Overview

Inconel alloy plates are flat-rolled products manufactured from a family of austenitic nickel-chromium-based superalloys, renowned for their ability to perform under extreme engineering environments . Developed by Special Metals Corporation, Inconel alloys are engineered to maintain exceptional strength, structural integrity, and corrosion resistance at temperatures and pressures that would overwhelm most conventional metals .

The defining characteristic of Inconel alloys is their high nickel content combined with significant chromium additions, typically ranging from 14-23% chromium depending on the specific grade . This composition creates a stable, protective chromium oxide layer that provides outstanding resistance to oxidation, carburization, and corrosion in aggressive environments . Many grades also incorporate molybdenum, niobium, titanium, and aluminum to enhance specific properties such as high-temperature creep resistance, precipitation hardenability, and resistance to localized corrosion .

Unlike standard stainless steels, Inconel alloys maintain their mechanical properties across an extraordinary temperature range—from cryogenic conditions down to -253°C (-423°F) up to continuous service at 980°C (1800°F) or higher . This remarkable thermal stability, combined with resistance to chloride-induced stress corrosion cracking, makes Inconel the material of choice for critical applications in aerospace, power generation, chemical processing, and marine engineering where failure is not an option .

Key Features

• Exceptional High-Temperature Strength: Inconel alloys are engineered to maintain mechanical properties at elevated temperatures where other materials creep and fail. Age-hardenable grades like Inconel 718 achieve tensile strengths exceeding 180 ksi (1240 MPa) through precipitation strengthening, with useful properties maintained up to 705°C (1300°F) . Solid-solution strengthened grades like 625 provide reliable service from cryogenic temperatures to 980°C (1800°F) .

• Superior Oxidation and Corrosion Resistance: The high chromium content (typically 14-23%) forms a tenacious, self-healing oxide layer that protects against oxidation, sulfidation, and carburization at high temperatures . Molybdenum additions in grades like 625 and 622 provide exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking in aggressive aqueous environments, including seawater and acidic media .

• Outstanding Creep Resistance: Inconel alloys resist gradual deformation under constant stress at high temperatures—a critical property for components subjected to prolonged thermal-mechanical loading. Grades like 617 and 622 incorporate cobalt and aluminum to enhance metallurgical stability and creep performance in gas turbine and petrochemical applications .

• Excellent Fatigue Resistance: The alloys demonstrate superior resistance to cyclic loading under both high-temperature and cryogenic conditions, making them ideal for safety-critical components in rotating machinery, pressure vessels, and aerospace structures .

• Good Fabricability with Proper Techniques: Despite their high strength, Inconel alloys can be successfully welded, formed, and machined using appropriate methods. Grades like 718 are designed to be welded in the fully aged condition without post-weld cracking, while 625 offers excellent weldability with matching filler metals . For complex thin-gauge components, advanced techniques like photochemical etching provide stress-free precision fabrication .

• Cryogenic Toughness: Unlike many materials that become brittle at low temperatures, Inconel alloys retain excellent ductility and toughness down to -253°C (-423°F), making them suitable for cryogenic storage tanks, LNG equipment, and space applications .

• Resistance to Chloride Stress Corrosion Cracking: The high nickel content provides immunity to chloride-induced stress corrosion cracking, a common failure mechanism for austenitic stainless steels in marine and chemical processing environments .

Specifications with Explanation

Inconel Alloy Plate Chemical Composition Comparison (Typical values, wt%)

Typical Mechanical Properties

Physical Properties

Applicable Standards

Available Dimensions

Surface Finishes Available

• Hot Rolled Annealed and Pickled (HRAP)

• Cold Rolled (2B, 2D, BA)

• No.1 Finish (Hot Rolled Annealed)

• Polished (No.4, No.8, Mirror)

• Satin / Hairline

• Sandblast / Etching

Applications

Inconel alloy plates, leveraging their exceptional combination of high-temperature strength and corrosion resistance, serve critical functions across demanding industries worldwide :

Aerospace Industry

• Gas Turbine Components: Combustion chambers, turbine disks, compressor blades, casings, and afterburner rings operating at extreme temperatures

• Rocket Motors and Thrust Reversers: Components requiring high strength-to-weight ratio and thermal stability under intense operational loads

• Engine Mounts and Fasteners: High-strength bolting and structural hardware for aircraft engines

• Airframe Components: Critical structural elements in high-performance aircraft and spacecraft

Power Generation

• Nuclear Reactor Components: Fuel element spacers, steam generator tubing, and control rod mechanisms requiring radiation resistance and high-temperature stability

• Gas Turbine Power Plants: Hot gas path components, transition ducts, and combustion liners

• Heat Recovery Steam Generators: Superheater and reheater tubes in combined cycle plants

Chemical and Petrochemical Processing

• Heat Exchangers and Condensers: For corrosive media at elevated temperatures, particularly in chloride-containing environments

• Reactor Vessels: Chemical reactors handling aggressive media at high temperatures and pressures

• Piping Systems: Transfer lines for corrosive chemicals in refining and petrochemical operations

• Nitric Acid Production Equipment: Components requiring resistance to oxidizing acids at elevated temperatures

Oil and Gas Industry

• Downhole Tooling: Shafting, packers, and completion equipment for sour service environments

• Subsea Components: Wellhead equipment, manifolds, and control lines requiring seawater corrosion resistance

• High-Pressure High-Temperature (HPHT) Wells: Components for extreme downhole conditions

Marine Engineering

• Propulsion Systems: Propeller shafts, pump bodies, and impellers for seawater handling

• Submarine Components: Pressure hull fittings and seawater systems

• Offshore Platform Equipment: Risers, chokes, and valves for deepwater applications

Industrial Heating and Heat Treating

• Furnace Components: Muffles, retorts, radiant tubes, and conveyor systems operating up to 1150°C

• Heat-Treating Baskets and Fixtures: For carburizing and nitriding atmospheres requiring oxidation resistance

• Annealing Covers: For batch annealing operations in steel processing

Pollution Control

• Flue Gas Desulfurization (FGD) Systems: Scrubbers, ductwork, and dampers requiring resistance to sulfuric acid condensate

• Waste Incineration Equipment: Components exposed to high-temperature corrosive flue gases

Cryogenic Applications

• LNG Storage and Transport: Tanks and piping for liquefied natural gas at -162°C

• Cryogenic Pressure Vessels: For storage of liquid hydrogen, oxygen, and nitrogen at temperatures down to -253°C

Comparison: Grade Selection Guide

Buying Guide

Selecting the appropriate Inconel alloy plate requires careful evaluation of service conditions, mechanical requirements, and fabrication considerations:

1. Define Service Environment:

   • Temperature Range: Maximum continuous operating temperature and any thermal cycling conditions

     • Up to 540°C (1000°F): 625, 718

     • Up to 815°C (1500°F): X-750

     • Up to 980°C (1800°F): 600, 601, 617, 625

     • Up to 1095°C (2000°F): 617

   • Corrosive Media: Identify specific chemicals, concentrations, and whether oxidizing or reducing conditions prevail

     • Seawater/chlorides: 625, 622

     • High-temperature oxidation: 601, 617

     • Sulfidizing/carburizing: 600, 330

   • Mechanical Loading: Static, cyclic, or impact loading conditions. For high fatigue applications requiring maximum strength, 718 is preferred

2. Select Strengthening Mechanism:

   • Solid-Solution Strengthened (600, 625, 622): Good fabricability, weldable without post-weld heat treatment, moderate-to-high strength

   • Precipitation-Hardenable (718, X-750, 725): Maximum strength through aging heat treatment, requires careful thermal processing

3. Consider Fabrication Requirements:

   • Forming: Annealed condition provides maximum ductility for complex shapes

   • Welding: For field welding or complex assemblies, consider alloys with good weldability (625, 718)

   • Machining: Expect rapid work hardening; plan for rigid setups, sharp tools, and appropriate speeds/feeds

   • Alternative Methods: For thin-gauge intricate components, consider photochemical etching to avoid work hardening and residual stress

4. Verify Specifications and Standards:

   • Confirm applicable ASTM/ASME standards (B168, B443, B670)

   • For aerospace applications, verify AMS specifications (AMS 5596, 5599, 5662)

   • For pressure vessel applications, ensure ASME code compliance

   • For oil & gas sour service, verify NACE MR0175/ISO 15156 compliance

5. Check Product Forms and Dimensions:

   • Thickness Availability: 0.1mm to 150mm+ depending on supplier

   • Width Requirements: Standard widths up to 3500mm; custom widths available from specialized mills

   • Surface Condition: Specify hot-rolled annealed and pickled (HRAP), cold-rolled, polished, or other finishes

   • Custom Cutting: Precision cutting services available for non-standard sizes

6. Request Documentation:

   • Mill Test Certificates (MTC) per EN 10204 3.1/3.2 with:

     • Heat number and full chemical composition

     • Complete mechanical property test results

     • Heat treatment records (solution annealing temperatures, aging cycles)

     • Grain size determination where applicable

   • Third-party inspection reports for critical applications

FAQ

Q1: What is the difference between Inconel and Incoloy?

A: The primary difference lies in nickel content and base composition. Inconel alloys are nickel-chromium based with nickel content typically above 50% (often 58-72%), making them the premium choice for extreme high-temperature and corrosion applications . Incoloy alloys are nickel-iron-chromium based with lower nickel content (typically 30-46%), offering a more economical solution for moderate-temperature service where stainless steel performance is inadequate but Inconel would be over-specified. Inconel generally provides superior high-temperature strength and oxidation resistance above 980°C, while Incoloy offers excellent performance in the 540-980°C range with better economy.

Q2: Is Inconel magnetic?

A: Most Inconel alloys are essentially non-magnetic in the annealed condition due to their austenitic structure. Inconel 600 has a Curie temperature of approximately -124°C, meaning it becomes slightly magnetic only at cryogenic temperatures below this point . Inconel 625, 718, and 690 remain non-magnetic across their service temperature range. Cold working may induce some magnetic response in certain grades. For applications requiring strictly non-magnetic materials (electronic housings, medical equipment), Inconel alloys are excellent choices.

Q3: What is the maximum service temperature for Inconel 718?

A: Inconel 718 maintains useful mechanical properties for continuous service up to approximately 705°C (1300°F) . For short-term exposure, it can withstand temperatures up to 980°C (1800°F) with good oxidation resistance . Above 705°C, the strengthening precipitates (γ' and γ") begin to overage and coarsen, gradually reducing strength. For applications requiring higher temperature capability, consider Inconel 617 (continuous service to 1095°C) or 625 (continuous to 980°C) .

Delivery, Certification & Service

Quality Certification

• Material Traceability: Complete heat traceability from melt to finished plate with unique identification markings per ASTM/ASME requirements

• Mill Test Certificates (MTC) : EN 10204 3.1/3.2 compliant certificates provided with every shipment including:

  • Heat number and full chemical composition analysis per applicable specifications

  • Complete mechanical property test results (tensile, yield, elongation, hardness)

  • Heat treatment records (solution annealing temperatures, aging cycles)

  • Grain size determination where applicable

  • Ultrasonic inspection reports (AMS 2631, ASTM E2375) when specified

• Third-Party Inspection: Available through Lloyds, DNV, Bureau Veritas, ABS, SGS, or customer-nominated agencies

• Special Testing Available:

  • Positive Material Identification (PMI)

  • Ultrasonic inspection (Flaw detection, thickness verification)

  • Mechanical testing at elevated or cryogenic temperatures

  • Microstructural evaluation (grain size, precipitate distribution)

  • Corrosion testing per applicable standards

  • NACE MR0175/ISO 15156 compliance verification for sour service

Available Product Forms and Dimensions

Weight Reference (Inconel 625, density 8.44 g/cm³):

Surface Finishes Available

• Hot Rolled Annealed and Pickled (HRAP) – standard for plates

• Cold Rolled Finishes:

  • 2B (Bright Cold Rolled)

  • 2D (Dull Cold Rolled)

  • BA (Bright Annealed)

• No.1 Finish (Hot Rolled Annealed)

• Polished Finishes:

  • No.4 (150-180 grit)

  • No.8 (Mirror finish)

  • 8K (Super mirror)

• Specialty Finishes:

  • Satin / Hairline

  • Sandblast / Etching

  • Brush finish

  • Plastic coated for protection

Packaging and Protection

• Interleaving: Paper, plastic, or foam interleaving between plates to prevent surface damage

• Bundling: Steel-strapped bundles with edge protectors for smaller plates

• Crating: Export-grade wooden crates for high-value or precision-cut plates

• Waterproofing: Waterproof paper, VCI (Vapor Corrosion Inhibitor) materials, and desiccant packs for marine shipment

• Iron-Free Protection: Special packaging protocols available for applications requiring strict iron contamination control (aerospace, nuclear)

• Custom Marking: Stenciling, tagging, or laser marking per customer specifications

After-Sales Technical Support

• Material Selection Assistance: Expert guidance on grade selection for specific applications based on service conditions

• Fabrication Support: Technical recommendations for forming, machining, welding, and heat treatment

• Welding Procedure Development: Assistance with procedure qualification and parameter optimization

• Heat Treatment Guidance: Recommendations for solution annealing and aging cycles to achieve optimal properties

• Failure Analysis: Investigation and analysis of in-service material performance issues

• Field Service: On-site technical support for critical applications and large fabrication projects

• Documentation Support: Assistance with certification requirements and quality documentation

Delivery Commitment

• Stock Items: 1-2 weeks for standard sizes and grades (600, 625, 718)

• Mill Orders: 8-12 weeks for non-standard dimensions, specialty alloys, or special certification requirements

• Express Service: 3-7 working days for expedited stock items

• Just-in-Time (JIT) Delivery: Coordinated delivery schedules to support lean manufacturing operations

• Global Logistics: International shipping with full export documentation, customs clearance support

Quality Assurance

All Inconel alloy plates are manufactured in accordance with strict quality management systems, certified to ISO 9001:2015 and AS9100D (aerospace) where applicable. Production facilities maintain:

• Advanced Melting Capabilities: VIM (Vacuum Induction Melting), VAR (Vacuum Arc Remelting), and ESR (Electroslag Remelting) for optimal purity and controlled solidification

• Precision Rolling: State-of-the-art hot and cold rolling mills with dimensional control systems

• Comprehensive Testing: In-house laboratories with full mechanical, chemical, and non-destructive testing capabilities

• Specialized Capabilities:

  • Production of wide plates for large structural components

  • Capability to produce thin sheets for precision applications

  • Custom processing including cutting, welding, and surface finishing

Industry-Specific Certifications Available

• Aerospace: AS9100, Nadcap, AMS specifications (5596, 5599, 5662, etc.)

• Pressure Equipment: PED (Pressure Equipment Directive), ASME Code (SB-168, SB-443, SB-670)

• Defense: ITAR compliance, MIL-SPEC certifications

• Oil & Gas: NACE MR0175/ISO 15156 compliance

• Nuclear: NQA-1, 10CFR50 Appendix B, ASME Section III

• Medical: ISO 13485 (for implantable grades where applicable)