Pickling method of surface of 430 stainless steel

Abstract

The invention relates to a pickling method of a surface of 430 stainless steel, which comprises the following steps: directly putting the 430 stainless steel after annealing into a pickling tank for pickling, wherein the pickling solution in the pickling tank comprises an additive and hydrochloric acid of which the concentration is 1-7mol/L, the adding quantity of the additive is 0.1-3% of the molar number of the hydrochloric acid, the pickling temperature is 20-80 DEG C, and the pickling retention time is 100-500s; washing the 430 stainless steel after pickling by water for the first time, wherein the water washing temperature is 20-60 DEG C, and the retention time is 80-120s; and washing the 430 stainless steel after washing by water for the first time by water for the second time, wherein the water washing temperature is 20-60 DEG C, and the retention time is 80-120s. The additive is hydrogen peroxide, potassium chlorate or sodium hypochlorite. The invention can enable the stainless steel surface to have higher smoothness and do not have a residual oxide layer and a pickling passivation layer, thereby saving the pickling cost, avoiding NOx gas and nitrite solution and simultaneously shortening the polishing time of the pickling process.

Description

technical field [0001] The invention relates to a pickling method for the surface of 430 stainless steel, in particular to a method for removing an oxide layer formed on the surface of a stainless steel hot-rolled or cold-rolled plate during finished annealing. Background technique [0002] As the output of stainless steel increases year by year, the requirements for product quality are becoming more and more stringent, and the surface quality, as an important factor to measure the quality of stainless steel plate and strip products, depends on the rationality of the heat treatment system and the pickling process in the later stage; at the same time, the surface quality of stainless steel cost and environmental issues are also becoming more prominent. At present, the final pickling process of stainless steel enterprises at home and abroad mostly adopts the hydrofluoric acid-nitric acid mixed acid process. The disadvantage of this process is that the nitric acid reduction pro...

AI Technical Summary

Problems solved by technology

At present, the final pickling process of stainless steel enterprises at home and abroad mostly adopts the hydrofluoric acid-nitric acid mixed acid process. The disadvantage of this process is that the nitric acid reduction product NO x Gas and nitrite solution, more serious environmental pollution; In addition, after pickling, the surface of the product produces a passivation layer (Cr 2 o 3 ) darkening phenomenon, severe intergranular corrosion and low surface finish, it is impossible to directly produce high-quality products, and mechanical and chemical polishing must be carried out, which greatly increases the production cost