AMS 5599 - Nickel 625 (Inconel 625) Sheet, Strip & Plate (Solution Annealed)
What is AMS 5599?
AMS 5599 is the SAE International aerospace material specification for Nickel 625 (Inconel 625, UNS N06625), a nickel-chromium-molybdenum-niobium superalloy supplied in the form of sheet, strip,and plate in the solution annealed condition.
The nominal composition is 62Ni-21.5Cr-9.0Mo-3.7Cb (Nb). Nickel 625 per AMS 5599 achieves a minimum tensile strength of 120 ksi (827 MPa) and a minimum yield strength of 60 ksi (414 MPa) with a minimum elongation of 30% in the solution annealed condition.
The alloy derives its strength from the combined solid-solution strengthening effect of molybdenum and niobium on the nickel-chromium matrix – no precipitation hardening heat treatment is required.
AMS 5599 is the standard procurement specification for Nickel 625 flat-rolled products used in aerospace exhaust systems, chemical processing equipment, marine structures, oil and gas downhole components, flare stacks, and nuclear reactor applications.
AMS 5599 Available Forms and Stocked Sizes
AMS 5599 covers Nickel 625 in flat-rolled forms. The SAE/AMS definitions for form by thickness are:
Thickness: 0.1875 inches (4.76 mm) and above
Thickness: 0.006–0.1874 inches; width ≤ 9.250 inches
Thickness: 0.006–0.1874 inches; width > 9.250 inches
Fighter Jet Metals supplies Nickel 625 per AMS 5599 in plate form starting at 0.187″ thickness up to 4.00″ thick.
Standard sheet and plate dimensions are **48.00″ Wide × 120.00″ Long**, though stocked sizes may vary.
Custom cut-to-size processing available.
Applications of AMS 5599
Aerospace Applications
- Jet engine exhaust systems, collector rings, and afterburner components
- Thrust reverser components and engine nacelle sheet metal fabrications
- Flare stacks and gas turbine combustion liner panels
- Engine bleed air ducts and hot-section structural shrouds
- High-temperature aerospace fastener blanks and shims
- Spacecraft attitude control system components requiring corrosion and oxidation resistance
Chemical Processing & Industrial Applications
- Chemical reactor vessels, heat exchanger baffles, and pressure vessels
- Flue gas desulfurization equipment in pollution control systems
- Nitric acid, phosphoric acid, and hydrofluoric acid handling equipment
- Seawater scrubber components in marine pollution control
- High-temperature industrial furnace fixtures and retorts
Marine & Naval Applications
- Submarine auxiliary propulsion motor components
- Seawater piping and valve bodies exposed to chloride environments
- Naval vessel exhaust system components
- Offshore oil and gas platform structural sheet metal in splash zones
Oil & Gas Applications
- Downhole completion tubing and wellhead sheet metal components
- Sour gas service equipment (H2S environment – meets NACE MR0175)
- Subsea connector and manifold panels
- Flexible riser and umbilical sheath components
Nuclear Industry
- Nuclear reactor structural sheet metal and cladding components
- Reactor pressure vessel internals and steam generator components
- Nuclear waste containment liner applications
Chemical Composition - AMS 5599
The following chemical composition limits apply to Nickel 625 (UNS N06625) per AMS 5599:
| Element | Symbol | Minimum % | Maximum % |
|---|---|---|---|
| Nickel | Ni | 58.0 | - |
| Chromium | Cr | 20.0 | 23.0 |
| Iron | Fe | - | 5.0 |
| Niobium + Tantalum | Nb+Ta | 3.15 | 4.15 |
| Molybdenum | Mo | 8.0 | 10.0 |
| Cobalt | Co | - | 1.00 |
| Titanium | Ti | - | 0.40 |
| Aluminum | Al | - | 0.40 |
| Carbon | C | - | 0.10 |
| Manganese | Mn | - | 0.50 |
| Silicon | Si | - | 0.50 |
| Phosphorus | P | - | 0.015 |
| Sulfur | S | - | 0.015 |
Chromium (20–23%) provides the primary oxidation and corrosion resistance of the alloy.
Molybdenum (8–10%) combined with niobium (3.15–4.15%) stiffens the nickel matrix through solid-solution strengthening – this is what makes Nickel 625 exceptionally strong without requiring a hardening heat treatment.
Niobium also stabilizes the alloy against sensitization in the heat-affected zone during welding, which is why Nickel 625 is one of the most weldable high-strength nickel alloys. Iron content (max 5.0%) is kept low to maintain corrosion resistance in reducing environments.
The combined effect of the high molybdenum and chromium content gives the alloy outstanding resistance to pitting and crevice corrosion in chloride-containing environments.
Mechanical Properties - AMS 5599
Minimum mechanical properties required by AMS 5599 for Nickel 625 sheet, strip, and plate in the solution annealed condition:
| Property | Imperial | Metric |
|---|---|---|
| Tensile Strength (min) | 120,000 psi (120 ksi) | 827 MPa |
| Yield Strength, 0.2% offset (min) | 60,000 psi (60 ksi) | 414 MPa |
| Elongation in 2 in. (min) | 30% | 30% |
Elevated Temperature Properties - AMS 5599
Nickel 625 per AMS 5599 retains useful strength at significantly elevated temperatures.
Representative typical properties at elevated temperature (solution annealed condition – from published data):
| Temperature | Tensile Strength (typical) | Yield Strength (typical) | Elongation (typical) |
|---|---|---|---|
| Room Temp (70°F / 21°C) | 135 ksi (931 MPa) | 75 ksi (517 MPa) | 42% |
| 400°F (204°C) | 125 ksi (862 MPa) | 65 ksi (448 MPa) | 40% |
| 800°F (427°C) | 115 ksi (793 MPa) | 58 ksi (400 MPa) | 38% |
| 1200°F (649°C) | 100 ksi (689 MPa) | 50 ksi (345 MPa) | 40% |
| 1500°F (816°C) | 70 ksi (483 MPa) | 35 ksi (241 MPa) | 45% |
Physical Properties - AMS 5596
| Property | Value (Imperial) | Value (Metric) |
|---|---|---|
| Density | 0.305 lb/in³ | 8.44 g/cm³ |
| Melting Range | 2350°F–2460°F | 1290°C–1350°C |
| Modulus of Elasticity | 29.8 × 10⁶ psi | 205 GPa |
| Thermal Conductivity | 6.9 BTU/(hr·ft·°F) | 12.0 W/(m·K) |
| Thermal Conductivity (1800°F) | 9.9 BTU/(hr·ft·°F) | 17.1 W/(m·K) |
| Coefficient of Thermal Expansion | 7.4 × 10⁻⁶ /°F | 13.3 × 10⁻⁶ /°C |
| Specific Heat | 0.098 BTU/(lb·°F) | 410 J/(kg·K) |
| Electrical Resistivity | 50.8 µΩ·in | 129 µΩ·cm |
| Max Service Temperature (Mechanical Load) | ~1500°F | ~816°C |
| Max Service Temperature (Oxidation Resistance) | 1800°F | 982°C |
| Melt Practice | EF-AOD or VIM + VAR or ESR (double melt) | - |
AMS 5599 vs AMS 5869 vs AMS 5879 - Which Specification Do You Need?
All three are SAE AMS specifications for Nickel 625 (UNS N06625) in sheet/strip/plate forms, but they differ in condition, application, and processing controls:
| Feature | AMS 5599 | AMS 5869 | AMS 5879 |
|---|---|---|---|
| Alloy | Nickel 625 (UNS N06625) | Nickel 625 (UNS N06625) | Nickel 625 (UNS N06625) |
| Product Forms | Sheet, Strip, Plate | Sheet, Strip, Plate | Sheet, Strip |
| Condition | Solution Annealed | Annealed | Solution Annealed (Bellows Quality) |
| Tensile Min | 120 ksi (827 MPa) | Similar range | Similar range |
| Primary Use | General aerospace, chemical, marine sheet/plate | Chemical, marine, industrial applications | Aerospace exhaust bellows, expansion joints, fatigue applications |
| Special Feature | Standard sheet/plate procurement | Alternate condition for broad industrial use | Tightly controlled for low-cycle and thermal fatigue - superior to AMS 5599 for cyclic thermal applications |
Use AMS 5599 for standard Nickel 625 sheet and plate procurement.
Specify AMS 5879 only where low-cycle fatigue or bellows/expansion joint applications require the tighter processing controls.
Approved Mill Producers
Fighter Jet Metals sources AMS 5599 Nickel 625 sheet and plate from AS9100-certified mill producers.
All material is supplied with full mill certifications, heat/lot numbers, chemical analysis reports, and mechanical test certifications traceable to the originating mill heat.
AMS 5599 Machining Guidelines
Nickel 625 sheet and plate is machinable but requires careful technique due to its high work-hardening rate and tendency to gall at the cutting interface:
- Work hardening: Nickel 625 work-hardens rapidly during cutting – use sharp, positive-rake tooling and maintain continuous cuts; dwelling in the cut causes work hardening at the tool tip
- Cutting speeds: Low to moderate (50–80 SFM for carbide tooling) – slower than stainless steel
- Feeds: Use aggressive feeds to minimize dwell and work hardening
- Tooling: Premium carbide grades (C-2 through C-5) or coated carbide; PVD-coated TiAlN recommended
- Coolant: Flood coolant required – sulfurized cutting oils provide best tool life; never use chlorinated fluids on Nickel 625 intended for corrosive service environments
- Chip control: Nickel 625 produces long, tough, stringy chips – chip breakers are important
- Stiffness: Rigid setup critical; minimize overhang on tooling and workholding to prevent chatter
Weldability of AMS 5599
Nickel 625 per AMS 5599 is one of the most weldable high-strength nickel alloys available.
It has excellent weldability due to the niobium-stabilized matrix, which resists sensitization and intergranular attack in the heat-affected zone:
- TIG (GTAW): Primary process for sheet and plate; argon or helium-argon shielding required; filler metal ERNiCrMo-3 (Inconel 625 matching filler) recommended
- MIG (GMAW): Used for higher deposition rate fabrications; shielding gas Ar + 25% He recommended
- Plasma Arc Welding (PAW): Suitable for thin sheet (below 0.060″)
- Electron Beam (EBW): Used in vacuum environments for critical aerospace welds
- Post-weld treatment: Generally NOT required for corrosion service; solution anneal at 2000°F–2100°F (1093°C–1149°C) can be performed if maximum corrosion resistance is needed
- No sensitization risk: Unlike austenitic stainless steels, Nickel 625’s high molybdenum and niobium content prevent sensitization in HAZ – a key reason it’s preferred for welded assemblies in corrosive environments
- Dissimilar metal welding: Nickel 625 weld wire (ERNiCrMo-3) is widely used as a filler metal for welding dissimilar metals (stainless steel to carbon steel, titanium transitions) in the oil and gas and chemical industries
AMS 5599 Cross-Reference Specifications
SHEET & PLATE
Sheets and plates for high-temperature aerospace and industrial applications. These are the other SAE AMS specifications that cover Nickel 625 in the same flat-rolled product forms as AMS 5599.
BARS & FORGINGS
Bars and forgings designed for high-strength, creep, and fatigue-resistant components. Same alloy as AMS 5599, different product form.
TUBING SPECIFICATIONS
Nickel 625 tubing specifications for aerospace hydraulic, fuel, and environmental control system applications.
BOEING SPECIFICATIONS
Boeing-approved Nickel 625 for airframe, engine, and hydraulic system applications. Boeing Material Specifications (BMS) and McDonnell Douglas Specifications (DMS) are Boeing-issued proprietary documents. Confirmed via site reverse lookup.
GULSTREAM SPECIFICATIONS
Outlines the specifications of the Nickel 625 material used in Gulfstream aircraft parts, including required material properties in areas of the engine where high temperatures exist.
HONEYWELL SPECIFICATIONS
Covers Nickel 625 used in Honeywell aerospace and industrial applications. Focuses on heat and corrosion resistance, durability, and long-term stability in extreme environments.
SAFRAN SPECIFICATIONS
Defines Safran’s standards for Nickel 625 used in aircraft engines and high-temperature structural parts, ensuring oxidation and corrosion resistance under sustained thermal loads.
AIRBUS SPECIFICATIONS
Outlines Airbus standards for Nickel 625 in aerospace manufacturing, emphasizing mechanical strength, heat tolerance, and resistance to chemical attack in critical engine and structural components.
Trade Names and Equivalent Designations
Nickel 625 per AMS 5599 is known by many trade names and equivalent designations across different standards systems:
| Designation | System | Notes |
|---|---|---|
| Inconel 625 | Trade name | Special Metals / Precision Castparts registered trademark - most widely used commercial name |
| Nickel 625 / Nickel Alloy 625 | Common name | Generic material designation used in procurement |
| ASTM B446 | ASTM specification | Rod and bar per ASTM system |
| ASTM B444 | ASTM specification | Seamless pipe and tube per ASTM system |
| ASTM B443 | ASTM specification | Plate, sheet, and strip per ASTM system |
| UNS N06625 | UNS (Unified Numbering System) | Standard material identifier in North America |
| DIN 2.4856 / W.Nr. 2.4856 | Werkstoff Nr. (German) | European material number designation |
| NiCr22Mo9Nb | DIN/EN alloy designation | German/European compositional shorthand |
| NACE MR0175 / ISO 15156 | Corrosion standard | Approved for sour oil and gas service (H2S environments) |
| 62Ni-21.5Cr-9.0Mo-3.7Cb | Nominal composition | SAE AMS compositional shorthand used in specification designation |
Why Source AMS 5599 from Fighter Jet Metals?
Full mill certifications on every order
Heat number, lot number, chemical analysis, and mechanical test reports included with every shipment
Complete heat-lot traceability
Full chain-of-custody documentation from mill to your door
AS9100-certified aerospace sourcing
Material from AS9100-certified mills only
OEM specification support
Stock and supply to Boeing BMS/DMS, Gulfstream GMS, Honeywell EMS, Safran DMD, and Airbus AIPS requirements
In-house processing
Plate saw cutting, shearing, and laser cutting available; custom-cut sizes to your dimensions
Same-day quote response
Competitive pricing with rapid quote turnaround
Certified Material for Critical Service
Materials supplied in 6Al-4V titanium must meet strict aerospace certification and traceability requirements. Fighter Jet Metals supports sourcing across a wide range of AMS, MIL, and OEM specifications, ensuring compliance with industry standards.
All material is supplied with full mill certifications, complete heat-lot traceability, and detailed documentation. This ensures reliability and suitability for safety-critical aerospace, defense, and high-performance engineering applications.