Stainless steel hot rolling strip steel acid pickling process

Abstract

The invention relates to a stainless steel hot rolling strip steel acid pickling process. The process comprises the steps of scale breaking unit scale removal pretreatment, wherein the total extensionrate of strip steel is controlled to be larger than or equal to 3.0%; first-segment hydrochloric acid acid pickling, wherein the strip steel is immersed in first-segment hydrochloric acid acid pickling liquid to be subjected to first-segment hydrochloric acid acid pickling, the hydrochloric acid concentration of the first-segment hydrochloric acid acid pickling liquid is controlled to 50 to 300 g / L, the iron ion concentration is controlled to 5 to 100 g / L, the temperature is controlled to 60 to 80 DEG C, and the acid pickling time is controlled to 25 s to 50 s; second-segment hydrochloric acid acid pickling, wherein the strip steel is immersed in second-segment hydrochloric acid acid pickling liquid to be subjected to second-segment hydrochloric acid acid pickling, the hydrochloric acid concentration of the second-segment hydrochloric acid acid pickling liquid is controlled to 50 to 250 g / L, the iron ion concentration is controlled to 5 to 100 g / L, the temperature is controlled to 50to 75 DEG C, and the acid pickling time is controlled to 25 s to 50 s; grinding scrubbing, wherein the strip steel is subjected to grinding scrubbing, the diameter of roller brush bristles is controlled to 0.7 to 1 mm, the bristles contain silicon carbide abrasives with meshes being 170 to 200 meshes, the rotating speed of a roller brush motor is controlled to 600 to 1000 rpm, and the current of the roller brush motor is controlled to 100 to 200 A.

Description

technical field [0001] The invention relates to the technical field of hot-rolled stainless steel production. More specifically, the present invention relates to a stainless steel hot-rolled strip pickling process. Background technique [0002] The production of stainless steel plates and strips must go through continuous casting, hot rolling and annealing. Due to the influence of high temperature and oxidizing atmosphere, continuous, dense black iron oxide scales with strong adhesion to the substrate are produced on the surface of stainless steel. From the perspective of steel rolling, if these strips with iron oxide scales are directly sent to the cold rolling mill for rolling, many problems will be caused. First, rolling under the condition of large reduction will cause the oxidation The iron scale is pressed into the matrix of the strip steel, affecting the surface quality and processing performance of the cold-rolled strip, and even causing waste products; second, the ...

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Problems solved by technology

[0003] The pickling of stainless steel hot-rolled strip usually adopts shot peening treatment + sulfuric acid pickling + mixed acid (HNO 3 +HF) pickling process, shot peening is to use the centrifugal force of shot blasting to hit the descaling medium on the surface of the steel plate at a certain speed, and remove the oxide layer on the surface of stainless steel through a large impact force. The descaling effect is good but the surface roughness is high , resulting in poor surface quality of the subsequent stainless steel cold plate, and the one-time investment of shot blasting machine is high, the consumption of shot blasting medium is large, and the maintenance and operation costs are high

A large amount of solid waste generated by sulfuric acid pickling waste acid discharge is mostly piled up to be treated, occupying a large amount of land, causing secondary pollution of soil and groundwater, and the acid sludge generated during the pickling process is easily deposited in the circulation In the pipelines and circulation tanks of the system, the acid circulation is affected, and frequent shutdowns are required for maintenance, which reduces production efficiency

A large amount of highly polluting NO is produced during the pickling process of mixed acid containing nitric acid x Gas and nitrate-containing wastewater bring serious harm to the natural environment and human production activities, and the cost of nitrogen oxide purification and treatment of nitrate-containing wastewater are also high

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