DE1957823A1 - Alloy, especially for parts of the valve system of internal combustion engines - Google Patents

Description

Z / DB-2 Sp uk patent application

Alloy, in particular for parts of the valve system of internal combustion engines

The invention relates to an alloy, in particular for parts of the Valve systems of internal combustion engines that are exposed to hot exhaust gases are and resistant to oxidation, suIfidation and impacts of lead compounds at high temperatures.

A typical alloy for such parts consists of 20 % chromium, 5 * 5 % aluminum, 2.5 % titanium, 7.5 % iron, 0.15 % carbon and the remainder nickel.

The invention is based on the observation that certain quaternary alloys of nickel, chromium, aluminum and titanium have a combination of properties that are essential for parts of the valve system of internal combustion engines that are exposed to hot exhaust gases, that are resistant to oxidation, sulfidation and the effects of lead compounds must be at high temperatures are particularly desirable.

In this context, it is most polite to refer to a scientific treatise on the properties of such alloys referred to in the journal "Journal of Metals" in October 1956 on pages 1356-1362 published by A Taylor.

5K-2531 / November 12, 1969

00982 3/1349

Society: Cologne - Chairman of the Supervisory Board: Erhard Vltger · Board of Directors: John A. Banning, Chairman Dr. Kl «u» B. AmedtcK - Hans-Adolf Barthelmeh ■ Hans Grand! - Paul H. Kuhn · Hermann Miüer · Hana Schmidt

The object of the present invention is to provide an alloy of the above Kind of creating that is much cheaper with the same good properties and can therefore be used for large-scale production.

According to the present invention, this object is achieved by adding up to 14 % iron to certain chromium-aluminum-titanium alloys based on nickel, which makes them particularly interesting for parts of the valve system of internal combustion engines.

Particular attention is paid to the heads of poppet valves and the To dedicate valve seat inserts, both of which are especially made with lead connections are exposed to contaminated hot exhaust gases. The inventive Alloys are used in their as-cast state. The cast heads of the poppet valves are friction welded to a Valve stem made of carbon steel connected to the application of the expensive Make alloy components in the head of the poppet valve more economical.

In order to demonstrate the properties of the alloys according to the invention, a typical alloy according to the invention, designated V 270, was compared with four other commercially known and available high temperature resistant alloys, one of which is an iron-based alloy and the other three alloys Are nickel-based. The chemical composition of five compared with each other alloys are compiled in the following journal ^r ~ ".

FK-2531 / November 12, 1969

009823/134 9-

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The invention is illustrated with reference to some in the accompanying drawings Diagrams explained in more detail.

Pig. 1 shows a graphic comparison of the favorable properties of alloy according to the invention compared with those of the three known, comparable, alloys resistant to high temperatures. The representations in the left part of FIG. 1 show the flow stress at room temperature, while the representations in the right part of FIG. 1 show the yield stress at the much more critical temperature of Show 871 ° C. The temperature of 87I ° C is about the maximum temperature which is considered today in the valve system of an internal combustion engine.

Fig. 2 shows a graph of the breaking stress in 100 hours at 871 ° C of the five compared alloys. This is where the excellent properties of the alloys according to the invention come into play, in particular clearly evident with regard to a creep rupture.

Fig. 3 shows a graph of the resistance of the compared Alloys against. The action of hot lead compounds, this resistance in a weight loss of a test object in grams / which is given per hour of exposure. This resilience against the influence of lead compounds is a critical parameter for metals that are exposed to hot exhaust gases from leaded petrol.

4 shows in a graphic representation that the iron content of the alloys according to the invention can be increased up to approximately 14% without having to accept a loss of resistance to the action of lead alloys. This is particularly important from an economic point of view, since it makes it possible to manufacture the alloys according to the invention from iron-chromium and iron-titanium alloys at a significantly lower cost. Of course, iron is the cheapest alloy component.

FK-2531 / November 12, 1969 '- 5 -

009823/1349

It is also important that these alloys have the maximum possible amount of gamna iron dissolved in a gamma structure at operating temperature. The amount of gamma iron should be at least 20 % . The presence of titanium in these alloys enables this particular structure to be achieved.

The following Table II is intended to show the resilience of a variety of alloys against molten lead oxide.

Table II Composition in percent by weight - Best Nickel

Pe Al Ti Weight loss Cr - 7.1 - p
Gram / dem / hour 20th - 7.0 "- 2.67 16 - 5.6 2.5 20th - 4.5 J5.6 8.4 20th 7.5 7.0 -. 3.1 20th 8.0 4.0 T- 11.5 20th 10.0 5.0 - 1.6 16 15.0 5.0 - 1.8 16 20.0 5.0 : - ' 15O 16 5.0 7.0 - 37.0 15th 7-5 .5.6 2.5 2.5 20th 12.0 6.1 1.8 4.8 20th 10.0 5.0 1.0 5.7 22nd 11.4 5.0 1.8 7.3 22nd 20.0 4.9 2.2 7.9, 15th 14.4 5.2 2.3 l8.5 15.8 7.7

All alloys contain about 0.15 % carbon. FK-2531 / November 12, 1969

009823 / 13A9

Claims (2)

Claims 1. Alloy, especially for parts of the valve system of internal combustion engines, characterized in that a nickel-based alloy which can be used in the as-cast state is essentially a salary of 15-24 % chromium 3 - 7.5 % aluminum 0.04-0.25 % carbon up to 4 % titanium having, with twice the sum of the content of aluminum and titanium 8-15 % and the alloy is essentially free of oxygen and is sulfur and at least one 20 #igen Has volume fraction of gamma iron dissolved in a gamma structure and the remainder of the alloy consists of nickel or an alloy of nickel and iron, with a content of 14 % iron is not exceeded. 2. Alloy according to claim 1, characterized in that that the alloy essentially has a content of 20 % chromium 5.5 % aluminum 2.5 % titanium 7.5 # iron has 0.15 $ carbon and a remainder of nickel. BK-2531 / November 12, 1969 009823/1349 L e r s e i t e