DE1231907B - Use of a kneaded and aged nickel-chromium-cobalt alloy for objects with high impact strength - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

C22c

German class: 40 b - 19/04

Number:
File number:
Registration date:
Display day:

1231907
J21225VI a / 40b
January 29, 1962
5th January 1967

The German Auslegeschrift 1 217 627 specifies the use of a kneaded and aged nickel-chromium-cobalt alloy with 10 to 20% cobalt, 11 to 16% chromium, 1.5 to 7% molybdenum, 0.1 to 0.2% carbon, 0.01 to 0.1% zirconium, 0.005 up to 0.05% boron, 6.3 to 14.2% (Al + Ti) in the ratio 0.7 <Ti: Al <1.0, the remainder nickel, with the proviso that the total content of the Alloy of aluminum plus titanium according to the chromium and molybdenum content of the alloy the following relationship is coordinated:

(% Mo) - [0.15 (% Cr) - 2.7] - 0.9 (% Cr) + 23.5

<(% A1) + (»/" TO

< ( ⁰ I ₀ Mo) - [0.15 - (% Cr) - 2.7] - 0.9 (% Cr) + 25.6.

These alloys are particularly suitable for purposes in which a service life in the creep test at 1000 ° C and 11 kg / mm ² load of at least 50 hours is required.

British patent specification 814 029 already discloses a heat-resistant and corrosion-resistant alloy with 7.5 to 15% chromium, 5 to 40% cobalt, 7 to 10.5% titanium plus aluminum at a ratio of Titanium to aluminum from 0.6 to 1.4, 0.005 to 0.1% boron, 0.05 to 0.5% carbon, 0 to 15% molybdenum, 0 to 0.8% silicon, 0 to 1% manganese, 0 to 10% iron, 0 to 0.2% zirconium, remainder nickel known, which is suitable as a material for the production of castings. Furthermore is from the British patent specification 733 489 a similar nickel-chromium-cobalt alloy known which is hardenable and whose Total aluminum and titanium content for good forgeability in the absence of Molybdenum must not exceed 8%. With a molybdenum content of 5%, for example, the In contrast, the total aluminum and titanium content does not exceed 7%.

Finally, from British patent specification 715 140, another is corrosion-resistant at high temperatures and nickel-chromium-cobalt alloy, which has good creep rupture strength, are known from 10 to 25% chromium, 1.8 to 4.0% titanium, 0.5 to 4% aluminum, 0 to 25% cobalt, 0 to 10% iron and 0.03 to 0.15% carbon depending on the cobalt content, the remainder being nickel. This known alloy can also up to 1% silicon, up to 2% copper, up to 10% molybdenum, up to 10% tungsten, up to 5% niobium and / or Contains tantalum and / or vanadium, up to 0.3% zirconium and up to 0.05% boron.

The object on which the invention is based now consists in the alloy according to the main patent use of a kneaded and aged
Nickel-chromium-cobalt alloy for objects with high impact strength

Addition to registration: M 45708 VI a / 40 b -
Interpretation document 1217 627

Applicant:

International Nickel Limited, London

Representative:

Dr.-Ing. G. Eichenberg

and Dipl.-Ing. H. Sauerland, patent attorneys,

Düsseldorf, Cecilienallee 76

Named as inventor:

Ernest James Bradbury, Solihull, Warwickshire

(Great Britain)

Claimed priority:

Great Britain January 30, 1961 (3533)

registration continues to improve and in particular its notched impact strength without impairing the To increase creep rupture strength. According to the invention, the carbon content of the alloy is below 0.1%, preferably below 0.08 or 0.05%. Carbon-free alloys can be practically do not produce, so that the carbon content should be in the range of 0.005 to 0.01%.

It was found that by reducing the carbon content, the impact strength of the Alloys according to the main patent application at high temperatures without impairing the creep strength can be increased considerably in the temperature range from 900 to 1000 ° C. This was so Surprisingly, when based on previous experiments with nickel-chromium-cobalt alloys the It was believed that in view of adequate creep rupture strength and deformability at high Temperatures a carbon content of at least 0.1% is required.

So the service life and the elongation decreased in a series of tests with a known alloy, the 18.7% chromium, 16.0% cobalt, 2.6% titanium, 1.3%

609 750/351

Aluminum, 0.003% boron and 0.05% zirconium, when the carbon content was reduced according to the values in Table I. Before the creep test, all alloys were subjected to an 8-hour solution heat treatment at 1080 ^° C. with subsequent air cooling and 16-hour hardening at 700 ^{° C.} The tests were carried out under a load of 33 kg / mm ² at 750 ° C.

Table I.

Carbon content
% Service life
hours strain
% 0.15
0.09
0.03 222
132
35 4.6
4.2
1.9

Notched impact strength at high temperatures is of considerable concern when using the alloys to be used for the manufacture of rotor blades for gas turbines. There is a risk that the blade with the turbine housing or with foreign bodies passing through the housing in Touch comes. An increased notched impact strength is therefore very advantageous.

The alloys according to the invention preferably contain 14.2 to 15.8% chromium, 14 to 20% cobalt, 3.5 to 5.5% molybdenum, 3 to 4.6% titanium and 4 to 5.4% aluminum, with the sum of the titanium and aluminum content is between 7.75 and 9.5% and the titanium-aluminum ratio is 0.7: 1 to 1: 1, 0.01 to 0.2% zirconium, 0.005 to 0.05 % Boron, the remainder nickel including impurities. The contents of silicon, manganese and iron present as impurities should be as low as possible. Appropriately, both the silicon and the manganese content should not exceed 0.5% and the iron content should not exceed 1%.
The alloy according to the invention advantageously consists of 0.005 to 0.1% carbon, 14.2 to 15.8% chromium, 14 to 16% cobalt. 3.5 to 4.5% molybdenum, 3 to 4.1% titanium and from 4 to 5.1% aluminum, the sum of the titanium and the

ίο the aluminum content is between 8.2% and 8.7% and the titanium-aluminum ratio 0.7: 1 to 1: 1 0.01 to 0.1% zirconium, 0.005 to 0.02% boron, the remainder nickel including impurities.

The alloys are preferably melted in a high vacuum, for example at approximately 10 ^-3 Torr, and, if necessary, also cast.

Regardless of whether the alloys are vacuum melted or not, it is advantageous to vacuum refine them by keeping them in the molten state under vacuum for at least 5 minutes. A useful Vakuumfeinung is that the melt at 1500 ⁰ C under a pressure of not more than 2 x 10- ¹ Torr is maintained for 90 minutes.

The alloys are particularly useful for as-wrought use.

The improved impact strength of a low carbon alloy according to the invention Compared to similar high carbon alloys, the following Investigation shown.

Two alloys with the composition given in Table II below were produced. The rest consists of iron and impurities.

Table II

alloy
No. C. Cr Co Mon Ti Al Zr B. 1
2 0.06
0.14 13.9
14.7 15.2
14.7 3.7
3.45 3.9
3.93 5.15
4.98 0.03
0.035 0.019
0.016

Samples of both alloys were produced from forged bars, which were ^{annealed at 1200 °} C., cooled in air, annealed again for 6 hours at 1050 ^° C. and then again cooled in air. The alloy no. 1 had a notched impact strength (Charpy V sample) of 0.76 mkg / cm ² at 900 ° C., compared to a value of 0.56 mkg / cm ² for alloy no. 2. In a creep test at 980 ° C under a load of 11 kg / mm ² , Alloy No. 1 broke after 186 hours, and the elongation was 6%. In contrast, alloy No. 2 had a service life of 161 hours and an elongation of 9%.

Even better values can be achieved with other heat treatments. Accordingly, were Alloys produced, the composition of which is given in Table III below. Of the The rest consists of iron and impurities.

Table III

alloy
No. C. Cr Co Mon Ti Al Zr B. 3 0.07 14.6 15.2 4.0 3.7 4.8 0.03 0.016 4th 0.15 14.9 15.1 4.0 3.5 4.9 0.03 0.018 5 0.06 14.9 15.1 4.1 3.8 4.8 0.04 0.021 6th 0.15 14.8 15.1 4.1 3.8 4.8 0.04 0.020 7th 0.06 14.3 15.1 4.0 4.0 5.4 0.03 0.023 8th 0.15 14.8 14.8 4.1 4.0 5.3 0.04 0.019 9 0.06 15.0 15.1 3.8 3.8 5.1 0.06 0.015 10 0.14 14.7 14.7 3.5 3.9 5.0 0.04 0.016

The alloys are to be compared with one another in pairs, e.g. B. No. 3 with No. 4 etc. The alloys with an odd number correspond to the invention, while the alloys with an even number correspond to the German Auslegeschrift 1 217 627 correspond. The values obtained after the heat treatment are in listed in Table IV below.

Table IV

alloy Notched impact strength Service life No. mkg / cm ² hours 3 1.56 239 4th 1.04 161 5 1.21 267 6th 0.96 227 7th 1.04 274 8th 0.51 309 9 1.25 170 10 1.04 142

It has further been found that in the alloys of the notched impact strength can be increased still further according to the invention is below 0.1 ° / ₀ lying carbon content, when the cobalt content is increased to over 20% with. At the same time, however, the service life is reduced so that the cobalt content must not exceed 25%.

The influence of an increased cobalt content on the notched impact strength and the service life result from the following Table V, which relates to heat-treated alloys with (apart from cobalt) refers to the following compositions:

0.05% C, 15% Cr, 4% Mo, 3.8% Ti, 4.7% Al, 0.05% Zr, 0.01% B, balance nickel including ^d5 impurities.

Table V

alloy Co Service life strain Notched impact strength No. % hours % mkg / cm ^a 11 15th 105 18th 0.95 12th 20th 154 20th 1.21 13th 25th 67.5 24 3.45 14th 30th 9 - 5.35

45

Claims (5)

Patent claims: 1. Use of a kneaded and aged nickel-chromium-cobalt alloy with 10 to 20% Cobalt, 11 to 16% chromium, 1.5 to 7% molybdenum, 0.1 to 0.2% carbon, 0.01 to 0.1% zirconium, 0.005 to 0.05% boron, 6.3 to 14.2% aluminum and titanium in the ratio 0.7 <Ti: Al <1.0, balance nickel, with the total aluminum and titanium content of the alloy on the chromium and the Molybdenum content according to the equation ( ⁰ ZoMo) x [0.15 CY ₀ Cr) -2.7] - 0.9 (% Cr) + 23.5 <(% Mo) * [0.15 ■ (% Cr) - 2.7] - 0.9 (% Cr) + 25.6 is matched, for objects that have both a high notch impact strength ^{and a service life of at least 50 hours at 1000 0} C and 11 kg / mm ² load, according to the German Auslegeschrift 1 217 627, although the carbon content is 0.005 to 0.1 %, for the purpose of the German Auslegeschrift 1 217 627. 2. Use of an alloy according to Claiml, the carbon content of which, however, is 0.01 to 0.08% for the purpose of claim 1. 3. Use of an alloy according to Claiml, consisting of 14.2 until 15.8 0 /
/ 0 Chrome, 14th until 20th 0 /
/O Cobalt, 3.5 until 5.5 0 /
/ 0 Molybdenum, 3 until 4.6 0 /
/ 0 Titanium, 4th until 5.4 0 /
/ 0 Aluminum, 0.01 until 0.2 0 /
/ 0 Zirconium, 0.005 to 0.05% Boron, Remainder nickel including impurities, with the proviso that the total titanium and aluminum content between 7.75% and 9.5% and the titanium-aluminum ratio is between 0.7: 1 and 1: 1 for the purpose of claim 1. 4. Use of an alloy according to claims 1 to 3, but whose cobalt content is 20 to 25%, for the purpose according to claim. 5. Use of an alloy according to Claiml, consisting of 14.2 until 15.8 0 /
/ 0 Chrome, 14th until 16 0 /
/ 0 Cobalt, 3.5 until 4.5 0 /
/ 0 Molybdenum, 3 until 4.1 % Titanium, 4th until 5.1 ' Vo Aluminum, 0.01 until 0.1 % Zirconium, 0.005 until 0.02% Boron, Remainder nickel including impurities, with the proviso that the total content of titanium and aluminum is 8.2% to 8.7% and the titanium-aluminum ratio 0.7: 1 to 1: 1 for the purpose of claim 1. Considered publications:
British Patent Nos. 715 140, 733 489,
029. 609 750/351 12.66 © Bundesdruckerei Berlin