DE1241625B - Process for the production of molded parts with a smooth surface and free of flow lines from AlCuMg or AlZnMg (Cu) alloys - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY Int. Cl .:

C22f

PATENT OFFICE

EDITORIAL

German class:

Number:
File number:
Registration date:
Display day:

1 241 625
V18751VI a / 40d June 4, 1960
June 1, 1967

The invention relates to a method for producing molded parts with smooth and flow lines Free surface made of AlCuMg or AlZnMg (Cu) alloys by cold forming of sheets, strips or the like, in which the semi-finished product used is longer before the shaping work is carried out Time and / or is annealed at higher temperatures.

As hardenable aluminum alloys of the types AlCuMg and AlZnMg (Cu) in the hardened state have only low deformability, it is common to use semi-finished products from these alloys, in particular Sheets and strips, either after quenching from solution annealing temperature or in the soft annealed Deform state. In the former case, the deformation must take place a few hours after quenching be carried out, since the deformability becomes more difficult as the hardening progresses. aside from that The material tends, especially after repeated repetition of this process, to coarse and Flow line formation, so that the deformed parts get a pitted and rough surface, thereby their Usability is impaired.

If the deformation is carried out in the soft-annealed condition, the tendency towards coarse-grain and The formation of flow lines is much lower. To the material the strength properties of the hardened To give state, the molded parts must either after the deformation has been completed or be subjected to a hardening treatment before the last deformation stage. With difficult However, stretch-drawn and deep-drawn parts often do not achieve the goal either.

Soft annealing of semi-finished products made of hardenable aluminum alloys for the purpose of shaping is usually carried out for 10 to 20 minutes at temperatures of 320 to 360 ° C.

It has now been shown, surprisingly, that the deformability of semi-finished products made of aluminum alloys of the genus AlCuMg or AlZnMg (Cu) and in particular the tendency to form flow lines Can be practically eliminated if the annealing treatment at temperatures of 360 to 450 ° C and the semi-finished product is then slowly brought to temperatures of 320 in the oven cooled to 360 ° C or the treatment in the high and low temperature range separately and is carried out with no limit to the time in between. The semi-finished product can advantageously be used also first at a higher temperature (e.g. 400 ° C) and then a second time at a lower temperature Glow at temperature (e.g. 360 ° C).

Process for the production of molded parts with a smooth surface free of flow lines AlCuMg or AlZnMg (Cu) alloys

Applicant:

United light metal works limited liability company, Bonn, at the north station

Named as inventor:

Dr.-Ing. Paul Brenner, Bad Godesberg; Dipl.-Ing. Günther Scharf, Bonn

Such annealing temperatures and annealing times who _ao indeed applied to sometimes in the production of semi-finished products, however, these are regularly to intermediate annealing during Abwalzens of sheets and strips, especially for larger Glühchargen, which are used in large furnaces and their soaking the use of higher Temperatures and longer times required.

The invention is evident from the following examples:

1. Sheets made of AICuMg (W 3116) 1 mm thick, which were present in the cured state, were divided into individual test strips, which were heat-treated as follows:

35
Ver
search
line A. 20th Heat treatment C. deformation
until
Appear
of flow lines,
Vo 40 B. 4th C. ⁴⁵ C 2
+ 2 Minutes at 360 ° C.
C. 2.5 Hours at 360 ° 5.0 Hours at 400 °
Hours at 360 ° j 20.8
[ (Fracture-
J elongation)

The test strips were placed in a tearing machine

clamped and stretched until the first flow lines observed on the surface. The measurements showed that in test series A, the corresponded to the usual soft-annealed condition,

709 588/287

Flow lines already appeared after a deformation of 2.5%. In test series B, in which the glow duration was extended according to the invention from 20 minutes to 4 hours, flow lines could only after a deformation of 5% can be determined. In test series C, in which the test strips initially 2 hours at 400 ° C and then 3 hours at 360 ° C were annealed, the test strips could be up to Load at break, which corresponds to a deformation of 20% without the formation of flow lines could be noticed.

The strength, yield strength and elongation values of the samples treated according to A, B and C. were the following:

The strength, yield strength and elongation values of the samples treated according to A, B and C were as follows:

Attempt
line tensile strenght
kp / mm ² Stretch limit
kp / mm ² strain
"/O A.
B.
C. 26.7
23.1
19.2 13.9
10.2
9.1 13.3
18.0
20.8

The samples B and C treated according to the invention accordingly have a lower strength and lower strength than the samples A, which are usually soft-annealed Yield strength, but a higher elongation on what to carry out shaping work is cheap. The surface of the B and especially the C samples was smooth after tearing while the Α samples showed a pitted surface.

Ver
search
line Heat treatment
Type AlZnMgCu deformation
until
Appear
of flow lines,
° / o A.
B.
C. 20 minutes at 450 ° C
4 hours at 450 ° C
4 hours at 450 ° C
with slow down
cooling to 320 ° C 2.0
3.5
17.0

5 test series kp / mm ² ° B
kp / mm ² <5i <T A.
B.
c 14th
16
13.5 34
29
28 12th
16
18th

In the case of multi-stage deformation, it is advisable to. only the first soft annealing in the one described Way to carry out, while the subsequent 'annealing takes place as usual.

Claims (2)

Patent claims: 1. Process for the production of moldings with a smooth surface free of flow lines Made of AICuMg and AlZnMg (Cu) alloys by cold forming of sheet metal, strips or the like, in which the semi-finished product used before the shaping work is carried out is annealed for a longer time and / or at higher temperatures, characterized in that that the annealing treatment is carried out at temperatures of 360 to 450 ° C and the semi-finished product then slowly cooled in the oven to temperatures of 320 to 360 ° C or that the treatment is performed in the high and low temperature ranges separately and without limitation of the time therebetween. 2. The method according to claim 1, characterized in that with multi-stage deformation only the first soft annealing is carried out in the manner described in claim 1, while the subsequent annealing takes place as usual. The heat-treated samples were tested in the same way as described under 1. The festivals Considered publications:
Aluminum-Taschenbuch, 11th edition, Aluminum-Verlag Düsseldorf, 1955, pp. 328 to 331;
Metallurgia, 44 (1951), pp. 287 to 289;
Journal of the Institute of Metals, 80 (1951/52), pp. 17 to 22.