MXPA01008075A - Aluminium alloy containing magnesium and silicon - Google Patents

Abstract

Aluminium alloy containing 0,5 - 2,5%by weight on alloying mixture of Magnesium and Silicon, the molar ratio of Mg / Si lying between 0,70 and 1,25, an additional amount of Si equal to approximately 1/3 of the amount of Fe, Mn and Cr present in the alloy, and the rest being made up of aluminium, unavoidable impurities and other alloying agents, which alloy after cooling has been submitted to homogenising, preheating before extrusion, extrusion and ageing, which ageing takes place at temperatures between 160 and 220°C. The ageing after cooling of the extruded product is performed as a dual rate ageing operation including a first stage in which the extrusion is heated with a heating rate above 30°C/hour to a temperature between 100 - 170°C, a second stage in which the extrusion is heated with a heating rate between 5 and 50°C/hour to the final hold temperature between 160 and 220°C and in that the total ageing cycle is performed in a time between 3 and 24 hours.

Description

ALUMINUM ALLOY CONTAINING ALUMINUM AND SILICON • DESCRIPTION OF THE INVENTION The invention relates to a process for treating an aluminum alloy consisting of. - 0.5 - 2.5% by weight of a mixture of magnesium and silicon alloy, the molar ratio of Mg / Si is between 0.70 and 1.25, • 10 - an additional amount of silicon equal to 1/3 of the amount of iron, manganese and chromium present in the alloy, expressed as a percentage by weight, other alloying elements and unavoidable impurities, and 15 - the rest is made of aluminum, whose alloy after cooling has been subjected to homogenization, preheating before extrusion, and ripening, whose ripening takes place after extrusion as a maturing operation in two steps at a final retention temperature between 160 and 220 ° C. A process of this kind has been described in the International Patent WO 95.06759. According to this publication, maturation is carried out at a temperature between 150 and 200 ° C, and the heating rate is REF: 131961 between 10-100 ° C / hour preferably 10-70 ° C / hour. A two-step alternative heating scheme is proposed, wherein a retention temperature in the range of 80-140 ° C is suggested in order to obtain a total heating rate between the above-specified range. It is generally known that higher amounts of magnesium and silicon will have a positive effect on the mechanical properties of the final product, while this has a negative effect on the extrudability of the aluminum alloy. It has been briefly anticipated that the hardening phase in Al-Mg-Si alloys had a composition close to Mg2Si. However, it was also known that an excess of silicon produced higher mechanical properties. Recent experiments have shown that the precipitation sequence is very complex and that except for the equilibrium phase, the involved phases do not have the stoichiometric proportion of Mg2Si. In a publication of S.J. Andersen, et al., Acta mater, Vol. 46, No. 9, p. 3283-3298 of 1998 it has been suggested that one of the hardening phases in Al-Mg-Si alloys has a composition close to Mg 5 Si 6. It is therefore an object of the present invention to provide an aluminum alloy which • - - - * - * "• * '* - * • - have better mechanical properties and better extrusion capacity, the alloy of which has the minimum amount of ^ Alloy agents and a general composition that is as close as possible to aluminum alloys traditional This and other objectives are obtained since the moderation after cooling of the extruded product is performed as a double speed maturing operation, including a first stage in which the extrusion is heated with a heating rate ^ P 10 above 30 ° C / hour up to a temperature between 100 - 170 ° C, a second stage in which the extrusion is heated by a heating rate between 5 and 50 ° C / hour up to the final retention temperature between 160 and 220 ° C, and because the total maturation site is made 15 in a time of 3 and 24 hours. The optimal magnesium / silicon ratio is one where all available magnesium and silicon are • transformed into the MgsSid phases. This combination of magnesium and silicon gives the highest mechanical strength with minimal use of magnesium and silicon alloy elements. It has been found that the maximum extrusion rate is almost independent of the magnesium / silicon ratio. Therefore, with the optimum magnesium / silicon ratio the sum of magnesium and silicon is minimized for a certain strength requirement, and IÁ j. A, ¿t i .. "^". ... ¡¡• »-:,, li ,,," .i, ll T 1 ni ^ Mafr? A ^ gJ | BMgBMJj ^ aÍ * it¿M this alloy will provide in this way also, the best Extrusion capacity. By using the composition according to the invention, combined with the double speed maturing process according to the invention, it has been obtained that the resistance and the extrusion capacity are maximized with a minimum total maturing time. In addition to the MgsSiß phase there is also another hardening phase that contains more magnesium than the ^ 10 g5Si6 phase. However, this phase is not as effective, and does not contribute as much to mechanical resistance as the Mg5Si6 phase. On the silicon-rich side of the Mg5Si6 phase there is probably no hardening phase, and magnesium / silicon ratios less than 5/6 will not be beneficial. The positive effect of the mechanical strength of the double speed maturation process can be explained by the fact that a prolonged time at low temperature generally improves the formation of a higher density of Mg-Si listed. If the complete ripening operation is performed at such a temperature, the total ripening time will be beyond the practical limits and the yield in the ripening kilns will be too low. By a slow increase in temperature to the final maturation temperature, the high number of nucleated precipitates at low temperature will continue to develop. The result will be a high number of precipitates and mechanical strength values associated with maturation at low temperature, but with a considerably shorter total maturing time. A maturing in two steps also gives improvements in mechanical strength, but with a rapid heating from the first retention temperature to the second retention temperature there is substantial chance of reversion of the smaller precipitates, with a smaller number of hardening precipitates and in this way a lower mechanical resistance as a result. Another benefit of the double speed maturation process, compared to normal maturation and also maturation in two steps, is that a slow heating rate will ensure a better distribution of the temperature in the load. The history of the temperature of the extrusions in the load will be almost independent of the size of the load, the packing density and the wall thicknesses of the extrusions. The result will be more consistent mechanical properties than with other types of ripening procedures. In comparison to the ripening process described in WO 95.06759, where the speed of When the slow heating is initiated from room temperature, the double speed maturing process will reduce the total ripening time by the application of a rapid heating rate from room temperature to temperatures between 100 and 170 ° C. . The resulting resistance will be almost as good when slow heating is initiated at an intermediate temperature as if slow heating will start at room temperature. • 10 Depending on the kind of resistance considered, different compositions are possible within the general scope of the invention. So it is possible to have an aluminum alloy with a tensile strength in class F19 fifteen - . 15 - F22, the amount of mixture of magnesium alloy and silicon that is between 0.60 and 1.10% by weight. For an alloy with a tensile strength in class F25 - F27, it is possible to use an aluminum alloy containing between 0.80 and 1.40 by weight of a mixture of alloy of magnesium and silicon, and for an alloy with a tensile strength in the class F29-F31, it is possible to use an aluminum alloy containing between 1.10 and 1.80% by weight of the mixture of magnesium alloy and silicon. * t- * e ,, Mmtfto «*, *, -m,. < *. *, __ »^. i,,. .. "._.....,, _ ^ ..-. Preferably and according to the invention a tensile strength in class F19 (185-220 MPa) is obtained by an alloy containing between 0.60 and 0.80% by weight of the alloy mixture, a resistance to 5 traction in class F22 (215-250 MPa) by an alloy containing between 0.70 and 0.90% by weight of the alloy mixture, a tensile strength in class F25 (245-270 MPa) by an alloy containing 0.85 and 1.15% by weight of the alloy mixture, a resistance to r ^ 10 traction in class F27 (265-290 MPa) by an alloy containing between 0.95 and 1.25% by weight of the alloy mixture, a strength tensile in class F29 (285-310 MPa) by an alloy containing between 1.10 and 1.40% by weight of the alloy mixture, and a tensile strength in class F31 (305-330 MPa) by an alloy containing between 1.20 and 1.55% by weight of the alloy mixture. With additions of copper, which as a rule increases the mechanical strength by 10 MPa by 0.10% in 20 weight of copper, the total amount of magnesium and silicon can be reduced and will still adjust to a higher strength class that could give it single additions of magnesium and silicon.

?MY ? t límt? For the reason described above, it is preferred that the magnesium / silicon molar ratio falls between 0.75 and 1.25 and more preferably between 0.8 and 1.0. In a preferred embodiment of the invention, the final maturation temperature is at least 165 ° C and more preferably the maturation temperature is at most 205 ° C. When these preferred temperatures are used it has been found that the mechanical strength is maximized while the total maturing time remains within 10 ^ 10 of reasonable limits. In order to reduce the total maturation time in the double speed maturing operation, it is preferred to perform the first heating step at the highest available heating speed, 15 while as a rule, this is dependent on the available equipment . Therefore, it is preferred to use a heating speed of at least 100 ° C / hour in the first heating stage. In the second heating step the heating speed 20 must be optimized with a view to the total efficiency in time and the final quality of the alloy. For this reason, the second heating rate is preferably at least 7 ° C / hour and at most 30 ° C / hour. At lower heating speeds 25 of 7 ° C / hour the total ripening time will be prolonged, ^^^^^ * with a low yield in maturing ovens as a result, and at higher heating rates of 30 ° C / hour, the mechanical properties will be less than ideal. Preferably, the first heating step will end up to 130-160 ° C, and at these temperatures there is sufficient precipitation of the g5S6 phase to obtain a high mechanical strength of the alloy. A lower final temperature of the first stage will lead to an increased total maturing time. Preferably, the total ripening time is at most 12 hours. In order to have an extruded product with almost all of the magnesium and silicon in the solid solution before the ripening operation, it is important to control the parameters during extrusion and cooling after extrusion. With the correct parameters this can be obtained by normal preheating. However, by using a so-called overheating process described in European Patent No. EP 0302623, which is a preheating operation where the alloy is heated to a temperature between 510 and 560 ° C during the preheating operation before extrusion, after which the ingots are cooled to normal extrusion temperatures, this will ensure that all the magnesium and silicon added to the alloy are dissolved. By adequately cooling the extruded product, magnesium and silicon are kept dissolved and available for the formation of hardening precipitates during the maturation operation. For low alloy compositions the solubilization of magnesium and silicon can be obtained during the extrusion operation without overheating, if the extrusion parameters are • 10 correct. However, with higher alloy compositions the normal preheating conditions are not always sufficient to keep all the magnesium and silicon in the solid solution. In such cases, overheating will make the extrusion process more robust and will always ensure that all magnesium and silicon are in solid solution when the profile leaves the press. Other features and advantages will be clear to • Starting from the following description of a number of tests carried out with alloys according to the invention. 20 Example 1 Eight different alloys with the composition given in Table 1 were cast as 95 mm ingots of diameter with standard emptying conditions for 6060 alloys. The ingots were homogenized with a heating rate of approximately 250 ° C / hour, the retention period was 2 hours and 15 minutes at 575 ° C, and the cooling rate after homogenization it was approximately 350 ° C / hour. The pieces were finally cut into ingots of 200 mg long.

Table 1 • 10 Alloy Si Mg Fe Total Si + Mg 1 0.34 0.40 0.20 0.74 2 0.37 0.36 0.19 0.73 3 0.43 0.31 0.19 0.74 4 0.48 0.25 0.20 0.73 5 0.37 0.50 0.18 0.87 6 0.41 0.47 0.19 0.88 • 7 0.47 0.41 0.20 0.88 8 0.51 0.36 0.19 0.87 The extrusion test was carried out on an 800-ton press equipped with a 100 mm diameter container, and an induction oven to heat the ingots before extrusion.

The matrix used for the extrusion capacity experiments produced a cylindrical rod with a diameter of 7 mm, with two ribs 0.5 mm wide and 1 itim high, located at 180 ° apart. In order to obtain good measurements of the mechanical properties of the profiles, a separate test was run with a matrix that gave a bar of 2 by 25 mm2. The ingots were preheated to approximately 500 ° C before extrusion. After the extrusion the profiles were cooled in air at rest giving a cooling time of approximately 2 minutes at temperatures lower than 250 ° C. After extrusion the profiles were stretched 0.5%. The storage time at room temperature was controlled before ripening. The mechanical properties were obtained by means of the tensile test. The complete results of the extrusion capacity tests for these alloys are shown in Table 2 and 3.

Table 2 Extrusion tests for alloys 1-4 Alloy Speed Temperature Notes Ingot Hammer No. mm / sec ° C •• - * "- • ** • 1 16 502 OK 1 17 503 OK • 1 18 502 Breakage 1 17 499 OK 1 19 475 OK 1 20 473 OK 21 Alloy Speed Temperature Notes Ingot Hammer No. • mm / sec ° C 2 16 504 OK 2 17 503 Small Break 2 18 500 Break 2 20 474 OK 2 19 473 OK 2 18 470 OK 2 21 469 Small Break 3 17 503 Break 3 16 505 OK 3 15 504 OK 3 19 477 OK 3 18 477 OK 3 20 472 OK • iÉIIÉi? Ii 21 470 Rompimiento Alloy Speed Temperature Notes Ingot Hammer No. mm / sec ° C 4 17 504 OK 4 18 505 Breaking 4 16 502 OK 4 19 477 OK 4 20 478 OK 4 20 480 Small Breaking 4 21 474 Breaking For alloys 1-4, which have approximately the same sum of magnesium and silicon but different magnesium / silicon ratios, the maximum extrusion rate before breaking is approximately the same at comparable barrel temperatures.

Table 3 Extrusion Tests for Alloys 5-8 • Alloy Speed Temperature Notes Ingot Hammer No. mm / sec ° C 5 14 495 OK 5 14.5 500 Break • 5 15 500 Breaking 5 14 500 Small Breaking 5 17 476 Breaking 5 16.5 475 OK 5 16.8 476 Small Breaking 5 17 475 Breaking 6 14 501 Small Breaking 6 13.5 503 OK • 6 14 505 Breaking 6 14.5 500 Breaking 6 17 473 Breaking 6 16.8 473 Breakage 6 16.5 473 OK 6 16.3 473 OK 7 14 504 Breakage 7 13.5 506 Small Break 7 13.5 500 OK 7 13.8 '503 Small Break 7 7 472 Small Break 7 16.8 476 Break Alloy Speed Temperature Notes Bull. / sec ° C • 7 16.6 473 OK 17 475 Break 13. 5 505 OK • 13.8 505 Breaking 13.6 504 OK 14 505 Breaking 17 473 Small Breaking 17.2 474 Small Breaking 17.5 471 Breaking 16.8 473 OK For alloys 5-8, which have approximately the same amount of magnesium and silicon but different proportions magnesium / In the case of silicon, the maximum extrusion rate before breaking is approximately 5 the same at comparable ingot temperatures. However, when comparing alloys 1-4 which have a lower amount of magnesium and silicon with alloys 5-8, the maximum extrusion rate is generally greater for alloys 1-4. • 10 The mechanical properties of the different alloys matured at different ripening cycles are shown in tables 4-11. As an explanation to these tables, reference is made to figure 1 in which 15 different ripening cycles are shown graphically and identified by a letter. In Figure 1, a total maturation time is shown on the x-axis, and the temperature • used is along the y-axis. In addition, the different columns have the following meaning: Total time = Total ripening time for the ripening cycle; Rm = final tensile strength; RP02 = elastic limit; 25 AB = lengthening to fracture táatkiÉlü Au = uniform elongation All these data have been obtained by means of • standard tensile tests and the numbers shown are the average of two parallel samples of the extruded profile.

Table 4 To the equation 1 - 0 40 Mg + 0 34 Yes Ti total Total Rm Rp02 AB Au • (hours) A 3 143.6 74.0 16.8 8.1 A 4 160.6 122.3 12.9 6.9 A 5 170.0 137.2 12.6 5.6 A 6 178.1 144.5 12.3 5.6 A 7 180.3 150.3 12.3 5.2 B 3.5 166.8 125.6 12.9 6.6 B 4 173.9 135.7 11.9 6.1 B 4.5 181.1 146.7 12.0 5.4 B 5 188.3 160.8 12.2 5.1 B 6 196.0 170.3 11.9 4.7 C 4 156.9 113.8 12.6 7.5 C 5 171.9 134.7 13.2 6.9 C 6 189.4 154.9 12.0 6.2 C 7 195.4 168.6 11.9 5.8 C 8 199.2 172.4 12.3 5.4 . -i Total Time Rm .Kp02 AB Au (hours) D 7 185.1 140.8 12.9 6.4 D 8.5 196.5 159.0 13.0 6.2 D 10 201.8 171.6 13.3 6.0 D 11.5 206.4 177.5 12.9 6.1 D 13 211.7 184.0 12.5 5.4 E 8 190.5 152.9 12.8 6.5 E 10 200.3 168.3 12.1 6.0 • E 12 207.1 176.7 12.3 6.0 E 14 211.2 185.3 12.4 5.9 E 16 213.9 188.8 12.3 6.6 Table 5 To the aeration 2 - 0 36 Mg + 0 37 Si Total Time Rm Rp02 AB Au • (hours) A 3 150.1 105.7 13.4 7.5 A 4 164.4 126.1 13.6 6.6 A 5 174.5 139.2 12.9 6.1 A 6 183.1 154.4 12.4 4.9 A 7 185.4 157.8 12.0 5.4 Total Time Rm Rp02 AB Au (hours) • B 3.5 175.0 135.0 12.3 6.3 B 4 181.7 146.6 12.1 6.0 B 4.5 190.7 158.9 11.7 5.5 B 5 195.5 169.9 12.5 5.2 B 6 202.0 175.7 12.3 5.4 • C 4 161.3 114.1 14.0 7.2 C 5 185.7 145.9 12.1 6.1 c 6 197.4, 167.6 11.6 5.9 c 7 203.9 176.0 12.6 6.0 c 8 205.3 178.9 12.0 5.5 D 7 195.1 151.2 12.6 6.6 D 8.5 208.9 180.4 12.5 5.9 D 10 210.4 181.1 12.8 6.3 D 11.5 215.2 187.4 13.7 6.1 D 13 219.4 189.3 12.4 5.8 E 195.6 158.0 12.9 6.7 E 10 205.9 176.02 13.1 6.0 E 12 214.8 185.3 12.1 5.8 E 14 216.9 192.5 12.3 5.4 E 16 221.5 196.9 12.1 5.4 Table 6 To the equation 3 - 0 31 Mg + 0 43 Si Ti e po Total Rm Rp02 AB Au (hours) A 3 154.3 111.0 15.0 8.2 A 4 172.6 138.0 13.0 6.5 A 5 180.6 148.9 13.0 5.7 A 6 189.7 160.0 12.2 5.5 • A 7 192.5 164.7 12.6 5.3 B 3.5 187.4 148.9 12.3 6.3 B 4 193.0 160.3 11.5 5.9 B 4.5 197.7 168.3 11.6 5.1 B 5 203.2 177.1 12.4 5.5 B 6 205.1 180.6 11.7 5.4 C 4 170.1 127.4 14.3 7.5 C 5 193.3 158.2 13.4 6.2 C 6 207.3 179.2 12.6 6.4 • C 7 212.2 185.3 12.9 5.7 C 8 212.0 188.7 12.3 5.6 D 7 205.6 157.5 13.2 6.7 D 8.5 218.7 190.4 12.7 6.0 D 10 219.6 191.1 12.9 6.7 D 11.5 222.5 197.5 13.1 5.9 D 13 226.0 195.7 12.2 6.1 Total Time Rm Rp02 AB Au (hours) E 8 216.6 183.5 12.6 6.8 E 10 217.2 190.'4 12.6 6.9 E 12 221.6 193.9 12.4 6.6 E 14 225.7 200.6 12.4 6.0 E 16 224.4 197.8 12.1 5.9 Table 7 Alloy 4 - 0.25 Mg + 0.48 Yes Total Time Rm Rp02 AB Au (hours) A 3 140.2 98.3 14.5 8.6 A 4 152.8 114.6 14.5 7.2 A 5 166.2 134.9 12.7 5.9 A 6 173.5 141.7 12.8 5.7 A 7 178.1 147.6 12.3 5.2 B 3.5 165.1 123.5 13.3 6.4 B 4 172.2 136.4 11.8 5.7 B 4.5 180.7 150.2 12.1 5.2 B 5 187.2 159.5 12.0 5.6 B 6 192.8 164.6 12.1 5.0 Total Time Rm Rp02 AB Au (hours) c 4 153.9 108.6 13.6 7.7 c 5 177.2 141.8 12.0 6.5 c 6 190.2 159.7 11.9 5.9 c 7 197.3 168.9 12.3 6.1 c 8 197.9 170.6 12.5 5.6 D 7 189.5 145.6 12.3 6.4 D 8.5 202.2 171.6 12.6 6.1 D 10 207.9 178.8 12.9 6.0 D 11.5 210.7 180.9 12.7 5.6 D 13 213.3 177.7 12.4 6.0 E 8 195.1 161.5 12.8 5.9 E 10 205.2 174.1 12.5 6.4 E 12 208.3 177.3 12.8 5.6 E 14 211.6 185.9 12.5 6.3 E 16 217.6 190.0 12.4 6.2 Table 8 Alloy 5 - 0 50 Mg + 0 34 Si Total Time Rm Rp02 AB Au (hours) A 3 180.6 138.8 13.9 7.1 A 4 194.2 155.9 13.2 6.6 Total Time Rm Rp02 AB Au (hours) • A 5 203.3 176.5 12.8 5.6 A 6 210.0 183.6 12.2 5.7 A 7 211.7 185.9 12.1 5.8 B 3.5 202.4 161.7 12.8 6.6 B 4 204.2 170.4 12.5 6.1 B 4.5 217.4 186.7 12.1 5.6 B 5 218.9 191.5 12.1 5.5 • B 6 222.4 198.2 12.3 6.0 C 4 188.6 136.4 15.1 10.0 C 5 206.2 171.2 13.4 7.1 C 6 219.2 191.2 12.9 6.2 C 7 221.4 194.4 12.1 6.1 C 8 224.4 202.8 11.8 6.0 D 7 213.2 161.5 14.0 7.5 D 8.5 221.5 186.1 12.6 6.7 D 10 229.9 200.8 12.1 5.7 • D 11.5 228.2 200.0 12.3 6.3 D 13 233.2 198.1 11.4 6.2 E 8 221.3 187.7 13.5 7.4 E 10 226.8 196.7 12.6 6.7 E 12 227.8 195.9 12.8 6.6 E 14 230.6 200.5 12.2 5.6 E 16 235.7 207.9 11.7 6.4 Table 9 Alloy 6 - 0 47 Mg + 0 41 Yes Total Time Rm Rp02 AB Au (hours) A 3 189.1 144.5 13.7 7.5 A 4 205.6 170.5 13.2 6.6 A 5 212.0 182.4 13.0 5.8 A 6 216.0 187.0 12.3 5.6 • A 7 216.4 188.8 11.9 5.5 B 3.5 208.2 172.3 12.8 6.7 B 4 213.0 175.5 12.1 6.3 B 4.5 219.6 190.5 12.0 6.0 B 5 225.5 199.4 11.9 5.6 B 6 225.8 202.2 11.9 5.8 C 4 195.3 148.7 14.1 8.1 C 5 214.1 178.6 13.8 6.8 • C 6 227.3 198.7 13.2 6.3 C 7 229.4 203.7 12.3 6.6 C 8 228.2 200.7 12.1 6.1 D 7 222.9 185.0 12.6 7.8 D 8.5 230.7 194.0 13.0 6.8 D 10 236.6 205.7 13.0 6.6 D 11.5 236.7 208.0 12.4 6.6 D 13 239.6 207.1 11.5 5.7 Time Total Rm Rp02 AB Au (hours) E 8 229.4 196.8 12.7 6.4 E 10 233.5 199.5 13.0 7.1 E 12 237.0 206.9 12.3 6.7 E 14 236.0 206.5 12.0 6.2 E 16 240.3 214.4 12.4 6.8 Table 10 • Alloy 7 - 0.41 Mg + 0.47 Yes Total Time Rm Rp02 AB Au (hours) A 3 195.9 155.9 13.5 6.6 A 4 208.9 170.0 13.3 6.4 A 5 216.2 188.6 12.5 6.2 A 6 220.4 195.1 12.5 5.5 • A 7 222.0 196.1 11.5 5.4 B 3.5 216.0 179.5 12.2 6.4 B 4 219.1 184.4 12.2 6.1 B 4.5 228.0 200.0 11.9 5.8 B 5 230.2 205.9 11.4 6.1 B 6 231.1 211.1 11.8 5.5 Total Time Rm Rp02 AB Au (hours) C 4 205.5 157.7 15.0 7.8 C 5 225.2 190.8 13.1 6.8 C 6 230.4 203.3 12.0 6.5 C 7 234.5 208.9 12.1 6.2 C 8 235.4 213.4 11.8 5.9 D 7 231.1 190.8 13.6 7.6 D 8.5 240.3 208.7 11.4 6.3 D 10 241.6 212.0 12.5 7.3 D 11.5 244.3 218.2 11.9 6.3 D 13 246.3 204.2 11.3 6.3 E 233.5 197.2 12.9 7.6 E 10 241.1 205.8 12.8 7.2 E 12 244.6 214.7 11.9 6.5 E 14 246.7 220.2 11.8 6.3 E 16 247.5 221.6 11.2 5.8 Table 11 To the eration 1 - 0 40 Mg + 0 34 Si Total Time Rm Rpo2 AB Au (hours) A 3 200.1 161.8 13.0 7.0 A 4 212.5 178.5 12.6 6.2 Total Time Rm Rp02 AB Au (hours) • A 5 221.9 195.6 12.6 5.7 A 6 • 222.5 195.7 12.0 6.0 A 7 224.6 196.0 12.4 5.9 B 3.5 222.2 186.9 12.6 6.6 B 4 224.5 188.8 12.1 6.1 B 4.5 230.9 203.4 12.2 6.6 B 5 231.1 211.7 11.9 6.6 • B 6 232.3 208.8 11.4 5.6 C 4 215.3 168.5 14.5 8.3 C 5 228.9 194.9 13.6 7.5 C 6 234.1 206.4 12.6 7.1 C 7 239.4 213.3 11.9 6.4 C 8 239.1 212.5 11.9 5.9 D 7 236.7 195.9 13.1 7.9 D 8.5 244.4 209.6 12.2 7.0 • D 10 247.1 220.4 11.8 6.8 D 11.5 246.8 217.8 12.1 7.2 D 13 249.4 223.7 11.4 6.6 E 8 243.0 207.7 12.8 7.6 E 10 244.8 215.3 12.4 7.4 E 12 247.6 219.6 12.0 6.9 E 14 249.3 222.5 12.5 7.1 E 16 250.1 220.8 11.5 7.0 With Based on these results, the following comments apply. The final tensile strength (UTS) of the alloy does not. 1 is rigidly less than 180 MPa after 5 ripening with cycle A and 6 hours of total cycle. With the double speed maturation cycles the UTS values are higher, but still not higher than 190 MPA after 5 hours of cycle B, and 195 MPa after 7 hours of cycle C, with cycle D, the values of UTS reach 210 10 MPa but not before a total maturing time of 13 hours. The final tensile strength (UTS) of the alloy does not. 2 is slightly higher than 195 MPa after cycle A and 6 hours of total time. The UTS 15 values are 195 MPA after 5 hours of cycle B, and 205 MPa after 7 hours of cycle C. With cycle D, the UTS values reach approximately 210 MPa after 9 hours and 215 MPa after 12 hours. The alloy does not. 3 which is more similar to line 20 of Mg 5 Si 6 on the magnesium-rich side, shows the highest mechanical properties of alloys 1-4. After cycle A the UTS is 190 MPa after 6 hours of total time. With a B cycle of 5 hours, the UTS is close to 205 MPa, and slightly above 210 MPa after a C cycle of 7 hours. With the maturation cycle D of 9 hours, the UTS is close to 220 MPa. The alloy does not. 4 shows lower mechanical properties than alloys 2 and 3. After an A 5 cycle with a total time of 6 hours, the UTS is not greater than 175 MPa. With the maturation cycle D of 10 hours, the UTS is close to 210 MPa. These results clearly demonstrate that the optimum composition to obtain the best mechanical properties with the lowest amount of magnesium and silicon, is close to the Mg5Si6 line on the magnesium rich side. Another important aspect with the Mg / Si ratio is that a low proportion seems to give short maturation times to give maximum resistance. 15 Alloys 5-8 have a constant sum of magnesium and silicon that is greater than alloys 1-4. Compared to the g5Si6 line, all the alloys 5-8 fl are located on the magnesium-rich side of Mg 5 Si 6. The alloy does not. 5 which is furthest from the 20 MgsSie line shows the lowest mechanical properties of the four different alloys 5-8. With cycle A alloy no. 5 has a UTS value of approximately 210 MPa after 6 hours of total time. The alloy does not. 8 has a UTS value of 220 MPa after the same cycle. 25 With cycle C of 7 hours of total time, the UTS values for alloys 5 and 8 are 220 and 240 MPa, respectively. With cycle D of 9 hours, the UTS values are approximately 225 and 245 MPa. Again, this shows that the 5 highest mechanical properties are obtained with alloys closest to the Mg5SÍ6 line. As for alloys 1-4, the benefits of double speed maturation cycles appear to be higher for alloys near the Mg5Si6 line. 10 Maturation times for maximum strength appear to be shorter for alloys 5-8 than for alloys 1-4. This is as expected because the maturation times are reduced with the increased alloy content. Also, for the alloys 5-8 15 the maturation times appear to be somewhat shorter for the alloy 8 than for the alloy 5. The total elongation values appear to be Mm. almost independent of the maturation cycle. At maximum strength, the total elongation values, AB, 20 are approximately 12%, even though the resistance values are higher for the double speed maturation cycles.

- ** Example 2 Example 2 shows the final tensile strength of the profiles from directly and superheated ingots of an alloy 6061. The directly heated ingots were heated to the temperature shown in the table, and extruded at extrusion speeds below the speed maximum before deterioration of the profile surface. The superheated ingots were preheated in a gas fired oven at a temperature above the temperature of solids solubility curves for the alloy and then cooled to a normal extrusion temperature shown in Table 12. After extrusion the profiles were cooled with water and matured with a standard ripening cycle until the maximum resistance.

Table 12. Final tensile strength (UTS) in different profile positions from directly heated and superheated ingots of an AA6061 alloy.

• • By using the overheating process the mechanical properties will be generally higher and also more consistent than without overheating. Also, with overheating the mechanical properties are practically independent of the ingot temperature before extrusion. This makes the extrusion process more robust with respect to the provision of consistent high mechanical properties, making it possible to operate at lower alloy compositions with lower safety losses, below the requirements for mechanical properties.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (20)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. An aluminum alloy treatment process containing from - 0.5 - 2.5% by weight of an alloy mixture of ^ T 10 magnesium and silicon the molar ratio of magnesium / silicon is between 0.70 and 1.25, an additional amount of silicon equal to approximately 1/3 of the amount of iron, manganese and chromium in the alloy, expressed as percentage by weight, 15 - other alloying elements and unavoidable impurities, and - the remainder is made of aluminum, ß whose alloy after cooling has has been subjected to homogenization, preheating before extrusion, extrusion and maturation, whose maturing takes place, after extrusion as a maturing operation in two steps, at a temperature between 160 ° C and 220 ° C, characterized by the maturation includes a first stage in which the extrusion is heated with a heating rate above 100 ° C / hour at a temperature between 100-170 ° C, a second stage in which extrusion is heated with a heating rate between 5 and 50 ° C / hour at the final retension temperature between, and because the total maturation cycle is carried out in a time between 3 and 24 hours.

2. A process according to claim 1, characterized in that the alloy contains between 0.60 and 1.10% by weight of the mixture of magnesium alloy and silicon and because it has a resistance to 10 traction in class F19-F22.

3. A process according to claim 1, characterized in that the alloy contains between 0.80 and 1.40% by weight of the mixture of magnesium alloy and silicon and because it has a resistance to 15 traction in class F25-F27. .

A process according to claim 1, characterized in that the alloy contains jfl? between 1.10 and 1.80% by weight of the magnesium-silicon alloy mixture and because it has tensile strength in class F29-F31.

5. A process according to claim 2, characterized in that the alloy contains between 0.60 and 0.80% by weight of the mixture of magnesium alloy and silicon and because it has a resistance to 25 traction in class F19 (185-220 MPa).

6. A process according to claim 2, characterized in that the alloy contains between 0.70 and 0.90% by weight of the mixture of magnesium alloy and silicon and because it has a resistance to 5 traction in class F22 (215-250 MPa).

7. A process according to claim 3, characterized in that the alloy contains between 0.85 and 1.15% by weight of the magnesium-silicon alloy mixture and because it has a tensile strength in class F25 (245-270 MPa). ).

8. A process according to claim 3, characterized in that the alloy contains between 0.95 and 1.25% by weight of the mixture of magnesium alloy and silicon and because it has a resistance to 15 traction in class F27 (265-290 MPa).

9. A process according to claim 4, characterized in that the alloy contains between 1.10 and 1.40% by weight of the magnesium-silicon alloy mixture and because it has tensile strength in class F29 (285-310 MPa). ).

10. A process according to claim 4, characterized in that the alloy contains between 1.20 and 1.55% by weight of the magnesium-silicon alloy mixture and because it has a tensile strength in class F31 (305-330 MPa). ).

11. A process according to any of the preceding claims, characterized in that the • Mg / Si molar ratio is at least 0.70.

12. A process according to any of the preceding claims, characterized in that the molar ratio of Mg / Si is at most 1.25.

13. A process according to any of the preceding claims, characterized in that the final maturation temperature is at least 165 ° C. IJ 10

14. A process according to any of the preceding claims, characterized in that the final maturation temperature is at most 205 ° C.

15. A process according to any of the preceding claims, characterized in that In the second heating stage, the heating rate is at least 7 ° C / hour.

16. A process according to any of the preceding claims, characterized in that in the second heating step the speed of 20 heating is at most 30 ° C / hour.

17. A process according to any of the preceding claims, characterized in that at the end of the first heating stage the temperature is between 130 ° and 160 ° C.

18. A process according to any of the preceding claims, characterized in that the total ripening time is at least 5 hours.

19. A process according to any of the preceding claims, characterized in that the total ripening time is at most 12 hours.

20. A process according to any of the preceding claims, characterized in that during the preheating before extrusion the alloy has been heated to a temperature between 510 and 550 ° C, after which the alloy has been cooled to extrusion temperatures normal.