Inconel 718

metal

nickel superalloy — precipitation-hardened

UNS N07718Alloy 718IN718Nicrofer 5219Haynes 718Udimet 718AMS 5664 (wrought ref.)

Density

8.19 g/cm³

YS (LPBF as-built (XY))

650–920 MPa

UTS (LPBF as-built (XY))

880–1120 MPa

Elongation (LPBF as-built (XY))

10.0–30.0 %

Elastic modulus

185–210 GPa

Thermal conductivity

11.4 W/m·K

Composition — UNS N07718 / ASTM F3055-14

Element	Min %	Max %	Notes
Ni	50.00	55.000	Base element. High Ni content drives creep resistance and oxidation protection
Cr	17.00	21.000	Oxidation resistance via Cr₂O₃ scale; pitting and SCC resistance
Nb	4.75	5.500	Primary strengthener via γ'' (Ni₃Nb) precipitation; must stay in solution after anneal
Mo	2.80	3.300	Solid solution strengthening; creep resistance
Ti	0.65	1.150	Forms γ' (Ni₃Ti,Al) precipitates; controls γ'/γ'' ratio

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Mechanical & thermal properties — 5 conditions

Property	LPBF as-built (XY)	LPBF as-built (Z)	LPBF SA+DA (XY) — primary service condition	LPBF SA+DA (Z)	LPBF + HIP + SA+DA (isotropic)
Elastic modulus	185–210 GPa	—	195–215 GPa	—	—
Yield strength (0.2%)	650–920 MPa	520–780 MPa	1070–1180 MPa	990–1110 MPa	1050–1150 MPa
Ultimate tensile strength	880–1120 MPa	750–1000 MPa	1310–1400 MPa	1240–1360 MPa	1270–1380 MPa
Elongation at break	10.0–30.0 %	8.0–28.0 %	12.0–22.0 %	10.0–19.0 %	14.0–24.0 %
Hardness (HV)	260–360 HV10	—	400–460 HV10	—	—
Fatigue strength	—	—	480–620 MPa	—	580–720 MPa
Density	8.19 g/cm³	—	—	—	—
Thermal conductivity	11.4 W/m·K	—	11.4 W/m·K	—	—
CTE	12.5–13.5 µm/m·K	—	—	—	—

Values shown as min–max where a spread is reported, otherwise as typical ± unit. Ranges reflect inter-source variation, not single-sample scatter. All values are for AM-processed specimens unless noted.

Engineering considerations

Always specify SA+DA post-processing: solution anneal at 980°C (not 1065°C — avoids δ-phase dissolution zone) + 720°C/8h FC to 620°C/8h. The exact temperature and time must be controlled to ±10°C.
Laves phase verification: before shipping structural parts, verify Laves dissolution via SEM-EDS or hardness mapping. Residual Laves will appear as Nb/Mo-rich particles and corresponds to hardness excursions.
Stress relief is mandatory before part removal: minimum 1000°C/1–2h in vacuum or argon. Removal without stress-relief will cause significant distortion in large or complex parts.
Build orientation: for fatigue-critical applications, ensure primary load axis is in the XY plane in as-built condition. After SA+DA, anisotropy reduces but does not disappear — document orientation on traveller.
HIP requirement: for NADCAP-controlled flight-critical parts, HIP (1163°C/100 MPa/4h) before SA+DA is standard practice at most Tier 1 aerospace AM suppliers. Budget 40–60% cost premium over SA+DA alone.
Cracking risk: IN718 has lower hot-cracking susceptibility than many other Ni superalloys (no high Al+Ti) but liquation cracking at grain boundaries can occur with improper preheating or excessive energy density.
Surface finish: as-built Ra 10–20 µm is too rough for many hot-section applications. Electrochemical machining (ECM) or abrasive flow machining (AFM) used for internal channel smoothing — specify finish method in design.
Creep design: use the 100,000h larson-miller parameter data for wrought IN718 as a conservative baseline. LPBF SA+DA creep data is still sparse — avoid creep-critical applications without specific test data.
Repair: LPBF IN718 can be laser-cladded or TIG-welded with IN625 or IN718 filler — widely used for cast/forged IN718 engine part repair. Process qualification required per OEM specifications.

Advantages

Highest retained strength of common AM metals at elevated temperature — YS remains >700 MPa at 650°C
Outstanding oxidation and hot corrosion resistance to 980°C
Well-characterised post-processing route (SA+DA) produces wrought-equivalent or better properties
LPBF enables complex internal cooling channels impossible in forging — critical for turbine thermal management
Wide LPBF process window — relatively low crack susceptibility vs IN625, IN939, or CM247LC
Comprehensive standards ecosystem: ASTM F3055, AMS 7009, NADCAP — clear qualification path
Good weldability (low B, controlled S) — allows hybrid LPBF + TIG repair strategies
Magnetic permeability of ~1.01 — effectively non-magnetic for sensor-critical applications

Limitations

SA+DA heat treatment is mandatory for structural use — as-built properties are unacceptable for high-temperature service
Laves phase formation during LPBF is intrinsic — Nb segregation cannot be fully prevented; only dissolved in post-processing
Residual stress is extremely high in as-built LPBF IN718 — stress-relieve before removal from build plate or part will distort
Very low thermal conductivity (11 W/m·K) — highest residual stress and cracking risk of the common LPBF metals
Powder cost is 3–5× that of 316L stainless — cost-justify with functional requirement, not just temperature tolerance
LPBF IN718 has lower oxidation resistance above 980°C than cast/wrought — chromia scale is not stable at higher temperatures
High γ'' precipitation kinetics during LPBF cooling may lead to over-aging in slow-cooling regions — parameter uniformity critical
Powder reactivity with moisture and oxygen — strict storage protocol; atmospheric control during process and powder handling mandatory

Typical applications

Turbine engine combustion chambers and linersTurbine blades and vanes (stationary airfoils)Fuel nozzles and injectorsExhaust housings and manifoldsRocket propulsion injectors and chambersOil & gas downhole tools and wellhead componentsCryogenic turbopump componentsStructural engine brackets and mountsHeat exchangers for high-temperature processesNuclear fasteners and pressure-boundary hardware

Standards & certifications

ASTM-F3055established

IN718 (UNS N07718) parts produced by powder bed fusion — composition, powder, and minimum mechanical property requirements

aerospacedefenceenergyindustrial

AMS-7009established

IN718 LPBF for aerospace structural applications — solution-annealed + double-aged (SA+DA) condition requirements

aerospacedefence

Required by most Tier 1 aerospace OEMs for structural and engine-adjacent IN718 LPBF parts. Sets UTS ≥1310 MPa, YS ≥1070 MPa, El ≥12%.

AMS-7000established

LPBF process requirements — machine qualification, atmosphere, process controls for aerospace production

aerospacedefence

ASTM-E8established

Tensile test method for acceptance testing

aerospaceenergyindustrial

ASTM-E466established

Force-controlled fatigue testing — critical for engine and rotating applications

aerospaceenergy

NADCAP-AC7110-14established

Third-party accreditation for AM metallic parts — required by most prime aerospace contractors

aerospacedefence

NADCAP accreditation required before supplying flight-critical IN718 AM parts to Airbus, Boeing, GE Aviation, Pratt & Whitney, Rolls-Royce, and Safran.

Inconel 718

Composition — UNS N07718 / ASTM F3055-14

Mechanical & thermal properties — 5 conditions

Engineering considerations

Advantages

Limitations

Typical applications

Industries

Standards & certifications

Compatible AM processes (6)

Other metal materials

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