JP2730415B2 - High-strength aluminum alloy for drilling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the creation of a high-strength aluminum alloy for drilling, which has favorable cutting properties, improves the properties of cutting chips, improves dischargeability from drilling, and has a processed structure. Another object of the present invention is to provide a high-strength aluminum alloy in which the growth of recrystallized grains during extrusion and heat treatment of a processed structure is controlled to stabilize the material quality.

[0002]

2. Description of the Related Art Free-cutting aluminum alloys with good machinability have been replaced by Al-Cu alloys.
A 2011 alloy containing Pb and Bi and a 6262 alloy containing Pb and Bi in an Al-Mg-Si-based alloy are known, and the latter is widely adopted as the former having improved corrosion resistance and alumite properties in the former. .

Further, in addition to the above-mentioned characteristics, JP-A-55-138054 and JP-B-54-8528, which improve the peel resistance of an anodic oxide film formed under high temperature conditions,
Japanese Patent Application Laid-Open No. 4-120236 has been proposed which also improves plastic workability.

[0004]

The above-mentioned conventional free-cutting alloy is intended to enhance the cutting ability of cutting chips, and it is important that the cutting chips be powdered. However, in the case of cutting a hole, even if there is a certain merit, it is difficult to remove the generated cutting chips in the machining hole, and it is difficult to remove the cutting chips. There is a disadvantage that cutting cannot be performed, and in any case, the tool is significantly worn due to cutting powder accumulated in the holes.

[0005] For example, in the drilling of components that require a large number of drills of various sizes, such as ABS components used in a brake control system, it is necessary to eliminate cutting chips as much as possible in the holes. It is necessary, and it is natural that it is not preferable that the chips become long for this purpose,
It is preferred that the chips have a moderate length. That is, it is difficult for the conventional ones described above to immediately respond to such a purpose,
Other characteristics cannot be sufficient.

[0006]

SUMMARY OF THE INVENTION The present invention has been studied to solve the problems in the prior art described above, and has been studied by utilizing an appropriate amount of Pb, formation of an appropriate amount of Mg ₂ Si, and an appropriate amount of V. The present invention has succeeded in effectively obtaining high strength, discharge of cutting chips, and avoidance of tool wear, and is as follows.

(1) Mg ₂ Si exceeds 1.2 % at wt%
And Mg: 0.8-1.5% and Si: 0.7-1.5% so that the excess Si is 0.17 % or more up to 2.5%. A high-strength aluminum alloy for drilling, characterized by containing Al and the balance consisting of Al and inevitable impurities.

(2) The high-strength aluminum alloy for drilling according to the above item (1), further comprising V: 0.05 to 0.2%.

[0009] _Mg 2 Si is up to 2.5% more than the 1.2%
Forming an intermetallic compound (eg, Mg ₂ Si)
0.17 excess Si, which is much more than the amount of Si
%: Mg: 0.8-1.5%, Si:
It increased _{T 6} strength of the aluminum alloy to improve the stability by containing 0.7 to 1.5%, yet M
It avoids a decrease in extrudability due to an increase in the amount of g and limits casting segregation.

Further, as described above, Mg: 0.8-1.5%, Si: 0.5%.
By setting the content to 7 to 1.5%, the T ₆ strength σ _B ≧ 38 kg
/ Mm ² , σ _0.2 ≧ 35 kg / mm ² , and hardness H _V ≧ 120 °, and at the same time appropriately increases tool wear and strength during cutting.

When Cu is contained in an amount of 0.15% or more, the precipitation of Mg ₂ Si due to artificial aging is promoted, which contributes to the improvement of the T ₆ strength, and the upper limit is 0.4%. Reducing the corrosion resistance of the seed 6000 series aluminum alloy, and appropriately obtaining the practical effect by age hardening.

By containing Mn: 0.30% or more and Cr: 0.10% or more, it is possible to effectively improve the strength and toughness by making the hot working structure finer or fibrous and contribute to the improvement of corrosion resistance. I do. On the other hand, the upper limit of this Mn is 0.60%,
By setting the upper limit of Cr to 0.3%, the generation of coarse crystals is suppressed, and the above-mentioned action is appropriately obtained.

Pb is the main additive element according to the present invention,
In the above-mentioned prior art, Sn and Bi are usually added in combination, but in the present invention, they are added alone to obtain chip breaking properties suitable for drilling with a drill. That is, when Pb is 0.3% or more, such an effect can be appropriately obtained, and by setting the upper limit to 0.6%, occurrence of casting cracks and casting segregation can be suppressed, thereby facilitating production. Get good quality.

Further, in the present invention, V is contained in an amount of 0.05% or more to prevent a change in the processed structure due to heat, to control the growth of recrystallization by extrusion and heat treatment, and to control the formation of a coarse-grained layer.
The variation due to the position in the extruded material of the machinability due to them is reduced, and the quality stability is increased.

[0015]

The present invention will be described in more detail with reference to the following examples.
And Comparative Alloys 7 and 8 were prepared, and each of these alloys was cast into a billet having a diameter of 325 mm and a length of 3000 mm.
After a homogenization treatment at 6 ° C. for 6 hours, the mixture was cooled at a cooling rate of 200 ° C./hr or more.

[0016]

[Table 1]

The billet obtained as described above is cut into a length of 1000 mm, heated to 500 ° C., and
Extruded at min speed. The extruded material was a bar having a cross section of 100 × 80 mm, which was used as a sample for tensile test, hardness measurement, and drilling.

In the T ₆ treatment, a solution was formed at 530 ° C. ± 5 ° C. for 2 hours, which is a normal condition of the 6061 alloy, and quenched in water. Within one hour thereafter, an artificial aging treatment was performed at 175 ° C. for 8 hours, and the above-described tests were performed. That is, the obtained mechanical properties, the results of the cutting test, and the mode of the cutting chips generated by the cutting are as shown in Table 2 below.
The evaluation of the mode of the cutting waste in Table 2 is as shown in Table 3 below.
FIG. 1 further shows a twice enlarged form of o.4, No. 6, and each comparative alloy.

[0019]

[Table 2]

[0020]

[Table 3]

That is, according to the results of Table 2 described above,
According to the present invention, the tip length generated by drill cutting has an appropriate length of about 1.0 to 3.0 mm,
In addition, both long chips of not less than 3.0 mm and fine powder chips of not more than 1.0 mm can be obtained in a substantially zero state, and the concrete form is shown in FIGS.
As shown in (c), it was excellent in discharging or handling from a hole, and was less likely to wear a drill or the like.

On the other hand, in the case of the comparative alloy 7, the tip length is long and the tip length is non-uniform and the shape is as shown in FIG. 1 (d). Are inferior in machinability. As shown in FIG. 1 (e), the powder of the comparative alloy 8 has a small chip length and is powdery. Is very inferior, and the shapes and properties of the cutting chips of the above-mentioned comparative examples (d) and (e) of FIG. 1 (a) to (c) according to the present invention are remarkably different. It was confirmed that.

[0023]

According to the present invention as described above, the length of the cutting chips (drill tip) at the time of drilling is appropriately controlled to facilitate the discharge and handling thereof, and to reduce the wear of the cutting tool. To provide a high-strength aluminum alloy capable of performing advantageous drilling, and to prevent the growth of reworked grains during extrusion and heat treatment of the processed structure and improve the stability of material quality. This is an invention having industrially great effects.

[Brief description of the drawings]

FIG. 1 is a drawing showing the state of chips together with an example according to the present invention and a comparative example thereof. That is, FIG. 1A shows the alloy No. 1 of the present invention, and FIG. 1B shows the alloy No. 1 of the present invention.
4, (c) shows alloy No. 6 of the present invention, (d) shows chips of comparative alloy No. 7, and (e) shows chips of comparative alloy No. 8.

Claims (2)

(57) [Claims] (1) Mg in wt%₂Si is 1.2Over%
2.5%Up to, Excess Si0.17% Or more
Contains 0.8 to 1.5% of Mg and 0.7 to 1.5% of Si,Containing Al and inevitable impurities.
High-strength aluminum alloy for drilling characterized by the following. 2. The high-strength aluminum alloy for drilling according to claim 1, further comprising V: 0.05 to 0.2%.