EP1279748B1 - Aluminum bronze with high wear resistance - Google Patents

Description

The invention relates to an aluminum bronze for the field of application the synchronizer rings.

Aluminum bronzes are considered due to their good properties mechanical strength, corrosion resistance and wear resistance esteemed construction material, especially in liquid media.

From DE 26 21 602 C3, for example, it is an aluminum bronze with 4-12 Weight percent Al, traces up to 1% Si and / or Be in solid solution and 4.2 - 10% iron silicide, rest of copper known. In the case of using beryllium up to 6% of iron not bound to iron silicide can be used. This alloy can also contain up to 7% nickel contain. With this known alloy there is the question of tensile strength and a high percentage elongation in the foreground. It is suitable for sliding parts in rolling mills, machine tools and the like.

This publication also includes the use of manganese silicides mentioned instead of iron silicides. In view of the percentage Elongation, which plays an essential role in the subject of this document plays, but this stretch is reduced due to the rigid manganese silicides Manganese silicides are not suitable for the desired purpose. It will be the Hope expressed that the percentage stretch would increase if that Manganese silicide in at least approximately spherical crystals would crystallize out. At that time, however, there was no solution for an alloy seen with these characteristics.

The term "wear resistance" used in this document refers resistance to corrosion erosion.

From JP 07138680 A there is also an aluminum bronze with 6-11% by weight Al, 3 - 8 wt .-% Mn, 1 - 4 wt .-% Si, balance copper and unavoidable Known impurities. Heat treatment turns manganese silicides small grain size.

JP 20 509 28 is another aluminum bronze with 8.5-15% by weight Al, 0.1-8% by weight Mn, 0.1-3.5% by weight of Si and as an optional component 0.1-6% by weight of Fe, Ni and / or Co as well as unavoidable impurities, rest copper, known from the Sintered metallurgy synchronizer rings with a certain porosity can be produced.

Aluminum bronzes have compared to other copper alloys, e.g. Brass has the advantage that due to the aluminum used Part weight reduction is possible. Such alloys are resistant to oxidation due to a caused by the aluminum Protective layer. Aluminum bronzes are also highly resilient and wear-resistant sliding materials, their high strength leads due to the good Sliding properties at a low wear rate. Beyond that Aluminum bronze easy to weld.

It is an object of the invention to provide an aluminum bronze which in contrast to the well-known aluminum bronzes, a high one at the same time Resistance to abrasive wear and a high coefficient of friction for is used for synchronizer rings.

To achieve this object, the invention proposes an alloy of 7.5 - 10% Al, 5 - 14% Mn, 1.5 - 4% Si, 5 - 9% Fe, 0 - 0.5% Pb, balance copper and usual impurities up to a total of 1%. All information is given in Weight.

The presence of sufficient silicon in is essential for the invention Associated with a high manganese content, which makes it too hard intermetallic phases, which has a high resistance to rubbing Have wear.

A further development of the alloy provides that it contains 8 - 9% Al, 7-8% Fe, 5-7% Mn and 3-4% Si, balance copper and usual Contamination up to a total of 1%.

With alloys of the aforementioned composition Achieve wear resistance values that are a multiple of those of hitherto usual brass materials for synchronizer rings. The coefficient of friction some of these alloys are even higher than those of the known materials, is at least the same. Through the aluminum bronzes according to the invention will therefore be a significant step forward compared to synchronizer rings used brass materials achieved.

To improve machinability, the inventive Aluminum bronze can optionally contain up to 0.5% lead.

Alloys produced in the test are explained below as examples.

The first test alloy has a composition of 75.4% Cu, 9.0% Al, 5.2% Fe, 7.1% Mn and 3.3% Si. This alloy has one Wear resistance of 2950 km / g. Their coefficient of friction is 0.116.

The second test alloy of the type FeMnSi has a content of 76.0% Cu, 8.2% Al, 7.2% Fe, 5.2% Mn and 3.1% Si. Your wear resistance is 2530 km / g, their coefficient of friction 0.130.

A comparison alloy of the type FeMnSi has a content of 83.6% Cu, 7.7% Al, 4.7% Fe, 2.5% Mn, 1.5% Si. Their wear resistance is 950 km / g, their coefficient of friction 0.115.

It can be seen that higher levels of iron, manganese and silicon are beneficial for are high wear resistance.

These properties of the alloys according to the invention are compared to set very good with the properties currently on the market Brass alloys for synchronizer rings where wear resistance is about 650 -700 km / g and the coefficient of friction is approximately 0.115 to 0.120.

As mentioned earlier, silicon is hard-wearing for the formation of hard intermetallic phases. There should be no free silicon in the Solution available, but be bound by iron and manganese. Iron and Manganese also promote the hardening process.

These alloys described above were at a casting temperature of 1120 cast in a strand up to 1180 ° C; then it is cooled in air, the cooling rate is not critical. After heating up again hot forming by extrusion at temperatures from 800 to 900 ° C and cooling again in air. Finally, after heating again drop forged at temperatures from 790 to 890 ° C and the alloy then cooled in air.

a) Es wird eine Homogenisierungsglühung bei 900° C während einer Stunde durchgeführt. Anschließend erfolgt ein Abschrecken, vorzugsweise im Wasser, und anschließend ein erneuten Anlassen bei einer Temperatur von 490° C während einer Zeit von einer Stunde und zum Schluss ein Abkühlen an Luft.

b) Unmittelbar auf die Abkühlphase nach dem Schmieden wird unter Weglassung der Homogenisierungsglühung sofort die Auslagerungsbehandlung bei einer Temperatur von 330° C während 6 Stunden oder alternativ bei 410° C während 3 Stunden begonnen, und anschließend die Abkühlung an Luft durchgeführt. Bei diesem Aushärtungsverfahren sind die Härtesteigerungen nicht ganz so groß wie im Falle des vorbeschriebenen Verfahrens, aufgrund des Wegfalls der Homogenisierungsglühung ist dieses Verfahren jedoch kostengünstiger.

In contrast to brass alloys, aluminum bronzes are suitable for hardening to increase strength; if desired, one can alternatively proceed as follows after forging the alloy.

a) Homogenization annealing is carried out at 900 ° C for one hour. This is followed by quenching, preferably in water, and then restarting at a temperature of 490 ° C. for a period of one hour and finally cooling in air.

b) Immediately after the cooling phase after forging, with the omission of the homogenization annealing, the aging treatment is started immediately at a temperature of 330 ° C. for 6 hours or alternatively at 410 ° C. for 3 hours, and then the cooling is carried out in air. In this hardening process, the increases in hardness are not quite as great as in the case of the above-described process, but because of the elimination of the homogenization annealing, this process is less expensive.

In addition to reducing the removal on the friction surfaces of the synchronizer rings due to the higher wear resistance is also due to the higher strength less wear on the ratchet teeth Synchronizer rings.

The shape of the intermetallic phases is MnSi for an alloy type more needle-like, but more spherical with the alloy type FeMnSi. Accordingly, alloys of the FeMnSi type have a better one Toughness and ductility as MnSi alloys.

Claims (2)

1. Aluminium bronze containing 7.5 - 10% Al, 5 - 14% Mn, 1.5 - 4% Si, 5 - 9% Fe, 0 - 0.5% Pb, the rest being copper and the usual impurities up to a total of 1%, having a high resistance to wear and tear and a high coefficient of friction, as a material for synchronous rings.
2. Aluminium bronze according to Claim 1, characterized in that it has a content of 8 - 9% Al, 7 - 8% Fe, 5 - 7% Mn and 3 - 4% Si, the rest being copper and the usual impurities up to a total of 1%.