|Publication number||US3135633 A|
|Publication date||Jun 2, 1964|
|Filing date||Sep 2, 1960|
|Priority date||Sep 8, 1959|
|Publication number||US 3135633 A, US 3135633A, US-A-3135633, US3135633 A, US3135633A|
|Inventors||Claude Hornus Jean|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (1), Referenced by (34), Classifications (5)|
|External Links: USPTO, USPTO Assignment, Espacenet|
June 2, 1964 J. c. HORNUS 3 135 633 HEAT TREATMENT PROCESS IMPROVING THE MECHANICAL PRorERTIEs OF ALUMINIUM-MAGNESIUM-SILICON ALLOYS Flled Sept. 2, 1960 4 Sheets-Sheet 1 Fig. 2
- 4 fifihours BREAKING LOAD kq/mm 10 50min.
EFFECTS OF TEMPERATLRE AND TIME OF DELAY BETWEEN QUENCHING AND AGING TIME OF DELAY BETWEEN QUENCHING AND AGING JEAN-CLAUDEJIORNUS ATTORNEYS June 2 1964 J. c. HORNUS 3 135 6 HEAT TREATMENT PROCESS IMPROVING THE MECHANICAL PRO1 ERTI ES OF ALUMINIUM-MAGNESIUM-SILICON ALLOYS 4 Sheets-Sheet 2 Filed Sept. 2, 1960 02:3 024 0250225 zmwgkmm 03w 3 :81 M 3 5 v 2 3 m v INVENTOR JEAN-CLAUDES HORNUS BY 4494;?
ATTOR'NEYS J. C. HORNUS June 2, 1964 HEAT TREATMENT PROCESS IMPROVING THE MECHANICAL PROPERTIES OF ALUMINIUM-MAGNESIUNFSILICON ALLOYS 4 Sheets-Sheet 3 Filed Sept. 2. 1960 02-04 024 wziozmnc ZmwEmm mfiw '9, INVENTOR JEAN-C LAUDE HORNUS BY M 7 ATTORNEYS J1me 1954 J. c. HORNUS 3,135,633
HEAT TREATMENT PROCESS IMPROVING THE MECHANICAL PROPERTIES OF ALUMINIUMMAGNESIUMSILICON ALLOYS Filed Sept. 2-. 1960 4 Sheets-Sheet 4 INVENTOR JEAN-CLAUDE HORNUS ATTORNEYS United States Patent 3,135,633 HEAT TREATMENT PROCESS IM'PRQVING THE MECHANICAL PROPERTIES OF ALUMINIUM- MAGNESHJM=SILICON ALLOYS Jean Ciaude Hornus, Neniily-sur-Seine, France, assignor to Compagnie Generaie du Duralurnin et du Cuivre, Paris, lh'ance, a French corporation Filed Sept. 2, 1960, Ser. No. 53,809 Claims priority, application France Sept. 8, 1959 Claims. (Cl. 148-469) below the use of a forced convection laboratory furnace for artificial aging instead of a salt-bath furnace led to a lowering of the mechanical properties E and R by about 3 kg./mm. although the necessary rise in temperature in the air furnace only took one hour, that is, much less than is used in industrial artificial aging of fagots.
TABLE Effect of Rate of Healing to Annealing Temperature Upon the Mechanical Properties of A-SG Type Alloys Eo,z(kg./ R(kg./ Amt mm] mm. Percent Soaked 20 min. at 550 C. and
water quenched Immediate aging in a salt bath for 6 hours at 175 C. (heating-up practically instantaneous) 34. 2 39.1 18. 8 Immediate aging in an air furnace:
Length of heating-up, 1 hr Hglfi at temperature (175 0.) 31 3 36. 1 l9. 7
The heat treatment of 20 min. at 550 C. is a solution treatment.
In practice, aluminium-magnesium-silicon alloys are obtained with considerably poorer mechanical properties (often 7 to 8 kg./mm. poorer) than the mechanical properties they could reach, for the following two reasons.
Firstly, handling difficulties and the necessity for finishing the surface before artificial aging prevent starting the aging immediately after quenching.
Secondly, by reason of the harmful consequences, to the surface of the sheets, when aging in a salt or an oil bath, it is customary to carry out the aging in air furnaces. When aging fagots, heating is of necessity slow.
On the other hand, the problem of full aging with rapid heating cannot be solved by using an air circulating continuous furnace because aging is a slow process which cannot be cut short, even by raising the temperature, Without greatly reducing the mechanical properties obtained. Now, a continuous air circulating furnace with passages, if it gives rapid heating only allows of relatively short treatments.
To remedy the inconveniences of an inevitable delay between quenching and artificial aging, it is proposed to subject the alloy, immediately after quenching, to a short preliminary aging, followed by a final full aging after a delay of a few days.
But application of such a process has run up against many obstacles up to the present. It is particularly difficult to make handling sufiiciently rapid and to carry out a perfect synchronizing of operations. Moreover, if the furnace used to obtain the high speed of heating up which is necessary is a salt-bath or oil-bath furnace, this results in the inconveniences already mentioned above.
The aim of the present invention is to carry out a pro-aging or stabilizing treatment of aluminum-magnesium-silicon alloys industrially in order to improve their mechanical properties by amounts up to 25% The invention consists in a heat treatment process for Wrought products of aluminium-magnesium-silicon alloys, in which the wrought products are moved along continuously through a first furnace to put an additive element or elements into solid solution in the base element, then through a quenching chamber and into a second furnace to be subjected to a stabilizing preliminary aging, at least the second furnace being heated by forced hot air circulation, and the time interval between quenching and reaching preliminary aging temperature being less than ten minutes, the stabilized wrought products being subjected to a final full aging at a later time. Conveniently the first furnace is also heated by forced hot air circulation.
The quenching may be by means of forced air cooling, water sprays or mist sprays.
The straightening or otherwise finishing of the wrought product is conveniently incorporated after the preliminary aging and before the final full aging.
The invention further consists in apparatus for carrying into practice a heat treatment process in which a conveyor bearing the wrought products to be treated is arranged to pass in series through a first furnace to put the additive elements in solution in the base element, a quenching chamber and a second furnace to subject the articles to a stabilizing preliminary aging, at least the second furnace being heated by forced hot air circulation. Means may be provided for heating both furnaces with forced hot air circulation and for quenching with forced air cooling, water spraying or mist spraying, if necessary.
Furthermore, a device for straightening or otherwise shaping of the wrought products may be provided after the second furnace.
Thus, all the steps needed, i.e., the solution treatment, the quenching proper, preliminary aging and straightening if performed are effected continuously, and the time interval between quenching and preliminary aging is re-. duced to less than ten minutes, even for low speeds of movement of the order of 1 meter per minute, which allows the alloy to be given the highest mechanical properties it can possibly get. Moreover, the preliminary aging or stabilizing treatment, as it is carried out in an air furnace, involves no cleaning, degreasing, or scouring which particularly allows, as already remarked upon, in-
tegrating the shaping or straightening of the product into a continuous series of operations.
The final aging may be carried out any time in the week following the stabilising preliminary aging.
The plant needed for this process is not unduly burdensome to construct, for the three operations needing heat, namely; solution treatment, quenching, and preliminary aging or pre-annealing may be carried out merely by blowing in air which has the correct temperature for the relevant step, i.e., of the order of 550 C. for the first step, about 20 C. for the second and between C. and 250 C. for the third.
Actually, use of water for quenching hardly changes the economic conditions, i.e., the process is still economically workable.
It is felt that the process according to the invention is the only one which allows the solution treatment, the quenching and the stabilizing preliminary aging to be carried out industrially in a short time, and results in good mechanical properties for aluminium-magnesiumsilicon alloys after final aging. The quenching and stabilizing preliminary aging may take place within five minutes of one another.
Carrying out these same steps by different methods (salt-bath, or air-furnace or oil-bath for preliminary aging or stabilization) militates against a short treatment because of accessory steps (intermediate cleaning or degreasing), or of handling.
The invention may be further described with reference to the accompanying drawings which are illustrative and are not intended to be limitative in any way.
FIGURE 1 shows, for a non-stabilized specimen, time of delay between quenching and full aging, plotted against temperature maintained during that delay, with the solid lines joining points where conditions give the same values for the yield strength.
FIGURE 2 is a similar graph, but in which the solid lines join points where conditions give the same values for the tensile strength.
FIGURES 3 and 4 show the eflect of stabilizing treatments as a function of their duration and of the gap between quenching and stabilization.
FIGURE 5 is a somewhat diagrammatic cross-section through an apparatus for carrying out the heat treatment process of the invention.
By way of example, FIGURES 1 and 2 of the accompanying drawing are provided to summarize the results of various experiments on plates of a thickness of 12/10 mm., made of an alloy known by the abbreviation of A$G.
In FIGURES 1 and 2, time of delay is shown on the abscissa from zero to 7 days, and temperatures of delay upon the ordinates. As may be seen from the curves, a delay of about one day between quenching and annealing lowers the yield strength to less than 26 kg./ mm. (FEGURE l) and the tensile strength to less than 32 kg./mrn. (FIGURE 2), although the same alloy, if it has undergone an artificial aging immediately after quenching has a yield strength of 35 to 36 kg./mm. (FIGURE 1) and a tensile strength of 39 to 40 kg./rnm. (FIGURE 2).
The FIGURES 3 and 4 were obtained with sheets 1.3 mm. thick; the solution treatment lasted 30 minutes at 540 C. and artificial aging lasted hours at 160 C.; the stabilization treatment by preliminary aging took place at 140 C.
As abscissa, lengths of time are shown from zero to 14 days between quenching and annealing or artificial aging. On the left hand ordinate, the values of the yield strength, and on the right, the values of tensile strength, are in dicated.
The curves drawn in solid lines are those obtained without stabilization; those drawn in dashed lines correspond to stabilization taking place 3 minutes after quenching; for those in dash-dot lines stabilization took place 7 minutes after quenching; for those drawn in dash-double dot lines stabilization took place minutes after quenching. Finally, for those drawn in dotted lines stabilization took place 2 hours after quenching.
In passing from FIGURE 3 to FIGURE 4 and from left to right in each figure, the curves below give the values of the yield strength and those above give the values of the tensile strength; the duration of the stabilization treatment is arranged in the order of the curves and was successively 2 minutes, 4 minutes, 8 minutes, 16 minutes, 32 minutes and 64 minutes.
Another advantage of a treatment of some minutes at a temperature between 100 C. and 250 C. is that it does not harden the alloy to the extent of hindering the straightening or shaping of the product, should this be done as usual prior to the final full aging.
In FIGURE 5, a high warm-up speed furnace It, in which the products may be kept for from 2 to minutes at temperatures between 450 C. and 600 C. is provided for the solution treatment. Following this, a
quenching chamber 2 where cooling is effected by known means, such as water, air, or some combination of both, is placed.
A preliminary aging, forced connection furnace 3 comes next in which the products are kept for from 1 to 10 minutes in circulating air at temperatures between C. and 250 C.
The plant is fed with products by a single conveyor 4- passing successively into the two furnaces and which provides perfect synchronization of the plant. An entry platform 5 and leaving platform 6 allows respectively for feeding, and recovering treated products from, the conveyor.
The interval between quenching and preliminary aging is automatically limited to a length of time under 5 minutes.
For sheets, the plant may be completed at the end of the pre-annealing furnace with some device to straighten or shape the sheets as they leave the conveyor 4.
Various modifications may be made within the scope of the invention.
1. A continuous heat treatment process for improving the physical properties of alloys of aluminium, magnesium and silicon, comprising subjecting an aluminium-magnesiurn-silicon alloy to solution heat treatment at a temperature of between approximately 450 to 600 C., quenching the alloy to approximately room temperature, reheating the alloy to a temperature of from approximately 100 to 250 C. to preliminarily age the alloy within a few minutes after quenching, and subsequently again heating the alloy in order to finally age the alloy.
2. A continuous heat treatment process for improving the physical properties of alloys of aluminium, magnesium and silicon capable of spontaneous aging, comprising subjecting an aluminium-magnesium-silicon alloy to solution heat treatment at a temperature of between approximately 450 and 600 C., quenching the alloy to approximately room temperature, briefly reheating the alloy to a temperature of from approximately 100 to 250 C. by hot air heating to preliminarily age the alloy within a few minutes after quenching, cooling the alloy after a short period of time, and subsequently again heating the alloy in order to finally age the alloy.
3. A continuous heat treatment process for improving the physical properties of aluminium containing alloys which spontaneously age with time, comprising subjecting such an alloy to solution heat treatment at a temperature between about 450600 C. cooling the alloy to approximately room temperature to quench the same, reheating the alloy within a few minutes after quenching to a temperature substantially lower than the solution heat treatment temperature for a period of approximately 10 minutes to preliminarily age the alloy, and cooling and storing the alloy to await a subsequent final aging.
4. An essentially continuous heat treatment process for improving the physical characteristics of an aluminiummagnesium, silicon alloy, comprising the steps of substantially continuously and successively passing said alloy through a first hot air furnace zone, solution heat treating the alloy in said first furnace zone at a temperature of approximately 450 and 600 C., passing the alloy into a cooling zone to quench the same to approximately room temperature, passing the quenched alloy into a second hot air furnace zone, preliminarily aging the alloy in said second hot air furnace zone by heating with circulating hot air to a temperature above approximately 100 C. and substantially below said first-mentioned temperature, and removing the preliminarily aged alloy from said second hot air furnace zone for storage prior to final aging thereof.
5. An essentially continuous heat treatment process for improving the physical characteristics of an aluminiummagesium-silicon alloy, comprising the steps of substantially continuously and successively passing said alloy through a first furnace zone, solution heat treating the alloy therein at a temperature of between approximately 450 and 600 C., passing the alloy into a cooling zone to quench the same to approximately room temperature, passing the quenched alloy into a second furnace zone within several minutes after quenching, preliminarily aging the alloy in said second furnace zone by reheating the alloy for a short period of time to a temperature of between approximately 100 and 250 C., and removing the preliminarily aged alloy from said second furnace zone for storage prior to final aging thereof.
6. A substantially continuous process for treating aluminium-magnesium-silicon alloys which age spontaneously with time at room temperatures, comprising the steps of solution heat treating an aluminium-magnesium-silicon alloy at a temperature between 450600 C., quenching the resultant product to approximately room temperature, and substantially immediately thereafter preliminarily aging the quenched product by heating to temperatures in the order of 100 to 250 C. whereby the physical properties of the alloy remain substantially unaffected by the passage of time while awaiting final aging treatment.
7. A process as defined in claim 6, wherein forced air is used to quench the alloy.
8. A process as defined in claim 6, wherein the preliminary aging is carried out in a forced air furnace.
9. A process as defined in claim 6, further comprising shaping the alloy to a desired configuration after the preliminary aging thereof.
10. An essentially continuous process for improving the physical characteristics of an aluminium-magnesium-silicon alloy which ages spontaneously with time at room temperatures, comprising the steps of substantially continuously and successively passing said alloy through a first heating zone, solution heat treating the alloy therein at a temperature between 450-600 C. for a period of about 2-20 minutes, passing the alloy into a cooling zone to quench the same to approximately room temperature, passing the quenched alloy into a second heating zone within several minutes after quenching, preliminarily aging the alloy in said second heating zone by reheating the alloy between -250 C. for about ten minutes by contact with forced heated air, and removing the preliminarily aged alloy from said second heating zone for storage prior to final aging thereof.
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