel in which niobium, vanadium, titanium and other microalloying elements are added to the steel. The existence of microalloying elements greatly improves the strength and toughness index of steel through mechanisms such as grain refinement, solid solution strengthening, precipitation strengthening, and dislocation strengthening, so as to realize the lightweight design of steel, which meets the requirements of energy saving, emission reduction, and low-carbon economy. Require. In recent years, the development and application of microalloyed steel has developed rapidly, and it has been widely used in many industries such as oil pipelines, automobiles, ships, construction mach...

AI Technical Summary

Problems solved by technology

[0003] However, it is the addition of micro-alloying elements that makes the high-temperature mechanical properties of micro-alloyed steel change greatly, the third embrittlement zone of the steel becomes wider and deeper, and the crack sensitivity of the steel increases, especially the continuous casting slab. The probability of transverse cracks at the corners is much greater than that of other steel types

The transverse cracks at the corners expand during the rolling process, causing edge crack defects on the steel plate or steel coil, resulting in the degradation of the steel plate or steel coil, or even scrapping, and the loss is large. Therefore, it is necessary to clean the transverse cracks at the corners before the slab enters the heating furnace. necessary

[0004] The method of cleaning the transverse cracks at the corners is generally to cut off the corners of the slab with a flame cutting machine. This cleaning method has the following disadvantages: first, the slab is reversed and the cleaning increases labor intensity; The lower the yield, the higher the cost; the third is that if the transverse cracks at the corners are not cleaned, the steel plate or steel coil has edge cracks after rolling, or the cleaning surface is not smooth, and the cutting slag generated by cleaning is not cleaned, the steel plate or steel coil after rolling There are scab defects on the roll; the fourth is that the billet needs to be cleaned, resulting in an increase in the storage time of the billet in the billet inventory, an increase in the inventory of semi-finished products, a longer period of input to output, and disrupted the production rhythm between continuous casting and rolling