Forged high strength corrosion resistant nickel alloy Incoloy 925 round bar
INCOLOY® alloy 925 (UNS N09925) is an age hardenable nickel-iron-chromium alloy with additions of molybdenum, copper, titanium and aluminum. The alloy’s chemical composition, listed in Chemical composition, is designed to provide a combination of high strength and excellent corrosion resistance. The nickel content is sufficient for protection against chloride-ion stress corrosion cracking. The nickel, in conjunction with the molybdenum and copper, also gives outstanding resistance to reducing chemicals. The molybdenum aids resistance to pitting and crevice corrosion. The alloy’s chromium content provides resistance to oxidizing environments. The titanium and aluminum additions cause a strengthening reaction during heat treatment.
INCOLOY alloy 925 is used in various applications requiring a combination of high strength and corrosion resistance. Because of the alloy’s resistance to sulfide stress cracking and stress-corrosion cracking in “sour” (H2S containing) crude oil and natural gas, it is used for down-hole and surface gas well components including tubular products, valves, hangers, landing nipples, tool joints and packers. The alloy is also useful for fasteners, marine and pump shafting and high-strength piping systems.
Chemical composition, %
Nickel...........................................................................42.0-46.0
Chromium....................................................................19.5-22.5
Iron...................................................................................22 min
Molybdenum....................................................................2.5-3.5
Copper.............................................................................1.5-3.0
Titanium...........................................................................1.9-2.4
Aluminum.........................................................................0.1-0.5
Manganese ...................................................................1.0 max.
Silicon ...........................................................................0.5 max.
Niobium.........................................................................0.5 max.
Carbon ........................................................................0.03 max.
Sulfur ..........................................................................0.03 max.
Metallurgy
INCOLOY alloy 925 is an austenitic nickel-iron-chromium alloy made precipitation hardenable by additions of titanium and aluminum. The precipitation-hardening (age hardening) heat treatment causes precipitation of gamma prime phase, Ni3 (Al, Ti). The phase greatly increases both the hardness and strength of the alloy.
Exposure to elevated temperatures also causes formation of other phases, including eta and sigma.
Corrosion Resistance
INCOLOY alloy 925 has a high level of corrosion resistance. In both reducing and oxidizing environments, the alloy resists general corrosion, pitting, crevice corrosion, intergranular corrosion and stress-corrosion cracking. Some environments in which INCOLOY alloy 925 is particularly useful are “sour” (H2S containing) crude oil and natural gas, sulfuric acid, phosphoric acid, and seawater.
Crevice corrosion
Crevice corrosion tests in a solution of 3.5% sodium chloride at 77°F (25°C) for 1000 h resulted in no crevice attack and a corrosion rate of less than 1 mpy (0.03 mm/a). Fluorocarbon washers bolted to strip specimens had twenty crevices each, or forty crevices per specimen.
Hot and cold forming
The hot working range for the alloy is 1600 to 2150°F (870 to 1175°C). At temperatures up to 2000°F (1095°C), INCOLOY alloy 925 has hot-working characteristics similar to those of INCOLOY alloy 825. For maximum corrosion resistance and highest strength after direct aging, final hot working should be done in the 1600 to 1800°F (870 to 980°C) range.
The cold-forming behavior of INCOLOY alloy 925 is similar to that of INCOLOY alloy 825 except that alloy 925 has a higher work-hardening rate.
Machining
INCOLOY alloy 925 is an age hardenable alloy with good machinability in the solution-annealed or aged conditions. Rigid tools with positive rake angles and techniques that minimize work hardening of the material are required. Cemented carbide tools produce the highest cutting rates and are recommended for most turning operations involving uninterrupted cuts. High speed steel tools may be used for interrupted cuts, finishing to close tolerances, finishing with the smoothest surfaces, and cutting with the least amount of work hardening. Best results are obtained by rough machining before age hardening and finishing after heat treatment. Table 13 lists the machining data for INCOLOY alloy 925.
Heat Treatment
Solution annealing in preparation for age hardening should be done at 1800-1900°F (980-1040°C) for a minimum of 30 min and a maximum of 4 h. Cool at a rate equivalent to air cooling, or faster, for sizes of 1 in (25 mm) or under. Water quench all sizes over 1 in (25 mm).
The following age hardening treatment is normally used: 1350-1380°F (732-749°C)/6-9 h, FC to 1150°F (621°C), hold at 1150°F (621°C) ± 15°F (8°C) for a total aging time of 18 h. Cool at a rate equivalent to air cooling, or faster.
INCOLOY alloy 925 is designated as UNS N09925.
Available as tube, round bar, flat bar and forging.
Product size range
Diameter: 100mm - 600mm
Length: on request
Production Process
