JPS62167835A - Nickel base superalloy - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to modifying the composition of a nickel-based superalloy known as Waspaloy so that the alloy can be better welded.

BACKGROUND OF THE INVENTION The alloy on which the present invention is based is called waspa+oy, which was developed in the early 1950's for use in gas turbine engines. The nominal composition of this alloy is 19.5% Cr, 13°5% Co, 3.7
5%Mo, 3.0%TI, 1゜12%AI,
0. 00596B, 0. 006% C2 remainder N1
It is. Additionally, this alloy contains small amounts of impurities. The element with the highest content of such impurities is Fo (Fc
is approximately 1 in 396 melons (shown to be an essential component of aspaloy).

Nickel, the remaining element in waspalQy, typically costs several dollars per pound. Steel, on the other hand, is much cheaper than $1 per bond.

There is thus an economic incentive for Waspaloy manufacturers to increase Fe content M m to reduce their raw material costs. Another motivation is that superalloy scrap is contaminated with iron, an element that is more difficult to remove than scrap.
Since scrap is easily accessible by hand, this also makes Waspaloy more likely to contain iron.

13 waspa+oy recently supplied to applicant
The material was analyzed for Fc content. The average Fc content is 1
．． The minimum Fc content was 0.70%. These data are available for many commercial waspa+o
y meets the aforementioned criterion that iron is present in the material in an amount over about a material amount.

Waspaloy is used extensively in the gas turbine industry, often in forged form and sometimes in cast form. Waspaloy is especially 538-8
It is more potent than many other compositions in the 16°C range.

Traditionally, this alloy has been used in forged form, where it is curved or otherwise formed into useful shapes, and in cast form, where the shape is formed by casting.

In both forged and cast forms, complex shapes and tight dimensional tolerances are achieved by machining. Modern gas turbine engines include components with fairly complex shapes. Furthermore, in conventional engines, the presence of excess weight in the castings was tolerated, but in modern engines there is a strong demand to reduce their weight, so all It is necessary to remove excess material. Casting technology has also advanced so that complexly shaped parts can be cast to near final or net shape, thereby requiring little finishing. Additionally, the operating temperatures and stresses experienced have increased over previous years, increasing the need for stronger materials.

From these points, designers of gas turbine engines
The use of complex castings of compositions such as spaloy is being explored. A major drawback in manufacturing such complex parts is that Vaspaloy is prone to cracking during casting, and therefore only relatively few parts of complex shapes without cracking have been produced by IJaspaloy castings to date. Not obtained. The practical application of Waspaloy castings therefore relies on the ability to repair castings with f'fr pin cracks and similar defects by welding. It is also preferred that overlay welding be able to repair minor machining cracks in non-critical parts of the part if excessive material is inadvertently removed. but otherwise preferable WaSpalO)'
This has caused problems due to the fact that it does not have better weldability than conventional methods.

Waspaloy type compositions have been described in numerous US patents dating from US Pat. No. 2,570,193, filed in 1946. Examples of these U.S. patents include U.S. Pat.
．． No. 222, No. 3,166゜412, No. 3,20
No. 7,599, No. 3゜512.963, No. 3,6
No. 25,678, No. 3,723,107, No. 3,
No. 850,624, No. 4,110,110, No. 4
, No. 213.026 and No. 4,456,481.

In view of the large number of U.S. patents in this limited field of alloys, it is possible to achieve a variety of objectives (such as when more elements are added to or removed from the basic composition than in the past). It's not surprising that it is. In particular, U.S. Patent No. 3.166.412 is
This U.S. patent relates to castings formed from aI oy-type compositions, in which iron is an undesirable element and is therefore more than 0.5%, preferably 0.2%.
It is stated that it must not be present in an amount of more than 5%. However, the nature of the various problems caused by the presence of iron or the various advantages obtained by limiting the Fe content to the above-mentioned range is not described. Further, the above US patent does not mention welding or weldability.

Similarly, several US patents describe the addition of manganese to superalloys for purposes related to improving weldability, such as US Pat. No. 4,213,026.
No. 1 proposes adding 0.5 to 396 manganese to nickel-based superalloy welding wires to improve the welding process and reduce the occurrence of cracking in the heat-affected zone. There is. However, Figures 2 and 3 and Table 4 of this US patent show that Waspaloy does not always have sufficient weldability even when it is modified with manganese.

SUMMARY OF THE INVENTION According to the present invention, the Fe content, which is unavoidably high in commercial wHspaloy compositions, is limited to about 0.2% or less, preferably 0.1% or less, and 0°3 ~0.5%
of manganese, limiting the sulfur, bismuth, and lead contents to as low values as possible, and preferably keeping the aluminum and molybdenum contents at the lower end of Vaspaloy's normal composition range.
The oyR2 composition has been modified to be weldable in cast form.

The present invention will be described in detail below with reference to Examples.

In this specification, all percentages are by weight.

Example Waspa! Oy's commercial specifications allow up to 2% iron to be present. Although iron is tolerated in various superalloys, especially the early developed superalloys,
The alloy composition differs from other superalloys currently in use in that it allows Fe contents of the values mentioned above.

According to the invention, about 0.2
It has been found that the presence of more than % iron has a significant effect on the weldability of such compositions. Table 1 shows various types of cast Wa that were repaired by welding at the applicant's equipment.
The composition of parts manufactured by Spaloy is shown. Compositions 1-6 were found to have particularly poor weldability, while compositions 7-12 formed in accordance with the present invention were found to have excellent weldability. Weldability was evaluated by evaluating welds formed using TIG welding equipment for cracks and other defects. The most notable difference between weldable and non-weldable compositions is the Fe-Mm content. All weldable compositions contain less than 0.2% Fe, whereas all non-weldable compositions contain more than 1% Fe.
was a commercially available Vaspaloy material containing . One major aspect of the present invention is therefore the discovery that by limiting the Fe content to less than 2%, preferably less than 0.1%, a significant improvement in the weldability of waspatoy-type materials is obtained.

In addition to limiting the Fe content, 0.3-0.5%
Preferably, manganese is intentionally added in an amount of . Furthermore, it is preferable to limit the ruconium content to 0.02% or less, and furthermore, it is preferable not to intentionally add zirconium. Zirconium has traditionally been added to waspa+oy with the belief that it improves stress rupture properties, but extensive testing has shown that normal amounts of zirconium are intentionally added to gold-plated Vaspaloy materials. Was not containing zirconium
It was found that there is no difference in stress rupture properties between the paloy material and the paloy material.

Additionally, there are several elements that were generally considered in the prior art to be detrimental to weldability, such as sulfur, bismuth, and lead. These elements are known to segregate at grain boundaries, and either they themselves have low melting points, or they form low melting point 111 at grain boundaries, thereby causing substantial cracking. It is. Sulfur forms a nickel sulfide phase with a low melting point. The aforementioned manganese reduces the effect of sulfur by forming manganese sulfide at the grain boundaries, which has a much higher melting point than the iron sulfide that would occur if no manganese was included, but the sulfur content should be kept as low as possible. It is preferable to limit it to

Furthermore, bismuth and lead are themselves elements with low melting points that segregate at grain boundaries, and therefore it is preferable to limit the content of these elements to as low a value as possible. Control of the amounts of these elements is accomplished by forming the alloy from virgin material (i.e., pure form of the alloying elements) rather than using scrap or recycled material.

Yet another compositional modification that may be made to improve the weldability of WaSpaloy materials is to limit the aluminum and molybdenum content to about the lower half of the normal range for these elements in Waspaloy specifications. It is.

Although aluminum and molybdenum are both reinforcing elements, the inventors have determined that aluminum and molybdenum are both reinforcing elements, but that these elements are in the lower half of their normal ranges (e.g. 1-1.125% AI, 3.5-
4.2596Mo) has no significant effect on strength, yet improves weldability. Therefore, in the most preferred form of the invention, these elements are restricted to the lower half of their normal ranges. Table 2
shows the typical composition of conventional foundry Waspaloy materials and the composition range of the present invention. The composition range of the present invention is the composition range of the present invention in its most preferred limited form. The order of benefits obtained by the present invention is that limiting the iron content is the most important factor in improving weldability, adding manganese is the next most important factor, and adding zirconium is the next most important factor. is the third important factor, limiting the content of sulfur, bismuth, and lead is the fourth important factor, and the fifth important factor is limiting the content of aluminum and molybdenum. to the lower half of their normal range.

CCr Co 71 B Cu
NI Ma specimen! 0.05 19.
4t! , 6 3.1 0.002 0.0
78 M 0.5@t-20,06L9j13.
s3.10.0OfiO,0fil! IMO, 46 Hiromoto 3 0.07 19.4 13. ll 3.
4 0.0I O,086! Part i 1.1 sample 4 0.03 1g, 9 +4.8 2J
t O,OH2Q,025! ! J 0.02
1Lt5Llj12. tt, i book zero book 0.05 seven one book 6 zero zero book zero kyohon chapter 0.22 book 7 0.06 19.2 12.3 3.
1 0.005 (0,051blSO,
+3 Okimoto 8 0.059 1L9 124 3.
G G, Ol <, 05 Kumayo 0.3
9WA book 90.0819.11513.512.99Q
,006Q,02!4HO,+5 sample 10 0. OB
19JS 13.3 2.98 0.004
0.01 Mt part O0 Tsuge specimen 11 0.07
+9.67 13.44 199 0.005
G, 02 Remainder 0.5 Specimen 12 0.0
1i 19.63 1L51 199 G, f
roll 0.02 remaining NG, 45 zero not analyzed St 1 Medical ΔL Mutual L Fe Seen L
肱 星書 連 0.17 0.027 3.9
1.09 0.091 1.17 <, 3pcw
+, 8ppI Not possible1), 17 0.017
3.9 L, 13 0.091 1.111
co, 3pH1,2pPl ”0.17
G, O123.9L, 12 0.092 L,
1g <jpw L7pp1”0.03 0
．． 007 4.3L, 04 0.03
QJ5 Umbrella Kyoda LI14
*4.4 L, L 11. L
L, 2 books “0.1
3.56 1.65 0. a 1.9
9 4J, SH<, open ”<, 016 0.0
0+7 3.7 1.15 0.02 0.0
B? cO, 2p failure <, 5p-possible 0.014
0. QGO83,71,19<0.112 0.066
@, wholesale-<+, t+p voice 'G, 02 G,
003 3. a 1.11 0.01 0.
09 <0. lp tan <, 2p disorder “0.02
0.0033J1.080. OlG, 09 (0,199
80,3p4”0.02G,002 347
1. G9 Lot O, L co, 1p
pI0.2p group is 0.02 0. OOm
3J 1.11 0.01 G, 09 0
．． 2p4 41p stomach 'Table 2 C'18~21 18~2118~21 18~21
Co 12~15 12~15 12~15 12~
15Tl 2.75-3.252.75-3.252.
75~3.25 2.75~3.25B 0.002~
0.008-0.002~0.00g 0.002~0
．． 008 0.002~0.008CO, 03~0.1
0.03~0.1 0.03~0.1 0.03~0
．． 1CuO,l (maximum) 0.1 (maximum)
0.1 (maximum') 0.1 (maximum) P O,
0150,0150,0150,015Sc 0.5
ppm (maximum) 0.5ppm (maximum) 0.
5ppm (maximum) 0.5ppl (maximum)To
0.2ppm (maximum) 0.2pp11 (maximum) 0.2ppm (maximum) 0.2ppm
(Max) TI+ 0.2pp11 (Max) 0.2
ppm (maximum) 0.2ppm (maximum)
0.2ppm (maximum) Fo 2.0 (maximum')
0.2 (maximum) 0.1 (maximum)
0.1 (maximum) Mn 0.5 (maximum) 0.3-0.
5 0.3~0.5 0.3~0.5Zr
O,12 (maximum) 0.12 (maximum) 0
．． 02 (maximum) 0.02 (maximum) SO
,03(max) 0.03(max) 0.00
5 (maximum) 0.005 (maximum) Al 1.0
~1.5 1.0~! , 5 1.0~1.5 1.0~
1.125Mo 3.5~5.0 3.5~5.0 3
．． 5-5.0 3.5-4.25Nl remainder
Remainder Remainder Remainder Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments may be made within the scope of the present invention. It will be obvious to those skilled in the art that this is possible.

Patent applicant: United Chiknorrhea
Corporation

Claims (1)

[Claims] 19.5% Cr, 13.5% Co, 3.75% Mo, 3
．． 0%Ti, 1.12%Al, 0.005%B, 0.0
A nickel-based superstructure with a nominal composition of 0.6% C, up to 2.0% Fc, and the balance substantially Ni, with an Fe content of 0.2% or less, thereby substantially improving weldability. alloy.