METALLIC NICKEL-BASED ACID-RESISTANT MATERIAL

Abstract

A weld filler includes a nickel-molybdenum-iron alloy with high corrosion resistance with respect to reducing media at high temperatures, consisting of (in % by mass): 61 to 63% nickel, 24 to 26% molybdenum, 10 to 14% iron, 0.20 to 0.40% niobium, 0.1 to 0.3% aluminum, 0.01 to 1.0% chromium, 0.1 to 1.0% manganese, at most 0.5% copper, at most 0.01% carbon, at most 0.1% silicon, at most 0.02% phosphorus, at most 0.01% sulphur, at most 1.0% cobalt, and further smelting-related impurities. The weld filler can be welded to fill a joint.

Claims

1. A weld filler for welding, the weld filler comprising a nickel-molybdenum-iron alloy consisting of in % by mass: 61 to 63% nickel; 24 to 26% molybdenum; 10 to 14% iron; 0.20 to 0.40% niobium; 0.1 to 0.3% aluminum; 0.01 to 1.0% chromium; 0.1 to 1.0% manganese; copper, the copper being present to a max. of 0.5%; max. 0.01% carbon; max. 0.1% silicon; max. 0.02% phosphorus; max. 0.01% sulfur; max. 1.0% cobalt; and further impurities from smelting.

2. The weld filler according to claim 1, wherein the nickel-molybdenum-iron alloy consists of in % by mass: 61.5 to 62.5% nickel; 24.5 to 26.0% molybdenum; 10.5 to 13.5% iron; 0.2 to 0.4% niobium; 0.1 to 0.3% aluminum; 0.01 to 1.0% chromium; 0.1 to 0.8% manganese; copper, the copper being present to a max. of 0.5%; max. 0.01% carbon; max. 0.1% silicon; max. 0.02% phosphorus; max. 0.01% sulfur; and max. 1.0% cobalt.

3. The weld filler according to claim 1, wherein the nickel-molybdenum-iron alloy consists of in % by mass: 61.5 to 62.5% nickel; 24.8 to 26.0% molybdenum; 10.5 to 12.5% iron; 0.2 to 0.4% niobium; 0.1 to 0.3% aluminum; 0.01 to 0.9% chromium; 0.1 to 0.5% manganese; copper, the copper being present to a max. of 0.3%; max. 0.008% carbon; max. 0.08% silicon; max. 0.015% phosphorus; max. 0.008% sulfur; max. 0.02% nitrogen; max. 0.012% magnesium; and max. 1.0% cobalt.

4. The weld filler according to claim 1, wherein the copper is present in a range of from 0.01% to 0.5%.

5. A method for welding, the method comprising steps of: (a) providing a weld filler comprising a nickel-molybdenum-iron alloy consisting of in % by mass: 61 to 63% nickel; 24 to 26% molybdenum; 10 to 14% iron; 0.20 to 0.40% niobium; 0.1 to 0.3% aluminum; 0.01 to 1.0% chromium; 0.1 to 1.0% manganese; copper, the copper being present to a max. of 0.5%; max. 0.01% carbon; max. 0.1% silicon; max. 0.02% phosphorus; max. 0.01% sulfur; max. 1.0% cobalt; and further impurities from smelting; and (b) welding a joint in that the weld filler is used to fill the joint.

6. The method according to claim 5, wherein the welding occurs at the joint of a material comprising a nickel-molybdenum-iron alloy.

7. The method according to claim 5, wherein the nickel-molybdenum-iron alloy consists of in % by mass: 61.5 to 62.5% nickel; 24.5 to 26.0% molybdenum; 10.5 to 13.5% iron; 0.2 to 0.4% niobium; 0.1 to 0.3% aluminum; 0.01 to 1.0% chromium; 0.1 to 0.8% manganese; copper, the copper being present to a max. of 0.5%; max. 0.01% carbon; max. 0.1% silicon; max. 0.02% phosphorus; max. 0.01% sulfur; and max. 1.0% cobalt.

8. The method according to claim 5, wherein the nickel-molybdenum-iron alloy consists of in % by mass: 61.5 to 62.5% nickel; 24.8 to 26.0% molybdenum; 10.5 to 12.5% iron; 0.2 to 0.4% niobium; 0.1 to 0.3% aluminum; 0.01 to 0.9% chromium; 0.1 to 0.5% manganese; copper, the copper being present to a max. of 0.3%; max. 0.008% carbon; max. 0.08% silicon; max. 0.015% phosphorus; max. 0.008% sulfur; max. 0.02% nitrogen; max. 0.012% magnesium; and max. 1.0% cobalt.

9. The method according to claim 5, wherein the copper is present in a range of from 0.01% to 0.5%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] FIG. 1 is an isocorrosion diagram containing the comparative plot of the resistance of various known metallic materials in pure sulfuric acid.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0061] Surprisingly, it has been found that the disadvantageous situation of the state of the art characterized by the high metal values of nickel and molybdenum can be appreciably alleviated if a nickel-molybdenum-iron alloy specified in advance is employed for the handling of hot sulfuric acid. The average content of nickel is advantageously between 61 and 63% by mass. This means a reduction of 6 to 7% by mass of the expensive alloying element nickel compared with the state of the art outlined initially as an example. The content of the alloying element molybdenum, which likewise is expensive, lies between 24 and 26% by mass on average, which is also clearly below that of the state of the art cited for the nickel-molybdenum alloys with 27 to 28% by mass for example (see High-Alloy Materials, Corrosion Behavior and Use, TAW Verlag, Wuppertal 2002, p. 192).

[0062] This is illustrated in detail in the following.

TABLE-US-00001 TABLE 1 Chemical composition of the investigated nickel-molybdenum-iron alloys according to determination by spectral analysis in comparison with a nickel-molybdenum alloy B-2 according to the state of the art in the literature (see High-Alloy Materials, Corrosion Behavior and Use, TAW Verlag, Wuppertal 2002, p. 192). Alloying element, % by mass Alloy Ni Mo Fe Cr Nb V Mn Cu Al According to 50 62.2 25.6 11.2 0.02 0.33 0.01 0.28 0.01 0.25 the invention 44 61.8 25.4 11.8 0.02 0.34 0.01 0.29 0.01 0.27 Outside the 51 63.3 20.4 11.6 0.63 0.01 2.34 0.30 1.00 0.26 invention 45 60.1 21.8 14.7 2.10 0.56 0.01 0.19 0.17 0.28 State of the B-2 69 28 1.7 0.7 not given art

[0063] Table 1 shows inventive nickel-molybdenum-iron alloys in comparison with nickel-molybdenum-iron alloys falling outside the invention and with the nickel-molybdenum alloy B-2 associated with the state of the art. Some admixtures and impurities from smelting are not listed. It is evident that iron contents between 11 and 12% by mass were tested, as was an iron content of 14.7% by mass in one case, in comparison with the iron content of only 1.7% by mass, which is given as an example for the alloy B-2 according to the state of the art. The tested molybdenum contents lie between 20.4 and 25.6% by mass, in comparison with the molybdenum content of 28% by mass, which is given as an example for the alloy B-2 according to the state of the art. The tested nickel contents lie between 60.1 and 63.3% by mass, in comparison with the nickel content of 69% by mass, which is given as an example for the alloy B-2 according to the state of the art.

[0064] Table 2 shows the corrosion losses of the alloys listed in

[0065] Table 1.

TABLE-US-00002 TABLE 2 Corrosion loss of the inventive embodiments 50 and 44 of the investigated nickel-molybdenum-iron alloy in hot moderately concentrated sulfuric acid in comparison with two nickel-molybdenum-iron alloys 51 and 45 falling outside the invention as well as in comparison with that of a nickel- molybdenum alloy B-2 according to the state of the art. Corrosion loss in g/m.sup.2h over 24 h 50% 30% H.sub.2SO.sub.4 H.sub.2SO.sub.4, and 50% 80% H.sub.2SO.sub.4 and 70% H.sub.2O H.sub.2O (mass %) and 50% H.sub.2O (mass %) boiling (mass %) Alloy at 100° C. (approx. 124° C.) at 130° C. According to 50 0.11 0.13 0.71 the 44 0.16 not determined 0.16 invention Outside the 51 0.20 0.99 4.70 invention 45 0.25 not determined 1.13 State of the B-2 0.10 0.12 0.08 art

[0066] Table 2 shows the corrosion loss of the inventive embodiments 50 and 44 of the investigated nickel-molybdenum-iron alloy in hot moderately concentrated sulfuric acid in comparison with two nickel-molybdenum-iron alloys 51 and 45 falling outside the invention as well as in comparison with the nickel-molybdenum alloy B-2 according to the state of the art. The corrosion loss of the inventive embodiments 50 and 44 is below the 0.5 mm/year isocorrosion line of FIG. 1, except for that of the inventive embodiment 50 in 80% H.sub.2SO.sub.4 at 130° C.

[0067] The corrosion resistance of the welded joints of the inventive embodiment 50 of the investigated nickel-molybdenum-iron alloys in hot moderately concentrated sulfuric acid (30 and 50%) is similar to that of the unwelded condition.

[0068] The inventive embodiment 50 of the investigated nickel-molybdenum-iron alloys exhibited a corrosion loss of 0.08 mm/year in the immersion test in 4% salt solution at 150° C. over 120 hours. This means an adequate resistance, in conformity with the set task, on the cooling-water side even in cooling waters highly contaminated with chloride.

[0069] The mechanical characteristics of the inventive embodiment 44 of the investigated nickel-molybdenum-iron alloys determined in the tension test at room temperature were Rp.sub.0.2≧350 N/mm.sup.2, Rp.sub.1.0≧380 N/mm.sup.2, Rm≧760 N/mm.sup.2 and A.sub.5≧40%, which are comparable with those of the nickel-molybdenum alloy B-2 according to the state of the art (see Sheet and Plate-High Performance Materials: Publication No. N 554 98-10 of Krupp VDM GmbH, pp. 34/35), whereas the embodiment 45 of the investigated nickel-molybdenum-iron alloys falling outside the invention did not achieve the cited strength values.