Super Alloy INCONEL 783 (UNS R30783)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Fabrication and Heat Treatment
     Machinability
     Hot Forming
Heat Treatment
Applications

Introduction

Super alloys are also known as high performance alloys specially designed to cater to environments with very high temperature of above 540°C (1000°F) where deformation resistance and high surface stability are essential.

Super alloy INCONEL 783 is a nickel-cobalt-iron alloy with chromium, aluminum, and niobium additions. It has oxidation-resistance, low coefficient of thermal expansion.

This alloy can be strengthened by a precipitation-hardening heat treatment. The presence of aluminum provides this alloy excellent resistance to oxidation at high temperature.

The following section explains in detail about super alloy INCONEL 783.

Chemical Composition

The chemical composition of INCONEL 783 is outlined in the following table.

Element Content (%)
Nickel, Ni 26-30
Iron, Fe 24-27
Aluminum, Al 5-6
Chromium, Cr 2.5-3.5
Niobium, Nb 2.5-3.5
Copper, Cu 0.50 max
Manganese, Mn 0.50 max
Silicon, Si 0.50 max
Titanium, Ti 0.10-0.40
Carbon, C 0.03 max
Boron, B 0.003-0.012
Phosphorus, P 0.015 max
Sulfur, S 0.005 max
Cobalt, Co Balance

Physical Properties

The physical properties of INCONEL 783 are tabulated below.

Properties Metric Imperial
Density 7.81 g/cm3 0.282 lb/in3
Melting point 1336-1407 °C 2437-2565 °F

Mechanical Properties

The following table shows mechanical properties of INCONEL 783.

Properties Metric Imperial
Tensile strength 1194 MPa 171 ksi
Yield strength 779 MPa 113 ksi
Poisson’s ratio 0.31 0.31
Elastic modulus 177.3 GPA 25.72 ksi
Elongation at break 24% 24%

Thermal Properties

The thermal properties of INCONEL 783 are tabulated below.

Properties Metric Imperial
Thermal expansion co-efficient (@93°C/200°F) 10.08 µm/m°C 5.60 µin/in°F
Thermal conductivity (@21°C/70°F) 10.1 W/m-°C 71 BTU in/hr.ft².°F

Fabrication and Heat Treatment

INCONEL 783 has good fabricability and can be formed, machined, and welded using all the traditional procedures for nickel alloys. This alloy’s reactions are similar to that of INCONEL 718.

Machinability

INCONEL 783 can be readily machined using the conventional practices for high-strength nickel alloys. In case of rough machining, the material has to be machined in the annealed condition.

Hot Forming

The temperature range for hot forming of INCONEL 783 is from 927°C to 1121°C (1700°F to 2050°F).

Heat Treatment

To heat treat this super alloy, the material has to solution annealed at 1121°C (2050°F) for 1 h, and air cooled. This should be followed by beta aging at 845°C (1550°F) for 4 h and air cooled to room temperature. Next the material is age hardened at 720°C (1325°F) for 8 h, furnace cooled at 55°C (100°F) for 1 hr to 620°C (1150°F) for 8 h and air cooled.

Applications

INCONEL 783 is widely used in gas turbine applications.

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