MS14181 Bolts, Inconel 718 220 KSI Spline-Drive Flanged Head
MS14181 is the United States military standard for high-strength tension bolts manufactured in nickel-alloy UNS N07718 (Inconel 718). The standard specifies a 220 ksi tensile strength, external wrenching spline-drive head, flanged shank-head transition, and dash-numbered sizes from 1/4 to 1-1/2 inch. The MS14181 family supersedes to NASM14181 under the National Aerospace Standard (NAS) consolidation. These bolts are the preferred fastener for gas-turbine compressor disc attachment, missile structural joinery, and high-cycle-fatigue aerospace bolted joints.
Quoting MS14181: send the full dash number (e.g. MS14181-5, MS14181-12, etc.), required grip length, drilled or non-drilled head, and ITAR clearance to
info@torqbolt.com or call
+91-22-66157017.
MS14181 originated as a U.S. Air Force Military Standard for tension fasteners in supersonic airframe and turbine engine applications. The bolts are characterized by:
- Material: nickel-alloy UNS N07718 (Inconel 718), age-hardened
- Ultimate tensile strength: 220 ksi (1517 MPa) minimum
- Service temperature: -65 °F to +1200 °F
- Head style: external wrenching, 12-spline drive, flanged shank-head transition
- Thread form: UNJF-3A (rounded thread root for improved fatigue)
- Surface finish: passivated per AMS 2700
- Identification: head-marked with manufacturer ID + "718"
| Nominal Size | Thread | Dash Number Range |
|---|
| 1/4 inch | 1/4-28 UNJF-3A | MS14181-04 through MS14181-04xxx |
| 5/16 inch | 5/16-24 UNJF-3A | MS14181-05 through MS14181-05xxx |
| 3/8 inch | 3/8-24 UNJF-3A | MS14181-06 through MS14181-06xxx |
| 7/16 inch | 7/16-20 UNJF-3A | MS14181-07 through MS14181-07xxx |
| 1/2 inch | 1/2-20 UNJF-3A | MS14181-08 through MS14181-08xxx |
| 9/16 inch | 9/16-18 UNJF-3A | MS14181-09 through MS14181-09xxx |
| 5/8 inch | 5/8-18 UNJF-3A | MS14181-10 through MS14181-10xxx |
| 3/4 inch | 3/4-16 UNJF-3A | MS14181-12 through MS14181-12xxx |
| 7/8 inch | 7/8-14 UNJF-3A | MS14181-14 through MS14181-14xxx |
| 1 inch | 1-12 UNJF-3A | MS14181-16 through MS14181-16xxx |
The numeric portion following the dash encodes nominal diameter in sixteenths of an inch. The 'xxx' suffix encodes grip length in thirty-seconds of an inch and drilled-head suffix.
Under the Aerospace Industries Association consolidation initiative, MS14181 was superseded by NASM14181 (National Aerospace Standard, derived from NAS, AS, and MS sources). For active procurement, NASM14181 is the current revision; legacy MS14181 part numbers remain valid for spare-parts inventory.
| Standard | Scope |
|---|
| MS14181 / NASM14181 | UNS N07718 tension bolts, 220 ksi, external wrenching spline drive |
| AS3418 | Similar SAE Aerospace standard, 12-point double-hex head |
| NAS1351 | UNS N07718 socket-head cap screws, lower strength |
| SAE AS 7467 | Procurement specification for UNS N07718 bolts and screws, 185 ksi |
| SAE AMS 5663 | Material specification for UNS N07718 bar (precipitation hardened) |
| SAE AMS 2700 | Passivation of corrosion-resistant steels (surface finish) |
MS14181 bolts are typically produced by:
- Vacuum-melted UNS N07718 bar to SAE AMS 5662 (solution treated) feed
- Hot or cold heading to form the flanged spline-drive head
- Threads rolled in one pass after oxide removal per ASTM A1014 §5.4
- Solution treatment + double age per SAE AMS 2774
- Passivation per SAE AMS 2700
- Fluorescent penetrant inspection
- Lot-traceable certification with mill test report + heat-treat charts
What is the MS14181 standard?
MS14181 is the United States military standard for tension bolts in nickel-alloy UNS N07718 (Inconel 718) with 220 ksi minimum tensile strength, external wrenching 12-spline drive, and flanged shank-head transition.
Has MS14181 been superseded?
Yes, by NASM14181 under the Aerospace Industries Association consolidation of MS, AS, and NAS standards. NASM14181 is the current revision for new procurement; legacy MS14181 part numbers remain valid for spare-parts inventory.
What does the dash number in MS14181 mean?
The numeric portion after the dash encodes nominal diameter in sixteenths of an inch. MS14181-04 = 1/4 inch, MS14181-06 = 3/8 inch, MS14181-08 = 1/2 inch, MS14181-16 = 1 inch. Further 'xxx' suffixes encode grip length in thirty-seconds of an inch plus drilled-head suffix.
Can MS14181 bolts be substituted with AS7467 bolts?
Generally no. MS14181 bolts are rated at 220 ksi minimum tensile strength, while SAE AS 7467 (referenced by ASTM A1014 2.3) covers UNS N07718 bolts and screws with 185 ksi [1275 MPa] tensile strength, stress rupture rated. The strength classes differ.
