KR20150044356A - Acid and alkali resistant ni-cr-mo-cu alloys with critical contents of chromium and copper - Google Patents

Abstract

A nickel-chromium-molybdenum-copper alloy resistant to acidic and alkali neutralization in the field of waste disposal 70% sulfuric acid at 93 ° C and 50% sodium hydroxide at 121 ° C; The alloy comprises, by weight percent, 27 to 33 chromium, 4.9 to 7.8 molybdenum, 3.1 to 6.0 wt.% Copper (when chromium is 30 to 33 wt.%), Or 4.7 to 6.0 wt. , At most 0.05 iron, at most 0.3 iron, at least 0.3 manganese, at least 0.1 manganese, at least 0.1 manganese, between 0.1 and 0.5 silicon, between 0.1 and 0.8 silicon, between 0.01 and 0.11 carbon, at most 0.13 nitrogen, at most 0.05 magnesium, at most 0.05 rare earth elements, Lt; / RTI > Titanium or another MC carbide former can be added to improve the thermal stability of the alloy.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a nickel-chromium-molybdenum-copper alloy having a critical content of chromium and copper and an alkali-resistant nickel-chromium-molybdenum-

The present invention relates generally to non-ferrous alloy compositions, and more particularly to nickel-chromium-molybdenum-copper alloys that provide a useful combination of resistance to 70% sulfuric acid at 93 DEG C and resistance to 50% sodium hydroxide at 121 DEG C. .

In the field of waste treatment, there is a need for metallic materials that resist hot, strong acid and hot, strong caustic alkali. This is because such chemicals are used to neutralize each other to produce more stable and less harmful compounds. Of the acids used in industry, sulfuric acid is the most important in terms of yield. Among the caustic alkalis, sodium hydroxide (caustic soda) is most commonly used.

Certain nickel alloys are strong and very resistant to hot sulfuric acid. Certain other nickel alloys are highly resistant to hot, strong sodium hydroxide. However, neither holds adequate tolerance for both chemicals.

Typically, nickel alloys with high alloy content are used to withstand sulfuric acid and other strong acids, the most resistant being nickel-molybdenum and nickel-chromium-molybdenum alloys.

Conversely, pure nickel (UNS N02200 / alloy 200) or a nickel alloy with a low alloy content is the most resistant to sodium hydroxide. Where higher strength is required, nickel-copper and nickel-chromium alloys are used. In particular, alloys 400 (Ni-Cu, UNS N04400) and 600 (Ni-Cr, UNS N06600) have good resistance to corrosion in sodium hydroxide.

During the discovery of the alloy of the present invention, two core environments were used: 70 wt.% Sulfuric acid at 93 ° C (200 ° F) and 50 wt.% Sodium hydroxide at 121 ° C (250 ° F). It is well known that 70 wt.% Sulfuric acid is highly corrosive to metallic materials, and the concentration is such that the resistance of many materials (including nickel-copper alloys) is degraded as a result of a change in the negative electrode reaction to be. 50 wt.% Sodium hydroxide is the most widely used concentration in the industry. In the case of sodium hydroxide, a higher temperature is used to increase the internal attack (the main form of nickel alloy decomposition in the chemical) and thus to increase the accuracy of the measurements during subsequent cross- .

In U.S. Patent No. 6,764,646, Crook et al. Describe nickel-chromium-molybdenum-copper alloys that are resistant to sulfuric acid and wet process phosphoric acid. These alloys require copper in the range of 1.6 to 2.9 wt.%, Which is below the level required to be resistant to 70% sulfuric acid at 93 ° C and 50% sodium hydroxide at 121 ° C.

Crook U.S. Patent No. 6,280,540 discloses copper-containing, nickel-chromium-molybdenum alloys that are commercially available as C-2000® alloys and correspond to UNS 06200. They have higher molybdenum levels and lower chromium levels than the alloys of the present invention and do not have the aforementioned corrosion characteristics.

U.S. Patent No. 6,623,869 to Nishiyama et al. Describes a nickel-chrome-copper alloy for metal dusting service at high temperatures, the maximum copper content of which is 3 wt.%. This range is below the range required to be resistant to 70% sulfuric acid at 93 占 폚 and 50% sodium hydroxide at 121 占 폚. More recent US patent application publications such as Nishiyama et al. (US 2008/0279716 and US 2010/0034690) describe additional alloys for resistance to metal dusting and carbonization. The alloys of US 2008/0279716 differ from the alloys of the present invention in that they have a molybdenum limit of 3% or less. The alloys of US 2010/0034690 are various, iron-based rather than nickel-based and have a molybdenum content of less than 2.5%. Ueyama et al., US Published Patent Application No. US2011 / 0236252, disclose nickel-chromium-molybdenum-copper alloys resistant to reducing hydrochloric acid and sulfuric acid. The range given for chromium in these alloys is 20 to 30% and the range for copper is 2 to 5%; However, the alloy embodiment of the present invention provided in this patent contains a maximum of 23% of chromium and a maximum of 3.06% of copper, which is less than the required level to be resistant to 70% sulfuric acid at 93 ° C and 50% sodium hydroxide at 121 ° C low.

The main object of the present invention is to provide a forged product (sheet, plate, sheet) exhibiting a useful and difficult to achieve combination of resistance to 70% sulfuric acid at 93 캜 (200)) and resistance to 50% sodium hydroxide at 121 캜 (250 ℉) Bar, etc.) of the alloy. These highly highly desirable properties include, based on nickel, 27 to 33 wt.% Of chromium, 4.9 to 7.8 wt.% Of molybdenum, And 3.1 wt.% To 6.0 wt.% Of copper. For a chromium content of 30 to 33 wt.%, A full range of copper (3.1 to 6.0 wt.%) Provides this highly desirable property.

To enable the removal of oxygen and sulfur during the melting process, such alloys typically contain small amounts of aluminum and manganese (up to about 0.5 and 1.0 wt.% Respectively in the nickel-chrome-molybdenum alloy), and possibly trace amounts of magnesium and It contains a rare earth element (up to about 0.05 wt.%). In our experiments it has been found that aluminum contents of 0.1 to 0.5 wt.% And 0.3 to 1.0 wt.% Manganese content produce successful alloys.

In such alloys, iron is the most likely impurity due to contamination from other nickel alloys dissolved in the same furnace, and up to 2.0 or 3.0 wt.% Of these nickel-chromium-molybdenum alloys are typical and no iron addition is required. In our experiments it was found that iron contents of up to 3.0 wt.% Were acceptable.

Other metallic impurities are possible in such alloys due to furnace contamination and impurities in the input material. The alloys of the present invention should be capable of accepting these impurities at levels often encountered in nickel-chromium-molybdenum alloys. Also, such high chromium content alloys can not be air-soluble without the acquisition of some nitrogen. Therefore, it is common in high chromium nickel alloys to allow a maximum amount of these elements up to 0.13 wt.%.

Regarding the carbon content, the successful alloys in the Applicant's experiments contained 0.01 to 0.11 wt.%. Surprisingly, alloy G having a carbon content of 0.002 wt.% Could not be processed into a forged product. Accordingly, carbon in the range of 0.01 to 0.11 wt.% Is preferred.

With respect to silicon, a range of 0.1 to 0.8 wt.% Is preferred, which is based on the fact that each end of the range provided satisfactory properties.

The microstructural stability of these alloys at elevated temperatures can be improved by promoting the formation of highly stable MC carbides.

Discovery of the above defined composition range involved the study of a wide range of nickel-based compositions of various chromium, molybdenum, and copper contents. These compositions are shown in Table 1. For comparison, the composition of the commercial alloy used to withstand 70% sulfuric acid or 50% sodium hydroxide is included in Table 1.

Table 1: Composition of experimental and commercial alloys

* Denotes the alloy of the present invention, ** denotes the nominal composition

Experimental alloys were prepared by vacuum induction melting (VIM) followed by electro-slag re-dissolution (ESR) with a heat size of 13.6 kg. Traces of nickel-magnesium and / or rare earths were added to the VIM furnace input to aid in minimizing the sulfur and oxygen content of the experimental alloys. The ESR ingot was homogenized, hot forged, and hot rolled into sheets of thickness 3.2 for testing. Unexpectedly, the three alloys (G, K, and L) cracked too heavily during forging and could not hot-roll them into sheets for testing. To determine the most appropriate annealing treatment (by metallurgical means), annealing tests were applied to the successfully rolled alloy to the required test thickness. 15 minutes at a temperature of 1121 DEG C to 1149 DEG C, and then water quenching was determined to be appropriate in all cases. All commercially manufactured alloys were tested under the conditions sold by the manufacturer, the so-called "factory annealed" conditions.

Corrosion tests were performed on samples of 25.4 x 25.4 x 3.2 mm in size. Prior to the corrosion test, the surface of all samples was manually ground using 120 grit paper to eliminate any surface films and defects that could affect corrosion resistance. The test in sulfuric acid was carried out in a glass flask / condenser system. Tests on sodium hydroxide were performed in a TEFLON system as the glass was damaged by sodium hydroxide. The sample was discontinued every 24 hours to allow weighing, and a period of 96 hours was used for the sulfuric acid test, while a period of 720 hours was used for the sodium hydroxide test. Two samples of each alloy were tested in each environment and the results were averaged.

In sulfuric acid, the main mode of decomposition is uniform damage, so the average corrosion rate is calculated from the weight loss measurement. In sodium hydroxide, the main mode of degradation is internal damage, which is either homogeneous or more aggressive, internal "dealloying" damage. De-constituent corrosion generally refers to the leaching of a particular element (e.g., molybdenum) from the alloy, which often also degrades mechanical properties. Maximum internal damage can only be measured by intercepting samples and studying them metallurgically. The values given in Table 2 indicate the maximum internal penetration measured in the alloy transverse-survey.

Good / bad criteria of 0.45 mm / y (uniform damage in the case of sulfuric acid and maximum internal penetration in the case of sodium hydroxide) were used to differentiate between the allowable and unacceptable rates of damage. Alloys exhibiting corrosion rates greater than or equal to 0.45 mm / y are considered to be unacceptable. The background to this criterion relates to such corrosion diagrams used in the industry to determine whether alloys are allowed or not allowed at specific concentrations and temperatures of different chemicals. Several samples or test specimens of the alloys under consideration are tested and the corrosion rates in each test are shown. Then draw a line to match the data points. In these diagrams, a corrosion rate of 0.45 to 0.55 mm / y will often produce a plot line of 0.5 mm / y to take into account random and regular changes. In many applications, the industry considers a corrosion rate of less than 0.5 mm / y to be acceptable. However, since an alloy having a corrosion rate of 0.45 to 0.55 mm / y can be considered to have a corrosion rate of 0.5 mm / y, the inventor has concluded that the corrosion rate should be less than 0.45 mm / y , The performance requirements were set for the alloy of the present invention.

Table 2 shows that the inventive alloy corrodes at a sufficiently low rate in 70% sulfuric acid to be industrially useful at 93 占 폚 and an internal penetration rate which corresponds to considerably less than 0.5 mm / y at 50% sodium hydroxide at 121 占 폚 Lt; / RTI > Interestingly, unlike nickel-chromium-molybdenum alloys (C-4, C-22, C-276 and C-2000) with a high molybdenum content, none of the alloys of the present invention exhibit corrosion- . The clue that copper should be at least 4.7 wt.% If the required copper range is between 3.1 and 6.0 wt.% And chromium is less than 30 wt.% Is the result for various alloys, especially A, B, C, E and N . The relationship between chromium and copper is possible due to their respective effects on the protective film in 70% sulfuric acid. It is known, for example, that chromium induces chromium-enriched coatings on metal surfaces in oxidizing acids and that copper can provide protection by applying metal surfaces in concentrated sulfuric acid. Alloys K and L with higher copper content could not be forged.

The chromium range is based on the results for alloys A and O (having contents of 27 and 33 wt.%, Respectively). The molybdenum range is based on the results for alloys H and A (with contents of 4.9 and 7.8 wt.%, Respectively), and the proposal of U.S. Patent No. 6,764,646, which mentions molybdenum content below 4.9 wt.%, It does not provide sufficient resistance to frontal corrosion of molybdenum-copper alloys. This is important for neutralization systems containing other chemicals.

Unexpectedly, when iron, manganese, aluminum, silicon, and carbon were missing (alloy G), the alloy could not be forged. In order to further confirm the effect of iron, an alloy P without deliberate iron addition was dissolved. The fact that alloys P successfully hot forged and hot rolled indicates that the presence of manganese, aluminum, silicon, and carbon is crucial to the successful processing of these alloys. In addition, the absence of iron in the alloy P was not disadvantageous in terms of corrosion, since the alloy exhibited excellent performance in both corrosive media.

Table 2: Corrosion test results for experiments and commercial alloys

* Indicates the alloy of the present invention

GC - Front corrosion

Observations on the effect of alloying elements are as follows:

Chromium (Cr) is a major alloying element known to improve the performance of nickel alloys in oxidizing acids. When combined with molybdenum and copper (where special relationships apply), chromium has been found to provide desirable corrosion resistance for both 70% sulfuric acid and 50% sodium hydroxide in the range 27-33 wt.%.

Molybdenum (Mo) is also a major alloying element known to improve the corrosion resistance of nickel alloys in reducing acids. In the range 4.9 to 7.8 wt.%, Molybdenum contributes to the excellent performance of the alloys of the present invention in 70% sulfuric acid and 50% sodium hydroxide.

Copper (Cu), which is 3.1 wt.% To 6.0 wt.%, And in combination with the abovementioned levels of chromium and molybdenum, has an acid and alkali in the form of 70% sulfuric acid at 93 DEG C and 50% sodium hydroxide at 121 DEG C To produce alloys with unusual and unexpected tolerances.

Iron (Fe) is a common impurity in nickel alloys. An iron content of up to 3.0 wt.% Was found to be acceptable in the alloys of the present invention.

Manganese (Mn) is used to minimize sulfur in these alloys and 0.3 to 1.0 wt.% Content has been found to produce successful alloys (in terms of processing and performance).

Aluminum (Al) is used to minimize oxygen in such alloys, and a content of 0.1 to 0.5 wt.% Has been found to produce successful alloys.

Silicon (Si) is not normally required in anti-corrosive nickel alloys, but is introduced during argon-oxygen decarburization (in alloys dissolved in air). Small amounts of silicon (in the range of 0.1 to 0.8 wt.%) Were found to be essential to the alloys of the present invention to ensure mono-composition.

Similarly, carbon (C) is not normally required in anti-corrosive nickel alloys, but is introduced during carbon arc melting (in dissolved alloys in air). Small amounts of carbon (in the range 0.01 to 0.11 wt.%) Were found to be essential for the alloys of the present invention to ensure mono-composition.

Trace amounts of magnesium (Mg) and / or rare earth elements are often included in such alloys to control undesirable elements such as sulfur and oxygen. Thus, a general range of up to 0.05 wt.% Is preferred for each of these elements in the alloy of the present invention.

Nitrogen (N) is easily absorbed by the high chromium nickel alloy in the molten state, and it is common for this type of alloy to allow up to 0.13 wt.% Of these elements.

Other impurities that may be present in these alloys due to contamination from previously-used furnace inner walls or from the interior of the feedstock include cobalt, tungsten, sulfur, phosphorus, oxygen, and calcium.

If enhanced microstructural stability is desired at elevated temperatures (such as may be experienced during welding or during elevated temperature service), deliberate, small additions of elements that promote the formation of MC carbides may be used. Such elements include titanium, niobium (columbium), hafnium, and tantalum. Another less preferred MC carbide former that can be used is vanadium, for example. MC carbides are much more stable than the M ₇ C ₃ , M ₆ C, and M ₂₃ C ₆ carbides usually encountered in chromium- and molybdenum-containing nickel alloys. In fact, it should be possible to control the levels of these MC-forming elements in order to tie as much carbon as would be appropriate to control the level of carbide precipitation at grain boundaries. Indeed, the MC-forming level could be fine-tuned during the melting process, depending on the real-time measurement of the carbon content.

When the alloy is used to withstand aqueous erosion, the level of MC-formers can be adjusted to the carbon level to prevent significant particle boundary carbide precipitation (so-called "stable" structure).

However, there are two possible problems. First, the nitrogen can compete with carbon to form nitrides or carbonitrides of the same active formulator (e.g., titanium) and therefore must be present at a higher level (which can be calculated based on real-time measurements of nitrogen content have). The second is the unintended formation of gamma-prime (with titanium) or gamma-duplex prime (with niobium); However, the order of cooling and post-processing may be adjusted to ensure that these elements are bound in the form of carbides, nitrides, or carbonitrides.

For example, ignoring the nitrogen effect and using titanium to bind all carbons to MC carbides may require atomic parity. Since the atomic weight of titanium is about four times that of carbon (47.9 vs. 12.0), this can be reflected in the weight percentage of the two elements. Thus, a stable version of these alloys for aqueous corrosion service may contain 0.05 wt.% Carbon and 0.20 wt.% Titanium. These alloys for elevated temperature service may contain 0.05 wt.% Carbon and 0.15 wt.% Titanium to allow a controlled level of secondary, grain boundary precipitation to improve creep resistance. For example, for nitrogen with an impurity level of 0.035 wt.%, An additional 0.12 wt.% Titanium would be needed to bind this element (because the atomic weight of nitrogen is 14.0). Thus, for a carbon content of 0.05 wt.%, 0.32 wt.% Titanium may be required for aqueous corrosion services and 0.27 wt.% Titanium may be required for elevated temperature service. Therefore, for a carbon level of 0.11 wt.%, And a nitrogen impurity level of 0.035 wt.%, 0.56 wt.% Titanium may be required for aqueous corrosion services.

The atomic weights of niobium, hafnium, and tantalum are 92.9, 178.5, and 181.0, respectively. Thus, the niobium content required to achieve the same benefit is approximately twice the titanium content. The hafnium or tantalum content required to achieve the same benefit is approximately four times the content of titanium.

Therefore, for the aqueous corrosion service, these alloys in the niobium stable version contain 0.05 wt.% Carbon and 0.40 wt.% Sodium oleum (when the alloy does not contain any nitrogen) and 0.035 wt.% Nitrogen impurity In this case, it may contain 0.64 wt.% Of niobium. At a carbon level of 0.11 wt.%, And a nitrogen impurity level of 0.035 wt.%, 1.12 wt.% Niobium may be required for aqueous corrosion services. The alloy for elevated temperature service may contain 0.05 wt.% Carbon and 0.30 wt.% Niobium in the absence of nitrogen impurities.

Similarly, for an aqueous corrosion service these hafnium stabilized versions of these alloys would contain 0.05 wt.% Carbon and 0.80 wt.% Hafnium (when the alloy did not contain any nitrogen), and a nitrogen impurity level of 0.035 wt.% May contain 1.28 wt.% Hafnium. At a carbon level of 0.11 wt.%, And at a nitrogen impurity level of 0.035 wt.%, 2.24 wt.% Hafnium may be required for aqueous corrosion services. The alloy for elevated temperature service may contain 0.05 wt.% Carbon and 0.60 wt.% Hafnium in the absence of nitrogen impurities.

Similarly, for austenitic corrosion services, these tantalum-stable versions of these alloys were found to contain 0.05 wt.% Carbon and 0.80 wt.% Tantalum (when the alloy contained no nitrogen) and 0.035 wt.% Nitrogen impurity % Tantalum can be contained. At a carbon level of 0.11 wt.%, And a nitrogen impurity level of 0.035 wt.%, 2.24 wt.% Tantalum may be required for aqueous corrosion services. The alloy for elevated temperature service may contain 0.05 wt.% Carbon and 0.60 wt.% Tantalum in the absence of nitrogen impurities.

Prior art (cf. US Pat. No. 6,740,291, Crook) on other high-chromium nickel alloys can tolerate impurity levels of cobalt and tungsten in this class of alloys at levels of up to 5 wt.% And 0.65 wt.%, Respectively Of course. The permissible impurity levels for sulfur (up to 0.015 wt.%), Phosphorus (up to 0.03 wt.%), Oxygen (up to 0.05 wt.%), And calcium (up to 0.05 wt.%) Are described in US Pat. No. 6,740,291 . These impurity limits are considered appropriate for the alloy of the present invention.

Although the tested sample was in the form of a forged sheet, the alloy should exhibit properties comparable to other forged forms, such as plates, bars, tubes, and wires, and cast and powder metallurgical forms. Furthermore, the alloys of the present invention are not limited to applications including neutralization of acids and alkalis. In fact, they can have a much wider application in the chemical processing industry and will be useful for enduring metal dusting, given their high chromium and copper presence.

Considering the desire to maximize the corrosion resistance of these alloys, the ideal alloys are 31 wt.% Chromium, 5.6 wt.% Molybdenum, 3.8 wt.% Copper, and the like, while optimizing their microstructural stability % Of iron, 0.5 wt.% Of manganese, 0.3 wt.% Of aluminum, 0.4 wt.% Of silicon and 0.03 to 0.07 wt.% Of carbon and nickel, nitrogen, impurities and trace amounts of magnesium and It is expected to contain the remainder of the rare-earth element (if used for control). In practice, the two alloys, Q and R, with this preferred nominal composition have been successfully melted, hot forged and rolled into sheets. As shown in Table 2, alloys Q and R both exhibited excellent corrosion resistance in selected corrosive media. In addition, with this desired nominal composition, the production scale heat of alloy S (13,608 kg) was successfully melted and rolled, thereby confirming that the alloy had excellent moldability. The alloy also has desirable corrosion properties at 70% sulfuric acid and 50% sodium hydroxide at 121 < 0 > C. Corresponding ranges (typical in steelworks practice) include 30 to 33 wt.% Chromium, 5.0 to 6.2 wt.% Molybdenum, 3.5 to 4.0 wt.% Copper, 1.5 wt.% Iron, 0.3 to 0.7 wt. 0.1 to 0.4 wt.% Aluminum, 0.1 to 0.6 wt.% Silicon, and 0.02 to 0.10 wt.% Carbon, and nickel, nitrogen, impurities and trace amounts of magnesium and rare earth (when used for the control of sulfur and oxygen) .

Claims (14)

Essentially equivalent to a corrosion rate of less than 0.45 mm / y at 70% sulfuric acid at 93 ° C and a corrosion rate of less than 0.45 mm / y at 50% sodium hydroxide, resistant to sulfuric acid at 121 ° C Nickel-chromium-molybdenum-copper alloy resistant to sodium hydroxide:
27 to 33 wt.% Chromium
4.9 to 7.8 wt.% Molybdenum
% Of copper is from 30 to 33 wt.%, Or from 4.7 to 6.0 wt.% Of copper is from 27 to 29.9 wt.%,
Up to 3.0 wt.% Iron
0.3 to 1.0 wt.% Manganese
0.1 to 0.5 wt.% Aluminum
0.1 to 0.8 wt.% Silicon
0.01 to 0.11 wt.% Carbon
Up to 0.13 wt.% Nitrogen
Up to 0.05 wt.% Magnesium
Up to 0.05 wt.% Rare earth element
Up to 0.56 wt.% Titanium
Up to 1.12 wt.% Nb
Up to 2.24 wt.% Tantalum
Up to 2.24 wt.% Hafnium
And the balance of nickel and impurities. The nickel-chromium-molybdenum-copper alloy according to claim 1, wherein the alloy is in the form of a forging selected from the group consisting of sheet, plate, bar, wire, tube, pipe, and forgings. The nickel-chromium-molybdenum-copper alloy of claim 1, wherein the alloy is in the form of a cast. The nickel-chromium-molybdenum-copper alloy of claim 1, wherein the alloy is in powder metallurgy form. The nickel-chromium-molybdenum-copper alloy according to claim 1, which consists essentially of:
30 to 33 wt.% Chromium
5.0 to 6.2 wt.% Molybdenum
3.5 to 4.0 wt.% Copper
Up to 1.5 wt.% Iron
0.3 to 0.7 wt.% Manganese
0.1 to 0.4 wt.% Aluminum
0.1 to 0.6 wt.% Silicon
0.02 to 0.10 wt.% Carbon. The nickel-chromium-molybdenum-copper alloy according to claim 1, which consists essentially of:
31 wt.% Chromium
5.6 wt.% Molybdenum
3.8 wt.% Copper
1.0 wt.% Iron
0.5 wt.% Manganese
0.4 wt.% Silicon
0.3 wt.% Aluminum
0.03 to 0.07 wt.% Carbon
And the remainder of nickel, nitrogen, impurities, and trace amounts of magnesium. The nickel-chromium-molybdenum-copper alloy according to claim 1, which consists essentially of:
31 wt.% Chromium
5.6 wt.% Molybdenum
3.8 wt.% Copper
1.0 wt.% Iron
0.5 wt.% Manganese
0.4 wt.% Silicon
0.3 wt.% Aluminum
0.03 to 0.07 wt.% Carbon
And the balance of nickel, nitrogen, impurities, and trace amounts of magnesium and trace rare earth elements. The nickel-chromium-molybdenum-copper alloy of claim 1, wherein the alloy contains at least one MC carbide former. 9. The nickel-chromium-molybdenum-copper alloy of claim 8, wherein the MC carbide former is selected from the group consisting of titanium, niobium, tantalum and hafnium. The nickel-chromium-molybdenum-copper alloy of claim 1, wherein the alloy contains 0.20 to 0.56 wt.% Titanium. The nickel-chromium-molybdenum-copper alloy of claim 1, wherein the alloy contains 0.30 to 1.12 wt.% Niobium. The nickel-chromium-molybdenum-copper alloy of claim 1, wherein the alloy contains 0.60 to 2.24 wt.% Tantalum. The nickel-chromium-molybdenum-copper alloy of claim 1, wherein the alloy contains 0.60 to 2.24 wt.% Hafnium. The nickel-chromium-molybdenum-copper alloy according to claim 1, wherein the impurity is selected from the group consisting of cobalt, tungsten, sulfur, phosphorus, oxygen, and calcium.