Welding alloy and articles for use in welding, weldments and method for producing weldments

Abstract

Nickel, chromium, iron alloys and methods for producing weld overlays and weldments formed therefrom. In percent by weight, the alloy comprises about 28.5% to 31.0% chromium; about 0 to 16% iron, preferably 7.0% to 10.5% iron; less than about 1.0% manganese, preferably 0.05% to 0.35% manganese about 2.1% to 4.0% niobium and tantalum, preferably 2.1% to 3.5% niobium and tantalum, and more preferably 2.2% to 2.8% niobium and tantalum; 0 to 7.0% molybdenum, preferably 1.0% to 6.5% Molybdenum, and more preferably 3.0% to 5.0% molybdenum; less than 0.50% silicon, preferably 0.05% to 0.30% silicon; 0.01% to 0.35% titanium; 0 to 0.25% aluminum; less than 1.0% copper less than 1.0% tungsten; less than 0.5% cobalt; less than about 0.10% zirconium; less than about 0.01% sulfur; less than 0.01% boron, preferably less than 0.0015% boron, and more preferably low less than 0.03% carbon; less than about 0.02% phosphorus; 0.002% to 0.015% magnesium and calcium; and the balance nickel and incidental impurities. The method includes the steps of forming an electrode from the alloy composition described above and melting the electrode to form a weld overlay. Preferred weldments made from the alloys and methods include alloy matrices in the form of nuclear reactor tube sheets.

Description

technical field [0001] The present invention relates to nickel, chromium, iron, molybdenum, niobium welding alloys for the production of weldments, articles produced therefrom, as well as weldments and methods for producing these weldments. Background technique [0002] Heretofore, in various welding applications including those used in nuclear power plants, it has been required to provide weldments that are resistant to various cracking phenomena. The cracking phenomenon includes not only intergranular stress corrosion cracking ("IGSCC") but also hot cracking, cold cracking (DDC) and root cracking. [0003] The nuclear industry has replaced first-generation nickel alloys containing only 14-15% chromium with alloy families currently containing about 30% chromium in commercial and military nuclear power plants. This family of alloys essentially avoids IGSCC, but other problems have been found with welded products of the same family. The original 30% chromium welding product...

AI Technical Summary

Problems solved by technology

Additionally, they offer improved resistance to DDC, but with unfavorable weld bead geometry and very high heat input added per unit volume of weld metal, occasional DDC cracks are found

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