Production method of hot-rolled 409l ultra-pure ferritic stainless steel strip by annealing and pickling

Abstract

The invention discloses a hot-rolled 409L ultra-pure ferrite stainless band steel annealing and acid-pickling production method, which comprises the following steps: performing scale breaking to the annealed band steel through a scale breaker; then carrying out scale removal through a shot blasting machine; flowing through a sulfuric acid electrolysis pickling bath; flowing through a sulfuric acid pickling bath after the sulfuric acid electrolysis pickling bath; flowing through a mixed acid pickling bath; flowing through a nitric acid pickling bath after being pickled by mixed acid, wherein the concentration of nitric acid in the bath ranges from 60g / L to 100g / L, the concentration of metal ions ranges from 5g / L to 20g / L, the temperature of acid ranges from 30DEG C to 45DEG C, and the speed of the band steel ranges from 50m / min to 70m / min. By effectively regulating the annealing temperature, band steel speed, elongation rate, the shot blasting quantity of the shot blasting machine, as well as the rotating speed, acid-pickling technology, current size, acid concentration, acid temperature and acid ingredients, the oxide scale on the surface of the band steel can be thoroughly removed, the grade of acid-pickled surface quality of the band steel can be improved, excellent surfaces can be obtained and the material yield can be increased.

Description

technical field [0001] The invention belongs to the field of stainless steel production, in particular to a production method for annealing and pickling hot-rolled 409L ultra-pure ferritic stainless steel strip. Background technique [0002] During the finishing rolling process of hot-rolled ultra-pure 409L ferritic stainless steel strip steel, a dense oxide layer will be formed on the surface of the strip steel. After annealing in a continuous annealing furnace, the thickness of the oxide layer will become thicker. , it is necessary to use a scale breaker and a shot blasting machine to remove most of the scale on the surface of the strip, and then go through sulfuric acid pre-pickling + mixed acid pickling process to remove the scale on the surface of the strip and form a dull layer on the surface of the strip. film. The production method currently used, because the hot-rolled ultra-pure 409L ferritic stainless steel surface oxide scale is closely combined with the metal m...

AI Technical Summary

Problems solved by technology

The production method currently used, because the hot-rolled ultra-pure 409L ferritic stainless steel surface oxide scale is closely combined with the metal matrix, the strip steel surface oxide scale is not cleaned during the pickling process, and the strip steel surface roughness after pickling is relatively high. Large, the surface quality of strip steel after pickling is low, and often cannot meet the surface quality requirements of NO.1 products

[0003] At present, after annealing and mechanical descaling, when hot-rolled 409L ultra-pure ferritic stainless steel strip is pickled, sulfuric acid pre-pickling + mixed acid pickling process is generally used, because the oxide scale on the surface of 409L strip steel is closely combined with the metal matrix , Sulfuric acid pre-pickling cannot effectively remove the scale on the surface of the strip, and the pickling effect of mixed acid on 409L is poor, resulting in frequent under-pickling