DE2216716B2 - Process for the production of sheet metal with superplastic properties from an alloy body - Google Patents

Description

40 turns.

The initial thickness of the alloy body is

in a particularly preferred embodiment

The invention relates to a method for producing the invention between 12.7 and 152.4 mm.
of sheet metal with superplastic properties. In detail, the invention can be designed in this way

• in an alloy body, consisting of 1 to 19.8% 45, that the initial state of the alloy

Aluminum, 0 to 5%, preferably up to 1% copper, by hot rolling at one temperature

up to i%, preferably up to 0.25% magnesium and between 200 and 350 C with one on the thickness

The remainder zinc, which at least in the initial state has a related degree of deformation between 40 and 99%,

have eutectic microstructure. preferably between 40 and 60%.

The production of a superplastic structure is particularly preferred, the sheet metal according to the

in zinc-aluminum alloys eutectoid composition of the superplastic state in a

Composition with 22% aluminum known. This temperature between 275 and 325 C is superplastic

Structure is made by deforming a heat treatment.

of the alloy above the eutectoid temperature As a result, compared to known eutectoid

(275 C) for homogenizing the structure of solid alloys the advantage was obtained that the

is performed, followed by cooling, in particular cooling from above 275 C in air or in the oven

Quenching follows and a machining or existing aluminum-rich phase turns into a lamellar

Deformation at a low temperature follows, transforms the Zn-Al structure and the alloys one

in order to obtain a fine-grained equiaxed structure with considerably greater creep resistance. this

form. Examples of such zinc-aluminum alloys are shown in Table 2 below,

gen eutectoid composition with additional other properties, such as strength, hardness and

Contained in ternary or quaternary constituents Bending extensibility can also be improved

are for example in the German disclosure, but these properties depend on up to one

font 19 22 213, the US Patent 34 20 717, the certain extent before the composition and the

British Patent 12 25 819 as well as the older 65 preceding manufacturing process.
German disclosure law to be taken into account In the following, the invention is based on the in

document 21 12 370 described. summarized in the tables below

In contrast to this, the invention has the task of explaining the embodiments in more detail:

fabeile 1

alloy % Al % Cu % Mg Molding processing temperature Cold rolling temperature VFT Hot rolling % Defor Seconds 5.5 0.5 0.1 CM % Defor 250 ° C efficiency i00 ° C 205 5.5 0.5 0.3 C. efficiency 250 ⁰ C 80% 100 ° C 80 1 5.3 - - C. 50% - 87% 100 ° C 125 2 5.3 - - C. 50% 300 ° C 93% 100 ° C 180 3 5.0 0.13 - C. - 300 ° C 87% 23 ° C 220 4th 5.2 0.15 0.03 DCC 50% 300 ° C 87% 100 ° C 110 5 5.2 0.15 0.03 DCC 50% 250 ° C 87% 23 ° C 90 6th 5.2 0.15 0.03 DCC 50% 200 ° C 87% 23 ° C 80 7th 5.1 0.07 C. 50% 300 ⁰ C 87% 23 ° C 100 8th 5.2 0.15 0.10 DCC 50% 300 ° C 87% 100 ° C 70 9 6.9 3.7 - C. 50% 250 ° C 87% 100 ° C 105 10 12.2 __ - C. 50% 300 ⁰ C 87% 100 ⁰ C 335 11 5.0 0.49 0.1 G 50% 300 ° C 87% 100 ⁰ C 265 12th 5.0 1.0 - C. 50% 300 ° C 87% 23 ° C 235 13th 5.2 0.15 0.03 DCC 80% 300 ° C 87% 23 ° C 90 14th 50% 87% 15th 50%

in the table are the percentages of Metals given in percent by weight of the alloy, with zinc in all cases is formed.

The first alloy body is either a 19 mm thick chill casting (C), a 19 mm thick continuous casting (DCC) or a 50.8 mm production trial chill casting (G). The material CM consists of a 19 mm thick Kokillengußmatcrial, which before processing was reduced to 12.7 mm by cutting.

The percentage of deformation is in all cases based on the thickness at the beginning of the respective stage based.

VFT denotes the vacuum deformation time, measured in seconds, for a sheet metal nominally 1.27 mm thick at 300 "C. This is a known measure of superplasticity and is determined by (1.) placing a disc of the alloy over the end of a Pipe with an inner diameter of 8i, 3n <m and held in a temperature-controlled air space, (2.) a diflerential pressure of 1 at is applied over the disk and (3.) the time required to move the disk is measured to deform into a curvature of 29.21 mm depth, ie in order to enlarge the relevant area by 50%. A suitable measuring sensor is used to determine when this reference state has been reached
(Comparison test)

As is intended, it has been found that VFT values less than about 300 seconds generally am are most beneficial.

While superplasticity is a complex phenomenon, which is largely due to variations can be influenced by time, temperature, composition and treatment and is precisely reproducible Results that are attainable only with considerable difficulty can be a number of general ones Observations were made by comparing the above examples with each other in the following manner will:

(a) The vacuum deformation time is determined by increasing the degree of deformation in the finish rolling decreased. This can be clearly seen in particular from a comparison of Examples 1 and 2, but it also works from Examples 3 and 4.

(b) The vacuum deformation time is reduced by the fact that the rolling temperature on the last pass is at temperatures is reduced, which are in the range used in the method according to the invention. this is based on a comparison of example la in the comparison table 1A, below, and Example 3 of Table 1 (without initial hot rolling) as well as from a comparison of Example 2a of Table 1A and Example 5 of Table 1 (which also shows that cold rolling according to the invention is the dominant factor). A comparison between Example 6 and Example 7 or 8 also confirm this.

alloy 7 "Cu % Mg Molding processing Rollers VFT Final temperature % Al % Ver Seconds degree of shaping

la 5.0 - 2a 5.0 0.13 3a 5.0 1.0

C. 93% 350 ° C 350 C. 93% 300 ° C 405 C. 93% 300 ° C 640

The examples given in table (IA) above serve only for comparison and are outside the basic concept of the invention.

(c) The vacuum deformation time is reduced by lowering the initial hot rolling temperature. This can best be seen from the comparison of those examples in which the finish rolling is carried out to 87% at 23 ° C, namely Examples 7 and 8. In general it can be said that the lower the initial hot rolling temperature, the lower it is Vacuum deformation time. Similar conclusions can be drawn from warping as those embodiments in which the cold rolling is performed with a Vcrformungsgrad of 87% at 100 ⁰ C. It is evident that the initial dimensions, the casting process and the alloy compositions are also variables which can have some influence on the vacuum forming times.

(d) The vacuum deformation time can be reduced by starting from a cast structure that is as fine as possible and thus the machining process for producing a fine-grained structure supports. In the examples given, the fineness of the cast structure decreases from the 50.8 mm cast iron as a production trial using 19 mm permanent mold casting to 19 mm continuous casting with direct cooling to.

(e) The lower the working temperature is within the range between 20 and 200 ° C, the lower the vacuum deformation time (see. Examples 6 and 15 of Table 1), although problems of cracking can occur at temperatures in the low range between 20 and 5O ⁰ C. For this reason, the preferred rolling or processing temperature is 100 ^° C.

The composition of the alloy has a much more complex effect. You can fine-grain it of the cast structure and, what is of far greater importance, the eutectic composition change, d. H. the proportion of aluminum that is necessary to be completely eutectic To achieve structure.

According to the invention, it is advantageous from a completely eutectic structure to assume the

ίο to achieve minimum vacuum deformation time, for example Example 4 in contrast to Example 12. The completely eutectic structure occurs with 5% aluminum in the binary alloy, a ternary surcharge element, for example copper (to increase the

J5 strength) increases the necessary aluminum content. Consequently supplements can increase the Vakuumverformzeit to a 5 ° / _o strength aluminum alloy. If necessary, these effects can be taken into account by appropriately changing the aluminum content in order to compensate for the effect of the additives on the eutectic composition, for example alloys 2 and 11.

When the above alloys are used in subsequent sheet metal fabrication operations the appropriate temperature range for deforming is between 200 "C and the Melting point. However, since the deformation takes place more slowly at lower temperatures and since the If the stability of the structure decreases at higher temperatures, the preferred temperature range is for deforming between 275 and 325 ° C. It is obvious that the additional step of the subsequent Deformation of the superplastic alloy together with the molded bodies thereby produced also forms an object of the present invention.

Table 2

alloy properties stigkeit (')
B. Hardness ( ² )
A. B. Flow stress
chung C) minimum creeping speed wedge C ¹ )
AWAY 1 × 10- ² absolute pull
A. 38 9.8 · 10-> 1.3 · ΙΟ- ³ 3 1504,574 - 38 - - 5.7 · 10- » 1.9 x ⁴ ΙΟ- 4th 1799.838 2161,940 39 63 87.884 4-10- 3.3 x 10- " 5 1631.122 3525.896 97 110 - 2.7 ΙΟ- ³ 1.4-10- ⁴ 6th 3782.517 3030.232 89 86 45,700 7.3 ΙΟ- ³ 1.1 x 10- ³ 9 3332,552 3613,780 97 110 - 6-10- ³ 2-10 * 10 3715.726 3624,326 74 - 63.277 2.6 x 10 ^a 1 × 10- ⁴ 11 2562,690 2351.769 48 62 - 1.4-10- » 12th 1806,890 - 93 104 94.915 1.6 x ³ ΙΟ- 13th 3912,585 3093.508 55 95 112.492 2.5 x 10- ² 14th 2502.929

C) Parallel to the rolling direction at 23 ° C., 0.1 min " ¹ (kp / cm ^a ).

(') 5 kg load for 20 seconds (Vickers hardness).

( ³ ) Parallel to the rolling direction at 300 ^° C., 0.2 min " ¹ (kp / cm ² ).

( ⁴ ) Parallel to the rolling direction at 23 ° C and 351.515 kgf / cm ' ² (% / hr).

A. As rolled. B. After a simulated deformation treatment, ie 30 minutes at 300 ^° C. and air-cooled.

7 8

The invention is illustrated by the following example: 1. 7.11 mm at 100 ° C. to 1.829 mm

game explained in more detail. (74% degree of deformation),

A zinc based alloy with the following 2.7.11 mm at 100 ⁰ C to 1.295 mm

Composition: 5.5% Al, 0.57% Cu, 0.009% Fe, 82% degree of deformation),

0.003% Pb, 0.001% Cd, remainder zinc, was on a 5 3. 7.11 mm at 100 ⁰ C to 0.711 mm

Hazelett continuous caster cast to a strip (90% degree of deformation),

of 12.7 mm thick and 1.016 mm wide to give u j ·. ι ·,

the total weight of the belt being 5 t. They were made according to the above

This tape was rolled at 240 ° C (hot rolling), ^Ve * ^h _f ^ren Vakuumverformversuche at 300 C transit

to reduce its thickness by 44% to 7.11 mm. g ^{efuhrt and he} ß ^ave * e following results:

gladly. 1.1.829mm 255 seconds

Samples of the hot rolled sheet were 1.295 mm in 95 seconds

Rolled as follows: 3. 0.711 mm for 30 seconds

Claims (6)

ι α 2 based on the setting supcrplastischer Eigen- patent claims: to enable shafts in alloys with a eutectic structure}. " 1. Process for the production of metal sheets with This object is achieved in a process for the superplastic properties from an alloy body consisting of minium, 0 to 5%, preferably up to 1% copper, 1 to 19.8% aluminum, 0 to 5%, preferably up to 0 to 1%, preferably up to 0.25% magnesium to 1% copper, 0 to 1%, preferably b :,: u 0.25 / _a and the remainder zinc, which at least in the initial state is magnesium and the remainder zinc, which at least partially has an eutectic structure in the initial state, at least in part an emectic structure, characterized in that it has a structure, solved by the fact that this Alloy body, its initial alloy body, its initial state either in the as-cast state or after the as-cast state or after hot rolling or hot rolling above 200 ° C nde is present state above 200 "C, at 20 to is cold-rolled at 20 to 200" C with a degree of deformation related to the thickness of 50 to a degree of deformation of 50 to 99% based on the thickness . 99% cold rolled. The invention in particular provides the advantage 2. The method according to claim 1, characterized in that it becomes possible because of the first time shows that the degree of deformation in the case of the cold eutectic structure is super-plastic roll at least 70%. preferably between 20 properties that require such properties-75 and 95 ° ;. the forming process also for alloys of these 3. The method according to claim I or 2, thereby being able to apply type. By the crfindungsgemüU characterized in that it is cold-rolled at 100 C. optionally provided hot rolling are over it 4. Process according to one or more of the addition obvious surface defects and internal Claims 1 to 3, characterized in that 25 defects in the cast alloy, the crack die Initial thickness of the alloy body between formation in the following rolls at lower 12.7 and 152.4 mm. Temperatures are reduced or avoided and the 5. The method according to one or more of the necessary rolling pressures as low as possible ge claims 1 to 4, characterized in that hold, so that the economy of the process the initial state of the alloy is increased by a 30. By machining alloy hot rolling at a temperature between the lamellar eutectic and some-200 and 350 C with a proportion of the primary phases present in relation to the thickness Degree of deformation between 40 and 99%, preferably fine coaxial grain structure are deformed, wisely between 40 and 60%. In the method according to the invention, in particular 6. The method according to one or more of the 35 particular in cold rolling a degree of deformation of Claims 1 to 5, characterized in that at least 70 ",,, preferably between 75 and 95" ,, the sheet metal pulled forward after the setting of the superplastic. State at a temperature between 275 and Particularly advantageous properties can be 325 C is superplastically deformed. can be achieved by that at 100 C Kaltgewal / l