DD270931B1 - WEAR-RESISTANT BRASS ALLOY - Google Patents

Abstract

The invention relates to a wear-resistant brass alloy, in particular with pronounced wear resistance under sliding stress at elevated temperatures and with sufficient cold workability, which finds application in narrowed hardness values for the production of valve stem guides of internal combustion engines. According to the invention the object is achieved in that an alloy 57 to 58.6 Ma .-% Cu, 1.4 to 1.8 Ma. % Al, 1.6 to 2.2 Ma. % Mn, 0.5 to 0.8 Ma. % Si, 0.4 to 0.6 mass% Pb, 0.5 to 0.8 Ma. % Fe, 0.2 to 0.4 Ma. % Sn, remainder Zn.

Description

Characteristic of the known technical readings Some copper-based alloys have pronounced wear resistance. With the advancement of the state of the Technology is therefore endeavored, these copper-base alloys in chemical and Krlstallographischer regard each

adapt to new technical tasks. Especially with valve stem guides and valve rings of internal combustion engines, which are exposed to the action of hot combustion gases, mechanical and chemical attack act simultaneously on the material under high thermal stress. For this application, complex alloys have been developed whose components, by combining their properties, are intended to guarantee the performance properties of the component produced therefrom.

Thus, the solid solution hardening associated with the addition of the zinc to the copper should increase the strength of the alloy and the Formation of thin oxide skins of both metals by self-lubricating properties improve wear resistance. In

Likewise, tin and aluminum increase the strength of the alloy and increase its wear resistance as well as the

Corrosion resistance. Low iron contents have a fine grain effect, while lead additives improve machinability. Silicon and manganese are major contributors to wear resistance through the formation of manganese silicides. To increase

the hardness is known to zuzulegieren additional metals, such as chromium and phosphorus (DE-AS 2145690).

By adding further elements, it was attempted to extend the service life of the material, in particular by improving the service life of the material Corrosion resistance, further increase. It is known such an alloy, the addition of Nicket and Tellurium

provides (DE-AS 1287313).

Furthermore, an alloy is known in which arsenic or beryllium is used in addition to other alloying constituents

or replace these elements by selenium and sulfur or zirconium or titanium (DE-OS 1558466, DE-OS 1558467).

Such complex alloys are difficult to control metallurgically. At least for their production Special cutting process or sintering necessary. Despite the improvement in the wear properties that have brought the measures described, these are sufficient Materials do not meet the demands of modern engine construction. It has therefore already been proposed that To increase wear resistance of valve stem guides in the manufacturing process by extrusion (DE-OS 1558470;

DE-OS 1558471).

In order to enable cold deformation of the semi-finished product by extrusion or by a calibration, the Composition of the alloys chosen so that they are present at least at room temperature in the α-region. Since it was also assumed that ß-shares in the structure especially the trumpet-shaped expansion of Valve Stem promoted, their shares were limited to £ 30% (DE-OS 1558470). This influence should be through Extruding be compensated. On the other hand, the high α content of the microstructure leads to difficulties in the hot processing of the alloys and

requires special measures during the extrusion process.

Object of the invention

The aim of the invention is to develop a wear-resistant brass alloy, which on the one hand requires no readjustment of valves produced therefrom and on the other hand considerably increases the running time of the internal combustion engine.

Explanation of the essence of the invention The invention is based on the object, a brass alloy with pronounced wear resistance at sliding To create stress under elevated temperatures, their processing on modern extrusion presses for the Further processing optimum press temperature should be easily possible and sufficient at room temperature

cold forming to be processed on continuous drawing machines can.

According to the invention the object is achieved in that an alloy 57 to 58.6Ma .-% Cu, 1.4 to 1.8Ma .-% Al, 1.6 to

2.2Ma .-% Mn, 0.5 to 0.8Ma .-% Si, 0.4 to 0.6Ma. % Pb, 0.5 to 0.8Ma .-% Fe, 0.2 to 0.4Ma .-% Sn, rest Zn has and their

Microstructure consists of more than 80% ß-Mi & chkristallen. It is also essential to the invention that the alloy is cold-formable by drawing.

-2- 270 Auszubihrungsbelsplel

The invention will be explained in more detail below by way of example. The following compositions of the alloys are significant for the production of valve guide bushings for internal combustion engines:

Example 1 Example 2

Cu: 58.3Ma .-% Cu: 57.5Ma .-%

Al: 1.41Ma% Al: 1.52Ma%

Mn: 1.61Ma .-% Mn: 1.99 Ma. %

Si: 0.65Ma% Si: 0.74Ma%

Pb: 0.49Ma .-% Pb: 0.46Ma .-%

Fe: 0.71Ma.% Fe: 0.68Ma.%

Sn: 0.29Ma.% Sn: 0.37Ma.%

Zn: residual% by weight Zn: residual% by weight

ß-share: 81% ß-share: 85%

The alloys mentioned in Examples 1 and 2 can be cold drawn on Fertigabmesaung on continuous drawing machines and are thus suitable for a large-scale manufacturing process.

Claims (1)

Wear-resistant brass alloy, in particular with pronounced wear resistance under sliding load under elevated temperatures, characterized in that an alloy contains 57 to 58.6 mass% Cu, 1.4 to 1.8 mass% Al, 1.6 to 2.2 mass%. % Mn, 0.5 to 0.8 mass% Si, 0.4 to 0.6 mass% Pb, 0.5 to 0.8 mass% Fe, 0.2 to 0.4 mass%. % Sn, remainder Zn. Field of application of the invention The invention relates to a wear-resistant brass alloy, in particular with pronounced wear resistance under sliding stress under elevated temperatures and with sufficient cold workability, which finds application in narrowed hardness values for the production of valve stem guides of internal combustion engines.