DE1533256C3 - Heat-resistant alloy based on cobalt - Google Patents

Description

Technically appropriate material was approximately 0.37 mm per side after 594 hours. The corresponding Corrosion depths of the materials mentioned in the above examples are shown in the table summarized.

The 1000 hour creep rupture strength of the prior art material was approximately 740 kgf / cm ^{2 at a temperature of approximately 870 ° C.}

It can be seen from the table that the alloys according to the present invention, which relatively larger additions of chromium have excellent corrosion resistance at higher temperatures exhibit. It should also be noted that the breaking strength behavior in the above sense that of Materials that correspond to the state of the art, but with the remarkable advantage the corrosion resistance is added. The elongation at break of those mentioned in the table Materials is cheap compared to that of the prior art material.

The present invention accordingly provides novel and useful alloys, in particular very solid at high temperatures and also to oxidizing and sulfiding combustion gas components are resilient. They are therefore particularly suitable for the production of

ίο gas turbine parts, such as nozzle partitions, and likewise for other parts and devices that cause corrosion at high temperatures and / or are exposed to influences that cause oxidation. They can also be generally used in ovens as Use fans, runners or any other device that is exposed to similar extreme conditions is.

Tabel

C. Composition in percent by weight (1) Cr Y Chemical Analysis W. Fe Mn B. Co corrosion Corro Fatigue strength Temp. Time 0.23 28.9 0.05 8.4 0.65 0.40 0.0010 Remainder ² ) as a result sion CC) until oxidation depth 790 fracture
(Hours) IIUU U (mm /
Page) Bean 870 331.4 0.24 29.6 0.38 Ni 8.4 0.70 0.41 approximately Remainder ² ) approximately spru 980 1726.0 10.4 0.002 0.15 chung
(Bp / cm ² ) 790 1490.8 0.24 28.6 0.39 8.3 0.66 0.41 0.0011 Remainder ² ) Time 1400 870 505.3 at
game (dta.) approximately 700 790 1075.6 2 0.26 31.0 0.17 10.4 7.9 0.72 0.29 0.0025 Remainder ² ) 635 0.11 350 870 409.1 approximately 1400 870 970.4 10.5 0.12 700 35.2 3 635 (3) 1400 8.5 700 4th 609 1050 5 (3)

*) Components and impurities with lower proportions in the usual starting materials are approximately as follows: Phosphorus at 0.02 percent by weight; Sulfur at 0.02 percent by weight.

² ) remainder essentially cobalt.

³ ) Not checked.

Claims (1)

1 2 State-of-the-art statements are Claim: for example in »Journal of the Electrochemical Society ", Vol. 103, No. 8, by P f a 1 η i k a r et al, Heat-resistant alloy based on cobalt, entitled “High Temperature Scaling of Cobalt-Chro from 0.10 to 0.60% carbon, more than 26.5 to 5 mium alloys”, further explained.
35% chromium, 6.0 to 9.0% tungsten, 8.5 to 11.5% / a The present substances consist of a carefully Nickel, maximum 0.05% boron, 0.61 to 1.0% yttrium, well-made combination of various maximums 6.0% iron and the rest cobalt with the components, each of which is desired and common manufacturing-related impurities contributes to the properties achieved. Deviations in the including a maximum of 1% manganese and a maximum of ίο proportions of these components destroy this 0.04% phosphorus and / or sulfur. - critical balance and lead to materials, which leave something to be desired with regard to essential properties. For example, if the proportion of carbon sinks below the above value, the strength drops 15 in an undesirable manner. On the other hand, an increased carbon content affects both the This invention relates to novel and weldability as well as elongation at break and Appropriate alloys, which a suitable one reduces the resistance to oxidation. The additions to Have heat resistance and to oxidizing, nickel, iron and tungsten are related to oxysulfidizing and other combustion gases of high aodation and corrosion resistance are not particularly Temperature resistant. critical, but it is useful to It is known that machines that adhere to the drive-given quantity limits in order to utilize suitable power of combustion gases with higher mechanical properties. Boron gives better working efficiency temperatures to the alloy, ductility, if so desired, and more power output. However, it is also known, 35 If the boron content rises above the above-mentioned value, so that at such elevated temperatures the harmful, low-strength of many materials that form in the alloy decreases rapidly, with melting phases emerging. If one uses less of these to corrode very quickly, which is due to oxidizing yttrium than stated above, the oxy- or other corrosion-causing constituents in dation resistance decreases. It is practically difficult to return larger amounts of yttrium than the above-mentioned maximum air to the burned fuel or in the combustion 30. In gas turbines, which can be effectively melted down into the product. The temperatures of about 870 ⁰ C and at maximum values, the basic substance forming cobalt is known about HOO ⁰ C are operated, a comparison means that the oxidation and Sulfidierungsfestigkeit improvement of about 38 ⁰ C with respect to the corrosion contributes . Quantities of up to about 1.00% of the strength of the measures used in the construction can be assumed, but manganese is not a significant advantage in any of the materials. For example, deliberately added case. Other impurities, the increase in the operating temperature from about caused by phosphorus and sulfur, 820 to about 870 ⁰ C in a typical gas turbine is a maximum of about 0.04% each.
Increase in the output power by approximately 14% In the following, the invention is based on two and an increase in efficiency by 1 to 40 games. 5 percent B e i s ρ i e 1 e 1 to 4 It is the object of the present invention to provide novel and to supply suitable alloys, which in Alloys were produced, their supply devices such as gas turbines an essential composition in percent by weight due to the Allow the operating temperature to be increased. 45 Analysis of casting samples shown in the following table This task is solved by a heat-resistant one. The alloys were in the form of Alloy composed of 0.10 to 0.60 percent carbon; Pieces about 3 cm in diameter and about 13 cm greater than 26.5 to 35.0% chromium; 6 to 9% tungsten; Cast length. Of these were for testing purposes 8.5 to 11.5% nickel; a maximum of 0.05% boron; 0.01 to disks with a diameter of about 2.5 cm and about 1.0% yttrium; A maximum of 6.0% iron and the remainder cobalt 50 1.5 mm thick cut off and with a stand compared with the usual production-related impurities corresponding to the technology, worked. which had the following composition, the All contents are given in percent by weight. The remaining constituent was essentially cobalt: 0.23% It has been found that alloys containing carbon; 25.5% chromium; 10.5% nickel; 6.9% carefully controlled above metallurgical 55 tungsten; 0.82% iron; 0.007% boron and as an impurity -Composition have significant corrosion cleaning 0.54% manganese; 0.02% phosphorus; 0.02% are more solid, while at the same time they are one for the loading sulfur. It should be noted that this dem drove suitable creep rupture at high temperatures - no alloy corresponding to the state of the art Maintain strength and ductility. These substances are yttrium, which contains the present alloy also particularly useful because it easily gives 60 extremely advantageous properties, can be welded and therefore the production is entirely possible. Material samples of the above examples and enable differently shaped structures. a state of the. Technology corresponding above- The chromium content according to the invention of more than the mentioned material was exposed and tested with its side surfaces 26.5 to 35% is in direct contrast to the statements corresponding to a combustion gas flow in a small state-of-the-art device, whereby alloys with a chromium content of gas with an air-fuel weight ratio of more than 25% at higher temperatures in increasing 50: 1 and at a temperature of about 1100 ⁰ C dimensions should peel off and wear out. This was burned. The depth of corrosion of the state of the