SI9700232A - Aluminium alloy with good machinability - Google Patents

Abstract

The invention refers to aluminium alloys with good machinability, particularly materials for automates based on ALCu or AlMgSi. As an addition they contain 0.2 to 1.2 mass% of tin and 0.2 to 1.0 mass% of bismuth for breaking the chips. The alloy based on AlCU contains the following amounts of metals expressed in mass%: copper 4.6-6.0 %, bismuth 0.2 - 1.0%, tin 0.2 to 0.7%, zinc up to 0.45%, iron maximum 0.7%, silicon maximum 0.4%, as well as further alloyed elements, max. 0.05% each, total share 0.15%, the remaining share is aluminium. The alloy based on AlMgSi contains the following substances in mass %: magnesium 0.6 to 1.2, silicon 0.6 to 1.4%, bismuth 0.2 to 0.7%. manganese 0.2 to 0.6%, iron maximum 0.5%, copper maximum 0.5% (preferably 0.15 to 0.4), titanium max. 0.2% (preferably 0.04 to 0.1), as well as other alloyed elements, each maximum 0.05, totally max. 0.15%, the rest is aluminium. By combined use of tin and bismuth, the use of lead, which is harmful to health, can be avoided.

Description

Aluminum alloy with good machinability

The invention relates to an aluminum alloy with good machinability, in particular to a material for AlCu or AlMgSi based automata.

Kneading alloys suitable for machine material based on AlCu and AlMgSi contain lead additives, optionally in combination with bismuth, as an additive for fracturing slices. According to EN 573: 1994, such alloys are designated as follows: EN AW-AlCu6BiPb, optionally EN AW-AlCu6BiPb (A) and EN AW-AlMgl SiPb, EN AW-AlMglSiPbMn, in the case of EN AW-AlMgSiPb.

Due to the health-damaging effect of lead, the use of lead is limited to a minimum. In addition, the presence of small amounts of lead in the aluminum alloy has also been shown to lead to an increase in permeability due to the stress at sustained load at room temperature.

In view of these circumstances, the inventor has set himself the task of providing a lead-free aluminum alloy with good machinability as a machine material, which has comparable or better mechanical properties compared to conventional machine materials.

The object of the invention is that the alloy contains 0.2 to 1.2% by weight of tin and 0.2 to 1.0% by weight of bismuth as an additive for fracturing the chips.

AICu-based aluminum alloy contains, by weight, copper bismuth tin zinc iron silicon

4.6 to 6.0 0.2 to 1.0 0.2 to 0.7 max. 0.45 max. 0.7 max. 0.4 as well as further legime elements, max. 0.05 and total max. 0.15 and the rest is aluminum.

For the AIC-based alloy, the preferred area for bismuth is at 0.4 to 0.9, in particular 0.6 to 0.8% by weight, and the preferred area for tin is at 0.3 to 0.6, especially 0.4 to 0.6% by weight.

AlMgSi-based alloy contains, by weight, magnesium 0.6 to 1.2 silicon 0.6 to 1.4 tin 0.6 to 1.2 bismuth 0.2 to 0.7 manganese 0.2 to 0.6 iron max. 0,5 copper max. 0.5, preferably 0.15 to 0.40 titanium max. 0.2, preferably 0.04 to 0.10 as well as further legime elements, individually max. 0.05, total max. 0.15 and the rest is aluminum.

For the AlMgSi-based alloy, the preferred area for the tin is 0.7 to 1.0, preferably 0.7 to 0.9% by weight, and the preferred area for bismuth is 0.3 to 0.6, especially 0.4 to 0.6% by weight.

The alloys of the invention can be processed in a known manner by semi-continuous strand casting or extrusion. Semi-continuous stranded cast beams are normally exposed to annealing at high temperatures; this may also fall off. The extruded products are then converted to different end states by heat treatment or thermomechanical processing.

For AlCu-based alloys, the following heat treatment processes are suitable to achieve different states of aging:

solvent insult followed by artificial aging solvent insult, reduction of internal stresses by superplastic elongation followed by artificial aging solvent annealing, cold transformation followed by natural aging for at least three days

For AlMgSi-based alloys, the following heat treatment processes are suitable to achieve different states of aging:

solvent insult followed by artificial aging solvent insult, reduction of internal stresses by superplastic elongation followed by artificial aging solvent insult, cold transformation followed by artificial aging solvent insult, artificial aging followed by cold transformation

The invention will now be further explained by way of example examples.

AlCu based alloy

Three alloys with the composition according to Table 1 made of aluminum 99.5, pre-alloy AlCu 45, tin 99.95 and bismuth 99.9 were melted in the crucible resistance furnace. From each melting batch, a 135 mm diameter bead was cast by semi-continuous strand casting using a water-cooled aluminum alloy mold using a lubricant. After turning to a diameter of 110 mm, a portion of the bead is fired at high temperature, leaving the remainder of the session in an annealed state without annealing. After heating to the temperature of the extrusion strand in a flow induction furnace, the annular strand extruded into 36 mm diameter rods as well as hexagonal profiles.

The strands extruded in this way were processed to the desired end states with various heat treatments. The final states and mechanical properties of the AlCu-based alloy according to the invention according to the various heat treatment processes are summarized in Table 2.

AlMgSi based alloy

Three alloys with the composition according to Table 3 of aluminum 99.5, magnesium in the crucible resisting furnace

99,9, tin 99,95, bismuth 99,9, as well as from alloys AlCu 45, AlMn 10, AlTi 6 and AlSi 30. From «

each melting batch is seeded with a strand cast using a water-cooled aluminum alloy mold using a 135 mm diameter bead using a lubricant. After turning to a diameter of 110 mm, a portion of the ball was annealed at high temperature and the remaining part was left in the cast state without regret. After heating to the temperature of the extrusion of the strands in the flow induction furnace, the circular strands are squeezed into 36 mm diameter rods as well as hexagonal profiles.

The strands extruded in this way were processed to the desired end states with various heat treatments. The final states and mechanical properties of the AlMgSi-based alloy according to the invention based on various heat treatment processes are summarized in Table 4.

Table 1

Si Fe Cu Sn Would Zn Second The rest individually together max. max. 0.11 1 0.21 5.06 0.49 0.60 0.42 0.05 0.15 Al 0.16 0.27 5.67 0.52 0.72 0.41 0.05 • 0.15 Al 0.10 0.16 5,24 0.50 0.63 | 0.02 0.05 0.15 Al

Table 2

and Status by EN 515 R p 0,2 (MPa) R m (MPa) A5 (%) HB T6, T651 min. 280 min. 370 min. 10 110 ί T3 min. 150 min. 270 min. 20 80

Table 3

Si Fe Cu Mn - Mg - _r I You i Sn Would Second --—, The rest alone. expensive. max. max. 1.16 0.39 0.45 0.32 0.93 0.042; ί. ____, ... J. 0.81 0.45 0.05 0.15 Al

Table 4

Condition R P 0,2 (MPa) R m (MPa) A5 (%) HB T6, T651 min. 240 min.320 min. 10 110 T8 min. 315 min. 350 min. 8 115 T9 min. 330 min. 360 min. 5 120

In Tables 2 and 4, the abbreviations used are:

EN 515 European standard EN 515: 1993 code for the state of materials for semi-finished products aluminum and aluminum alloys ^R p0,2 flow limit R m tensile strength A5 elongation at rupture HB hardness according to Brinell

ALUSUISSE TECHNOLOGY & MANAGEMENT AG

For:

irii »! h / »d.o.o.

ljubljana / tcmcm a ¹⁴

Claims (12)

Patent claims Claims 1. Aluminum alloy with good machinability, in particular on the material for AlCu or AlMgSi based automata, characterized in that the alloy contains 0.2 to 1.2% by weight of tin and 0.2 to 1.0, as an additive for fracturing wt.% bismuth. Aluminum alloy according to claim 1, characterized in that the alloy contains, by weight, copper 4.6 to 6.0 bismuth 0.2 to 1.0 tin 0.2 to 0.7 zinc max. 0.45 iron max. 0.7 silicon max. 0.4 as well as further legime elements, max. 0.05 and total max. 0.15 and the rest is aluminum. Aluminum alloy according to claim 2, characterized in that the alloy contains 0.4 to 0.9% by weight, preferably 0.6 to 0.8% by weight of bismuth. Aluminum alloy according to claim 2, characterized in that the alloy contains 0.3 to 0.6% by weight, preferably 0.4 to 0.6% by weight of tin. Aluminum alloy according to claim 1, characterized in that the alloy contains in wt.% magnesium 0.6 to 1.2 silicon 0.6 to 1.4 tin 0.6 to 1.2 bismuth 0.2 to 0.7 manganese 0.2 to 0.6 iron max. 0.5 copper max. 0.5, preferably 0.15 to 0.40 titanium max. 0.2, preferably 0.04 to 0.10 as well as further legime elements, individually max. 0.05, total max. 0.15 and the rest is aluminum. Aluminum alloy according to claim 5, characterized in that the alloy contains 0.7 to 1.0 wt.%, Preferably 0.7 to 0.9 wt.% Tin. Aluminum alloy according to claim 5, characterized in that the alloy contains 0.3 to 0.6% by weight, preferably 0.4 to 0.6% by weight of bismuth. Aluminum alloy according to one of Claims 2 to 4, characterized in that the alloy, after semi-continuous casting, high temperature milling and extrusion milling, with subsequent solvent milling, quenching and artificial aging, has a maximum tensile strength of at least 370 MPa , a yield stress of at least 280 Mpa, a Brinell hardness of at least 110, and an A5 elongation at break of at least 10%. Aluminum alloy according to one of Claims 2 to 4, characterized in that the alloy after semi-continuous casting, high temperature milling and extrusion milling with subsequent solvent milling, quenching and artificial aging, has a tensile strength of at least 270 Mpa, yield strength at least 150 Mpa, Brinell hardness at least 80, as well as A5 elongation at break of at least 20%. Aluminum alloy according to one of Claims 5 to 7, characterized in that the alloy has tensile strength after at least three days at room temperature after semi-continuous strand casting, high temperature milling and strand extrusion, followed by solvent melting, quenching and natural aging. at least 320 Mpa, yield strength at least 240 Mpa, Brinell hardness at least 110, as well as A5 elongation at break of at least 10%. Aluminum alloy according to one of Claims 5 to 7, characterized in that the alloy after semi-continuous casting, high temperature milling and strand extrusion with subsequent solvent milling, quenching, optionally by superplastic elongation and artificial aging to the maximum degree The hardening shall have a tensile strength of at least 370 Mpa, a yield stress of at least 315 Mpa, a Brinell hardness of at least 115 and an A5 elongation at break of at least 8%. Aluminum alloy according to one of Claims 5 to 7, characterized in that the alloy, after semi-continuous casting, high temperature milling and strand extrusion, with subsequent solvent milling, quenching, cold forming and artificial aging, has the highest tensile strength at least 370 Mpa, at a flow limit of at least 330 Mpa, a Brinell hardness of at least 120, as well as an A5 at break of at least 5%.