CS258934B1 - Complex hardening agent - Google Patents

Abstract

The hardening agent for heat treatment of steels contains from 0.1 to 1.5 wt. the sodium salt of alkylbenzene sulfonate having a carbon number of 12 from 0.1 to 6.0 wt. sodium polyacrylate having a molecular weight of from 20,000 to 50,000 and from 0.1 to 3.5% by weight; sodium carbonate and the remainder to 100 wt. water.

Description

The invention relates to a complex quenching agent based on sodium salt of alkylbenzene sulphonate, polyacrylate and sodium carbonate, which is particularly suitable for heat treatment of steels.

In the heat and chemical-heat treatment of metals, the choice of the right quenching environment is very important as it leads to the required cooling rate to the required depth for the given cross-section and the selected steel. At the same time, however, it is also necessary to address other technological requirements, such as preventing cracking and cracking of steel, ie reducing the amount of internal stress or reducing deformations. These requirements make it necessary to slow cooling in the temperature region above and between M _g M _g and to reduce the thermal stress caused by large temperature differences between the surface and the core, and thus the total stress generated by superposing the thermal stress and the stress-induced martensitic transformation. So far, various types of hardening oil have been used as the quenching medium.

Working with oils is unhygienic, generating considerable amounts of smoke and soot, which pollute the air. It is therefore an attempt to develop another type of quenching medium which has quenching properties similar to those of oil, but which is more hygienic.

Therefore, a number of new hardening media have been developed. These are in particular mixed compounds of various higher organic polymers which dissolve in water at certain temperatures.

According to the basic substances, existing quenching agents can be divided into the following main groups:

polyalkyl glycol from 6 to 20 May % wt polyvinyl alcohol from 0, 15 to 0.15 % wt polyvinylpyrrolidine from 5 to 25 % wt polyacrylate from 10 to 20 May % wt polyalkylene glycol from 15 Dec to 20 May % wt sulphidic lye from 5 to 10 % wt

These organic polymers themselves have a number of disadvantages; on the one hand, they are highly sensitive to changes in the flow of the quenching liquid, furthermore to temperatures of the quenching medium, and especially in many cases a considerable amount of insoluble polymers remains on the surface of the quenched components. While most commonly used in the world is polyvinylpyrrolidine, which is non-toxic, it slowly decomposes thermally, but is bacteriologically unstable. The situation is similar when sulphite lyes are used as a quenching medium, which ferment and smell over time. Its advantage is that it does not have to be mixed with the quenching bath.

However, practical tests have shown that the prior art aqueous polymers have the considerable disadvantage that at 200 to 400 ° C their cooling rate is quite high, leading to the cracking of some hardened parts.

The above-mentioned disadvantages are overcome by the complex quenching agent based on the sodium salt of alkylbenzene sulphonate, sodium polyacrylate and sodium carbonate according to the invention, characterized in that it contains from 0.1 to 1.5% by weight. % sodium alkylbenzene sulfonate having a carbon number of 12, from 0.1 to 6.0 wt. % sodium polyacrylate having a molecular weight of from 20,000 to 50,000 and from 0.1 to 3.5 wt. sodium carbonate and the rest water.

The quenching agent according to the invention exhibits considerable chemical and thermal stability and can be used for quenching of low carbon, high carbon and alloy steels.

In addition to its considerable stability, it is not toxic and has a low cooling rate at 200 to 400 ° C. The temperature of the quenching bath is preferably from 20 to 45 ° C.

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Exemplary embodiments of the quenching agent according to the invention do not limit its scope according to the subject matter.

Example 1

For hardening of steel of the chrome-aluminum-molybdenum type, a hardening agent of the following composition was used:

Ex

0.8 3 wt 2.5 ’ % wt. 2 % wt 94.7 % wt í k 1 . and d For hardening 1.3 % wt 1.5 % mass, 0.5 % wt 96.7 % mass,

sodium alkylbenzene sulfonate having a carbon number of 12 polyacrylate having a molecular weight of 25,000 sodium carbonate water of a chrome vanadium steel was used with a quenching agent having the composition:

sodium alkylbenzene sulfonate having a carbon number of 12 sodium polyacrylate having a molecular weight of 35,000 sodium carbonate water

Example 3

For hardening of steel of chrome-manganese-boron type was used hardening agent with composition:

0.5 wt. sodium alkylbenzene sulphonate having a carbon number of 12

1.0 wt. sodium polyacrylate, molecular weight 35 000

0.5 wt. sodium carbonate

98.0 wt. water

Example 4

For hardening of nickel-chroro steel was used hardening agent of composition?

2.2 wt. sodium alkylbenzene sulphonate having a carbon number of 12

3.1 wt. sodium polyacrylate, molecular weight 46 000

3.0 wt. sodium carbonate

91.7 wt. water

Claims (1)

SUMMARY OF THE INVENTION Copper-based hardening agent based on sodium salt of alkylbenzene sulphonate, sodium polyacrylate and sodium carbonate, characterized in that it contains from 0.1 to 1.5% by weight of the composition. % sodium alkylbenzene-carbonate having a carbon number of 12, from 0.1 to 6.0 wt. % sodium polyacrylate having a molecular weight of from 20,000 to 50,000 and from 0.1 to 3.5 wt. sodium carbonate and the remainder up to 300 wt.