The hardening environment

 

(57) Abstract:

The invention relates to heat treatment of metals and can be used for hardening tool of unalloyed cast iron ledeburite structure. The technical result is the preservation of the quenching ability of the environment while increasing its temperature, less prone to cracking tool from cast iron. For this offer the following medium composition, wt. %: copper sulphate - 0,4-3,0; ice-cold acid - 1-12; sodium chloride - 2,8-4,5; sodium nitrate - 3,0-3,6; water - the rest. table 1.

The invention relates to metallurgy, in particular to heat treatment, and can be used for hardening tool of unalloyed cast iron ledeburite structure.

As environments for hardening of cast iron is widely used for water, oil (see C. A. Filonov, I. C. finger. Handbook of heat-treater, L.: engineering, 1975, S. 63-69).

Closest to the technical essence of the present invention is tempering medium containing, wt.%:

Triethanolamine - 8 - 12

Copper sulphate - 0,1 - 0,5

Water - the Rest

(see and. C. 863671, class C 21 D 1/60, Appl. 28.06.79, publ. 15.09.81, bull. N 34).

The disadvantage with which counteracted the ability of known environments decreases with increasing temperature.

Object of the invention is the preservation of the tempering capacity environments while increasing its temperature, less prone to cracking tool of iron.

This object is achieved in that the tempering medium containing copper case and water further comprises an ice acid, sodium chloride and sodium nitrate in the following ratio, wt.%:

Copper sulphate - 0,4 - 3,0

Ice acid - 1 - 12

Sodium chloride - 2,8 - 4,5

Sodium nitrate - 3,0 - 3,6

Water - the Rest

Aqueous solutions of copper sulphate, glacial acid, sodium chloride and sodium nitrate in these percentages accelerate breakdown of the steam film on the cooled surface of the hardened products in the temperature range smallest stability of undercooled austenite due to the rapid heat dissipation. These solutions also provide a reduction in the cooling rate in the temperature range of martensitic transformation, which allows to avoid crack formation. In addition, the proposed quenching medium in the quenching of steel products provides education on their surface (physically and chemically) adsorption film, which creates a uniform heat is a waste sodium, which is an inhibitor provides additional corrosion protection during the quenching process and after it.

Introduction in an aqueous solution of copper sulphate, glacial acid, sodium chloride and sodium nitrate in quantities smaller and larger the stated limits, does not lead to the achievement of the objectives of the invention.

Example. To validate the properties of the proposed quenching medium was heat treated knives disk cutters l = 42 mm; b = 20,6 mm and h = 14,6 mm made of cast iron the following chemical composition in %: C - 3,94; Si 0,22; Mn - 0,3; S - 0,01; P is 0.2; Fe - rest, at different temperatures of the heated and then cooled in the quenching media of different composition and temperature. Tempering the ability of the environment was evaluated by monitoring the hardness of the surface of the knives and their hearts. Corrosion resistance - in appearance of the surface of the hardened knives after maturing within 1 - 6 hours After quenching knives checked for cracks using magnetic flaw detector. The test results presented in the table.

As can be seen from the above results, the proposed hardening the environment in comparison with the known, along with the absence of cracking, has a higher tempering pic is food, containing copper sulphate and water, characterized in that it further comprises an ice acid, sodium chloride and sodium nitrate in the following ratio, wt.%:

Copper sulphate - 0,4 - 3,0

Ice acid - 1 - 12

Sodium chloride - 2,8 - 4,5

Sodium nitrate - 3,0 - 3,6

Water - The Rest

 

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