FI74049B - VAT HEADING SYSTEM FOR FOUNDATION METALS PAO ALUMINUM. - Google Patents

Description

74049

This invention relates to an aqueous hardener for aluminum-based light alloy alloys.

FR Patent 2,507,209 describes and defines a novel aqueous hardener based on a water-soluble organic polymer for the heat treatment of metals and iron alloys, in particular carbon steels and alloys, which can shorten the heating step, increase the cooling rate during the heating step, during the bubble boiling step and prevents the precipitation of the organic polymer on the hardened bodies, characterized in that it comprises 0.1 to 30% by weight of a polyoxyalkylene glycol ether having a molecular weight of between 4,000 and 30,000, and preferably between 10,000 and 12,000, or 000 to 25,000, and 0.5 to 15% by weight of a corrosion inhibitor selected from the oxo acid salts of an alkanolamine having 7 to 13 carbon atoms and the cinnamates of the alkanolamines, the remainder being water.

However, it is known that the hardening of aluminum-based alloys is a different phenomenon than the hardening of steels, with different structural phenomena.

When tempering water using aluminum-based alloys, the best possible compromise is sought between the mechanical tensile properties and shape stability of thin bodies, with surface isotherms, repeatability of cooling steps being important criteria, and the mechanical tensile properties and residual stresses of thick products. accelerated and reproducible cooling rates enabling the alloys to be hardened rapidly over a critical hardening range (400 to 250 ° C) without excessive softening of the metal surface, especially at high temperatures between 500 ° C and 400 ° C.

It has now been found that an aqueous hardener is surprisingly also suitable for the hardening of aluminum-based alloys and that it allows the best possible trade-offs to be made in terms of mechanical properties and dimensional stability.

The invention relates to the application of the aqueous hardener covered by FR patent 2,507,209 to aluminum-based alloys.

The following examples illustrate the practice of the invention:

The hardener is prepared by dissolving in water EMKAROX FC 31/45000 produced by Societö des Produits Chimiques Ugine Kuhlmann and I. .P .9 of the same company, the quality and properties of which are mentioned above.

Comparative experiments were performed using water at 20 and 60 ° C as a reference hardener. The hardeners according to the invention are an aqueous solution containing 15% by weight of EMKAROX, to which 4% by weight of IP9 has been added (hereinafter abbreviated as 15/4) and an aqueous solution containing 12% by weight of EMKAROX, to which 4 wafers have been added. -% IP9 (hereinafter abbreviated as 12/15).

Hardening of test pieces from 500 ° C was performed. It was found that: 1) the annealing phase lengthens and its stability at high temperature (500-480 ° C) increases 2) the cooling rate in the critical hardening range (400-250 ° C) increases significantly 3) in general the repeatability of hardening is certain, which is not the case if use cold or hot water.

i 3 74049 Cooling is accelerated between 500 and 250 ° C with the following optimal compositions: 15% by weight EMKAROX PC31 + 4% by weight IP9 12% by weight EMKAROX FC31 + 5% by weight IP9 10% by weight EMKAROX FC31 + 6% by weight -% IP9.

These solutions give similar or slightly higher cooling rates (EMKAROX 15%) at high temperature ranges (500-400 ° C) than those obtained in 60 ° C unmixed water and a less abrupt transition from annealing to bubble boiling than in 60 ° C water, which is favorable for the shape stability of hardened products.

When the cooling rates in the critical hardening range (400-250 ° C) are 30-50% lower than with unmixed 60 ° C water, these solutions are preferably used for products made of relatively thick aluminum-based alloys with a high critical hardening rate (7075) or thinner parts, made from alloys having a lower critical hardening rate (6061, 7020, 7010 or the like) for hardening.

The following tables summarize the results of hardening tests on aluminum-based alloys showing the advantage of solutions fortified with EMKAROX and I.P.9:

Test conditions: - Optimal conditions: aqueous solution containing 5-20% by weight of EMKAROX FC 31/45000 + 2-10% by weight of I.P.9.

- Most preferred conditions tested: 15% by weight of EMKAROX + 4% by weight of I.P.9 (marked in Tables 15/4) and 12% by weight of EMKAROX + 5% by weight of I.P.9 (marked 12/5).

Example 1

An experiment to measure the deformation caused by hardening was performed on a pipe made of AU4G (2017), length: 230 mm, 0: 60 mm, thickness: 2.5 mm, the pipe was split 74049 4 along the base line, with a gap between both edges. came 25 mm.

The tube was subjected to the usual solid dissolution treatment for 15 minutes at 485 ° C.

Batches of 4 tubes were treated / hardened by immersion perpendicular to a 100 liter pool that was not mixed. The convergence (-) or deviation (+) of the edges at 5 points 40 mm apart was then measured and the average of these 5 measurements was calculated for each of the 4 tubes.

Comparative experiments were performed by air hardening, water hardening at 20 ° C and 60 ° C and 10% EMKAROX solution without other additives.

Hardening- Cooling- Pipe Deformation Medium Changes Liquid Speed _imi_ Value Minimum / ° C / s 1 2 3 4 Maximum

Air 1.1 +0.14 +0.08 +0.10 +0.06 +0.0095 0.02 / 0.18

Water at 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 H-KARQX 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 hardening on the mechanical properties and deformation of plates made of 7075 (AZ8GU) with dimensions of 400 x 400 x 8 mm after hardening by rapid immersion perpendicularly in a 200 liter basin was then measured. The plates were pre-treated with a conventional solid dissolution treatment for 4 hours at 480 ° C.

Comparative experiments were performed in 20 ° C and 60 ° C water. The results are as follows: 5,74049

Karkai- Kίππο- Marto- Elongation Deformation Cooling resistance limit Limit Depression- Roofing speed te 1¾) 0.2hb Pm, hb A% type- type_,, nen pinen c's _ _ _ _ nm nm_ _

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; Hardening solutions based on EMKAROX and I.P.9 are very advantageous for thin parts made of alloys with a high critical hardening rate and which are easily deformable (forged parts, extruded parts, complex shaped castings).

They avoid the deformations caused by hardening, while still maintaining good mechanical properties, which makes EMKAROX + I.P.9 solutions very advantageous in terms of the best possible compromise when dealing with mechanical properties and hardening deformations or residual stresses.

In addition, in contrast to hot water hardening (at temperatures of 40 ° C or higher) in EMKAROX + I.P.9 solutions, the results are reproducible, which increases the reliability of the manufacture and saves stress and heating costs for water tanks.

Claims (2)

6 74049 Aqueous hardening agent for aluminum-based alloys, characterized in that it consists of 0.1 to 30% by weight of a polyoxyalkylene glycol ether having a molecular weight of between 4,000 and 30,000 and preferably between 10,000 and 12,000 or 20,000 and 25,000 from 0.5 to 15% by weight of a corrosion inhibitor selected from the oxo acid salts of an alkanolamine having 7 to 13 carbon atoms and the cinnamates of the alkanolamines, the remainder being water, preferably 5 to 20% by weight of said polyoxyalkylene glycol ether and 2-10% by weight of additive. Hardening agent according to Claim 1, characterized in that it comprises 12 to 15% by weight of EMKAROX FC 31 / 45,000 and 4 to 5% by weight of I.P.9R.