RU2770148C1 - Method for manufacturing rolled products with increased corrosion resistance from deformable thermally non-hardening alloys of the aluminium-magnesium system - Google Patents

Abstract

FIELD: metallurgy.SUBSTANCE: invention relates to non-ferrous metallurgy and can be used in production of bands with a thickness of 3 mm from alloys of the Al-Mg system. The method for producing sheets with a thickness of 3 mm from the 1565ch alloy includes multi-pass rolling of a 1565ch alloy ingot, producing a recrystallised hot-rolled workpiece of a band, subsequent cold rolling, annealing, cold rolling, and final annealing, wherein the last pass on the hot-rolling mill is performed at the end rolling temperature in the range of 350 to 360°C with a degree of deformation greater than 30% forming an equiaxial fine-grain structure with a conditional average grain diameter of 25 to 35 mcm and grain orientation forming a mixed texture with a cubic texture content of at least 20%, subsequent cold deformation at the first stage is executed with a degree of 30 to 35% and annealing at a temperature of 330 to 350°C with sustaining for 2 hours for dissolution and subsequent uniform extraction in a solid aluminium solution of β phase (Al3Mg2), the following cold deformation stage is executed with a degree of 25 to 30% and annealing at a temperature of 230 to 240°C until uniform extraction of the β phase (Al3Mg2) according to the structure of the alloy, followed by cutting the band wound into a roll into sheets.EFFECT: increase in the corrosion resistance and enhancement of the mechanical properties of bands made of Al-Mg aluminium alloys.1 cl, 2 dwg, 5 tbl, 1 ex

Description

The invention relates to non-ferrous metallurgy, in particular to a method for thermomechanical processing of deformable thermally non-hardened aluminum alloys of the aluminum-magnesium system, obtaining rolled products, such as sheets, as a result of processing, and can be used in the production of 3 mm thick tapes from alloys of the Al-Mg system.

Alloys of the aluminum-magnesium system are deformable, thermally indestructible. The main way to increase the strength of these alloys is cold plastic deformation. To increase the elongation and maintain the required level of properties, it is necessary to carry out a special heat treatment

A known method includes casting ingots, three-stage homogenization annealing of ingots (245-280°C - 2-10 hours, 320-360°C - 2-8 hours, 400-495°C - 1-12 hours), hot rolling, cold deformation with a total deformation of up to 35% (see C22F 1/04 (2020.08); RU 2734675, 05/21/2020).

The disadvantage of this method is the long annealing before thermomechanical processing and the high thickness of the final product - 30 and 5 mm.

The closest analogue to the claimed object is a method for manufacturing rolled products from a deformable thermally non-hardening alloy, including casting ingots, homogenization, hot deformation, cold deformation and low-temperature annealing with a temperature of 25 to 330 ° C and cold deformation up to 50%, as well as the thickness of the final products - (see C22F 1/04 (2006.01); RU 2483136, 12/30/2011).

The disadvantages of the known method include:

1. The method does not provide the required level of properties on sheets less than 5 mm thick, because describes actions with plates up to 30 mm and tapes up to 5 mm, resulting in a decrease in strength characteristics by 20-30%.

2. The required corrosion resistance is not provided.

The task of the claimed invention is aimed at obtaining sheets from an aluminum alloy of the aluminum-magnesium group, with a magnesium content of more than 5% and the addition of alloying elements Zr, Mn, Cr, Ni, Zn, Si, Fe, Ti, which guarantees the achievement of the level of properties indicated in the table 1 and a processing method that guarantees the achievement of high corrosion characteristics due to the uniform distribution of the β-phase (Al ₃ Mg ₂ ) over the alloy structure _.

The technical result to which the invention is directed is to increase the corrosion resistance and improve the mechanical properties of tapes made of Al-Mg aluminum alloys.

The technical result is achieved due to the fact that in the method of cold multi-pass rolling of thin strips made of aluminum alloys of the Al-Mg system, a workpiece is used, obtained during hot rolling to a degree of deformation of more than ε=98% with a temperature of the end of rolling in the range of 350-360, at the same time, in the last pass, the degree of deformation is at least 30%; if these parameters are observed, a component-free texture with a small content of the cubic component is formed in the workpiece after self-annealing, and the thickness is 2 times higher than the final thickness of the tape. Then the resulting hot-rolled billet is deformed by cold rolling with a deformation of more than 25% (in two passes), after which annealing is carried out at a temperature of 330-350 ° C and holding for 2 hours, which allows the particles of the β-phase (Al ₃ Mg ₂ ) to dissolve in a solid solution aluminum, followed by cold deformation with a degree of deformation of 25-30%, hardening is carried out with the achievement of strength characteristics higher than specified, during the final annealing at a temperature _of 230-240 ° C and a holding time of 4-6 hours, a uniform precipitation _of the β-phase ) and there is a partial softening to properties higher than specified.

The essence of the invention is illustrated by two figures:

Fig. 1 - uniform distribution of the p-phase (Al ₃ Mg ₂ ) over the structure of the alloy;

Fig. 2 - The hardening curve of the alloy 1565h depending on the degree of deformation.

The method is carried out as follows:

The last pass at the hot rolling mill is carried out with parameters that do not allow spontaneous recrystallization (the temperature of the end of rolling is in the range of 350-360, the degree of deformation is more than 30%), so that immediately after rolling a deformed structure remains, which completely transforms into a recrystallized structure during the cooling of the coil, through static recrystallization with the formation of an equiaxed fine-grained structure (conditional average grain diameter 25-35 microns) and grain orientation forming a mixed texture with a cubic texture content of at least 20%.

During cold deformation with a degree of deformation of 30-35% at the first stage and annealing at a temperature of 330-350°C with a holding time of 2 hours, the β-phase (Al ₃ Mg ₂ ) is dissolved in the aluminum solid solution with the aim of its subsequent uniform separation.

During subsequent cold deformation with a degree of deformation of 25-30% at the last stage and annealing at a temperature of 230-240°C, the β-phase (Al ₂ Mg ₂ ) is uniformly precipitated over the alloy structure, which ensures high corrosion resistance, and partial softening occurs. material and strength properties are reduced to the required.

The developed method makes it possible to obtain a guaranteed level of corrosion resistance, indicated in Table No. 3 and mechanical properties, presented in Table No. 2, on an aluminum tape made of 1565ch alloy (chemical composition is presented in Table 1) with a thickness of 3 mm.

Implementation examples:

So, for example, a tape of 1565ch alloy (Al-Mg system, the chemical composition is given in table No. 1) 3 mm thick, manufactured by the proposed method, makes it possible to obtain the following mechanical properties stably (table 2) and high corrosion characteristics - table 3. The manufacturing route is presented in table 4.

Claims (1)

A method for producing sheets with a thickness of 3 mm from alloy 1565ch, including multi-pass rolling of an ingot from alloy 1565ch at a hot rolling mill to obtain a recrystallized hot-rolled strip blank with a cubic texture content, subsequent cold rolling, annealing, cold rolling and final annealing, characterized in that the last pass on a hot rolling mill, it is produced with parameters that do not allow spontaneous recrystallization at a temperature of the end of rolling in the range of 350-360 ° C and a degree of deformation of more than 30% so that immediately after rolling a deformed structure remains, which completely transforms into a recrystallized structure during the cooling of the coil through static recrystallization with the formation of an equiaxed fine-grained structure with a conditional average grain diameter of 25-35 microns and grain orientation that forms a mixed texture with a cubic texture content of at least 20%, subsequent cold deformation at the first stage carried out with a degree of 30-35% and annealing at a temperature of 330-350 ° C with a holding time of 2 hours for dissolution and subsequent uniform separation of the β-phase (Al ₃ Mg ₂ ) in a solid solution of aluminum, the next stage of cold deformation is carried out with a degree of 25-30 % with annealing at a temperature of 230-240 ° C until the β-phase (Al ₃ Mg ₂ ) is uniformly separated over the alloy structure to ensure corrosion resistance, partial weakening of the material and reduce the strength properties to the required ones, after which the tape wound into a roll is cut into sheets .

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