SU827595A1 - Steel pickling solution - Google Patents

Description

of the spent pickling sulfate solution, and the upper limit on the content of sulfuric acid (240 g / l) is specified by the peculiarity of the regeneration process of the spent pickling solution. When the content of sulfuric acid is below 90 g / l, the etching process is impractical due to the increase in the time of etching of the metal.

Ferrous sulphate in the initial solution contains not less than 100 sod / kitts, which also results from the preparation of the solution on the mother liquor. The upper limit on the content of seric acid iron is 260 g / l. The iron sulfate is associated with the production of sulfuric acid. When its content in the etching solution is higher than 260 g / l, an increase in the etching time of the metal is observed, to decrease which it is necessary to increase the etching temperature above 90 ° C.

When etching a metal in an etching solution at a temperature below 80 ° C, increase the effect of the KIO4 additive on the descaling time

The etching time of the metal is reduced, and at temperatures above 90 ° C, the working conditions deteriorate as the atmosphere becomes more polluted with sulfuric acid vapor above the pickling baths. In addition, the temperature rise above 90 ° C unproductively increases energy costs.

An example of the application of the solution. Scale removal from carbon rod samples of carbon and alloyed steels is carried out in a solution of sulfuric acid and ferrous sulphate. The initial pickling solution contains P25O4 240 g / l, FeSO4 90 g / l. In the process of etching occurs the production of sulfuric acid with the corresponding accumulation of iron sulfate. Metal etching takes place at a temperature of 80 ° C. After etching, the metal is washed in running cold water. Carbon st. 10 and art. 35, doped ZOHHSA, 12HMF. Test data are given in table. 1-3.

Table 1

Thus, for carbon steels, the optimum concentration of KIO4 is 0.5-2, and for alloyed G2X1MF it is 0.1-0.5 g / l.

In tab. 2, data on surface roughness (Ra, μm) of carbon and alloyed steels are introduced when KIO4 is added to the pickling solution of the composition: П25О4 240 g / l; FeSO4 100 g / l at temperaura 80 ° C.

So, when etching carbon steel without the addition of potassium iodic acid, the roughness is 3.12-3.42 microns, for alloyed steel 12Х1МФ 3 microns.

Table Data steel roughness

3.35

1.38

3.42 2.01 3.12 3.05 3.00 2.60 3.22

The addition of potassium iodic acid supplement (at a concentration of 0.1-1.0) makes it possible to somewhat improve the surface microrelief within the limits of one purity class.

For carbon steel, the surface roughness (Ra, m) is 1.38-3.35, and for steel 12X1MF — 2.60-3.22.

Along with a decrease in the surface roughness of carbon and alloyed steels, the introduction of an additive of potassium sulfate to the pickling solution makes it possible to obtain a surface of etched light-colored metal with a strong metallic sheen.

. The proposed additive, potassium iodide, is an acidic inhibitor.

carbon and alloyed

corrosion of steel.

In tab. Figure 3 shows the corrosion rates (p, 2 / .i; 2 hours) and the drag factors Y, depending on the concentration of the additive at an etching temperature of 80 ° C and 90 ° C.

Table 3

Claims (1)

Claim A solution for steel pickling containing sulfuric acid, iron sulfate and a corrosion inhibitor, characterized in that, in order to increase the rate of descaling and prevent the base from being pickled, it contains potassium iodide as an inhibitor in the following ratio of components, g / l : Sulfuric acid Iron sulfate Potassium sulfate