Nov 23 2012
Topics CoveredIntroductionChemical CompositionPhysical PropertiesMechanical PropertiesThermal PropertiesFabrication and Heat Treatment Machinability Forming Welding Heat Treatment Forging Hot Working Cold Working Annealing HardeningApplications
Super alloys or high performance alloys have high creep and oxidation resistance. They can be strengthened by solid-solution hardening, work hardening, and precipitation hardening. They can be used in environments with high temperatures and mechanical stress, and also where high surface stability is required. There are three groups of alloys such as cobalt-based, nickel-based, and iron-based alloys.
Incoloy(r) alloy 925™ is a precipitation-hardenable nickel-iron-chromium alloy. It can be age-hardened by adding aluminum and titanium. On the other hand, copper and molybdenum are added to increase its resistance to corrosive media. The datasheet given below discusses about Incoloy(r) alloy 925™ in detail.
The following table shows the chemical composition of Incoloy(r) alloy 925™.
The physical properties of Incoloy(r) alloy 925™ are given in the following table.
The mechanical properties of Incoloy(r) alloy 925™ are outlined in the following table.
|Tensile strength (precipitation hardened, value at room temperature)
|Tensile strength (@ 550°C/1020°F, precipitation hardened prior to test)
|Yield strength (@ strain 0.200%, precipitation hardened. value at room temperature)
|Yield strength (@ strain 0.200%, temperature 550°C/1020°F, precipitation hardened prior to test)
|Elongation at break (precipitation hardened)
The thermal properties of Incoloy(r) alloy 925™ are displayed in the following table.
|Thermal expansion co-efficient (@ 20-100°C/68-212°F)
Fabrication and Heat Treatment
Incoloy(r) alloy 925™ can be machined using conventional machining methods which are used for iron based alloys. Tooling and heavy duty machining equipments are used to reduce work-hardening of this alloy. Machining operations can be performed by using commercial coolants. High speed operations such as grinding, turning, or milling, are usually performed using water-based coolants.
Incoloy(r) alloy 925™ can be easily formed using all conventional techniques. Heavy-duty lubricants are used while cold forming.
Shielded metal-arc welding, gas metal-arc welding, gas-tungsten arc welding, and submerged-arc welding methods are preferred for welding Incoloy(r) alloy 925 ™.
Incoloy(r) alloy 925™ is heat treated by annealing at 983 to 1038°C (1800 to 1900°F) followed by cooling.
Forging of Incoloy(r) alloy 925™ is done at 927 to 1177°C (1700 to 2150°F).
Incoloy(r) alloy 925™ is hot worked at 872 to 983°C (1600 to 1800°F). Temperature should not exceed above 983°C (1800°F) in order to restore corrosion resistance of this alloy.
Incoloy(r) alloy 925™ can be cold worked using standard tooling. Soft die materials such as zinc alloys and bronze are used to produce good finishing and avoid galling problems.
Incoloy(r) alloy 925™ is annealed at 1010°C (1850°F) for 2 h followed by air cooling.
Incoloy(r) alloy 925™ is hardened by heat treatment and cold working.
Incoloy(r) alloy 925™ can be used in high-strength piping systems and petroleum industry.