Inconel 706

Introduction

Super alloys are also known as high performance alloys. They have good creep and oxidation resistance, and are formed in different shapes. They can be strengthened by solid-solution hardening, work hardening, and precipitation hardening. They are classified into three groups such as cobalt-based, nickel-based, and iron-based alloys. They have the ability to function under high temperatures and severe mechanical stress, and also where high surface stability is required.

Inconel 706™ is a nickel-chromium-iron precipitation-hardening alloy. The following datasheet gives an overview of Inconel 706™.

Chemical Composition

The following table shows the chemical composition of Inconel 706™.

Elements	Content (%)
Nickel, Ni	39-44
Iron, Fe	38
Chromium, Cr	14.5-17.5
Niobium, Nb	2.50-3.30
Cobalt, Co	≤ 1
Titanium, Ti	≤ 0.40
Copper, Cu	≤ 0.35
Manganese, Mn	≤ 0.35
Silicon, Si	≤ 0.35
Carbon, C	≤ 0.30
Aluminum, Al	≤ 0.060
Phosphorous, P	≤ 0.020
Sulfur, S	≤ 0.015
Boron, B	≤ 0.0060

Physical Properties

The physical properties of Inconel 706™ are outlined in the following table.

Properties	Metric	Imperial
Density	8.05 g/cm³	0.291 lb/in³
Melting point	1360°C	2480°F

Mechanical Properties

The mechanical properties of Inconel 706™ are given in the following table.

Properties	Metric	Imperial
Tensile strength	757 MPa	109800 psi
Yield strength (at strain 0.200%)	383 MPa	55500 psi
Poisson’s ratio (precipitation hardened, calculated by mfr)	0.382	0.382
Modulus of elasticity (precipitation hardened, dynamic method)	210 GPa	30500 ksi
Elongation at break	47%	47%

Thermal Properties

The thermal properties of Inconel 706™ are displayed in the following table.

Properties	Metric	Imperial
Thermal expansion co-efficient (at 24-100°C/75.2-212°F)	13.46 µm/m°C	7.478 µin/in°F
Thermal conductivity	12.5 W/mK	86.8 BTU in/hr.ft².°F

 

Other designations that are equivalent to Inconel 706™ include:

AMS 5605

AMS 5606

AMS 5701

AMS 5702

AMS 5703

Fabrication and Heat Treatment

Machinability

Inconel 706™ can be machined using conventional machining methods which are used for iron-based alloys. Machining operations are performed using commercial coolants. High speed operations such as grinding, milling, or turning are performed using water-based coolants.

Forming

Inconel 706™ can be formed using all conventional techniques.

Welding

Inconel 706™ is welded using gas-tungsten arc welding, shielded metal-arc welding, submerged-arc welding, and gas metal-arc welding methods.

Heat Treatment

Inconel 706™ is heat treated by annealing at 927 to 1010°C (1700 to 1850°F) followed by cooling.

Forging

Inconel 706™ is forged at 983 to 1149°C (1800 to 2100°F).

Hot Working

Inconel 706™ is hot worked at 872 to 1149°C (1600 to 2100°F).

Cold Working

Inconel 706™ is cold worked using standard tooling.

Annealing

Inconel 706™ is annealed at 927 to 1010°C (1700 to 1850°F) followed by cooling.

Hardening

Inconel 706™ is hardened by heat treatment.

Applications

Inconel 706™ is mainly used in gas turbines for shafts, cases, turbine discs, and fasteners.