RU2501881C2 - Method of multipass cold rolling of thin bands from aluminium alloys - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: in compliance with proposed method of rolling thin bands from aluminium Al-Mg or Al-Mg-Mn system alloys fully recrystallised hot-rolled band blank is subjected to rolling. Band blank features cubic texture and depth 9-10 times larger than band final depth. Rolling causes 45-47% reduction at every of two last passes at deformation rate of at least 10 m/s and band coiling temperature of 140-160°C, coil weight making at least 8 t.

EFFECT: higher metal ductility, decreased scatter of mechanical properties.

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Description

The invention relates to the processing of metals by pressure, for example, to the production of thin tapes and foils from alloys of Al-Mg, Al-Mg-Mn systems and can be used, for example, in the metallurgical industry in the manufacture of thin tapes, for the production of packaging containers in the food industry.

A known method of rolling Al-Mg systems, comprising cold rolling with intermediate recrystallization annealing, rolling before and after annealing is carried out with a total degree of deformation of 75-95%, the degree of deformation before annealing is 1-1.25 of the degree of deformation after annealing (see.a. 850235, B21B 3/6, USSR, 1981).

The disadvantages of this method include:

1. The presence of intermediate annealing, which during rolling at stage II does not provide the necessary strength characteristics.

2. The method does not allow for high ductility.

3. A wide range of mechanical properties.

4. The required level of festivals is not provided.

A known method of rolling Al-Mg alloys containing cold rolling in several passes, in which rolling is carried out with a degree of deformation per pass of 40-45%, while the metal is cooled between 70 passes to 70-80 ° C (a.s. 878386, B21B 3 / 0, USSR, 1981).

The disadvantages of this solution include:

1. The cooling of the metal between the passes complicates the process and reduces productivity.

2. The implementation of rolling in each pass with a degree of deformation of 40-45% is possible on a single-camp mill, but practically impossible on a multi-camp.

3. It does not allow for highly fretted metal to obtain increased ductility.

The closest technical solution to the proposed invention is a method for producing foil by the method of cold multi-pass rolling of thin strips of aluminum alloys, where at each of the last two passes, the rolling is carried out with the degree of compression according to a given ratio between the parameters of the tape

E = 1-K · h / H

where H is the initial thickness of the tape, h is the desired final thickness of the tape, K is a coefficient equal to 0.05-0.07 (see RU 2226437, ⁷ B21B 3/00 of 04/10/2004), with a total degree of compression that is not less than 85%, with a speed of at least 500 m / min and with a temperature at the end of rolling equal to 140-160 ° C with a coil weight of 5 tons

The disadvantages of this method include:

The degree of deformation calculated by this formula is extremely small, which does not provide the necessary heating of the strip during cold rolling.

The task of the invention is to increase the ductility and formability of the processed metal and reduce the dispersion of mechanical properties.

The problem in the present invention is achieved by the method of cold multi-pass rolling of thin strips of aluminum alloys of the Al-Mg or Al-Mg-Mn system. In this case, a completely recrystallized hot-rolled strip of a strip having a cubic texture and a thickness 9-10 times greater than the final thickness of the strip is subjected to rolling, while rolling is carried out with a degree of deformation of 45-57% in each of the last two passes and with a strain rate of at least 10 m / s in the last pass with a temperature of 140-160 ° C in the roll when winding the tape into a roll weighing at least 8 tons

When the degree of deformation <45%, it is impossible to achieve the required temperature in 140-160 degrees C in two passes. If the degree of deformation is> 57%, then the temperature will be more than necessary, and the rolling process will become unstable. At a rolling speed of <10 m / s, a thin strip does not ensure the maintenance of the achieved required interval when winding into a roll. Without a fully recrystallized hot rolled billet, the plasticity resource necessary for high-speed rolling without fracture is not provided. In the absence of a cubic texture in the hot-rolled billet, strong scalloping occurs at an angle of 45 ° to the rolling direction. The need to maintain the interval of thickness multiplicity 9-10 times greater than the final thickness of the tape is due to the fact that at <9 no strength is gained, and at> 10 there is intense cracking and loss of stability during rolling, as well as the required festooning is not provided. For the mass of the rolled billet <8 t, the rate of natural cooling of the coil in air does not provide the necessary residence time in the temperature range required for relaxation processes.

The proposed method of cold rolling for the above systems allows to obtain a tape with high characteristics of strength, plastic properties and stampability and reduce the dispersion of mechanical properties. So, for example, a strip of alloy 3104 (Al-Mg-Mn system) 0.265 mm thick, manufactured by the proposed method, allows to obtain stably the following mechanical properties (table 1):

Table 1 options units measurements required by T.U. by proposal way σ _in MPa 295-335 300-310 σ ₀₂ MPa 275-315 280-285 δ % > 3.5 > 5 f % <3.2 <1.5

It can be seen from the presented indicators that, according to the parameter σ _{, the} spread decreased by 4 times, and by the parameter σ ₀₂ , by 8 times.

Achieving the goal of the invention is checked repeatedly, the results indicated above are stably provided.

Claims (1)

The method of cold multi-pass rolling of thin strips of aluminum alloys of the Al-Mg or Al-Mg-Mn system, characterized in that the rolling is subjected to a fully recrystallized hot-rolled preform of a tape having a cubic texture and thickness 9-10 times greater than the final thickness of the tape, while rolling is carried out with a degree of deformation of 45-57% in each of the last two passes and with a deformation rate of at least 10 m / s in the last pass with a temperature of 140-160 ° C in the roll when the tape is rolled into a roll weighing at least 8 tons.