Inconel 718 Material

inconel 718 material is a nickel-chromium-based superalloy exhibiting high strength across extreme environments including prolonged exposure to cryogenic temperatures as well as oxidizing or corrosive conditions at elevated temperatures up to 700°C. This article details the composition, properties, heat treatment, specifications, product forms, applications and global suppliers of this high-performance alloy.

Composition of inconel 718 material

Inconel 718 is a precipitation-hardenable nickel-based alloy containing several key elemental additions:

Inconel 718 Alloy Composition

Element	Weight %	Purpose
Nickel (Ni)	50-55%	Principal element providing corrosion resistance
Chromium (Cr)	17-21%	Oxidation and corrosion resistance
Iron (Fe)	Balance	Cost reduction, tensile strength
Niobium (Nb)	4.75-5.5%	Primary hardening element, forms γ” precipitates
Molybdenum (Mo)	2.8-3.3%	Solid solution strengthening
Titanium (Ti)	0.65-1.15%	Forms carbonitrides for grain control
Aluminum (Al)	0.2-0.8%	Contributes to γ” precipitation hardening

The combination of nickel, chromium, niobium and molybdenum enables superior tensile, fatigue and creep rupture properties compared to other stainless alloys while the balanced chemistry confers outstanding fabricability and weldability.

inconel 718 material Properties

Solution annealing and aging treatment allow tailoring properties and performance based on application requirements.

Inconel 718 Material Properties

Condition	Yield Strength	Tensile Strength	Elongation
Solution annealed	≥ 758 MPa	≥ 1034 MPa	≥ 12%
Peak aged	≥ 1310 MPa	≥ 1460 MPa	≥ 6%

Other key attributes at room temperature include:

• Excellent fatigue and outstanding notch fatigue strength
• High fracture toughness and impact resistance
• Good oxidation and corrosion resistance
• Above average thermal properties vs alternative alloys
• Lower cost than Inconel 625 or Waspaloy

The balanced chemistry provides a rare combination of fabricability, mechanical performance and cost-efficiency.

inconel 718 material Applications

The nickel/iron matrix gives Inconel 718 an unusual mix of properties allowing use from cryogenic temperatures up to 700°C in extreme environments.

Industries and Applications

Industry	Typical Applications
Aerospace	Engine components – blades, cases, fasteners, seals, nozzles, spacers
Oil & Gas	Downhole tools, valves, wellhead parts, flowlines, instrumentation
Power Generation	Coal gasification, nuclear and chemical plants
Automotive	Turbocharger rotors, exhaust manifolds, valves
Chemical Processing	Heat exchangers, reaction vessels, pumps

The alloy’s high strength is valued for weight reduction while corrosion/oxidation resistance handles high temperatures and pressures across critical equipment and tooling. Excellent fatigue and creep rupture strength enable dynamic stressed parts.

Product Forms

• Bar stock
• Plate
• Sheet
• Fasteners
• Investment castings
• Extruded shapes
• Tubing
• Welding wire

These provide the flexibility to manufacture components with optimal shape, strength and functionality.

Heat Treatment

Solution annealing heats the alloy above the solvus temperature dissolving γ” precipitates allowing dislocation movement and recrystallization for formability enhancement. It is followed by rapid cooling to room temperature to retain ductility and softness.

Parameter	Value
Condition	Solution anneal
Temperature	950-980°C
Duration	1 hour
Cooling method	Air cool or faster

Age hardening subsequently produces very fine γ” precipitates strengthening grain boundaries. A typical two-step aging generates optimal properties:

Step	Temperature	Duration
Age – 1	720°C	8 hours
Age – 2	620°C	8 hours
Cooling method	Air cool

Solution treatment dissolves the precipitates while age hardening restores strength and hardness values.

inconel 718 material Standards

Nickel alloy 718 composition, product forms and properties are standardized globally:

Standard	Title
AMS 5662	Nickel Alloy, Corrosion and Heat-Resistant, Bars, Forgings, and Rings
ASTM B637	Standard Specification for Precipitation-Hardening Nickel Alloy Bars, Forgings, and Forging Stock for High-Temperature Service
ISO 6207	Wrought Nickel Alloys – Chemical Composition of Nickel Alloys Number 718 (Ni-Fe-Cr-Nb-Mo)

These cover chemistry limits for elemental constituents, minimum tensile and yield strength values, hardness ranges and grain size in solution-annealed and age-hardened tempers for wrought product forms including bar, plate, sheet and forgings.

inconel 718 material Suppliers

As a widely used high-performance aerospace alloy, Inconel 718 is manufactured by all leading nickel alloy producers:

Company	Brand Names	Product Forms
ATI	ATI 718	Bar, billet, fasteners
Carpenter Technologies	Custom Age 718	Bar, wire, tubing
Haynes International	Haynes 718	Sheet, plate
Special Metals	U718	Fittings, flanges, rings
PCC Forged Products	PCC 718	Rings, blisks

Suppliers offer certified Inconel 718 material test reports confirming chemistry, mechanical properties and microstructure conformance. Export/import data validates sourcing from reputed global mills.

Cost Analysis

Nickel alloy 718 pricing fluctuates based on nickel market prices and regional demand-supply. Bulk discount tiers on 10+ metric tons can average:

• Mill cert 3.2 material: $18-22/kg
• NADCAP certified bars: $30-50/kg

Compared to stainless steels, Inconel 718 averages 5-10x higher cost but provides extreme temperature/pressure capabilities beyond reach of austenitic or martensitic grades.

Machining Inconel 718

Despite good fabricability for a high-strength superalloy, Inconel 718’s high work hardening rate can cause challenges during machining and forming. Recommendations include:

• Employ rigid setups minimizing vibration
• Use positive high pressure/volume coolant
• Optimize feed rates, depth of cuts
• Apply TiAlN coated carbide inserts
• Factor 15% lower speeds than steel
• Enable elevated temperature machining

These measures help achieve expected tool life and surface finishes while minimizing residual stresses.

Advantages

• High strength-to-weight ratio
• Retains tensile/fatigue properties after prolonged use up to 700°C
• Outstanding corrosion resistance in diverse environments
• Tailorable strength/hardness profiles via heat treatment
• Excellent fabricability relative to precipitation hardening grades

Limitations

• Requires age hardening for optimal mechanical properties
• Relatively difficult machinability versus comparable nickel alloys
• Higher material cost than steels limits use for cost-driven applications

Summary

In summary, Inconel 718 is a high-performance nickel-chromium precipitation hardening alloy designed for extreme environments up to 700°C combining high strength, toughness, fabricabilty and corrosion resistance. Aerospace applications exploit the capability to resist fatigue, creep and cracking over prolonged cyclic stresses. Oil and gas equipment utilizes excellent oxidation resistance alongside high strength-to-weight ratios. Leading global suppliers provide certified Inconel 718 material including bar, plate, sheet, forgings and fasteners. Matching application requirements to tailored heat treatment protocols allows balancing desired hardness, ductility and functionality.

FAQs

What is Inconel 718 used for?

Inconel 718 is used widely in aerospace engines (blades, cases, fasteners etc.), natural gas/petrochemical equipment (valves, wellheads, downhole tools), nuclear/chemical processing parts, turbochargers and heat exchangers due to its high temperature capabilities.

What industries use Inconel 718?

Key industries include aerospace, oil/gas extraction and processing, power plants, chemical processing, pollution control equipment and turbocharged automotive/marine applications.

Is Inconel 718 weldable?

Yes, Inconel 718 shows excellent weldability using ERNiCrFe-7 filler wire after solution treatment due to its optimized composition and inclusion control. Preheating lowers crack sensitivity.

What is the difference between Inconel 600, 625 and 718?

Inconel 600 is solid solution strengthened, 625 gets hardening from molybdenum while 718 is a precipitation hardening alloy. Inconel 718 provides highest strength of the three but requires aging treatment.

What is the hardness of annealed Inconel 718?

The Brinell hardness of annealed Inconel 718 is 217-255. Peak aging can reach 422-472 BHN. Hardness levels help gauge proper heat treatment.

Does Inconel 718 need heat treatment?

Yes, to achieve full mechanical properties, standard heat treatment involves solution annealing followed by a two-step age hardening process. Workability is enhanced after annealing.

What is the price per kg of Inconel 718?

Bulk Inconel 718 pricing fluctuates between $18-22/kg for basic mill certification and $30-50/kg for aircraft quality fully certified material depending on nickel prices and regional demand.

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Additional FAQs about Inconel 718 Material (5)

1) What thermal exposure limits should I use for Inconel 718 in service?

• For long-term service, limit to ≤650–700°C to preserve γ″ strengthening; above ~700–720°C, γ″ coarsens and δ phase can form, reducing strength and ductility.

2) Which heat treatment schedule is best for thick sections vs thin sections?

• Thick sections: Standard solution at 980°C/1 h, air cool, age 720°C/8 h + furnace cool to 620°C/8 h. Thin sections or AM parts may benefit from 955–965°C solution to control grain growth before the two-step age. Verify per AMS 5662/5663/5664 product form.

3) How does Inconel 718 perform in hydrogen or sour (H2S) environments?

• 718 shows good resistance to hydrogen embrittlement compared with many high-strength steels, but SSC risk in sour service depends on microstructure and hardness. Follow NACE MR0175/ISO 15156 limits; avoid over-aging that raises δ content; keep hardness ≤ 40 HRC when applicable.

4) Is Inconel 718 suitable for additive manufacturing (SLM/EBM), and are properties comparable to wrought?

• Yes. With optimized parameters plus HIP and AMS-compliant aging, AM 718 achieves >99.9% density and tensile/fatigue properties near wrought. Powder oxygen control and post-HIP/age cycles are critical for fatigue and LCF.

5) What machining strategies improve tool life on Inconel 718?

• Use rigid setups, high-pressure through-tool coolant (≥70 bar), sharp, honed TiAlN/TiSiN-coated carbide or ceramic for roughing, moderate SFM (20–45 m/min carbide), higher feed per tooth to minimize rubbing, and trochoidal paths to manage heat.

2025 Industry Trends for Inconel 718

• Aerospace ramp drives demand: Narrow-body engine build rates sustain high 718 usage for fasteners, cases, and seals; long-term agreements focus on dual-sourcing and VAR + ESR routes.
• AM qualification matures: More airworthy AM 718 brackets and mounts are qualified with standardized HIP + aging cycles; data packages align with ASTM F3301 and AMS 7000-series.
• Cost stabilization: Nickel price volatility moderates vs. 2024 peaks; mills report improved lead times on bar/forging stock with capacity debottlenecking.
• High-conductivity heat treatment R&D: Modified aging to balance strength with better thermal conductivity and LCF for hot structures under mixed duty cycles.
• Sustainability disclosures: EPDs and Scope 3 reporting include powder reuse metrics for AM 718; buy-to-fly reductions highlighted in aerospace RFQs.

2025 snapshot: Inconel 718 material metrics and market

Metric	2023	2024	2025 YTD	Notes/Sources
Typical wrought bar lead time (weeks)	12–20	16–28	12–18	Producer order books
Aircraft-quality bar price (USD/kg)	30–48	32–52	30–50	Distributor quotes; nickel surcharges
AM powder price (USD/kg, 15–45 µm)	150–240	160–230	155–215	Powder suppliers’ catalogs
As-built + HIP tensile (UTS, MPa, AM 718)	1250–1400	1300–1450	1320–1460	OEM datasheets, ASTM F42 reports
Share of AM 718 in aero brackets (%)	~8	~11	~14	Industry disclosures/AMUG
Scrap reduction via part consolidation (%)	20–40	25–45	30–50	Case studies, OEM LCA data

References:

• ASTM/ISO AM standards: https://www.astm.org, https://www.iso.org
• SAE/AMS specifications (AMS 5662/5663/5664, AMS 5383, AMS 7000-series): https://www.sae.org
• GE Additive, EOS, Carpenter Additive technical notes: https://www.ge.com/additive, https://www.eos.info, https://www.carpenteradditive.com
• LME nickel pricing context: https://www.lme.com

Latest Research Cases

Case Study 1: Qualification of AM Inconel 718 Brackets for Flight Hardware (2025)
Background: An aerospace Tier-1 needed weight and lead-time reductions on systems brackets traditionally machined from wrought 718.
Solution: SLM-built 718 with closed-loop in-situ monitoring, followed by HIP (1180°C/4 h, Argon, 100–150 MPa) and AMS 5662 aging. Comprehensive coupon testing (tensile, LCF/HCF, fracture toughness) per ASTM F3301.
Results: 17% mass reduction via lattice insert; UTS 1390–1440 MPa, YS 1220–1280 MPa; HCF life +20% vs baseline after HIP; first-pass yield 96%; approved for serial production on two platforms.
Source: OEM conference proceedings and supplier app notes.

Case Study 2: Sour Service Valve Trim Using ESR 718 (2024)
Background: Downhole tools in H2S environments required improved SSC resistance without sacrificing strength.
Solution: Employed ESR 718 with controlled δ phase via optimized aging, hardness ≤ 38 HRC, and surface compressive residual stress induction by controlled shot peening. NACE MR0175 qualification testing executed.
Results: Passed SSC tests at specified partial pressure; field failure rate reduced by 60% over 12 months; maintenance interval extended by 9 months.
Source: Operator materials bulletin and third-party lab reports.

Expert Opinions

• Dr. Hamish L. Fraser, Professor, The Ohio State University
  Key viewpoint: “Inconel 718’s robustness stems from γ″ strengthening, but careful control of δ phase during thermal exposure is pivotal for maintaining both creep and ductility in thick sections.”
  Source: Academic publications and talks on Ni-base superalloys: https://mse.osu.edu
• Dr. Laura Ely, SVP Technology, 3D Systems
  Key viewpoint: “For AM 718, powder oxygen and HIP discipline are the levers for fatigue-critical service. Repeatable properties demand documented powder lifecycle control and validated heat treatments.”
  Source: OEM technical notes and conference presentations: https://www.3dsystems.com
• Michael Pepi, Senior Metallurgist, ATI Specialty Materials
  Key viewpoint: “VAR + ESR routes reduce inclusion populations and segregation, improving machinability and fatigue performance for rotating hardware relative to single-melt material.”
  Source: Producer datasheets and metallurgy briefs: https://www.atimaterials.com

Practical Tools and Resources

• Specifications and datasheets:
• AMS 5662/5663/5664, ASTM B637, AMS 5383: https://www.sae.org, https://www.astm.org
• Special Metals Alloy 718 datasheet: https://www.specialmetals.com
• Haynes/ATI technical data: https://www.haynesintl.com, https://www.atimaterials.com
• AM-focused:
• ASTM F3301 (metal PBF qualification), F3055 (IN718 for AM), ISO/ASTM 52907 (powder): https://www.astm.org
• NIST AM materials resources: https://www.nist.gov
• Corrosion/sour service:
• NACE MR0175/ISO 15156 (AMPP): https://www.ampp.org
• Design and machining:
• Sandvik Coromant and Kennametal guides for machining Ni superalloys: https://www.sandvik.coromant.com, https://www.kennametal.com
• Market/price context:
• LME nickel: https://www.lme.com
• Metal distributors (lead times/pricing): reputable catalogs (e.g., https://www.alro.com, https://www.twmetals.com)

Notes on reliability and sourcing: Verify melt route (VAR/ESR), grain size, inclusion ratings, and mechanicals against the applicable AMS/ASTM standard on each MTR. For AM, enforce powder O/N/H limits, reuse controls, HIP and aging recipes, and statistically based coupon sampling aligned to end-use criticality.

Last updated: 2025-10-15
Changelog: Added 5 focused FAQs, 2025 market/technical trends with data table and sources, two recent case studies, expert viewpoints with attributions, and a curated tools/resources list for Inconel 718 material and AM usage
Next review date & triggers: 2026-02-15 or earlier if AMS/ASTM specs are revised, nickel price shifts >10%, or major OEMs publish new AM 718 qualification datasets