Nickel-base alloy for the electro-welding of nickel alloys and steels, welding wire and use

Abstract

The alloy contains, by weight, less than 0.05% of carbon, from 0.015% to 0.5% of silicon, from 0.4% to 1.4% of manganese, from 28% to 31.5% of chromium, from 8% to 12% of iron, from 2% to 7% of molybdenum, from 0% to 0.75% of aluminium, from 0% to 0.8% of titanium, from 0.6% to 2% in total of niobium and tantalum, the ratio of percentages of niobium plus tantalum and of silicon being at least 4, less than 0.04% of nitrogen, from 0.0008% to 0.0120% of zirconium, from 0.0010% to 0.0100% of boron, less than 0.01% of sulphur, less than 0.020% of phosphorus, less than 0.30% of copper, less than 0.15% of cobalt and less than 0.10% of tungsten, the remainder of the alloy, with the exception of unavoidable impurities of which the total content is at most 0.5%, consisting of nickel. The alloy is used, in particular, for the production of wires for the electro-gas welding of units or components of nuclear reactors and, more particularly, of pressurised water-cooled nuclear reactors.

Description

[0001] The invention relates to a nickel-based alloy for the electro-welding of nickel alloys and steels, in particular non-alloyed or sparingly alloyed steels and stainless steels.[0002] The invention also relates to wires and electrodes for the electro-welding of parts made of nickel alloy and / or steel, in particular in the field of the construction, assembly and repair of components of nuclear reactors.BACKGROUND TO THE INVENTION[0003] It is known to use chromium-containing nickel-based alloys for the production of certain components or units of nuclear reactors.[0004] In particular, a nickel alloy containing approximately 15% of chromium, known as alloy 600, has been used for the production of units or components of pressurised water-cooled nuclear reactors.[0005] To improve the corrosion resistance of the units or components of pressurised water-cooled nuclear reactors, there is a tendency to replace the alloy 600 containing approximately 15% of chromium by an alloy 690 contain...

AI Technical Summary

Problems solved by technology

During these tests, it was demonstrated that commercially available wires, in particular alloys 52 for the welding of nickel 690 alloys, gave poor results when they were deposited on nickel alloys containing 15% or 30% of chromium or else stainless steels deposited by welding, in the form of a coating of sparingly alloyed steel components.

It has been found that the improved commercially available alloys gave good results in the diluted zones during the welding of nickel alloys containing 15% or 30% of chromium, these zones being virtually exempt from fissuring in heat, but poor results in diluted zones in the case of welding on stainless steels, the type 2 heat fissures being detected in these diluted zones.

The tests carried out showed that there are no commercially available wires for producing homogeneous or heterogeneous electro-welds, which are exempt from fissuring and oxidation, on nickel alloys and on steels.