LEAD-FREE BRASS ALLOY AND ITS USE

Abstract

The invention relates to a lead-free brass alloy containing 57.0 to 60.0% Cu, 1.0 to 2.0% Al, 1.5 to 2.5% Mn, 0.1 to 1.0% Fe, at most 0.5% Ni, at most 0.5% Sn, 0.5 to 2.0% Si, less than 0.1% Pb, balance Zn and also unavoidable impurities, wherein the copper equivalent (CuÄq) is in the range of 52.0 to 58.0%.

Description

LEAD-FREE BRASS ALLOY AND ITS USE FIELD OF INVENTION The invention relates to a lead-free brass alloy and also to its use. BACKGROUND OF THE INVENTION US patent 10,287,653 B2 describes a lead-free brass alloy with a composition reproduced in claim 1 of that patent. The known brass alloy has a zinc equivalent in the range of 51% to approximately 58%. The proposed brass alloy is particularly suitable for producing turbocharger bearings. The industry requires a suitable lead-free brass alloy especially for producing hydraulic pump parts and hydraulic components. BRIEF DESCRIPTION OF INVENTION It is an objective of the invention to specify a lead-free brass alloy distinguished by its good machinability, emergency operating properties, compatibility with oils, and the like. The brass alloy should be particularly suitable for producing parts for hydraulic pumps and hydraulic components. This objective is achieved through the features of claims 1 and 7. The judicious modalities are evident from the features of the dependent claims. DETAILED DESCRIPTION OF THE INVENTION According to the invention, a lead-free brass alloy is proposed containing 57 to 60.0% Cu, 1.0 to 2.0% Al, 1.5 to 2.5% Mn, 0.1 to 1.0% Fe, at most 0.5% Ni, at most 0.5% Sn, 0.5 to 2.0% Si, less than 0.1% Pb, the remainder Zn and also unavoidable impurities, wherein the copper equivalent (CuAq) is in the range of 52.0 to 58.0%. The specified copper equivalent (CuAq) is calculated as follows: 1) If Siiibre = Si · 3.26 - (Fe+Mn) < 0 then CuÁq = Cu / {[100 - Fe - Mn + (|Sii¡bre| · 0.7) - Al + (ΑΙ·6) - S¡)] / 100} 2) If Siiibre = Si · 3.26 - (Fe+Mn) > 0 then CuÁq = Cu / {[100 - Fe - Mn - Al + (ΑΙ·6) - Si + ((Sii¡bre / 3.26)· 10)] / 100} Cu: % copper Fe: % iron Al: % aluminum Yes: % Silicon For the purposes of this description, [%] is understood as percentage by weight. In the previous calculation of the copper equivalent (CuAq), two cases are distinguished, numbers 1 and 2. In case number 1, there is no free silicon (SiI) in the alloy. In this case, the silicon in the alloy is completely bonded with Fe and / or Mn. Intermetallic compounds of FeMnSi are formed. In case number 2, there is free silicon (Sifree) in the alloy. The distinction between the first and second cases is necessary because free silicon (Shifree) in the alloy produces a strong shift in the phase diagram in the β-phase direction. In this case, the shift in the phase diagram in the β-phase direction is approximately 10 times stronger than in the case of fully bonded silicon (see the calculation above, case number 1). It has emerged that the proposed brass alloy with a copper equivalent (CuAq) in the range of 52.0 to 58.0% exhibits friction properties comparable to those of conventional lead-containing alloys. The proposed lead-free brass alloy is further distinguished by its good machinability, emergency operating properties, compatibility with oils, and similar characteristics. According to an advantageous modality, Si is contained in an amount of no more than 1.0%. In this way, a particularly suitable β-phase content is established. According to another embodiment, Sn is contained in an amount of at most 0.2%, preferably at most 0.1%, and more preferably less than 0.06%. Sn increases the relaxation resistance of the alloy. The proposed lead-free brass alloy may contain nickel in an amount of up to 1.0%, preferably up to 0.5%. Additionally, iron may be present in an amount of up to 0.5%, preferably up to 0.4%. Manganese may be present in an amount of up to 2.1%. The aforementioned elements are added to form intermetallic phases in the alloy. These intermetallic phases enhance the wear resistance and ductility of the alloy. In accordance with the invention, a use of the lead-free brass alloy of the invention is proposed for producing parts for hydraulic pumps and hydraulic components. The parts may be selected in particular from the following group: sliding block, distributor plate, retaining segment, bearing cap. What makes the proposed brass alloy particularly suitable for producing parts for hydraulic pumps and hydraulic components are its good friction properties. According to an exemplary embodiment of the invention, the alloy of the invention has, for example, the following composition: i nnpnn / zznz / E / YiAi Alloy constituent % by weight Cu 57.96 Al 1.56 Mn 1.94 Fe 0.36 Ni 0.06 Sn 0.01 Si 0.59 Pb 0.02 The alloy with the composition indicated above exhibits the properties identified in the following table: Properties Coefficient of friction / wear Coefficient of friction, lubricated Splash lubrication in a Spirax / Fusus mixture in a ratio of 3 to 1 at 95°C under a surface load of 52 N*mm 2 and a rubbing speed of 1.65 m / s in the pin-on-disc method 0.11 Wear, lubricated, in km / g Splash lubrication in a Spirax / Fusus mixture in a ratio of 3 to 1 at 95°C under a surface load of 52 N*mm 2, a rubbing speed of 1.65 m / s and a distance of 2500 m in the pin-on-disc method 226 km / g Coefficient of friction, dry under a surface load of 10 N^mm 2 and a rubbing speed of 0.55 m / s in the pin-on-disc method 0.20 Dry wear, in km / g under a surface load of 10 N·πιιϊγ2 and a friction speed of 0.55 m / s 121 km / g The good friction properties of the alloy of the invention make it particularly suitable for the manufacture of hydraulic pumps and hydraulic components, more particularly skids, distributor plates, retaining segments and bearing bushings.

Claims

1. A lead-free brass alloy characterized in that it contains 57.0 to 60.0% Cu, 1.0 to 2.0% Al, 1.5 to 2.5% Mn, 0.1 to 1.0% Fe, at most 0.5% Ni, at most 0.5% Sn, 0.5 to 2.0% Si, less than 0.1% Pb, balanced Zn and also unavoidable impurities, wherein the copper equivalent (CuAq) is in the range of 52.0 to 58.0%.

2. The lead-free brass alloy according to claim 1, further characterized in that it contains Si in an amount of at most 1.0%.

3. The lead-free brass alloy according to any of the preceding claims, further characterized in that it contains Sn in a maximum amount of 0.2%, preferably at most 0.1%, more preferably less than 0.06%.

4. The lead-free brass alloy according to any of the preceding claims, further characterized in that it contains Ni in an amount of at most 1.0%, preferably at most 0.5%.

5. The lead-free brass alloy according to any of the preceding claims, further characterized in that it contains Fe in an amount of at most 0.5%, preferably at most 0.4%.

6. The lead-free brass alloy according to any of the preceding claims, further characterized in that it contains Mn in an amount of at most 2.1%.

7. Use of the lead-free brass alloy according to one of the preceding claims for manufacturing parts for hydraulic pumps and hydraulic components.

8. Use according to claim 7, wherein the parts are selected from the following group: sliding block, distributor plate, retaining segment, bearing bushing.