Control method of white spot defects on surface of cold rolled low-carbon steel

Abstract

The invention relates to a control method of white spot defects on the surface of a cold rolled low-carbon steel, and belongs to the technical field of production of metallurgical plates. The controlmethod comprises the following processes of continuous casting, hot rolling, acid rolling and continuous annealing, wherein the hot rolling process, H2S in a hot rolling heating furnace is less than or equal to 120 mg / Nm<3>, the rough rolling dephosphorizing pass is larger than or equal to 3, the water temperature for preliminary dephosphorizing, rough rolling dephosphorizing, finish rolling dephosphorizing and laminar cooling is lower than or equal to 40 DEG C, the finish rolling inlet temperature is lower than or equal to 1100 DEG C, the laminar cooling adopts a front-section cooling mode that cooling is started to be performed from the cooling end of a cooling end, the finish-rolling temperature is 800-950 DEG C, and the coiling temperature is 600-750 DEG C; in the acid rolling process, on-line hot rolling temperature is lower than or equal to 80 DEG C, the acid solution temperature control range is 70-100 DEG C, the acid concentration control range is 30-190 g / L, and the picklingtape speed is smaller than or equal to 200 m / min; and the elongation of a withdrawal and straightening machine is 1.5%-3.0%. The control method can effectively avoid or reduce various white spot defects on the surfaces of cold rolled low-carbon strip steels.

Description

technical field [0001] The invention relates to a method for controlling white spot defects on the surface of cold-rolled low-carbon steel, and belongs to the technical field of metallurgical plate production. Background technique [0002] The surface quality of strip steel is an important embodiment of the quality of strip steel products; due to the long process flow of cold-rolled low-carbon steel production, the defect morphology will evolve through different processes, resulting in the variety and complexity of the surface defects of the final product; at the same time, Some defects with different causes have very similar appearance characteristics to the final process, which brings great difficulties to the surface quality research work, resulting in the stable production of cold-rolled automotive sheets with excellent surface quality, especially automotive outer sheets nationwide. There are only a few enterprises, and the overall pass rate is also at a low level. The ...

AI Technical Summary

Problems solved by technology

[0003] The thesis "Control Measures for Scale Indentation Defects on Cold-rolled Substrates" combined with actual production experience, only elaborated on several common hot-rolled scales caused by slab heating temperature, dephosphorization pressure and roll problems, and did not involve to the specific process parameters, and does not reflect the white spot defects caused by insufficient control of the acid rolling process

[0004] The paper "The Influence of Hot Rolling Process Parameters and Differences in Oxygen Supply on Scale Structure and Thickness" explored the influence of different process parameters on scale, but there are few process points, and there are deficiencies in the content related to production line equipment

[0005] The Chinese patent application with the application number 201610127232.2 discloses a hot rolling control method for the edge scale of low-carbon aluminum killed steel, which solves the problem that the scale of the strip steel edge is not easy to be pickled in the prior art, and can effectively avoid The white spot defects caused by the willow-shaped secondary oxide scale are only applicable to the production of aluminum killed steel, and the key control points such as cooling water temperature, hot coil cooling method and pickling process are not involved

[0006] The Chinese patent with application number 201810387617.1 discloses a processing method of low-carbon aluminum-killed steel pickling plate. The pickling plate is formed by heating, rough rolling, finish rolling, cooling, coiling, and pickling steps to form an acid pickled plate. Washed finished board can effectively avoid landscape-like white spot defects, but it is only suitable for the production of pickled boards

Images