Acid-pickling-free hot rolled strip steel with high surface quality and manufacturing method thereof

Abstract

The invention discloses acid-pickling-free hot rolled strip steel with the high surface quality. Oxide layers are arranged on the surface of the acid-pickling-free hot rolled strip steel and comprise the surface oxide layer and the inner oxide layer, wherein the inner oxide layer closely adjoins the surface oxide layer and is located on the inner side of the surface oxide layer. The surface oxide layer comprises a pure iron layer relatively located on the outer layer and a ferric oxide layer relatively located on the inner layer. The appearance and surface quality of the acid-pickling-free hot rolled strip steel approximate to those of a cold-rolled plate, the acid-pickling-free hot rolled strip steel is excellent in formability, and the oxide layers cannot fall in the stamping process. In addition, the invention discloses a manufacturing method of the acid-pickling-free hot rolled strip steel. The method includes the steps of (1) smelting and casting, (2) hot rolling and (3) finishing. According to the step of hot rolling, the heating temperature is 1100-1300 DEG C, heat preservation is conducted for 1-5 h, the final rolling temperature is not smaller than 850 DEG C, the strip steel is cooled at the speed of 1-10 DEG C/s after finish rolling, and a hot-rolled plate is reeled at the temperature of 600-750 DEG C. The acid-pickling-free hot rolled strip steel can be obtained through an existing hot rolling production line, acid pickling is not needed, the cost is low, and the quality is high; and the acid-pickling-free hot rolled strip steel has the application prospects of replacing acid-pickled plates and part of cold-rolled plates.

Description

technical field [0001] The invention relates to a hot-rolled steel strip and a manufacturing method thereof, in particular to an pickling-free hot-rolled steel strip and a manufacturing method thereof. Background technique [0002] Hot-rolled steel strip is formed by rolling the heated slab at high temperature and then coiling. After hot rolling, the surface will be formed by Fe 2 o 3 , Fe 3 o 4 , FeO oxide scale, the appearance is red or black, and the surface appearance quality is poor, so it generally needs to be removed by pickling. [0003] Although the currently widely used pickling method can remove scale, the waste acid and other pollution produced is serious and the manufacturing cost is relatively high. Therefore, some users hope to directly use the hot-rolled strip with scale for stamping parts, but due to the poor formability of iron oxide, the stamping process will cause the scale on the surface of the hot-rolled strip to fall off and become powder, which no...

AI Technical Summary

Problems solved by technology

Although Fe in the iron oxide scale in black steel 3 o 4 After the content is increased, its adhesion is improved, which can reduce the stamping shedding, but it cannot completely avoid the stamping shedding, and the hot-rolled sheet with iron oxide can not always reach the surface quality of the pickled sheet and cold-rolled sheet

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