CH268221A - Alloy. - Google Patents

Description

Alloy. The subject of the present invention is an alloy having a mechanical resistance band with high tinting.

The development of thermal machines, especially gas turbines and engines, requires more. in addition the manufacture of factory elements presenting a Brande mechanical resistance < at high temperature. Several alloys have already been proposed for this purpose; Their use, however, remains very limited, either because their hot working is not possible, or because they become fragile after prolonged exposure to high tenacity. Indeed, a particularity of highly alloyed ferretix alloys which makes the problem particularly difficult to solve is that the addition of components which increase the mechanical strength at high temperature leads to a reduction in the stability which results in alloys become brittle as a result of prolonged exposure to high temperature.

1, the need for an alloy which can be worked hot, of a mechanical resistance brand with a high temperature and which possesses good stability at said temperatures, must therefore be felt.

It has been noticed that the addition to the alloys of erreul au ehronia and Bobalt of small (liiantites and without the right proportions of tungsten and at least one metal of group <B>111</B> of the periodic table Binding of elements (possibly also of one or more elements such as niobium, tantalum, titanium and va anadium) causes a remarkable -mentation of the mechanical resistance to, <B>,</ B> -i-rin high temperature without impairing the stability The present invention relates to an alloy, since it is aterized in that it contains, by weight, from 10 to 30% of chromium, from 10 to 45% of Bobalt , from 0.5 to 15% of tungsten, at least one metal from group III of the periodic table of the elements, the content of the alloy in ee or in inetaui es being comprised between 0.01 and 3% , manganese in proportion not exceeding ?,'o, silicon in proportion not exceeding 1/o, carbon in proportion not exceeding 1%, nitrogen in proportion not exceeding not exceeding 0.25%, and iron, in a proportion of less than 5%.

The metauz of the RTI group ID="0001.0274" WI="5" HE="4" LX="1500" LY="1717"> III of the periodic table of the elements which fall more particularly into the line of the eonipte are boron and aluminum.

In some cases, the alloy of the invention may also contain 0.5 A. `? % titanium, 0.5 to 7% niobium or tantalum, or 0.5 to 7% total Au. at least two of the following elements: niobium, titanium and tantalum, the titanium content being at most 2 0/0.

The alloy may also contain up to 75% molybdenum, the most suitable molybdenum content being, however, between 0.5 and 51%. When the alloy does not contain molybdenum, its tungsten content is preferably greater than 7.51%. On the other hand, if molybdenum is present, the tungsten content will preferably not exceed 1011/o.

In general, the alloy will also contain small amounts of unavoidable impurities. By adhering to the composition data indicated above, one can obtain alloys which can be easily forged, welded and machined and whose mechanical strength and stability at high temperature (370 C and more) are excellent. Parts of machines made of such alloys can work under high stress For a long time up to 648 C or at higher temperatures (up to about 815 C) For short periods and without stress excessive.

To determine the qualities of a material at high temperature, a rupture test is carried out under the following conditions. Several samples of the material are each subjected to a different tensile stress at a determined temperature. The time necessary for the rupture to take place under these conditions is noted. The values obtained are plotted on a graph in the form of a curve indicating the stress which the material can withstand at said temperature and for any given time. It is thus possible to determine the stress which the material withstands for a Good time, for example 1000 hours, at the temperature for which the curve was constructed. This test Good practical information on the mechanical resistance of the matbiel. It also makes it possible to know if the material becomes fragile after prolonged exposure to the temperature of the test. The rupture of a fragile material will take place without elongation, Belle of a delicate material will only occur after Brande deformation.

The rupture test carried out according to the indications above shows the alloys in accordance with the invention have a high mechanical resistance at temperatures up to 815 C, and that, even at. At high temperatures, they have good flexibility.

Table I shows the characteristic values obtained with alloys in accordance with the invention constituting eronium-cobalt steels improved by the addition of molybdenum, tungsten, niobium and boge or aluminum, in the various proportions indicated in this table. The repoi-your results are those of samples of eonforme alloys. the invention in the state of the art, subject to the invention. the breaking stress test at 815"<B>C</B>, the processing stress being 1750, `?100, ?450 and. `ü800 lig/eiil`. time needed to break the sample in very severe conditions is given in hours.

Exposure: approximately 1.5 /,;, Mn and 0.5,6 Si, Number of hours at the nitrogen uel (in a proportion not exceeding 0.25,@) produces failure at 815a D and the constituents indicated below, the balance being iron and under the stress indicated Dr <B>% CO</B> %Mo % W <B>%</B> Gb 0/a B <B><U>% AI %(]</U></B> 1250 2100 2800 kg/cm= kg/cm kg/cm' <B>1.8, 5</B> 3> 4 4 - 0.51 <B>1</B > 0.08 164 *e <B>* 11</B> 20 35 2 10 - 0.57 - 0.11 1483 787 18.5 35 3 10 - 0.55 - 0.07 825 18.5 35 - 10 - 0.61 - 0.09 1992* 556 18 40 - 15 - 0.55 - 0.07 460(a) 148 18 40 - 15 - 0.52 - 0.84 285 1.8 40 - 15 - 0.63 - 0.12 285* 1.8 40 - 15 -- 0.62 - 0.07 2184 399(a) 169 18 40 - 15 - 1.3 - 0.05 2160` 235 18.5 35 4 4 1 0.5 <B>1</B> - 0.10 97.7 195 ** 18.5 35 4 4 1 - 1 0.11 1<B>1</B>_3 14 18 40 3 10 1 0.5 - <B >0.1()</B> 451 18 40 - 15 1 0.5 - 0.10-i" 443 @" no break *@K no test (a-) test for a stress of. 2450 kg/em@ The values given in the above table clearly show that the alloys in accordance with the invention are able to withstand, without fracture, high stresses, high temperatures for a prolonged time.

During the production (of the alloys according to the invention, the proportions indicated must be carefully observed, taking into account the way in which they affect the qualities of the alloy and the applications. - auxqtial tions the alloy is intended For example, if the alloy must be sold, the carbon content may exceed 0.35 O/o, but if it must be worked hot, it is hazardous desirable which does not exceed 0.35% and, preferably, 0.20/n.

Likewise, the proportions of molybdenum, tungsten, niobium, tantalum, titanium, aluminum and boron have a marked influence on the ability of the alloy to be heat-worked and welded. The most appropriate upper limit for niobium and tantalum is 5%. A very high proportion of one of these elements has a detrimental effect on the heat workability of the alloy and on its weldability, especially on this latter property. The alloys eom.pris dann los given eomposition limits can be welded eouremment by] eommunes methods of welding, for example are eleetric, oxyaeetvlenique welding, with metal of appoi ~ t or. by eontaet. The welds obtained are sound and resistant, there is no increase in the brittleness to the right of the weld or its surroundings. These welds retain their strength even at high temperatures. However, if 1a. The proportion Tun of these elements is too high, the strength of the welds is generally affected and decreases at high temperature. Likewise the proportion of cobalt is important, it must be sufficient for the material. sofft a stable atistenitic alloy.

The amount of nitrogen in the alloy, within the limits given, is important, the nitrogen having a favorable effect on the stability of the alloy at high temperature. The alloys conforming to the invention can be worked hot, factories, sodas and balls, and possessing a high mechanical resistance to temperatures up to about 815 C, are doped particularly indicated for the manufacture of articles such as ele- components of superchargers, gas turbines, reactors and other devices that have to withstand high mechanical stresses at low temperatures. The fact that they do not become fragile after prolonged exposure to high temperatures makes them particularly suitable for devices where safe operation is essential.

Claims (13)

CLAIM: Alloy having a high mechanical resistance, characterized in that it contains, by weight, from 10 to 30% of elirome, from 10 to 45% of cobalt, from 0.5 to 151/o of tungsten , at least one metal from group III of the periodic table of the elements, the content of the alloy in this or these metals being between 0.01 and 3%, of inanganese; in a proportion not exceeding 2%, of silicon, in a proportion not exceeding 10/0, of carbon, in a proportion not exceeding 1%, of nitrogen, in a proportion not exceeding 0.25 %, and iron, in a proportion of at least 5%. SUB-CLAIMS 1. Alloy according to claim, characterized in that it contains, as a metal from group III of the. periodic table of the elements, boron, in a proportion not exceeding 0.7%. 2. Alloy according to claim, carae- teris6 in that it contains, as metal of mroupe III of the periodic table of the elements, (1e 1'altiminium, in a proportion of at least 0.5%. 3. Alloy according to claim, characterized in that it contains, as chi group III metals of 1a. periodic table of elements, boron and ahiminium, the boron content not exceeding 0.7%. 4. Alloy according to claim, characterized in that it additionally contains from 0.5 to 7% niobium. 5. Alloy according to claim, characterized in that it additionally contains from 0.5 to 7% tantalum. 6. Alloy according to claim, earac- t6rise in that it additionally contains 0.5 A, 2% titanium. 7. Alloy according to claim, characterized in that it additionally contains from 0.5 to 7% in total of niobium and tantalum. B. Alloy according to the claim, characterized in that it additionally contains 0.5 ä. 7% total niobium and titanium, 1a. titanium content not exceeding 2%. 9. Alloy according to 1a. claim, characterized in that it additionally contains from 0.5 to 7% in total of tantalum and titanium, the titanium content not exceeding 2%. 10. Alloy according to claim, characterized in that it additionally contains from 0.5 to 7% in total of niobium, titanium and tantalum, the titanium content not exceeding 2%. 11. Alloy according to 1a. claim, characterized in that it contains 7.5 to 15% tungsten. 12. Alloy according to claim, carae- teris6 in that it contains molybdenum, in a proportion not exceeding 7.5%. 13. Alloy according to 1a. claim, carae- terise in qii'il contains at most 0.3.5% ca.rbone.