Inconel 718(Ni-Cr-Nb-Ta-Mo)

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1. Introduce

– Ni-Cr precipitation hardening alloy containing Nb, Mo, Fe, Al and Ti

– Alloy designed to reduce cost by adding about 20% Fe in place of Co, which is a significant amount in nickel-base super heat-resistant alloys

– Excellent tensile, fatigue, and fracture strength up to 704°C and oxidation resistance up to 1000°C

– Relatively good cryogenic properties, weldability, and formability compared to other precipitation hardening Ni alloys

– Mechanical properties of Inconel 718 are mainly determined by the precipitation of γ” phase consisting of Ni, Nb, Ti and γ” phase containing Ni, Al, Ti, Nb

– Limitation : Lack of microstructural thermal stability above 650℃ due to γ” phase transformation at high temperature

– UNS N07718

* Inconel

Features
– Resists oxidation and submersion in oxidizing and sulfurizing atmospheres above 900℃
– Non-corrosive to organic and salt solutions
– Excellent mechanical properties such as tensile and yield strength up to about 600℃
Applications
– High temperature heat resistant equipment(Heat treatment furnace, boiler, jet engine parts, electric heater parts)
Types
– Incoenl 600/601, Inconel 625, Inconel 690, Inconel 718, Inconel 718+, Inconel X-750, etc.

* Precipitation hardening Ni-based superalloys

– Most nickel-based superalloys are strengthened by precipitation of intermetallic compounds, primarily within the austenitic face cubic (FCC) base

– This is accomplished with elements such as Al, Ti, Nb, etc.

Strenthening Phase	Type
γ’ strengthened nickel-based superalloys	Inconel 718+, Waspaloy, Astroloy, U-700, U-720
γ” Reinforced nickel-based superalloys	Inconel 718
γ’ and γ” strengthened superalloys	Inconel 706, Inconel 909

* UNS

Abbreviation for Unified Numbering Systems for Metals and Alloys
Unified unique numbering system for metals and alloys
A representative number that is compatible with metals and alloys defined in many material-related codes such as ASTM, AISI, ASME, AWS, etc.

* N : Nickel and Nickel Alloys

* UNS N07718 : 07XXX : Chromium(Precipitation-hardenable alloy)

2. Property

– High temperature strength, corrosion resistance, oxidation and erosion resistance, yield and tensile strength, good creep resistance

Element	Impact
Cr	Provides corrosion resistance, oxidation resistance
Nb	Highly strengthening element, provides strength
Ta	Highly tempered, provides creep resistance, heat resistance, corrosion resistance
Mo	Highly strengthened element, high temperature oxidation resistance, cryogenic oxidation resistance, weldability

[Inconel 718 Chemical Composition (%)]

Ni	Cr	Fe	C	Al
50.00 ~ 55.00	17.00 ~ 21.00	11.12 ~ 24.60	Max. 0.08	0.20 ~ 0.80

Ti	Cu	Si	Mn	Mo
0.65 ~ 1.15	Max. 0.30	Max. 0.35	Max. 0.35	2.80 ~ 3.30

S	Co	Nb	P	B
Max. 0.02	Max. 1.00	4.75 ~ 5.50	Max. 0.02	Max. 0.01

[Inconel 718 Mechanical Properties]

Tensile Strength (Mpa)	Yield Strength (Mpa)	Elongation (%)
Max. 1275	Max. 1034	Max. 6

[Inconel 718 Physical Properties]

Density (g/㎤)	Melting Range (℃)	Specific Heat (0-100℃), J/kg*℃	Curie Temperature (℃)
8.23	1260 ~ 1335	435	-112

3. Standard & Specification

– Specification : UNS N07718

Available Form	ASTM	SAE	ASME	AWS
Bar, Rod	B637	AMS 5662, AMS 5663, AMS 5664, AMS 5832, AMS 5914, AMS 5962	SB637	–
Plate, Sheets, Strip	B670, B906	AMS 5596, AMS 5597	SB670	–
Wire	B637	AMS 5596, AMS 5597	SB670	5.14ERNiFeCr-2
Pipe, Tube	B983	AMS 5589, 5590	–	–
Forgings	B637	–	–	–
Fastener	F2281	–	–	–

4. Available Form

– Bar, Rod

– Plate, Sheets, Strip

– Wire

– Pipe, Tube

– Forgings

– Fasteners

5. Application & Product

– Aerospace, Chemical, Automotive, Oil and gas

Application	Product
Aerospace	Gas turbine parts, Jet engines, Liquid fuel rocket motors, Bolts, Fasteners, Shafting, Blades, Cases, Nozzles, Seals, Spacers
Chemical	Pumps, Cryogenic storage tanks, Heat exchangers, Reaction vessels
Automotive	Turbocharger rotors, Exhaust manifolds, Valves
Oil and gas	Downhole tools, Valves, Wellhead components, Well lines, Instrumentation