DE1213625B - Metal powder mixture for the powder metallurgical production of steel objects - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C22c

German KL: 40 b -39/56

Number: 1213 625

File number: B 56428 VI a / 40 b

Armtelltag: January 28, 1960

Opening day: March 31, 1966

The invention relates to mixtures of metal powders based on iron, which are used for powder metallurgy Manufacture of steel objects are intended.

The manufacture of steel objects by means of powder metallurgical processes is usually done so that you can use the individual powders in the amounts required for the desired composition mixes together. It is also known to use powders made from steel of the desired type Composition made by itself through a normal fusion process became. In general, it was found that in the first process, significantly better mechanical Properties are obtained, and this process is also the subject of the invention.

Metal powder mixtures are known which mainly consist of powdered soft iron with an addition of 2 to 8% nickel, 0.2 to 1.4% manganese and 0.08 to 1.0% graphite and, compared to the previously known powder mixtures, objects with increased Provided strength, toughness and corrosion resistance. Furthermore, an alloyed sintered steel with 0.2 to 2.5% carbon, 1 to 20% manganese, 7.5 to 30% copper, the remainder iron belongs to the state of the art. With compositions of this type it was possible to produce steel objects which have a Vickers hardness of up to 840 kg / mm ² . Finally, a copper-containing sintered manganese steel with 0.2 to 2.5% carbon, 6 to 20 ¹ Vo manganese, more than 10 and up to 30% copper, the remainder iron was known, the optionally nickel, cobalt and tungsten up to a total of 20% and may optionally contain vanadium, niobium, tantalum, molybdenum, titanium, zirconium, aluminum and boron up to a total of 5%. A Vickers hardness of 800 kg / mm ² could also be achieved with such a sintered steel. However, there was still a need for powder mixtures which would give sintered steel articles with extremely high tensile strengths without impairing ductility.

The aim of the invention is therefore to create metal powder mixtures for powder metallurgy Manufacture of steel articles that have greatly improved tensile strength without undue loss exhibit elasticity.

Surprisingly, it has now been possible to use metal powder mixtures for the stated purpose that create up to 100% better tensile strength for the steel objects made from them to lend.

The invention consists in that one for powder-metal powder mixture for
powder metallurgical production of
Steel objects

Applicant:

The Birmingham Small Arms Company, Limited, Birmingham (Great Britain)

Representative:

Dipl.-Ing. E. Prince and Dr. rer. nat. G. Hauser,

Patent attorneys,

Munich-Pasing, Ernsbergerstr. 19th

Named as inventor:

Peter Robert Marshall,

Shirley, Solihull, Warwickshire; '

Philip James Ridout,

South Yardley, Birmingham (Great Britain)

Claimed priority:

Great Britain January 31, 1959 (3522) -

metallurgical production of steel objects a powder mixture of 5 to 15 percent by weight Nickel, 0.4 to 1 weight percent manganese, 0 to weight percent cobalt, 0.5 to 5 weight percent Molybdenum, 0.1 to 1 percent by weight carbon, preferably graphite, the remainder iron and common impurities used.

The individual powders can be made from elemental metals, alloys of two or more, however not all of the metals desired in the steel to be produced or from compounds of the Metals exist. Ferro compounds are also often used.

Subsequently, preferred narrower ranges for the content of alloy elements are given, of which each one or more in the further areas of the corresponding given above Element can be used:

Nickel 7 to 13%

Manganese 0.5 to 0.6%

Cobalt 0 to 1%

Molybdenum, 1.5 to 2.5%

Carbon, preferably graphite 0.4 to 0.8%

609 540/33 +

A small part of the iron content can be due to the same weight from one or more others Elements are replaced that increase the tensile strength and ductility of the objects made from the powders not adversely affect. Preferably, the amount of iron so replaced exceeds 5% of the total weight of the mixture does not. The following are the possible additions Elements listed: up to 1% aluminum, up to 0.3% boron, up to 5% chromium, up to 5% copper, up to 4% niobium and / or tantalum, up to 0.3% phosphorus, up to 1% silicon, up to 2% titanium, up to up to 4% tungsten, up to 0.3% vanadium, up to 0.6% zirconium, up to 0.6% selenium, up to 0.5% Lead, up to 1% magnesium.

The nickel is expediently in the form of a fine powder, preferably as a fine nickel carbonyl powder, admitted. The manganese can be added in the form of ferro-manganese powder or as manganese carbonate powder and should have a fineness of about 0.053 mm, i.e. i.e., it should go completely through a Go sieve with a mesh size of 0.053 mm. The cobalt should preferably be in the form of a Fine powder can be added, which is also passed through a sieve with a mesh size of 0.053 mm should go. The molybdenum can be in the form of ferro-molybdenum powder, which is preferably passed through a sieve 0.053 mm clear mesh size should be used. Soft iron powder is said to be iron powder be used, which is completely through a sieve with a mesh size of 0.152 mm passes through. 75% of the iron powder should pass through a sieve with a clear Mesh size of 0.076 mm and 50% through a sieve with a mesh size of 0.053 mm go through.

To make a steel article, the powders are weighed out in the desired proportions and mixed thoroughly to achieve a homogeneous mixture. In this process step you can Lubricants such as paraffin wax, stearates, or other lubricants customary in the industry in the desired Quantities to be incorporated. Then it will be

ίο brought the mixture into a mold which has the desired shape of the object to be produced and solidifies ^{under a pressure which should be at least 31.50 kg / mm 2.} The solidified powder is then ejected from the die cavity and heated in a non-oxidizing atmosphere at a temperature between 1200 and 1400 ° C. for so long that sintering can occur. This time is preferably at least 30 minutes. Of course, one can use slightly lower pressures and / or temperatures and / or shorter times and thereby obtain products that, although

"They have slightly inferior properties, however are useful for certain purposes; however, the limits given are the lowest acceptable.

An example of a suitable non-oxidizing atmosphere is a mixture of 75% hydrogen and 25% nitrogen.

The following table shows, as examples of the improved mechanical properties achieved by the invention, the tensile strengths and elongations of a number of steel articles obtained by solidifying the powder mixture at 55.00 kg / mm ² and sintering at 1300 ° C. for 1 hour were won.

Ni Mn Percentage composition Mon carbon
(Graphite) iron tensile strenght strain mixture 0.3 with Ver No. 5.0 0.5 Co 1.0 0.3 impurities kg / mm ² % 10 0.5 1.0 0.3 rest 67.70 5 1 10 0.5 1.0 3.0 0.6 rest 80.80 4th 2 10 0.5 1.0 2.0 0.6 rest 90.70 3 3 15th 0.5 3.0 2.0 0.3 rest 101.00 4th 4th 5.0 1.0 3.0 4.0 0.6 rest 94.50 5 5 10 0.5 3.0 2.0 rest 74.00 3 6th 3.0 rest 98.40 4th 7th 0

These properties are to be compared with samples which were produced under similar conditions from powders which contained 0.5%> manganese, 5% nickel and 0.2% carbon in the form of graphite and which otherwise consisted of iron with impurities. These samples had a tensile strength of 41.00 to 50.40 kg / mm ² and an elongation of 6 to 12%.

After solidification and sintering, the steel objects produced from the powder mixture to be used according to the invention can additionally be re-pressed at pressures of up to 94.50 kg / mm ^{2 in} order to achieve increased strength and toughness or better dimensional accuracy. These re-pressed steel objects can also be subjected to re-sintering at a temperature of up to 1400 ° C. in a suitable atmosphere.

The sintered or re-pressed and re-sintered steel articles can undergo heat treatment according to the usual methods, such as those used for welding steel, are subjected and can be case hardened, electroplated or phosphated or with chrome, which diffuses into the object, coat.

Claims (1)

Patent claims: 1. Use of a powder mixture of 5 to 15 percent by weight nickel, 0.4 to 1 percent by weight Manganese, 0 to 3 percent by weight cobalt, 0.5 to 5 percent by weight molybdenum, 0.1 to 1 percent by weight carbon, preferably graphite, the remainder iron and usual impurities for the powder metallurgical production of steel objects. 5 6 2. Use of a powder mixture according to one or more, but in an overall claim 1, consisting of 7 to 13 percent by weight including 5 percent by weight not exceeding percent nickel, 0.5 to 0.6 percent by weight amount, for the purpose according to Manganese, 0 to 1 percent by weight cobalt, 1.5 to claim 1. 2.5 percent by weight molybdenum, 0.4 to 0.8 Ge 5 5. Use of a powder mixture according to weight percent carbon, preferably graphite, the preceding claims, with individual Remainder iron and impurities for the purpose of the mixture of an alloy of powder according to claim 1. two or more components of the mixture are 3. Use of a powder mixture according to stand for the purpose according to claim 1.
Claim 1 or 2, wherein the manganese by the io 6. Use of a powder mixture according to the corresponding weight amount of manganese carbonate the preceding claims, wherein all is occupied, for the purpose of claim 1. components of the mixture except for the iron powder 4. Use of a powder mixture according to the preceding claims through a sieve with a clear mesh size, where the 0.053 mm pass through, for the purpose powder mixture in addition i ₅ according to claim 1. 7. Use of a powder mixture according to Aluminum up to 1% of the preceding claims, wherein the Boron up to 0.3% iron powder mix a sieve with a Chromium up to 5% mesh size of 0.152 mm completely, Copper up to 5% 20 a sieve with a mesh size of Magnesium up to 1% 0.076 mm to 75% and a sieve a clear one Niobium and / or tantalum up to 4% mesh size of 0.051 mm to 50% through Phosphorus goes up to 0.3% for the purpose of claim 1. Silicon up to 1% Titanium up to 2% 25 Publications considered: Tungsten up to 4% German Patent No. 1011909; Vanadium up to 0.3% German patent application M13655 VI / 18 d (beZirkonium up to 0.6% announced on August 11, 1955); Selenium up to 0.6% Swiss patent specification No. 275 201; Lead up to 0.5% 30 British Patent No. 587 320. 609 540/334 3.66 © Bundesdruckerei Berlin