Nickel Alloy 718 – Properties, Composition, Heat Treatments and Specifications

Features of Nickel Alloy 718

The key features of Nickel Alloy 718 include:

Highly resistant to chloride and sulfide stress corrosion cracking
High strength in the aged condition
Good corrosion resistance

Performance Profile for Nickel Alloy 718

Nickel Alloy 718 is a precipitation hardenable nickel-chromium alloy. It combines high strength in the aged condition with good corrosion resistance and weldability.

Applications of Nickel Alloy 718

Typical Applications for the Nickel Alloy 718 include:

Valves
Well head completion equipment
Fasteners
Blow out preventers (BOPs)
Tubing hangers
Mandrels

Composition of Nickel Alloy 718

The composition range for Nickel Alloy 718 is provided in table 1.

Table 1. Composition of nickel alloy 718.

Chemistry, %	AMS 4967
	Min	Max
Nickel	50.0	55.0
Chromium	17.00	21.00
Molybdenum	2.80	3.30
Carbon	-	0.045
Columbian + Tantalum	4.87	5.20
Manganese	-	0.35
Silicon	-	0.35
Phosphorus	-	0.010
Sulfur	-	0.010
Copper	-	0.230
Cobalt	-	1.00
Lead	-	10 ppm
Selenium	-	5 ppm
Bismuth	-	30 ppm
Magnesium	-	60 ppm
Iron	-	remainder

Specifications

The various forms of nickel alloy 718 are covered by the following standards:

API 6A
API 6A718
NACE MR0175, MR0103
ISO 15156-3
ASTM B 637

Heat Treatments

718 NACE is annealed between 1875-1925°F and water quenched. Subsequently it is aged in the range of 1425°-1475°F for 6-8 hours and air cooled or faster to room temperature.

Physical Properties of Nickel Alloy 718

Density:	0.297 lb/inch³
Melting Range:	2160 - 2449°F

Thermal Properties of Nickel Alloy 718

The thermal properties of Nickel Alloy 718 are summarised in table 2.

Table 2. Thermal properties of Nickel Alloy 718.

Temp	Coefficient of Thermal Exp.	Thermal Conductivity	Modulus of Elasticity Dynamic
°F	in/in °F x 10^-6	Btu. ft/ft².hr°F	psi x 10⁶
70	-	6.4	29.0
200	7.3	7.2	28.4
400	7.5	8.2	27.6
600	7.7	9.3	26.7
1000	8.1	11.3	24.8
1200	8.4	12.3	23.7

Typical Mechanical Properties of Nickel Alloy 718

The minimum mechanical properties of nickel alloy 718 are provided in table 3.

Table 3. Minimum specified properties of nickel alloy 718, solution annealed and aged condition.

Property	Minimum	Maximum
Ultimate Tensile Strength	150 ksi	-
0.2% Yield	125 ksi	145 ksi
Elongation	20%	-
Reduction of Area	35%	-
Impact Strength* Min Average/Min Single	40/35 ft-lbs	-
Hardness	32 R_C	40 R_C

* Charpy V notch impact test performed at -75 ˚F

This information has been sourced, reviewed and adapted from materials provided by NeoNickel.

For more information on this source, please visit NeoNickel.

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