SU1250586A1 - Quenching medium - Google Patents

Description

The invention relates to the heat treatment of metals, namely to quenching media based on aqueous solutions of polyacrylamide.

The purpose of the invention is the elimination of stainless steel hardened parts. In addition, the corrosion resistance of brass parts of hardening equipment increases.

The proposed quenching medium contains an aqueous solution of polyacrylamide and, as an anticorrosive additive, soda ash in the following ratio of components, wt.%:

Polyacrylamide 0.5-3.0 Soda ash 1, 0-2, 0 Water Else Tab. 1 shows the data on the change in the pH of the aqueous solution of polyacrylamide (PAA), depending on the soda content in the solution.

The use of soda additives in the amount of 1% is higher than the pH of the aqueous solution of polyacrylamide to 9.8. Increasing pH pH reduces the rate of corrosion of metals. Thus, the addition of kalypsevaya SALT to the aqueous solution of polyacrylamide in colloidal compounds protects steel and brass from corrosion. With further increase in soda, the pH does not change significantly. Under production conditions, due to the removal of soda from the solution by the surface of parts, it is advisable to increase the soda concentration to 2%.

Example 1. In order to determine the corrosion rate, steel cylindrical samples d 20 mm and 1 50 mm and brass hexagonal samples R 16 mm and h 15 mm are placed in 1.5% polyacrylamide (PAA) solutions and 1.5% in PAA solutions with the addition of soda 1.0%; 1.5% and 2.0% and release at room temperature for 135 hours. Then, an external examination of the samples is performed and the corrosion rate is determined.

The results of comparative tests on the corrosion rate in a solution of PAA and in solutions of PAA with soda ash additives are presented for steel in Table. 2, for the date - in the table. 3

As can be seen from the tables, corrosion of steel in aqueous solutions of polyacrylamide with additives of soda ash is completely absent.

The corrosion rate of brass in water. solutions of polyacrylamide with soda additives are 3 times less than in solutions of polyacrylamide without soda.

Example 2. Determination of the corrosion rate of steel and brass samples in solutions of polyacrylamide and in solutions of polyacrylamide with the addition of sodium nitrite (quenching medium adopted for the prototype). The sample is placed in 3.0% polyacrylamide solutions with the addition of sodium nitrite (NaN) in an amount of 0.1; 0.3; 0.5; 1.0; 5.0; .10.0; 20.0%. The tests were carried out at room temperature for 120 hours. Every 2A hour, an external examination of the specimens was carried out to detect traces of corrosion. According to the test, the corrosion rate of the samples is determined.

The test results are presented for steel in table. 4, for brass - in table. five.

As can be seen from the table. 4 and 5, nitrite

sodium in aqueous solutions of polyacrylamide (PAA) well protects steel from corrosion, significantly reducing its corrosion rate at concentrations

NaNO 1.0%. However, the corrosion rate of brass increases 6 times in these solutions.

Sodium nitrite reliably protects only the stage from corrosion.

Comparative analysis of the table. 2, 3, and 4.5 allows us to make it possible that in aqueous solutions of polyacrylamide, soda is the most effective corrosion inhibitor for both steel and brass.

When using an aqueous solution of polyacrylamide with a concentration of 1.5% with additives of soda ash in the amount of 1.0-2.0% as a quenching medium for parts made of steel 40X and 45X, the pH value is 9.5-10.0; the surface of the parts after the heat treatment has no corrosion traces; the equipment is practically non-corrosive; Soda additives in the amount of 1.0-2.0% do not impair the hardening ability of the solution; the medium is stable in operation, does not decompose and does not emit toxic gases, is not fire hazardous.

Hydrogen solution pH

7.48.96 9.8

Note. PAA concentration in 1.5 Mac.Z solution

Table 2

PAA 3.0%

7.9

PAA 3.0% + 1.0% Soda Ash

PAA 3.0% 1.5% Soda Ash

PAA 3.0% -f 2.0% soda ash

The solution of PAA 3.0% 7.9

PAA 3.0% + I, 0% soda ash

PAA 3.0% + 1.5% Soda Ash

PAA 3.0% 2.0% soda ash

Table 1

9.9

9.85 9.95

0.063

Sample in corrosion products at the first inspection

No changes

ABOUT

Also

After testing the surface of the mat samples, there are dark spots.

0.0874

No changes

0.0786

Also

0.0763

Table 4

The composition of the solution Speed Note

corrosion, g / mh

PAA 3, OH0.02. The corrosion traces appeared after 24 hours.

PAA 3.07, + 0.5%, 00126 The environments did not appear to corrode

PAA 3.07, +, 01, 00075 The same

PAA 3.0% 1.5% NaNOj0,00078- PAA 3.0% 4-2.0 NaNO, j0,00078 - Table 5

The composition of the solution Speed Note

corrosion,

I

PAA 3.0%

PAA 3.0% + I iO% NaNO,

0.116 0.677

PAA 3.0% 1.5% NaNO0,712

PAA 3.0% + 2.0% NaNOj

0.738

Compiled by I. Lipgart Editor L. Avramenko Tehred O. Gortvay Corrector I. Muska

Order A378 / 21 Circulation 552Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, F-33, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

Traces of corrosion appeared after 2 h

From the moment the samples were lowered, corrosion was observed (gas was released, the solutions turned green).

From the moment the samples were lowered, corrosion was observed (gas was released, the solutions turned green).

Also

Claims (1)

Hardening medium containing an aqueous solution of polyacrylamide and an anti-corrosion additive, characterized in that, in order to eliminate corrosion of steel parts, it contains soda ash as an anti-corrosion additive in the following ratio of components, wt.%:. Polyacrylamide Soda Ash Water 0.5-3.0 1-2 The rest and * to Joint venture Q0