JPH1068042A - Alloy cast iron for producing piston ring of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide alloy cast iron having high strength and heat resistance for producing a piston ring in particular of an internal combustion engine. SOLUTION: This alloy cast iron mainly has a pearlite type fundamental structure contg. spheroidal or vermicular precipitated graphite and has the following compsn. of by weight, 2.5 to 4.0% carbon, 1.5 to 4.0% silicon, 0.2 to 2.0% manganese, <=0.35% phosphorus, <=0.03% sulfur, <=3.0% chromium, <=1.5% vanadium, <=2.5% molybdenum, <=0.2% nickel, 1.0 to 3.5% copper, 0.02 to 2.5% aluminum, 0.02 to 2.5% magnesium, and the balance iron.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alloy cast iron for manufacturing a piston ring for an internal combustion engine having a high temperature load.

[0002]

2. Description of the Related Art Piston rings for internal combustion engines mainly consist of a gray cast iron alloy having a spherical or lamellar portion of precipitated graphite. Above all, the piston ring, which is arranged in the uppermost piston groove adjacent to the combustion chamber, is subjected to high temperature loads and therefore requires a mechanical strength value with high temperature stability. For example, according to DE OS 3 628 157, a spherical graphite alloy cast iron having a martensitic base structure is used for a piston ring exposed to high temperatures,
It contains from 1 to 15% by weight of copper precipitated in its base structure in the form of spheres or granules, which, due to its high thermal conductivity, rapidly dissipates heat and thus reduces the temperature loading of the piston ring material. Lower.

Particularly in modern internal combustion engines, a short-stroke machine (Kurzhuber) having a light-weight box-shaped piston is used in order to improve the driving, running and noise comfort, at the same time as the output rises significantly, In this case, the mounting member of the piston ring is extremely shifted upward in order to achieve operation with less vibration. Among them, the top piston ring, and partially 2
The second, so-called scraping ring, is also exposed to higher temperatures, so that the material is required to have a mechanical strength value with improved temperature stability. The heat resistance of the martensitic cast iron alloys known from DE OS 3 628 157 is insufficient for these high requirements.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention is directed to an internal combustion engine having a durable strength value at elevated temperatures.
It is an object to provide a cast iron alloy for piston rings exposed to high temperatures.

[0005]

This object is achieved according to the invention by means of a spherical or worm-like (vermiklarfoermi).
g) having a pearlite-type structure containing precipitated graphite and having the following composition: carbon 2.5-4.0% by weight silicon 1.5-4.0 {manganese 0.2-2.0} phosphorus max. 35 硫黄 sulfur maximum 0.03 ク ロ ム chromium maximum 3.0 〃 vanadium maximum 1.5 〃 molybdenum maximum 2.5 ニ ッ ケ ル nickel maximum 0.2 銅 copper 1.0-3.5 ア ル ミ ニ ウ ム aluminum 0.02-2.5 ア ル ミ ニ ウ ムSolved by alloy cast iron with 0.005-0.04% magnesium and the balance iron.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Several piston rings are cast on a trial basis using the alloy cast iron according to the invention and are heat treated to a temperature between 500 ° C. and 700 ° C. for 30 minutes in order to determine the heat resistance. Exposed. A normal decrease in hardness value was confirmed without essentially changing the basic pearlite structure of the alloy cast iron. The strength values are essentially unchanged by this temperature load, so that the material has the required high heat resistance.

For further pearlitization, the alloy cast iron may contain up to 0.4% by weight of antimony, which may have been added to the alloy during its melting or via addition means. Similarly, the alloy may be alloyed with at least one of the elements nickel, cobalt, tin, titanium, niobium, tantalum, boron and / or bismuth up to a total of 4.0% by weight. The alloy cast iron additionally has a fill wire injection (Fueldraht-Inject) up to 300 ppm.
ion). This alloy cast iron can be annealed at temperatures up to 750 ° C. to improve workability. In addition, each piston ring may be additionally provided on its entire surface or on its sliding and / or side surfaces to improve its wear resistance, usually by immersion nitriding, gas nitriding, plasma nitriding or pulsed plasma nitriding. The nitriding treatment can be performed by one of the conventional methods. In this case, all cast iron materials within the claimed alloy range can be suitably nitrided, but silicon, chromium,
Preference is given to using the alloy cast iron of the invention, which contains vanadium, molybdenum and aluminum in its composition according to the invention at its upper limit, for nitriding. In that case, the unnitrided alloy cast iron preferably has the following composition: carbon 2.5-4.0% by weight silicon 1.5-2.5% manganese 0.2-2.0 phosphorus up to 0.35% Sulfur up to 0.03 ク ロ ム Chromium up to 0.3 〃 Vanadium up to 0.2 〃 Molybdenum up to 0.3 ニ ッ ケ ル Nickel up to 0.2 〃 Copper 1.0-3.5 ア ル ミ ニ ウ ム Aluminum up to 0.1 〃 Magnesium 0.005- 0.04% and the balance iron.

The alloy cast iron used especially in the nitrided form has the following composition: carbon 2.5-4.0% by weight silicon 2.0-4.0% manganese 0.2-2.0% phosphorus maximum 0 0.35% sulfur maximum 0.03% chromium 0.2-3.0% vanadium maximum 1.5% molybdenum maximum 2.5% nickel maximum 0.2% copper 1.0-3.5% aluminum 0.02- It has 2.5% magnesium 0.005-0.04% and the balance iron.

Both of these alloys can contain elements added for improving wear resistance, improving pearlite, and improving nitriding.

Accordingly, the present invention provides an alloy cast iron suitable for a piston ring exposed to high temperatures in an internal combustion engine. The cast iron material exhibits good heat-set behavior and its metallographic structure shows no substantial change even under prolonged high temperature loading. This alloy cast iron can be used equally well in static casting and in centrifugal casting to produce piston rings of all diameters up to 1 m. The alloy cast iron is also preferably used for components of an internal combustion engine, such as a cylinder liner, a piston, a connecting rod, a general packing wheel, a packing ring, a gear and a transmission ring, which are subjected to similar loads.

[0011]

EXAMPLES Both of the following alloy cast irons are preferably used,
In this case, the alloy cast iron 1 is preferably used without nitriding, and the alloy cast iron 2 is preferably used in a nitrided form.

Element Alloy cast iron 1 Alloy cast iron 2 Carbon 3.76% by weight 3.78% by weight Silicon 2.16 〃 2.98 マ ン ガ ン Manganese 0.88 〃 0.86 燐 Phosphorus 0.10 ０．０ 0.09 〃 Sulfur 0.008 〃 0.007 ク ロ ム Chromium 0.04 ２．０ 2.04 〃 Vanadium 0.01 ０ 0 0.01 〃 Molybdenum 0.02 ０．０ 0.02 ニ ッ ケ ル Nickel 0.05 ０．０５ 0.05 〃 Copper 2.46 〃 2.38 チ タ ン Titanium 0.01 〃 0.01 〃 Tungsten 0.03 ０．０ 0.03 ニ Niobium − 0.02 〃 magnesium 0.011 ０．０ 0.010 鉄 iron residue residue

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location F16J 10/00 F16J 10/00 A

Claims (9)

[Claims] 1. An alloy cast iron for producing a piston ring for an internal combustion engine having a high temperature load, wherein the alloy cast iron has a pearlite-type structure containing spherical or worm-like precipitated graphite, and has the following composition: 5-4.0% by weight Silicon 1.5-4.0 マ ン ガ ン Manganese 0.2-2.0 〃 Phosphorus up to 0.35 硫黄 Sulfur up to 0.03 〃 Chromium up to 3.0 〃 Vanadium up to 1.5 〃 Molybdenum Characterized by having a maximum of 2.5% nickel a maximum of 0.2% copper 1.0-3.5% aluminum 0.02-2.5% magnesium 0.005-0.04% and a balance of iron. The above alloy cast iron. 2. The alloy cast iron according to claim 1, wherein the alloy cast iron contains up to 0.4% by weight of antimony. 3. The alloy cast iron according to claim 1, wherein at least one of the elements nickel, cobalt, tin, titanium, niobium, tantalum, boron and / or bismuth is present in a total amount of up to 4.0% by weight. Or the alloy cast iron according to 2. 4. The alloy cast iron has a maximum of 300 ppm of nitrogen introduced into the molten metal by filled wire injection.
The alloy cast iron according to any one of claims 1 to 3, wherein the alloy cast iron is contained in an amount of 5. A workpiece cast from the alloy having a thickness of 73%.
The alloy cast iron according to any one of claims 1 to 4, wherein an annealing treatment is performed at a temperature up to 0 ° C. 6. The alloy cast iron according to claim 1, wherein a workpiece cast from the alloy is subjected to a nitriding treatment by one of ordinary methods. 7. The alloy cast iron to be nitrided is carbon 2.5-4.0% by weight silicon 2.0-4.0% manganese 0.2-2.0 phosphorus maximum 0.35% sulfur Maximum 0.03 〃 Chromium 0.2-3.0 〃 Vanadium maximum 1.5 〃 Molybdenum maximum 2.5 ニ ッ ケ ル Nickel maximum 0.2 銅 Copper 0.1-3.5 ア ル ミ ニ ウ ム Aluminum 0.02-2.5 最高The alloy cast iron according to any one of claims 1 to 6, comprising magnesium 0.005 to 0.04% and the balance of iron. 8. The alloy cast iron, preferably non-nitrided, has a carbon content of 2.5-4.0% by weight silicon 1.5-2.5% manganese 0.2-2.0% phosphorus maximum 0.35% sulfur maximum 0.03 〃 Chromium up to 0.3 〃 Vanadium up to 0.2 〃 Molybdenum up to 0.3 ニ ッ ケ ル Nickel up to 0.2 銅 Copper 0.1-3.5 〃 Aluminum up to 0.1 〃 Magnesium 0.005--0. The alloy cast iron according to any one of claims 1 to 6, wherein the alloy cast iron comprises 04% and the balance of iron. 9. The use of an alloy cast iron according to any of the preceding claims in the manufacture of cylinder liners, pistons, connecting rods, transmission rings, general packing wheels, gears or packing rings.