EP1098009B1 - Aluminium alloy of AlMgSi type with Sn and Mn - Google Patents

Abstract

Aluminum wrought alloy of the AlMgSi type contains alloying additions of (in wt.%): 0.6-2.0 magnesium, 0.6-3.0 silicon, 0.6-1.5 tin, 0.4-1.0 manganese, maximum 0.25 chromium and titanium, and impurities containing maximum 0.4 iron, maximum 0.1 copper and maximum 0.2 zinc. An Independent claim is included for a process for the production of a continuously cast object made of the aluminum wrought alloy of the AlMgSi type comprising solution annealing during extrusion, quenching the extruded object and hardening.

Description

The invention relates to a wrought aluminum alloy of the AlMgSi type for high-performance machining.

Aluminum alloys of this type are used as high performance machining materials used because these place particularly high demands on machinability is sufficient. They are therefore also known as machine alloys. To the desired chip break in a cutting Machining of a workpiece consisting of such an alloy, such as turning, milling or drilling, is an alloy component Lead (Pb) alloyed in contents of 2% or more. A disadvantage of alloying lead to achieve this desired However, the property is the health hazard posed by this element, especially for those who have such a workpiece to edit. In addition, the lead content has a negative effect on the Creep behavior of the aluminum alloy, so that the workpieces or the products made from it at higher temperatures only to a limited extent can be used.

Such machine alloys are from CH 239 996 and from FR 977 514 known. The alloys described in these documents In addition to lead, elements that promote chip breakage can also be beneficial contain: tin (Sn), bismuth (Bi), cadmium (Cd) or thallium (TI), which alone or in a mixture also with lead together with proportions between 0.3 and 4 wt .-% can be involved in the structure of the alloy. However, such alloys have actually been used very significant proportions of these elements, as is also shown from the Embodiment of CH 239 996 can be seen in which more than 2 wt .-% of a chip-promoting additive used is namely lead alone with a proportion of 2.56% by weight. In addition to lead use of bismuth, cadmium or thallium is also undesirable because the environmental compatibility of these elements is sometimes not without problems is or are costly.

Regarding the alloy components that improve the mechanical Properties of the alloy used are the metals Copper (Cu), nickel (Ni) or zinc (Zn) provided in proportions of contain a maximum of 6 or 4 or 10% by weight in the known alloys could be. The generous dimensioning of the above-mentioned status the specified interval in which these alloy components can be included, makes it clear that actually not insignificant Shares in these elements are required or available Must be the properties you want in these documents to achieve alloys described. The same show the embodiments described in these documents. It should be noted that lead is fundamentally a very suitable one Element for achieving the desired machinability.

To those resulting from the use of lead, bismuth, cadmium or thallium To avoid disadvantages, AlMgSi alloys have been proposed been used instead of the lead element to achieve the desired Machinability properties include tin. Such alloys are, for example, in US 5 810 952 A or in US 5 776 269 A. Additional component of these alloys in addition to tin is bismuth, which is used as an element to improve machinability to optimize. So such a lead-free AlMgSi alloy has sufficient strength, copper contents are between 0.3 and 0.4 wt .-% alloyed. Also at the Aluminum Association the designation AA 6020 registered, hardenable alloy Copper essential component intended to increase strength. The copper content can be between 0.3 and 0.9% by weight. This alloy has a tin content between 0.9 and 1.5% by weight.

Even if reading CH 239 996 or the FR 977 514 basically shows that tin alone can be contained as a component which promotes chip breaking, so such an alloy is actually never made without additional additives Service. Have been made, as is already the case results in the exemplary embodiments mentioned in these documents, only such wrought aluminum alloys that regularly add other contain.

The strength values achieved with the lead-free Al alloys described above correspond approximately to those of the lead-containing variants. in the Contrary to the previously known lead-containing Al high-performance machining materials but must be lead-free with the described Variants disadvantages are accepted. One disadvantage is, for example when processing such an Al alloy during extrusion with solution annealing in the press heat that the to carry out the Pressing necessary temperature must be relatively high. Since that Extrusion only in between the necessary minimum pressing temperature and the melting temperature lying temperature window take place can, this has the consequence that at the high necessary pressing temperature the processing window with a temperature range between 20 is very small up to 40 ° C. Firstly, compliance with the process parameters difficult in such a narrow temperature window, on the other the pressing process can only be carried out slowly due to of the additional frictional heat, the temperature window not to leave and also the press tool used to overheat, resulting in deformation or even destruction of the pressing tool can lead. Solution annealing can be done in an economical reasonable way with the known machine alloys not made in the press heat for these reasons become. The extruded products are therefore in another Process step subjected to solution annealing, which is necessary to achieve the desired material properties. Due to the construction in such a furnace intended for solution annealing only such Profiles or profile sections are introduced that have a certain maximum length do not exceed. These sections are considerably shorter than the profiles produced in the extrusion process. The solution glow has however, mostly a change in shape of the objects, for example a discard. The objects must therefore be after solution annealing be directed in a further step, the Raising ends, which are about 50 cm long, can no longer be used can.

JP-A-07 197 163 discloses an Al alloy, the Composition: 0.2-0.75 wt% Mg; 0.2-1.5 wt% Si; 0.05-1.0 wt% Cu; 0.01-1.0 wt% Sn; 0.005-0.20% by weight Ti; at least one of: 0.1-1.0 wt% Fe; 0.1-1.0 wt% Mn; 0.05-0.3 wt% Cr; Balance Al, contains.

The invention is based on the state of the art discussed therefore based on the task of a lead-free wrought aluminum alloy Type AlMgSi with a strength and machinability accordingly to provide the known machine alloys, their manufacturability is improved, and especially in an extrusion has a larger temperature-related processing window.

• 0,6 bis 2,0 Gew.-% Magnesium (Mg),
• 0,6 bis 3,0 Gew.-% Silizium (Si),
• 0,6 bis 1,5 Gew.-% Zinn (Sn),
• 0,4 bis 1,0 Gew.-% Mangan (Mn),

und mit Chrom (Cr) und Titan (Ti) als fakultativen Legierungsbestandteilen mit Anteilen von maximal 0,25 Gew.-% bzw. 0,1 Gew.-% sowie mit einem Rest Aluminium (Al) nebst unvermeidbaren Verunreinigungen, in denen Eisen (Fe) mit maximal 0,4 Gew.-%, Kupfer (Cu) mit maximal 0,1 Gew.-% und Zink (Zn) mit maximal 0,2 Gew.-% enthalten sein können.According to the invention, this object is achieved by an aluminum wrought alloy of the type AlMgSi with the following proportions of its main alloy components:

• 0.6 to 2.0% by weight of magnesium (Mg),
• 0.6 to 3.0% by weight silicon (Si),
• 0.6 to 1.5% by weight of tin (Sn),
• 0.4 to 1.0% by weight of manganese (Mn),

and with chromium (Cr) and titanium (Ti) as optional alloy components with a maximum of 0.25% by weight or 0.1% by weight as well as with a remainder of aluminum (Al) together with unavoidable impurities in which iron ( Fe) with a maximum of 0.4% by weight, copper (Cu) with a maximum of 0.1% by weight and zinc (Zn) with a maximum of 0.2% by weight.

The invention provides a wrought aluminum alloy which not just an unusually small amount - namely only 0.6 to 1.5 % By weight - of an element which favors machining and yet the same and in some cases even improved cutting properties has, but only a single element as one Machining-favoring element - contrary to the previously known proposals, where in addition to this element other elements regularly have been added - contains. The use of tin is the only one Chip breaking is a key element in terms of its environmental compatibility harmless. Because in the known machine alloys several elements that favor machining in larger ones Shares were not included in the light of this prior art to be expected that the alloy according to the invention with the defined Narrow share intervals of the elements used such positive cutting properties would have. So comes the claimed Wrought aluminum alloy without the addition of lead, bismuth or other Heavy metals from the known machine alloys had been installed. Those who accomplished this invention Inventors involved have found that exactly in the claimed Intervals of the elements used phases are formed the machinability of one made from such an alloy Favor the object to a high degree. The inventors had to do this First of all, let go of the prevailing teaching.

To achieve the desired strength of the aluminum alloy in addition to the components magnesium, silicon and manganese Tin used. Bismuth and / or indium is used in the invention Wrought aluminum alloy to achieve the desired Strengths are no more necessary than the use of copper. As an optional Alloy ingredient can further reduce the alloy Proportions also contain chrome. Also the use of this additional alloy component within the scope of its claimed shares positive for the strength and machinability of the wrought aluminum alloy out. In contrast, higher levels adversely affect the alloy properties. Titanium contents of up to 0.1% by weight can be used for grain refinement the alloy may be included. Titanium contents between are preferred 0.02 and 0.08 wt .-% used.

The wrought aluminum alloy according to the invention has compared to the Known wrought aluminum alloys, a lot in extrusion larger temperature related working window, so that with this Wrought aluminum alloy solution heat treatment in the heat of pressing can. This property can also be the prior art can not be removed at any point. In particular, in the light of State of the art not to expect the alloy at a low Press temperature could be processed. Therefore there is also a downstream one Solution annealing with the resulting disadvantages avoided. Since solution annealing with the alloy according to the invention can be done in the heat of extrusion, can by extrusion manufactured objects in their full length subjected to the stretching process are and do not need - as with the known state of the art Technology - be cut into pieces that fit into a solution annealing furnace. Consequently, the number of useless stretchers is at one such manufacturing processes as with the alloy according to the invention possible, significantly reduced.

In the case of the wrought aluminum alloy according to the invention, this is to be carried out the extrusion process necessary pressing temperature considerably among those for the previously known copper-containing wrought aluminum alloys are necessary. The necessary pressing temperature is around 30 - 50 ° C reduced compared to copper-containing AlMgSi alloys. consequently the temperature-related work window is larger, so that not only a solution heat treatment in the heat of pressing in a larger temperature range can be done, but also makes a faster extrusion as well as an extended quenching delay. Make these advantages is also involved in a forging or rolling process Workpiece made of such a wrought aluminum alloy, noticeable. Furthermore, the claimed wrought aluminum alloy compares better with that of the prior art Corrosion resistance.

The targeted selection of the approved elements in the claimed An aluminum wrought alloy of the type AlMgSi has produced parts by weight, which not only have excellent properties in terms of their Machinability and its strength, but also special inexpensive, especially in extrusion processing can. Above all, the exclusion of copper as an alloy component, the is deliberately not integrated into the alloy and only as an impurity tolerated, allows an extrusion product with solution heat treatment in which press heat and press quenching are manufactured can. A machine alloy is thus provided, which is not only particularly economical in their production but also in their processing is.

The elements iron are only inevitable impurities, Copper and zinc without impairing the determined alloy properties tolerated up to certain proportions in the alloy. higher On the other hand, contents impair the desired alloy properties. However, these elements do not need to be part of the alloy to be.

Other unavoidable impurities in the wrought aluminum alloy should have a maximum content of 0.05% by weight not exceed, otherwise the desired alloy properties may be affected.

Due to the particular use of the claimed Wrought aluminum alloy in extrusion is one of the advantages a preferred use of this alloy is to manufacture extruded Products.

• 1,0 bis 1,2 Gew.-% Magnesium,
• 0,8 bis 1,0 Gew.-% Silizium,
• 0,9 bis 1,1 Gew.-% Zinn und
• 0,6 bis 0,8 Gew.-% Mangan.

Der Chromgehalt dieser Aluminiumknetlegierung sollte 0,1 Gew.-% nicht überschreiten.In a preferred embodiment of the wrought aluminum alloy, in the group of its main alloy components, it comprises:

• 1.0 to 1.2% by weight of magnesium,
• 0.8 to 1.0% by weight of silicon,
• 0.9 to 1.1% by weight of tin and
• 0.6 to 0.8 wt% manganese.

The chromium content of this wrought aluminum alloy should not exceed 0.1% by weight.

• 1,1 Gew.-% Magnesium,
• 0,95 Gew.-% Silizium,
• 1,1 Gew.-% Zinn,
• 0,65 Gew.-% Mangan,
• 0,19 Gew.-% Eisen
• Rest Aluminium,
• alle weiteren Elemente in ihrer Summe kleiner 0,05 Gew.-%

untersucht worden. Ein aus dieser Aluminiumknetlegierung stranggegossenes Blockformat (Probe 1) mit einem Durchmesser von 360 mm wurde in einem ersten Schritt nach dem Guß homogenisiert und anschließend bei einer Blocktemperatur von 510 - 520°C zu unterschiedlich dickwandigen Profilen mit Wandstärken von 30 - 60 mm im Zuge eines Strangpreßvorganges verpreßt. Das Lösungsglühen dieser Legierung erfolgte beim Verpreßvorgang. Nach dem Auspressen kühlten die Profile an Luft auf Temperaturen bis zu 470°C ab und wurden erst anschließend in Wasser abgeschreckt. Ohne ein zwischengeschaltetes Lösungsglühen durchführen zu müssen, wie beim vorbekannten Stand der Technik, wurden die so behandelten Profile bei 170°C auf höchste Härte warm ausgelagert und anschließend im Zugversuch auf ihre typische Festigkeit und Duktilität hin untersucht. Die Profile zeichneten sich in Längsrichtung durch eine 0,2%-Streckgrenze R_p0,2 von 345 Mpa und eine Zugfestigkeit R_m von 367 Mpa bei einer Bruchdehnung A₅ von 10 % aus.
Eine zweite Probe mit demselben Blockformat derselben Legierung wurde bei einer Blocktemperatur von 530 - 540°C nach dem Guß homogenisiert und mit unmittelbarer Wasserabschreckung bei einer Mindesttemperatur von 530 - 540°C verpreßt, wobei auch bei dieser Probe der Schritt des Lösungsglühens durch die beim Verpressen notwendige Wärme automatisch mit durchgeführt worden ist. Anschließend wurde dieses Profil ebenfalls bei 170°C auf seine höchste Härte warm ausgelagert. Bei dieser Probe wurde eine 0,2%-Streckgrenze R_p0,2 von 348 Mpa, eine Zugfestigkeit R_m von 371 Mpa und eine Bruchdehnung A₅ von 10 % ermittelt. Die nachfolgende Tabelle zeigt die Untersuchungsergebnisse zusammengefaßt und im Vergleich zu denjenigen einer vorbekannten Aluminiumknetlegierung: Fertigungsparameter Zugversuchskennwerte Strangpresstemperatur [°C] Strangpressgeschwindigkeit [m/min] separates Lösungsglühen R_p0,2 [MPa] R_m [MPa] A₅ [%] AlMgSi1Cu0,5 (AA6110A) 510 6 nein 275 305 12 540 3 nein 314 338 12 500 6 ja 352 372 12 Probe 1 510 6 nein 345 367 10 Probe 2 540 3 nein 348 371 10 In two samples, the temperature-related machining window and the tensile strength of an extruded wrought aluminum alloy consist of

• 1.1% by weight of magnesium,
• 0.95% by weight silicon,
• 1.1% by weight of tin,
• 0.65% by weight of manganese,
• 0.19 wt% iron
• Rest aluminum,
• all other elements in total less than 0.05% by weight

been examined. A block format (sample 1) with a diameter of 360 mm, which was continuously cast from this wrought aluminum alloy, was homogenized in a first step after casting and then at a block temperature of 510 - 520 ° C to profiles of different thicknesses with wall thicknesses of 30 - 60 mm in the course of a Extrusion process pressed. The solution annealing of this alloy was carried out during the pressing process. After pressing, the profiles cooled in air to temperatures of up to 470 ° C and were only then quenched in water. Without having to carry out an intermediate solution heat treatment, as in the prior art, the profiles treated in this way were aged at 170 ° C to the highest hardness and then tested for their typical strength and ductility in a tensile test. The profiles were characterized in the longitudinal direction by a 0.2% yield strength R _p0.2 of 345 Mpa and a tensile strength R _m of 367 Mpa with an elongation at break A ₅ of 10%.
A second sample with the same block format of the same alloy was homogenized at a block temperature of 530-540 ° C after casting and pressed with immediate water quenching at a minimum temperature of 530-540 ° C, the solution annealing step being also carried out in this sample by pressing necessary heat has been carried out automatically. Then this profile was also aged at 170 ° C to its highest hardness. A 0.2% yield strength R _p0.2 of 348 Mpa, a tensile strength R _m of 371 Mpa and an elongation at break A ₅ of 10% were determined for this sample. The following table shows the test results in summary and in comparison to those of a previously known wrought aluminum alloy: production parameters Zugversuchskennwerte Extrusion temperature [° C] Extrusion speed [m / min] separate solution annealing R _p0.2 [MPa] R _m [MPa] A ₅ [%] AlMgSi1Cu0.5 (AA6110A) 510 6 No 275 305 12 540 3 No 314 338 12 500 6 Yes 352 372 12 Sample 1 510 6 No 345 367 10 Sample 2 540 3 No 348 371 10

The strength and ductility values of the two from the samples (sample 1, Sample 2) profiles are produced despite the different treatment almost identical. It also becomes clear from this comparison that with copper-containing wrought aluminum alloys the best possible strength values cannot be achieved if these alloys are not one are subjected to separate solution annealing. The results also show of the prior art that solution annealing in the press heat to different strength values depending leads from the extrusion temperature. As a result, temperature fluctuations result within the extrusion temperature during extrusion also in different strength values of the extruded profiles, however, which is undesirable. These alloy-related disadvantages can only by the step of separate solution annealing with the resulting ones resulting disadvantages (see above) can be avoided. The investigations thus show that the processing window for processing of a wrought aluminum alloy according to the invention - for example one Extrusion processing shown - with the same strength and ductility values is much larger and the results are improved.

To illustrate the different cutting behavior of different AlMgSi alloys, reference is made to the table below, in which the cutting behavior of an object, produced from the alloy according to the invention, namely samples 1 and 2, is compared with the cutting behavior of previously known alloys in the last line. Some of the data listed in the table are taken from the corresponding material sheets, in which the same evaluation levels as shown for the other alloys were used: Machining behavior in mill Drill Reduce threading saw Rotate AlMgSi0,5 C D B C A C AlMgSi1 B ¹⁾ C ²⁾ B ³⁾ B ⁴⁾ A B ⁵⁾ AlMgSiCuSnBi (Stanal 32) A A ^X) A ^X) A ^X) A ^X) A ^X) AlMgSiCuSn (AA6020) A A ^Y) A ^Y) A ^Y) A ^Y) A ^Y) AlMgSiCuSnBi (KA62) B B ^Z) B ^Z) B ^Z) B ^Z) B ^Z) AlMgSi1 Pb 1.4 A A A A A A AlMgSi1 Sn 0.8 samples 1.2 A A A A A A

It should be noted that the alloys "Stanal 32", "AA6020" and "KA62" according to the so-called T6 process and the one contained therein separate solution annealing step. The remaining Alloys are solution annealed using the T5 process produced in the heat of pressing. The above comparison becomes clearly that the cutting behavior of objects manufactured is distinguished from an alloy according to the invention and that corresponds to that previously achieved only with lead-containing AlMgSi alloys could be. It should be noted in particular that the copper-containing AlMgSi alloys a separate step of solution annealing have been subjected to before the step of thermosetting to achieve at least partially the same cutting behavior as a Article made from an alloy according to the invention.

Claims (11)

1. Wrought aluminium alloy of the AlMgSi type, characterised by the following proportions of its main alloy constituent ingredients:

   0.6 to 2.0 % by wt. magnesium (Mg),

   0.6 to 3.0 % by wt. silicon (Si),

   0.6 to 1.5 % by wt. tin (Sn),

   0.4 to 1.0 % by wt. manganese (Mn),

   and having chromium (Cr) and titanium (Ti) as optional alloy constituent ingredients with maximum proportions of 0.25 % by wt. and 0.1 % by wt. respectively, as well as having a residue aluminium (Al) together with unavoidable impurities, which may contain iron (Fe) with a maximum 0.4 % by wt., copper (Cu) with a maximum 0.1 % by wt. and zinc (Zn) with a maximum 0.2 % by wt.
2. Wrought aluminium alloy according to claim 1, characterised in that the unavoidable impurities, in an element related manner, do not exceed a particular maximum proportion of 0.05 % by wt.
3. Wrought aluminium alloy according to claim 1 or 2, characterised in that the proportion of magnesium is 1.0 to 1.2 % by wt.
4. Wrought aluminium alloy according to claim 1 or 2, characterised in that the proportion of silicon is 0.8 to 1.0 % by wt.
5. Wrought aluminium alloy according to claim 1 or 2, characterised in that the proportion of tin is 0.9 to 1.1 % by wt.
6. Wrought aluminium alloy according to claim 1 or 2, characterised in that the proportion of manganese is 0.6 to 0.8 % by wt.
7. Wrought aluminium alloy according to claim 1 or 2, characterised in that the maximum proportion of chromium is 0.1 % by wt.
8. Use of a wrought aluminium alloy of the AlMgSi type according to one of claims 1 to 7 to produce extruded products.
9. Use according to claim 8, characterised in that, during the extrusion process, the extruded product is quenched directly in the region where it emerges from the tool.
10. Method of producing an extruded article from a wrought aluminium alloy of the AlMgSi type according to one of claims 1 to 7, characterised in that, during the extrusion process, a solution annealing is effected in the extrusion heat, and in that, once the extruded article has emerged from the pressing tool, the extruded article is quenched, and in that the extruded article is subsequently subjected to the process of age-hardening.
11. Method according to claim 10, characterised in that, once the article has emerged from the pressing tool, it is initially cooled in air down to a temperature of substantially 460 - 485° C before the quenching step is undertaken.