DE1533324B1 - USE OF A HIGH STRENGTH COBALT ALLOY AS A MATERIAL FOR OBJECTS WITH A HIGH DAMPING CAPACITY - Google Patents

Description

The invention relates to and relates to a material for the existence of such alloys with high damping capacity and '.'; Turning of alloys of the 'claimed to high mechanical strength. composition as materials for objects with

Machine parts, for example turbine blades, with a high damping capacity are not taken into account, often show in operation after repeated loading 5 This property of the claims according to the invention e.g. when shaking and vibrating, set alloys is therefore from the proven and Due to shock and sound vibrations, prior art not known and not either fatigue fractures. That is why it is obvious.

desirable, by damping the vibration, the serve for a better understanding of the invention

Bring stresses to a minimum. This io drawings.

is achieved in that the machine parts from F i g. 1 is a diagram showing the relationship

a material with a high damping capacity ·, between Vickers hardness and yield point as well as the z. B. a material that the internal friction damping ability of a process according to the invention Can absorb vibrations, made the alloy compared with the similar curve the mechanical energy in heat 15 of a stainless steel with 13% chromium content is converted. The aforementioned ability is limited;

the development of very high vibration loads. Fig. 2 is a diagram showing the relationship

chings of the material, the durability of the material between dampening capacity and maximum bending increased in the case of severe vibrations. - · stress of corresponding samples of the inven-

Such a material with a high damping alloy used according to the invention shows, stainless steels with a 13% strength. The cobalt alloys used according to the invention

Chromium content, such as AISI 403 steel (composition: genes are characterized by having a higher C <0.15, Mn <1.00, Si <0.50, S <0.030, Cr 11.50 cobalt content than: those-known for this purpose up to 13.00), as well as cobalt alloys with a high cobalt alloys, with the addition of cobalt content, such as NIVCO-10 (described in »Ma- 25 Molybdenum and / or Tungsten the same hardening magnetic properties of Metals and Alloys "ASM [1959], gives properties. The addition is made with pp. 251 to 253; Composition: Co 72%, Ni 23%> iron, which with the usual impurities, remainder Ti, Al; mechanical properties: 0, 2%. Yield, for example, remaining carbon, phosphorus ^{limit 77 kg / mm a} , tensile strength 112 kg / mrn ^, amounts of stretch and sulfur, as well as those of the usual voltage 30%, necking at break 35%). like manganese and silicon, however, such materials have references that are at best impure. The aforementioned elements do not contribute to a maximum yield strength of 80 kg / mm ² . In doing so, the desired alloy properties can be achieved and the yield strength of stainless steel should preferably be kept to a minimum with a 13% chromium content by heat treatment. "·.

to be improved. In this case, however, the steel that is treated together loses a large part of its damping properties of the legibility used in accordance with the invention a. struggle within the limits specified below

The aim of the invention is to find a rich listed: material which can avoid the shortcomings of the known cobalt alloys. 4O TT- 1 ^ '' ■■■ · Λ J. - ™ SI ■ 1, - χ J

This goal is achieved according to the invention by the ^cobalt · at least 60 percent by weight or

A twist of a high-strength cobalt alloy, consisting of a maximum of 75 percent by weight

from 60 to 75 percent by weight cobalt, 0.5 to 4.0 Ge molybdenum or

weight percent molybdenum and / or tungsten, 20 to tungsten or

39 percent by weight iron and from 0.003 to 0.005 Ge 45 _em mixture

weight percent boron, dissolved. . ■ '-. the same ..... at least 0.5 percent by weight or

According to the invention, the carbon content fe is at most 4 percent by weight

The alloy used should preferably be at most

0.06 percent by weight, the iron being the carbon ... at most 0.06 percent by weight may have the usual impurities. This is 5 °

are composed of phosphorus and sulfur as well as deoxy manganese at most 0.5 percent by weight

agents such as manganese and silicon.

According to a further preferred embodiment silicon at most 0.5 percent by weight

According to the invention, a high-strength cobalt alloy '_,,, "," ... "_. ,

used, in which the usual 55 phosphorus ..... maximum 0.010 percent by weight

impurities in an amount of at most 0.5 _{wt. sulfur} at most 0.010 percent by weight

percent by weight manganese, at most 0.5 percent by weight

cent silicon, at most 0.010 weight percent phos-iron remainder

phosphorus and not more than 0.010 percent by weight sulfur,

based on the cobalt alloy. 60

From US Pat. No. 2,215,459, the cobalt content of the alloy should be within the high strength cobalt alloys consisting of 58 to range from 60 to 75 weight percent, and 68% cobalt, 28 to 38% iron, 1.0 to 6% molybdenum because with a cobalt content of less and less than 0.05% carbon. From the 60 percent by weight the alloy in Zimmerdeutsche Auslegeschrift 1180 139 is also known 65 temperature would be extremely brittle, so that it would be suitable for the that boron additives as usual and permissible admixtures would be unsuitable for practical use. Should are to be considered. however, the cobalt content is over 75 percent by weight

However, these publications only describe the increase in a typical face-centered ku-

bische crystal structure, so that the yield strength of the Alloy is decreased.

Molybdenum and tungsten or a mixture thereof are intended to increase the hardening properties of the alloy; should the content of pre. If the elements mentioned are less than 0.5 percent by weight, the curing properties are impaired. This leads to a content of the aforementioned. Elements of more than 4 percent by weight to for. practical applications to hard alloys, 'so that the ductility and toughness thereof are substantially reduced. In addition, there is an addition of more than 4 percent by weight of molybdenum and / or tungsten after quenching, an increase in Hardness, which also creates a face-centered cubic crystal structure. '

The manganese and silicon content should not exceed 0.5 percent by weight each. The aforementioned elements are normal impurities occurring in iron, those in iron after it has been deoxidized remain and contribute nothing to the desired alloy properties. Because of this need the aforementioned elements to iron, which by means of ■ Melting is deoxidized under vacuum or another process, 'so that there is no silicon and Contains manganese, not to be added. ; According to general practice, both the .'Phosphorus and sulfur content up to a maximum 0.01 percent by weight reduced.

The iron content of the cobalt alloys used according to the invention depends primarily on the cobalt content and less on the amount of the other constituents of the alloy. The the varies Alloy to supplement the amount of iron added between 20 and 39 percent by weight. That of the alloy the added amount of iron aims to maintain the body-centered cubic crystal structure of the base metal. In the case of a body-centered cubic crystal structure of the base metal, the sliding system is dominant in the dislocation, so that the extension • availability and toughness of the alloy can be increased.

The alloy contains 0.003 to 0.005 percent by weight boron. The addition of boron improves the properties of the alloy by improving its ductility and toughness during tempering the alloy will not be adversely affected because the nucleation of precipitates occurs the grain boundaries is inhibited. ;

The alloys used according to the invention are subjected to a heat treatment. Initially is carried out by quenching in water or oil of a temperature of 950-1050 ⁰ C to room temperature and then tempering at a temperature between 450 and 65O ⁰ C for a period of .1 to 100 hours!

The alloys used according to the invention have a hardness of slightly less than 380 in the Vickers hardness test after quenching; included there is no excessive brittleness even at high temperatures. For this reason, the aforementioned alloys have good weldability. In addition, the alloys can be easily machined after quenching them the tempering takes place afterwards. The relatively low hardness of the alloys after Quenching has an easy processability of the same result. The temperatures required for tempering are not excessively high, so that the warping and warping of the machine parts • after starting them to a minimum is limited.

. Table 1 shows the chemical composition of some typical alloys used in accordance with the invention and the amount in percent by weight of the constituents thereof.

Table 2 lists the mechanical properties the alloys according to table !, which were subjected to a heat treatment, shown; it will pointed out that the alloys A three ver. have been subjected to various heat treatments; Table 2 shows the results obtained after various heat treatments. The samples were square bars of 40 x 40 mm forged from 30 kg blocks, taken. The alloys were melted in a high frequency induction furnace.

Tabel

alloy

No.

Co Mon C.
W. Chemical 2
B. 'together
C. Now (Ge
Mn weight process
Si -. nt)
P. S. 71.23 2.23 0.03 0.30 0.22 0.006 0.003 71.25 2.24 0.003 0.03 0.31 0.21 0.006 0.004 73.53 3.32 0.04 0.23 0.24 0.007 0.007 72.54 0.71 0.02 0.32 0.31 0.005 0.005 65.52 2.21 0.01 0.22 0.23 0.008 0.006 70.56 2.26 0.03 0.27 0.22 0.007 0.004 71.24 1.12 1.35 0.04 0.26 0.25 0.006 0.005

Fe

AI
A-2
A-3
B ..
C ..
D- ..
E ..
F ..
G..

rest

rest
rest
rest
rest
rest
rest

5 1 533 324 strain
(50 mm
Measuring length)
% 6th Notch impact
bend
strength**) Damping *
capability
(logarithmic
Acceptance) 13.6 3.2 1 as in Table 2 15.3 4.3 Fig. 2 Heat treatment *)
Tempering Mechanical properties 13.6 fracture
constriction
% 3.5 J shown Le
yaw
Nn 10 hours at 500 ° C Stretch limit,
Turn
(Offset)
kp / mm ² train
strength
kp / mm ² 15.2 49.1 3.4 0.015 A-I .... 2 stood at 500 ⁰ C 154.3 170.5 14.6 55.6 3.5 0.010 A-2 .... 1 hour at 600 ^° C 127.1 152.3 18.6 34.5 4.6 0.092 A-3 .... 10 hours at 500 ^° C 99.3 121.4 14.0 55.3 4.2 0.018 B. 3 hours at 500 ° C 149.2 163.1 14.3 52.5 4.4 0.013 C. 30 hours at 500 ^° C 153.2 172.4 13.2 56.2 4.7 0.012 D, 10 hours at 500 ^° C 103.2 119.3 51.2 E. 10 hours at 500 ^° C 148.3 168.0 52.1 F. 10 hours at 500 ° C 147.5 163.2 51.2 G 148.2 170.1

*) All samples were ^{quenched in oil from 1000 °} C. to room temperature and then tempered at the temperature given in the table.

**) Charpy impact strength with a 2 mm V-notch shape. Values in kp m / cm ³ .

It should be emphasized that the heat treatment has a very good tensile strength of the one used according to the invention Alloys granted, with elongation, drawing and Charpy notch impact strength tests at the same time the special properties of the alloy can be seen.

The damping properties of the alloys are shown in FIGS. 1 and 2 shown. As in the curves of fig. 1, in which the maximum damping capacity in logarithmic decrease <5 of the alloys are those that have been heat-treated to achieve adequate strength Alloys graphically on a logarithmic scale against Vickers hardness and yield strength shown. It can be seen that the damping ability of the alloys by far that of the known stainless steel with 13% chromium content. On the other hand, according to the invention Alloys used are subjected to a heat treatment, so that the mechanical strength and the hardness thereof far higher than the same properties of the 13% stainless steel Chromium content is.

The damping capacity was determined in accordance with the "Turbine-Blade Vibration due to Partial Admission" by R. P. K r ο ο η, in the "Journal of Applied Mechanics", December 1940, pp. A-161 to A-165, given instructions.

The curve in FIG. 1 was calculated after testing some samples of the alloys used according to the invention which were subjected to a heat treatment in order to achieve the desired properties. Curve B was calculated using the same method for testing several samples of a stainless steel with 13% chromium content, which was also subjected to a heat treatment to achieve the corresponding yield point and hardness.

In FIG. 2, the damping capacity (logarithmic decrease) of three samples AI, A-2 and A-3, which have the composition given in Table 1 and have been heat-treated as detailed in Table 2, are shown against the maximum bending stress in kg / mm ² graphically recorded.

It should be noted that the sample AI, which has a yield strength of 154.3 kg / mm ² j as shown in Table 2, has a very good cushioning ability although it is smaller than that of the samples A-2 and A-3 which have been heat treated to achieve a lower yield strength as compared to Sample AI.

From the foregoing it is clear that the cobalt alloys used in the invention have improved properties, with the high damping ability even after heat treatment to achieve a high yield strength and a high hardness is retained. It is also it is apparent that the alloys are easy to process after quenching them And that the heat treatment can be carried out without difficulty.

Claims (3)

Patent claims: 1. Use of a high-strength cobalt alloy, consisting of 60 to 75% cobalt, 0.5 to 4.0% Molybdenum and / or tungsten, 20 to 39% iron and 0.003 to 0.005% boron as material for objects with a high damping capacity. 2. Use of an alloy according to claim 1, which contains at most 0.06% carbon, to the Purpose mentioned in claim 1. 3. Use of an alloy according to claim 1 or 2, which contains the impurities customary in iron in an amount of not more than 0.5% manganese, not more than 0.5% silicon, not more than 0.010% Contains phosphorus and a maximum of 0.010% sulfur, based on the cobalt alloy, in addition to the in Claim 1 stated purpose. 1 sheet of drawings