Stable rolling method of 600μm thin gauge 250mpa high phosphorus if steel

Abstract

The invention relates to a stable rolling method for 250MPa high-phosphorus IF steel with a thickness of 600 μm and belongs to the technical field of production technology of thin-gauge high-strength deep-drawing steel. The technical solution is: ① The mass percentage of the final chemical composition of steelmaking is: C: 0.020%‑0.04%; Si: 0.30‑0.50%; Mn: 0.60‑0.80%; S: ≤0.012%; P: 0.08%‑0.09%; Ti: 0.002%~0.01%; Nb: 0.04%~0.05%; B: 0.0005%‑0.001%; ​​the rest is Fe; The temperature is 700±20°C; ③The reduction rate of continuous acid rolling is 76%‑77%. The beneficial effects of the invention are: by adding a certain amount of boron in the smelting process, optimizing the process of the hot rolling process and the continuous acid rolling process, the stable production of 250MPa high-phosphorus IF steel with a thickness of 600 μm is realized.

Description

technical field [0001] The invention relates to a stable rolling method for 250MPa high-phosphorus IF steel with a thickness of 600 μm and belongs to the technical field of production technology of thin-gauge high-strength deep-drawing steel in the metallurgical industry. Background technique [0002] With the continuous improvement of automobile lightweight, cost reduction and safety requirements, the proportion of thin-gauge high-strength deep-drawing steel used in automobile structural steel is increasing year by year. Phosphorus-containing high-strength IF steel can maintain excellent deep drawability and obtain high strength only through the intergranular strengthening effect of P. It has been widely used in automotive structural parts, especially phosphorus-containing IF steel with a strength of 250MPa and below. [0003] In the metallurgical industry, phosphorus in IF steel is easy to segregate at the grain boundary, causing cold-working brittle cracking to occur freq...

AI Technical Summary

Problems solved by technology

Unstable temperature control in hot rolling of high-phosphorus IF steel causes segregation of P elements and excessive reduction rate of recompression, resulting in brittle fracture of stacked steel due to fluctuations in plate shape and rolling force during hot rolling and acid rolling; hot rolling stock preparation 2.7mm and above rolling 600μm cold plate, high rolling force due to high reduction rate in the acid rolling process of strip steel, high tension deviation fluctuation, reduced rolling stability, and increased probability of strip strip deviation

[0005] Second, the shape and thickness fluctuations of the steel strip head and tail directly affect the welding quality, and the rolling force is unstable after entering the rolling mill, resulting in broken strips; the cutting blades of the disc shears have been used for a long time, and the cutting blades are aging and worn. The problem directly causes the quality of edge trimming to drop and leads to broken belt

[0006] Third, the pickling speed, acid concentration and acid temperature directly affect the pickling quality of its strip steel, thereby affecting the stability of its subsequent rolling, and the thickness of parking spots caused by too slow rolling speed and over pickling It often causes the strip to deviate during the rolling process, and the rolling speed is too fast and the pickling is not enough, which will lead to the wear of the roll surface and the reduction of the surface quality of the strip

[0008] Fifth, the factors that directly affect the rolling shape of 600μm thin gauge 250MPa high-phosphorus IF steel include the roll bending value. If the bending roll is too large, it will easily cause the center wave and the strip steel to be folded. Ripping with strip deviation

[0009] Sixth, if the exit speed of the rolling mill is too low or too high, it will affect the quality of acid rolling

If the exit speed of the rolling mill is too low, the thickness fluctuation of the steel strip will increase; if the exit speed of the rolling mill is too high, the vibration of the rolling mill will obviously intensify, which will affect the stability of the rolling process and the accuracy of the thickness control of the plate

[0010] Seventh, in the pickling production process, the working kilometers of the working rolls and intermediate rolls of the rolling mill also have a great influence on the thickness and shape quality of the pickling strip. The surface of the rear roller is severely worn, which cannot guarantee good shape quality

Images