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Publication numberUS3723077 A
Publication typeGrant
Publication dateMar 27, 1973
Filing dateApr 21, 1970
Priority dateApr 21, 1970
Publication numberUS 3723077 A, US 3723077A, US-A-3723077, US3723077 A, US3723077A
InventorsF Frehn
Original AssigneeDeutsche Edelstahlwerke Gmbh
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Sintered alloys
US 3723077 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

United States Patent US. Cl. 29-182.7 7 Claims ABSTRACT OF THE DISCLOSURE Sintered alloys are prepared consisting of 50 to 90% of (1) a hard carbide alloy containing 10 to 70% titanium carbide and 30 to 90% steel alloy and (2) 10 to 50% ceramic which is insoluble in the matrix.

The invention is concerned with a powder metallurgical method of producing alloys by pressing and sintering from metal carbides, especially titanium carbide, a steel alloy and ceramic material.

The problem, which is the basis of the invention, is the creation of a material which is specifically light, mechanically poor or unworkable, i.e., hard and resistant to Wear at adequate toughness, its shape is not lost at very high heat action and adequately withstands temperature change. The objects produced from the materials of the invention should, above all, not be able to be separated mechanically, e.g., by means of a grinding wheel, they should not be piereeable and should not be cuttable, by a cutting torch to a temperature of about 2000 C. These properties are required, for example, of materials for armor plate used to produce safes for money and documents.

The steels used for these purposes until now only very unsatisfactorily fulfill the above required conditions.

According to the invention, there is proposed a better material which fulfills the above named requirements. The invention comprises a sintered alloy consisting of (1) 50 to 90 weight percent of hard carbide alloy consisting of 10 to 70 weight percent titanium carbide and 30 to 90 weight percent steel alloy and (2) 10 to 50 weight percent ceramic which is insoluble in the matrix.

The production of the sintered alloy of the invention takes place by grinding preliminarily crushed titanium carbide and steel alloy powder with addition of a grinding agent to a particle size of about 2 to 3 microns. Instead of the finished steel alloy, there can also be ground with the titanium carbide the individual components. After separation of the grinding liquid, crushed ceramic is added, mixed with the titanium carbide and steel alloy powder, pressed and sintered at a temperature of 1350 to 1450 C.

Up to 40 weight percent, e.g., 10 to 40% of the added amount of titanium carbide and steel alloy powder can be replaced by ground chip's of a sintered hard carbide alloy from titanium carbide and steel alloy of the same composition. In this manner, it is possible to make further use of the resulting scrap from hard carbide alloys.

The ceramic added in an amount of 10 to 5'0 weight percent can consist of metal oxide, e.g., MgO, BeO, Zr0 or preferably A1 0 It is also possible to use boron carbide or silicon carbide as the ceramic component, of course, the individual carbide powder particles must be provided with a preeminently ceramic coating to prevent the hard carbide alloy from going into solution. Mixtures of compounds can also be added as ceramic components. Those ceramic or carbide components fulfill the requirement that they are not soluble in the hard carbide alloy matrix.

The particle size of the ceramic portion added in powdered form to the titanium carbide and steel alloy powder should lie in the order of magnitude of 0.5 to 20 mm., preferably 2 to 5 mm. At such particle size of the ceramic, there results a good and adequately fine distribution of the ceramic in the matrix and there is formed the desired resistance against mechanical working and flame cutting.

A portion of the titanium carbide in the sintered alloy of the invention can preferably be replaced by all together 50 weight percent of one or more metal carbides. For this purpose, the carbides of chromium, molybdenum, vanadium, tantalum, niobium, tungsten or hafnium especially are sintered. When such additional carbide is employed, it can be used in an amount of as little as 10 Weight percent of the titanium carbide.

The sintered alloys of the invention are sintered on account of their depicted properties, especially for armored plate from which money and document safes or the like are produced. The armored plate produced from the sintered alloys of the invention can, moreover, preferably be plated on one or both sides with a metal layer, preferably stainless steel plate. Thereby the toughness can be improved and besides an optically pleasing form can be produced. Moreover, if it is not important that the plates be outwardly plated with steel or another metal, they can be placed on the inside. This makes dilficult burglary attempts. Each stainless steel layer can be 3 to 50 mm. thick and the armor plate 10 to 60 mm. thick.

The use of the sintered alloys of the invention for armored plate is only given as an example, they can be installed everywhere with advantage where high hardness combined with adequate toughness and a high heat resistance, as well as resistance to change in temperature are necessary.

Unless otherwise indicated, all parts and percentages are by weight.

In an example according to the invention, tests with 15 mm. thick plates were made of a sintered alloy from (1) 60% hard carbide alloy from 33% titanium carbide and 67% steel alloy made from 3.0 Cr, 3% M0, 0.4% C, balance iron and (2) 40% A1 0 of 2 to 4 mm. particle size, covered on both side's with 5 mm. thick plates of alloyed steel have shown that it is not possible to create holes or cuts by means of diamond wheels, hard metal drills, or acetylene torches. Besides the separating wheels, hard metal drills and burner nozzles became glowing red and lost their ability to function.

According to the size of the ceramic additive, the specific weight of the sintered alloy of the invention is between 4 and 5 g./cm. In the annealed condition, the hardness value is from 40 to 45 HRG and in the hardened condition it reaches over 70 HRC.

Additional examples of suitable sintered alloys are set forth below:

EXAMPLE A (l) 60% hard carbide alloy, consisting of 50% titanium carbide and (2) 40% A1 0 particle size 23 mm.

3 EXAMPLE B l) 60% hard carbide alloy, consisting of 33% titanium carbide and 67% steel alloy, consisting of Percent Mo 6.0 Ni 15.0

Al 0.75 Co 9.0 Ti 0.6 B 0.02 Fe Remainder and (2) 50% A1 particle size 2-3 mm.

EXAMPLE C (1) 70% hard carbide alloy, consisting of 70% titanium carbide and 30% steel alloy, consisting of Percent Cr 18.0 N1 12.0 Cu 1.0 Cb 0.5 B 0.02 Fe Remainder and (2) 30% A1 0 particle size 2-3 mm.

EXAMPLE D (1) 90% hard carbide alloy, consisting of 60% titanium carbide and 40% steel alloy, consisting of Percent Cr 14.0 Mo 14.0 Cu 0.54 W 3.40 B 0.015 Fe Remainder and (2) A1 0 particle size 1-2 mm.

EXAMPLE E (1) 60% hard carbide alloy, consisting of 33 carbide in form of WC/TiC 50:50 67% steel alloy, consisting of Percent Cr 3.0 Mo 3.0 C 0.4 Fe Remainder and (2) 40% A1 0 particle size 2-3 mm.

4 EXAMPLE F (1) hard carbide alloy, consisting of 50% carbide inform of chromiumcarbidetitaniumcarbide (50% Cr C and 50% TiC) and 50% steel alloy, consisting of Percent C 0.9 Si 1.0 Mn 2.9 Cu 0.8

Fe Remainder and (2) 30% A1 0 particle size 2-3 mm.

What is claimed is:

1. A sintered alloy consisting essentially of (1) 50 to 90% of a matrix which is a hard carbide alloy consisting essentially of (a) a mixture of 10 to 70% of titanium carbide or a carbide according to (a) wherein up to 50% of the titanium carbide is replaced by another metal carbide and (b) 30 to 90% of steel alloy; and (2) 10 to 50% of aluminum oxide having a particle size of 0.5 to 20 mm.

2. A sintered alloy according to claim 1 wherein a portion of (1) up to 40% consists of ground chips of a sintered alloy of 10 to 70% titanium carbide and 30 to 90% of steel alloy.

3. A sintered alloy according to claim 1 wherein the carbide is a mixture of titanium carbide and the carbide of a metal of the group consisting of chromium, molybdenum, vanadium, tantalum, niobium, tungsten and hafnium.

4. Armor plate for protecting valuables composed of the alloy of claim 1.

5. Armor plate according to claim 4 having on at least one side a coating of steel plate.

6. Armor plate according to claim 5 having a thickness of 10 mm. and having on both sides a 5 mm. coating of rust free steel alloy.

7. A sintered alloy according to claim 1 composed of (a) 60% of a mixture of (1) 33% titanium carbide and (2) 67% steel alloy composed of 3% Cr, 3% M0, 0.4% C, balance Fe; and (b) 40% A1 0 References Cited UNITED STATES PATENTS 3,249,407 5/ 1966 Alexander et al. 29182.7 3,143,413 8/1964 Krapf 203 3,542,529 11/1970 Bergna et al. 29182.5 3,493,351 2/1970 Bergna et al 29-182.5

CARL D. QUARFORTH, Primary Examiner B. HUNT, Assistant Examiner US. Cl. X.R.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3966423 *Nov 6, 1973Jun 29, 1976Mal M KumarGrain refinement of titanium carbide tool steel
US3967935 *Sep 5, 1973Jul 6, 1976Deutsche Edelstahlwerke Gesellschaft Mit Beschrankter HaftungCorrosion and wear resistant steel sinter alloy
US4030427 *Oct 30, 1974Jun 21, 1977The United States Of America As Represented By The Secretary Of The NavyArmor plate
US4365997 *May 7, 1980Dec 28, 1982Fried. Krupp Gesellschaft Mit Beschrankter HaftungWear resistant compound material, method for manufacturing it and use of such compound material
US4561272 *Jul 5, 1984Dec 31, 1985The United States Of America As Represented By The Secretary Of The NavyPadlock shackle
US4792353 *Oct 10, 1986Dec 20, 1988Massachusetts Institute Of TechnologyAluminum oxide-metal compositions
US5154984 *Dec 6, 1991Oct 13, 1992Sumitomo Metal Industries, Ltd.Metal-ceramic composite
US5358545 *May 4, 1993Oct 25, 1994Carmet CompanyCorrosion resistant composition for wear products
EP0263427A2 *Sep 30, 1987Apr 13, 1988Ufec Universal Fusion Energie Company S.A.Metal-ceramic composite material and process for its manufacture
EP0263427A3 *Sep 30, 1987Sep 27, 1989Stellram S.A.Metal-ceramic composite material and process for its manufacture
Classifications
U.S. Classification428/554, 75/242, 419/17, 75/233, 428/926, 419/19, 75/235, 109/82
International ClassificationC22C29/06, C22C29/12
Cooperative ClassificationC22C29/12, Y10S428/926, C22C29/067
European ClassificationC22C29/06M, C22C29/12