HU193543B - Process for quenching aluminium alloys in aquous bath - Google Patents

Description

The present invention relates to a method for hardening aluminum alloys with an aqueous hardening fluid.

French Patent No. 2,507,209 discloses a water-soluble organic polymer-based aqueous hardening fluid for the heat treatment of iron alloys, in particular carbon steels and steel alloys, which during the annealing phase provides reduction, increase in cooling rate, the maximum cooling rate occurs at the beginning of the phase and prevents the precipitation of organic polymers on the materials to be hardened. The solution disclosed in the patent is characterized in that from 0.1 to 30% by weight of polyoxyalkylene glycol ether having a molecular weight of 4000 to 30 000, preferably 10 000 to 12 000 or 20 000 to 25 000, and It contains 15% by weight of an anticorrosive additive, preferably a salt of alkanolamines or alkanolamine cinnamates of C 7 -C 13 oxocarboxylic acids.

It is known that hardening of aluminum-based alloys is fundamentally different from hardening of steels.

When aluminum-based alloys are hardened in aqueous media, the aim is to achieve the best compromise between mechanical extensibility and dimensional stability of thin products or precise extruded parts, the basic criterion of surface isotherm and cooling effect reproducibility, on the other hand, the mechanical extensibility properties and the residual stress during hardening of the thick material, the basic criterion of which is accelerated and reproducible cooling. This allows the alloys to be hardened quickly within the critical hardening range (400-250 ° C) without causing the surface layer or metal skin to soften excessively, especially at high temperatures between 500 and 400 ° C.

It has now been found that, surprisingly, when used to harden aluminum-based alloys, the hardening aqueous hardening fluid disclosed in the above-mentioned patent results in the best compromise between mechanical properties and dimensional stability.

The present invention therefore relates to U.S. Patent No. 2,507,209. The use of an aqueous hardening fluid for the hardening of aluminum-based alloys as described in French Patent No. 5,600,198.

The invention is illustrated by the following examples.

The aqueous composition was prepared by dissolving EMKAROX ^ FC 31/45000 (manufactured by Produits Chimiques Ugine Kuhlmann) in water and adding I.P. 9 (manufactured by the same company) as described above (composition after Examples 1).

A comparative test was performed using 20 ° C and 60 ° C water as reference training fluid. The training fluids of the present invention are 15% aqueous solutions of EMKAROX containing 4% by weight of the composition I.P.9 (hereinafter abbreviated as 15/4) and 12% aqueous solutions of EMKAROX containing 5% by weight I.P. They also contain 9 products (hereafter abbreviated as 12/5).

The specimens were tempered at an initial temperature of 500 ° C. We observed the following:

1. Increased length and high temperature stability of the annealing phase (500-480 ° C);

2. the cooling rate increased significantly during the critical training period (400-250 ° C);

3. the reproducibility of the training effect was generally assured, which is not the case with cold or warm water.

Accelerated cooling is achieved between 500 and 250 ° C with the following optimal compositions:

t% EMKAROX FC31 + 4 t% I.P. 9 12t% EMKAROX FC31 + 5t% I.P. 9 10 t% EMKAROX FC31 + 6 t% I.P. 9 Among the solutions in which

EMKAROX contents of 15 wt% or slightly higher at high temperatures (500-400 ° C) show a better cooling rate than 60 ° C water without mixing, and the transition from heating to core heating is less steep than 60 ° C, which is more favorable for dimensional stability of hardened products.

The cooling rate in the critical hardening range (400-250 ° C) is 30-50% lower than the same when using 60 ° C water in a non-mixed condition, preferably the above solutions are relatively thin, high performance hardening aluminum -alloy products (7075) or thicker aluminum alloy products (6061, 7020, 7010) with a lower critical hardening range.

The following tables summarize the results of the aluminum alloy hardening experiments and show EMKAROX + I.P. 9 concentrated aqueous solution.

Experimental conditions:

Optimal conditions: 5-20% by weight EMKAROX FC 31/45000 + 2-10% by weight I.P. Aqueous solution of 9 - preferred conditions: 15% EMKAROX + 4% I.P. 9 (ref. 15/4) and 12% w / w EMKAROX + 5% w / w I.P. 9 (Ref. 12/5).

Example 1

The purpose of the experiments was to determine the deformation due to the hardening process. Test material: tube AU4G (2017).

-2193543 has a length of 230 mm, a diameter of 60 mm and a thickness of 2.5 mm. The tube was cut along one of its components and the cutting surfaces were removed 25 mm apart. The tube was subjected to standard solid solution treatment for 15 minutes at 5,485 ° C. Four to four tubes were hardened by immersing vertically in a 100 L tank without stirring. Approximation (-) and displacement (+) of the cutting surfaces were measured at 5 points, 40 mm apart, and the average of the 5 measurements was evaluated on tube 4.

Comparative measurements were made with air hardening and with water at 20 and 60 ° C and 10% EMKAROX without additive.

Training medium cooling speed ° C / sec Pipe deformation (mm) Average Min / max difference 1 2 3 4 Air 1.1 +0, 14 +0.08 +0.10 +0.06 +0.0095 0.02 / 0.18 Water 20 ° C 600 +0.58 +0.50 +0.30 +0.61 +0.50 0.22 / 0.92 Water 60 ° C 200 +0.26 +0.05 -0.03 +0.08 +0, 11 -0.09 / + 0.30 EMKAROX 10% 190 +0.33 +0.12 +0.15 +0, 14 +0.19 0.08 / 0.37 15/4 80 +0.05 +0.06 +0.07 +0.06 +0.06 0 / 0.10 12/5 100 +0.10 +0.07 +0.08 +0.09 +0.0085 0/0, 14

Example 2

The effect of the training process on the mechanical properties was investigated on sheets of 7075 (AZ8GU) 400x400x8 mm, which were hardened by rapid immersion in a 200 l bath. The sheets were previously hardened by standard solid solution treatment at 480 ° C for 4 hours.

comparative measurements were made with water at 20 ° C and 60 ° C. The results are as follows:

Fluid trainer Rugalmassási border Scrap Processing stress Stretching Sheet Cooling % joint deformation KAS gold C Water 20 ° C 498 568 11.6 1.5 1.5 200 Water 60 ° C 488 559 12.5 5 7 60-100 15/4 458 543 13 0 0 25 12/5 469 551 14.2 0 0 30

Conclusion:

EMKAROX and IP9-containing training fluids are very effective for products with high deformation requirements (precision extrusion, extruded products, complex castings). These solutions allow _v to eliminate strain caused by hardening while maintaining mechanical properties. Solutions containing EMKAROX + IP9 are thus highly advantageous in terms of compromise between mechanical properties and strain or residual strain.

This is further supported by the fact that, in contrast to training with hot water (40 ° CtOs or more), EMKAROX I.P. Training with 9-content solutions gives reproducible results, which improves the reliability of product manufacture and eliminates the cost of hot water tanks. EMKAROX: glycol ether of ethylene oxide and propylene oxide, average molecular weight:

000-22,000, the molar ratio of ethylene oxide to propylene oxide being 3: 1.

I. P. 9: Corrosion inhibitor additive salt of azopropa45 nolamines (a mixture of mono, di and tertiary amines) with 9 aliphatic carboxylic acids.

Claims (1)

Patent Claim Point A method for hardening aluminum alloys with an aqueous hardening fluid, characterized in that: The aluminum alloys are preheated to 480-500 ° C and 10-18% by weight of polyoxyalkylene glycol ether having a molecular weight of 4000-30,000, preferably 10,000-12,000 or 20,000-25,000, and 2-7 % by weight · anti-corrosion 60 additives, namely salts of C 7 -C 13 aliphatic carboxylic acids and C 1 -C 6 alkanolamines, are immersed in an aqueous solution.