Inconel 718 Round Bar (ASTM B637 / UNS N07718) is a precipitation-hardened nickel-chromium superalloy that achieves tensile strength above 1275 MPa in the aged condition — outperforming 316L stainless steel by a factor of 2.5x at room temperature and retaining over 80% of that strength at 650°C. Unifit Fastener stocks 3 mm to 600 mm diameters from its Mumbai warehouse with full AMS 5662 / AMS 5663 / NACE MR0175 certification and EN 10204 3.1 MTCs dispatched the same day.
Compliant with ASTM B637 and designated UNS N07718 (also known as Werkstoff 2.4668 or DIN 2.4668), this precipitation-hardenable alloy delivers an extraordinary combination of tensile strength, creep resistance, and oxidation resistance — even under continuous operating temperatures up to 700°C (1300°F). The secret to its exceptional strength lies in its unique metallurgical structure: the formation of a gamma double prime (γ″) phase through the interaction of niobium, nickel, and other trace elements. This phase, generated during the precipitation hardening heat treatment process, locks dislocations within the alloy matrix and dramatically boosts mechanical performance compared to conventionally processed nickel alloys.
We maintain a ready stock of Inconel 718 Round Bars in diameters ranging from 3 mm to 600 mm, covering all standard and custom lengths. Our bars conform to AMS 5662, AMS 5663, ASME SB 637, and NACE MR0175/ISO 15156, and are available in multiple surface finishes including bright, polished, rough turned, and centreless ground. Whether you are procuring bar stock for jet engine turbine discs, subsea wellhead packers, nuclear control rod mechanisms, or NACE MR0175-compliant downhole tooling, Unifit Fastener offers the technical expertise, full mill test certificates (MTC), and competitive pricing that Indian and global buyers demand.
Industries & Applications of Inconel 718 Round Bar
Inconel 718 is the alloy of choice wherever high strength at elevated temperatures, corrosion resistance, and dimensional stability are non-negotiable. Unifit Fastener supplies Inconel 718 bars to the following industries:
Aerospace & Defense
Jet engine turbine discs, blades, and blade retainers
Rocket motor components and thrust chambers
Airframe fasteners and structural components
Cryogenic storage tank hardware
Oil, Gas & Petrochemical
Wellhead completion equipment and packers
Downhole tooling and drill collars
Sour-gas service (NACE MR0175 compliant bars)
Subsea manifold components
Power Generation
Land-based gas turbine engine components
Steam generator parts and heat exchanger internals
Nuclear reactor internals and control rod mechanisms
Industrial & Precision Engineering
High-performance bolts, studs, and fasteners
Mandrels, shafts, and precision ground bars
Instrumentation components and sensor housings
Pollution-control and chemical-processing equipment
Key Properties & Performance Advantages of Inconel 718
Performance Property
Why It Matters
Outstanding High-Temperature Strength
Maintains tensile strength above 1000 MPa even at 650°C — ideal for jet engine and gas turbine components where other alloys fail.
Superior Corrosion & Oxidation Resistance
The passive chromium-oxide layer formed on the surface resists aggressive media including chlorides, sulfides, and high-temperature steam.
Excellent Weldability
Unlike many precipitation-hardenable alloys, Inconel 718 can be welded in both annealed and aged conditions without post-weld cracking.
Good Machinability
Can be machined in both annealed and aged states with the right tooling, cutting speeds (10-40 m/min), and feed rates.
Cryogenic Toughness
Retains ductility and impact resistance at temperatures as low as -196°C, making it viable for liquid nitrogen and LNG applications.
NACE / Sour-Gas Compliance
Meets NACE MR0175 / ISO 15156 for H2S service — critical for offshore and downhole oil & gas components.
Gamma Double Prime Strengthening
Unique γ″ strengthening phase (Ni3Nb) provides superior creep and stress-rupture resistance compared to gamma-prime alloys.
Inconel 718 vs Inconel 625 — Comparative Overview
Property
Inconel 718
Inconel 625
Strengthening Mechanism
Precipitation hardening (γ″ phase)
Solid solution + carbide strengthening
Tensile Strength (room temp)
130 ksi (900 MPa) typical
100 ksi (690 MPa) typical
Yield Strength
70 ksi (480 MPa) typical
60 ksi (414 MPa) typical
Elongation
25% min (in 2 in.)
30% min (in 2 in.)
Max Service Temp
Up to 700°C (1300°F)
Up to 1093°C (2000°F)
Density
8.19 g/cm3 (0.296 lb/in3)
8.44 g/cm3 (0.305 lb/in3)
Thermal Conductivity
9.6 BTU/hr·ft2·°F (16.7 W/m·K)
6.8 BTU/hr·ft2·°F (11.9 W/m·K)
Primary Industry
Aerospace, oil & gas, nuclear
Marine, chemical, offshore
Weldability
Excellent (both conditions)
Outstanding (no cracking)
NACE Compliance
Yes — MR0175 / ISO 15156
Yes — MR0175 / ISO 15156
Inconel 718 International Equivalent Grades
Standard
Country/Region
Designation
UNS
North America
N07718
ASTM
United States
B637
ASME
United States
SB-637
AMS
United States
5662 / 5663 / 5664
JIS
Japan
NCF718
DIN / W.-Nr.
Germany
2.4668
EN
Europe
NiCr19Fe19Nb5Mo3
GOST*
Russia
KhN45MVTYuBR (Approx.)
Indicative Inconel 718 Round Bar Price List
Note: Prices are indicative and subject to change based on current LME nickel rates, order quantity, heat treatment condition, and surface finish. Contact Unifit Fastener for the most current pricing.
Description
Size / Quantity
Price (USD)
Price (GBP)
Alloy 718 Round Bar — 10 mm dia × 500 mm
1 pc
Contact for Quote
~£65
Alloy 718 Round Bar — 10 mm dia × 500 mm
2 pcs
Contact for Quote
~£96
Alloy 718 Round Bar — 10 mm dia × 2000 mm
2 pcs
Contact for Quote
~£202
Alloy 718 Hex Bar — 10 mm (A/F) × 1000 mm
1 pc
~$101
£101
Alloy 718 Hex Bar — 10 mm (A/F) × 2000 mm
3 pcs
~$427
£427
OD 1.4" × 11" Long
1 pc
$130.19
—
40 mm dia × 1.00 m Long
1 pc
$512.02
—
60 mm dia × 1.00 m Long
1 pc
$1,186.65
—
100 mm dia × 0.50 m Long
1 pc
$1,661.67
—
Machining Guidelines for Inconel 718 Round Bar
Inconel 718 is a challenging alloy to machine due to its high work-hardening rate and elevated hot hardness. The following recommended cutting parameters help achieve optimal tool life and surface finish:
Operation
Cutting Speed Vc (m/min)
Feed Rate f (mm/rev)
Notes
Rough Turning
20-40
0.20-0.40
Use carbide (K20-K30) or ceramic inserts
Finish Turning
10-25
0.10-0.25
Positive rake geometry; flood coolant
Drilling
10-20
0.05-0.20
High-speed steel or solid carbide; peck drill
Rough Milling
15-30
0.05-0.15 mm/tooth
Avoid interrupted cuts where possible
Finish Milling
10-20
0.03-0.10 mm/tooth
Maintain chip control; inspect inserts frequently
Quality Certifications & Testing at Unifit Fastener
Inconel 718 is a nickel-chromium-iron-niobium superalloy designated UNS N07718 (also Werkstoff Nr. 2.4668 under DIN and NCF 718 under JIS). Its primary alloying elements are nickel (50-55%), chromium (17-21%), iron (balance), and niobium+tantalum (4.75-5.50%), with controlled additions of molybdenum, titanium, and aluminum.
AMS 5662 covers Inconel 718 round bars in the solution-annealed condition (softened, ready for precipitation hardening by the end user), while AMS 5663 covers bars that are already solution-annealed AND precipitation-hardened (age-hardened) by the manufacturer. Buyers who intend to do their own heat treatment should specify AMS 5662; those needing ready-to-use maximum-strength bars should specify AMS 5663.
Inconel 718 retains adequate mechanical properties up to approximately 700°C (1300°F) under continuous service. Bright bar forms may operate intermittently up to 982°C (1800°F). Beyond these temperatures, other superalloys such as Inconel 625 or Hastelloy X are recommended.
Yes, Inconel 718 has excellent weldability in both annealed and age-hardened conditions — a significant advantage over many other precipitation-hardenable superalloys. Recommended welding processes include TIG (GTAW) and MIG (GMAW) using Inconel 718 filler wire (ERNiFeCr-2). To minimize heat-affected zone cracking, use low heat input, avoid large weld beads, and post-weld heat treat if required by the design code.
NACE MR0175 (ISO 15156) specifies material requirements for equipment used in oil and gas production environments containing hydrogen sulfide (H2S), commonly called sour service. Inconel 718 bars in the solution-annealed and aged condition with hardness not exceeding 40 HRC are qualified for sour-gas service under this standard. Unifit Fastener supplies NACE MR0175 compliant bars with full documentation.
