A Method for Reducing Shape Defects of Ingot-Cr-Mo Steel Plate

Abstract

The invention discloses a method for reducing shape defects of a steel ingot into a Cr-Mo steel plate. The method includes steel ingot smelting, heating and rolling processes; the steel ingot rolling process includes roll shape control, rolling process control, Cooling control after rolling, straightening process control. In the steel ingot smelting process of the present invention, the composition segregation is improved through precise control of the argon blowing process after the refining furnace adds the alloy to ensure uniform composition of the molten steel; a certain heating temperature and holding time are guaranteed during the heating process of the steel ingot to ensure uniform heating of the steel ingot and further reduce the composition segregation of the steel ingot ;During the steel plate rolling process, the downward pressure rolling can reduce the phenomenon of rolling buckle, improve the shape of the steel plate, control the straightening temperature and straightening force, and ensure the straightening effect of the steel plate. The ingot-finished Cr-Mo steel plate produced by the method of the present invention has no obvious defects such as buckling and wavy bending, the head-to-tail width difference is ≤20mm, the unevenness of the steel plate is ≤5mm / m, and the difference between steel plates is ≤0.3mm.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a method for reducing plate shape defects of Cr-Mo steel plates formed from steel ingots. Background technique [0002] It is very difficult to control the shape of Cr-Mo steel with a thickness of 140-200 mm from steel ingot, which is mainly manifested in the following aspects. The first is that the content of alloying elements in Cr-Mo steel is relatively high, and the content of main alloying elements has exceeded 3%. Segregation is prone to occur when the content of alloying elements is high. Secondly, during the heating process of the steel ingot, it is easy to have temperature unevenness, and there are differences in the amount of reduction during the rolling process, and the steel plate is prone to defects such as scooping and wave bending; Large width difference; during the ingot rolling process, the temperature of the roll is too high, resulting in excessi...

AI Technical Summary

Problems solved by technology

The first is that the content of alloying elements in Cr-Mo steel is relatively high, and the content of main alloying elements has exceeded 3%. Segregation is prone to occur when the content of alloying elements is high. Secondly, during the heating process of the steel ingot, it is easy to have temperature unevenness, and there are differences in the amount of reduction during the rolling process, and the steel plate is prone to defects such as scooping and wave bending; Large width difference; during the ingot rolling process, the roll temperature is too high, resulting in excessive roll convexity, which affects the thickness control of the steel plate

[0003] If the Cr-Mo steel with large thickness has the defect of the same plate difference, in order to ensure that the thickness of the steel plate meets the requirements, the overall thickness of the steel plate needs to be increased, which will reduce the yield of the steel plate and increase the difficulty of subsequent processing of the steel plate; if the steel plate is warped And wavy bends and other defects, because the thickness of Cr-Mo steel reaches 140-200mm, and the tensile strength reaches more than 620MPa, the scoop and wavy bends cannot be straightened through pre-heating and flattening, which will increase the production process. It will also increase the production cost and affect the surface quality of the steel plate. During the flattening process, iron marks are easy to appear, and in severe cases, it will directly cause the steel plate to be unplanned.