ES2648668T3 - Heat resistant alloy for the production of aerosol cans - Google Patents

Abstract

Heat resistant alloy for the production of aerosol cans from a material with the following content of alloy additions, in percentage by weight: according to standards EN 573-3 EN AW 3102 Si <= 0.40; Fe <= 0.70; Cu <= 0.10; Mn 0.05 ÷ 0.40; Zn <= 0.30; Ti <= 0.10; or with more specific compositions - If> = 0.05 ÷ 0.09; Fe> = 0.23 ÷ 0.27; Cu <= 0.005; Mn> = 0.28 ÷ 0.32; Mg <= 0.005; Zn <= 0.015; Ti> = 0.01 ÷ 0.03; characterized in that each composition contains Zr added in an amount ranging from 0.10 to 0.15% by weight, the sum of the amounts contained of all secondary elements <= 0.10% by weight and the rest It is Al content.

Description

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DESCRIPTION

Heat resistant alloy for the production of aerosol cans Background of the invention

Currently, aerosol cans are manufactured from pure aluminum or aluminum alloys. In the first case, mostly 1000 series aluminum is used, according to European standard EN 573-3. The most common grades of aluminum are EN AW 1050A, which has a minimum Al content of 99.5% and EN AW 1070A, which has a minimum Al content of 99.7%.

In the second case, aerosol cans are mainly manufactured from 3000 series aluminum alloys, according to European standard EN 573-3. The most common grades of aluminum alloy are EN AW 3102, which has an Mn content of approximately 0.3% and EN AW 3207, which has an Mn content of approximately 0.6%.

For the manufacture of aerosol cans, aluminum and its alloys are supplied mostly in the form of blanks.

These blanks are manufactured in a continuous two-phase process that includes the following stages.

to. ) Phase 1 - Manufacturing of strips

• Melt the ingots in the melting furnaces.

• Transfer the molten aluminum to a maintenance oven.

• Strain a strip continuously.

• Hot strip the strip.

• Cold strip the strip.

• Roll up the laminated strip.

b. ) Phase 2 - Manufacturing of blanks

• Unwind the laminated strip.

• Drill the blanks in a stamping press.

• Anneal the blanks.

• Cool the blanks.

• Give surface finish to the blanks (flipping, sandblasting, vibration).

• Pack the blanks.

The manufacturing process of aerosol cans can be described as follows:

Apply a lubricant to the blanks.

Extrude on impact backwards.

Flat press the can wall.

Brush the can.

Degrease the can.

Apply the inner varnish layer + cure in a polymerization oven Apply the base coat + cure in the oven.

Apply decorative inks + cure in oven.

Apply the coating layer + cure in the oven.

Shape the cans in the closing press.

The materials described above, according to the standards EN AW 1050A and EN AW 1070A respectively, have significant levels of formability and hardening by mechanical means, which make them ideal for the manufacture of aerosol cans in a back impact extrusion process. The aluminum alloys EN AW 3102 and EN AW 3207 offer improved mechanical properties (strength) and, therefore, better rigidity and pressure resistance of the final aerosol cans. However, the mechanical properties of these materials change when the cans pass through a curing oven in which polymerization of the inner varnish layer takes place. Curing (polymerization) temperatures of the inner varnish layer range between 210 and 255 ° C, and the respective curing process takes about 10 minutes. At these temperatures, partial annealing of the can body takes place, causing its mechanical strength to decrease.

To eliminate the above undesirable effect, thicker walls of the aerosol cans must be selected, which are necessary to achieve safety and technological specifications, particularly sufficient pressure resistance of the cans. This causes a significant increase in consumption of starting materials.

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In US Pat. No. 6,543,636 a process for manufacturing cans from aluminum alloy is disclosed and the 1050 A alloy was chosen as appropriate. This alloy is known as EN AW 1050A according to the European standard and is widely used. However, for some application the tensile strength (Rm) of the cans is not satisfactory enough, when they are subject to higher temperatures.

Characteristics of the invention.

The above drawbacks are eliminated by the heat-resistant alloy for the production of aerosol cans with the characteristics defined in the characterization part of claim 1.

Brief description of the drawings

The present invention will be further explained with reference to the accompanying drawings, in which Figure 1 shows the temperature dependence of the resistances of the new alloys compared to the standard alloys by means of a graphic representation.

The object of the present invention is a new, modified and heat-resistant aluminum-based alloy, to eliminate the weakening effect of the material of the cans passing through the curing oven. In this way, the desired improvement of the mechanical properties of the aerosol cans is achieved in comparison to the standard (conventionally used) materials, together with the reduction of the wall thickness and the increase in the pressure resistance thereof. . Particularly, the above favorable effect is achieved by the addition of an antirecrystallization additive formed by Zr (zirconium) in order to modify the aluminum compositions and their alloys: EN AW 1050A, EN AW 3102, EN AW 3207.

The chemical compositions of the alloys commonly used, unmodified, have the following limit values according to EN 573-3, in percentage by weight:

If <0.25; Fe <0.40; Cu <0.05; Mn <0.05; Mg <0.05; Zn <0.07; Ti <0.05; At 99.5 min.,

EN AW 3102

If <0.40; Fe <0.70; Cu <0.10; Mn 0.05-0.40; Zn <0.30; Ti <0.10; rest Al EN AW 3207

If <0.30; Fe <0.45; Cu <0.10; Mn 0.40-0.80; Mg <0.10; Zn <0.10; Al rest

The alloy, according to the present invention, has a new chemical composition with Zr added, the proportion of the new constituent being between 0.10 and 0.15% by weight. The addition of Zr results in completely new alloys that cannot be classified into existing classes according to EN 573-3. Therefore, the new alloys will be referred to below as MC alloys, ie MC3 (EN AW 3012A + Zr). The composition of the new alloy (in percentage by weight) is as follows:

MC3 Alloy

If <0.40; Fe <0.70; Cu <0.10; Mn <0.05 ^ 0.40; Zn <0.30; Ti <0.10; Zr = 0.05 ^ 0.20; Al rest; (sum of all secondary elements <0.10)

To verify the antirecrystallization effect during the production process of aerosol cans, the new alloys were compared with known and commonly used materials. The result is represented graphically in Figure 1 in which the first standard material, according to EN AW 1050A, in this document specifically designated as the A5 alloy, is compared with the new MC1_A alloy, which is not the object of the This application, and the second standard material, according to EN AW 3102, in this document specifically referred to as A3Mn alloy, is compared to another new MC3_A alloy containing the added Zr constituent antirecrystallization. The cans, which were made from these materials under the same technological conditions, had identical wall specifications.

Standard alloys, used for the purposes of comparing the antirecrystallization effect, are indicated as follows:

Alloy A5 (aluminum according to EN AW 1050A) that has the following chemical composition in% by weight:

Si = 0.08; Fe = 0.24; Cu <0.005; Mn <0.005; Mg <0.005; Zn = 0.01; Ti = 0.02; Al rest

The A3Mn alloy (aluminum alloy according to EN AW 3102) which has the following chemical composition in% by weight:

Si = 0.07; Fe = 0.25; Cu <0.005; Mn = 0.29; Mg <0.005; Zn = 0.01; Ti = 0.02; Al rest

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The newly developed alloy used for the purposes of comparing the antirecrystallization effect is designated as follows:

MC3_A alloy that has the following chemical composition in% by weight:

Si = 0.06; Fe = 0.23; Cu <0.005; Mn = 0.30; Mg <0.005; Zn = 0.01; Ti = 0.03; Zr = 0.12; Al rest

Table 1 shows the mechanical properties of cans produced from the above materials. During the comparison, the tensile strength (Rm) values of the cans measured before and after the curing oven were evaluated, in which the inner varnish layer was polymerized. In addition, the hardness (HB) of the semi-finished input products (blanks) was measured.

Table 1

 Alloy

 Workpiece hardness Tensile strength Rm [MPal

 After extrusion back

 After the curing oven (polymerization) of the inner varnish layer

 210 ° C / 10min

 230 ° C / 10min 255 ° C / 10min

 TO 5

 20.8 164.1 154.8 150.5 135.1

 A3Mn

 22 180.7 172.6 167.9 151.2

 MC1 A

 22 171.0 171.1 168.3 167.2

 MC3 A

 23.5 182.5 179.2 179.0 178.3

The results listed in Table 1 clearly show that standard materials lose their tensile strength when subjected to the temperature of 255 ° C in the furnace, reducing the resistance by 17.7% for A5 aluminum and 16.3 % for the A3Mn alloy. In contrast to this, the loss of strength of Zr-containing alloys is significantly less, that is, only 2.2% for the MC1_A alloy and 2.3% for the MC3_A alloy. In several cases, even an increase in the tensile strength of the new alloys was observed after they had passed through the curing oven.

The comparison of the A5 aluminum with the MC1_A alloy shows that the tensile strength value of this latter alloy was 32.1 MPa higher after passing through the polymerization furnace at the temperature of 255 ° C.

The comparison of the A3Mn and MC3_A aluminum alloys shows that the resistance value of this latter alloy was 27.1 MPa higher after passing through the polymerization furnace at the temperature of 255 ° C.

It is also advantageous that, although the MC1_A alloy containing the added Zr component has its tensile strength, after extrusion back, 9.7 MPa lower compared to the A3Mn alloy, the passage of the MC1_A alloy through the polymerization furnace at temperatures above 226 ° C causes the strength of this alloy to exceed the resistance of the A3Mn alloy, although the MC1_A alloy does not contain manganese.

Among the main advantages of the new MC1, MC3 alloys (which is not within the scope of the present invention) and (which is not within the scope of the present invention) are particularly included:

to. ) Due to the addition of Zr, the MC1, MC3 and MC4 alloys contain a fine dispersion of A ^ Zr.

b. ) The presence of manganese in MC3 and MC4 alloys also results in an increase in the resistance of these alloys after undergoing a forming process, this is due to the formation of AlaMn, Als (FeMn) and a- particles. AI (Mn, Fe) Yes.

C. ) The above particles are trapped in the subgranular boundaries, thus preventing any recovery or formation of recrystallization nuclei or growth of recrystallized grains (increased resistance to recrystallization).

Claims (1)

1. Heat-resistant alloy for the production of aerosol cans from a material with the following content of alloy additions, in percentage by weight: according to standards EN 573-3 EN AW 3102 If <0.40; Fe <0.70; Cu <0.10; Mn 0.05-0.40; Zn <0.30; Ti <0.10; or with more specific compositions 10 - Si = 0.05 - 0.09; Fe = 0.23-0.27; Cu <0.005; Mn = 0.28-0.32; Mg <0.005; Zn <0.015; Ti = 0.01 - 0.03; characterized in that each composition contains Zr added in an amount ranging from 0.10 to 0.15% by weight, the sum of the amounts contained of all secondary elements being <0.10% by weight and the rest is Al content. fifteen