The present invention describes coating processes and the resultant coated articles for use in high temperature sodium environments, such as those found in liquid metal fast breeder reactors and their associated systems. The substrate to which the coating is applied may be either an iron base or nickel base alloy. The coating itself is applied to the substrate by electro-spark deposition techniques which result in metallurgical bonding between the coating and the substrate. One coating according to the present invention involves electro-spark depositing material from a cemented chromium carbide electrode and an aluminum electrode. Another coating according to the present invention involves electro-spark depositing material from a cemented chromium carbide electrode and a nickel-base hardfacing alloy electrode.

Low friction and galling resistant coatings and processes for coating

A nickel base superalloy composition useful in the cast+HIP+heat treated condition is described. Articles having the invention composition have properties which are significantly better than similarly processed IN718 articles. This is achieved by modifying the chromium, columbium, and titanium contents in the alloy composition, relative to the IN718 composition.

High strength cast+HIP nickel base superalloy

A fusion weldable superalloy containing 0.005-0.5 wt. % scandium. In one embodiment, the superalloy may have a composition similar to IN-939 alloy, but having added scandium and having only 0.005-0.040 wt. % zirconium. A gas turbine component may be formed by an investment casting of such a scandium-containing superalloy, and may include a fusion weld repaired area. A scandium-containing nickel-based superalloy coated with an MCrAlY bond coat will have improved cyclic oxidation resistance due to the sulfur-gettering effect of the scandium.

Superalloy material with improved weldability

A method for manufacturing a Ni-based super-heat-resistant alloy includes: a first cold working step for cold working a Ni-based super-heat-resistant alloy ingot, which has a composition in which the γ′ mole ratio is at least 40%, at a working ratio of 5% to less than 30%; and a first heat treatment step for heat-treating the cold worked material, on which the first cold working was performed, at a temperature exceeding the γ′ solid solution temperature. It is preferable that the manufacturing method also includes a second cold working step for performing, after the first heat treatment step, a second cold working on the heat-treated material at a working ratio of at least 20%, and a second heat treatment step for heat-treating the second cold worked material, on which the second cold working has been performed, at less than the γ′ solvus temperature.

Method for manufacturing Ni-based super-heat-resistant alloy

A method for welding to a superalloy material without causing cracking of the material. The method includes the steps of depositing a weld strip (18) of a weldable material onto a superalloy substrate material (12) using a spray deposition process (20) and then forming a weldment (26) to the weld strip. None or a controlled amount of the substrate material (12) is melted during the weld in order to maintain the concentration of strengthening elements in the local melt within a zone of weldability. The spray deposition process may be a thermal process such as HVOF or a cold spray process. A groove (16) may be formed in a surface (10) of the superalloy substrate material to receive the weld strip. A diffusion heat treatment step may be used to improve adhesion between the weld strip and the superalloy material.

Sprayed weld strip for improved weldability

This is a nickel-base superalloy with excellent weldability and high strength. Its composition consists essentially of, by weight percent, 10-20 iron, 57-63 nickel, 7-18 chromium, 4-6 molybdenum, 1-2 niobium, 0.2-0.8 silicon, 0.01-0.05 zirconium, 1.0-2.5 titanium, 1.0-2.5 aluminum, 0.02-0.06 carbon, and 0.002-0.015 boron. The weldability and strength of this alloy give it a variety of applications. The long-time structural stability of this alloy together with its low swelling under nuclear radiation conditions, make it especially suitable for use as a duct material and controlling element cladding for sodium-cooled nuclear reactors.

High weldability nickel-base superalloy

A method for heat treating an age-hardenable iron-nickel-chromium alloy to obtain a morphology of the gamma-double prime phase enveloping the gamma-prime phase, the alloy consisting essentially of about 40 to 50% nickel, 7.5 to 14% chromium, 1.5 to 4% niobium, 0.3 to 0.75% silicon, 1 to 3% titanium, 0.1 to 0.5% aluminum, 0.02 to 1% carbon, 0.002 to 0.0015% boron and the remain substantially all iron. To obtain optimal results, the alloy is cold-worked 20 to 60% followed by heating at 1050° C. for 1/2 hour with an air-cool plus heating at 800° C. for 2 hours with a furnace cool to 625° C. The alloy is then held at 625° C. for 12 hours, followed by an air-cool.

Method for heat treating iron-nickel-chromium alloy

Nickel matrix alloy

A solid solution strengthened Ni-Cr-Fe alloy capable of retaining its strength at high temperatures and consisting essentially of 42 to 48% nickel, 11 to 13% chromium, 2.6 to 3.4% niobium, 0.2 to 1.2% silicon, 0.5 to 1.5% vanadium, 2.6 to 3.4% molybdenum, 0.1 to 0.3% aluminum, 0.1 to 0.3% titanium, 0.02 to 0.05% carbon, 0.002 to 0.015% boron, up to 0.06 zirconium, and the balance iron. After solution annealing at 1038° C. for one hour, the alloy, when heated to a temperature of 650° C., has a 2% yield strength of 307 MPa, an ultimate tensile strength of 513 MPa and a rupture strength of as high as 400 MPa after 100 hours.

Michael K Korenko

Papers

High weldability nickel-base superalloy

Method for heat treating iron-nickel-chromium alloy

Nickel matrix alloy

High strength nickel-chromium-iron austenitic alloy

Hochfeste austenitische nickel-chrom- eisen-legierung