1.Can Incoloy 800 Be Processed into Tubes, Plates, Bars, etc.?

1. Processable Product Forms of Incoloy 800

(1) Plates and Sheets

Incoloy 800 is widely manufactured into plates (thickness ≥ 3 mm) and sheets (thickness < 3 mm) in compliance with standards like ASTM B409. These products are commonly used as furnace liners, heat exchanger shells, and chemical reactor cladding. The alloy's high-temperature stability and corrosion resistance make it suitable for these applications.

(2) Tubes and Pipes

Tubular products of Incoloy 800, including seamless tubes (ASTM B163) and welded tubes (ASTM B407), are among its most in-demand forms. Seamless tubes are preferred for high-pressure and high-temperature service scenarios (e.g., steam generator tubes in nuclear power plants, heat exchanger tubes in petrochemical refineries), while welded tubes are cost-effective options for low-pressure pipeline systems.

(3) Bars and Rods

Incoloy 800 bars and rods (ASTM B408) are typically supplied in annealed or cold-drawn states. They are used to fabricate fasteners, valve stems, pump shafts, and other mechanical components that require both high-temperature strength and corrosion resistance in harsh environments.

(4) Other Forms

Forgings: Produced via hot forging processes, Incoloy 800 forgings are used for heavy-duty components such as turbine blades, pressure vessel heads, and furnace nozzles.

Wires: Drawn into fine wires, it is applied in heating elements, thermocouple sheaths, and precision instrumentation parts.

info-448-444 info-444-447

info-444-447 info-448-448

2.And What Are the Suitable Processing Methods?

Suitable Processing Methods for Incoloy 800

The processing of Incoloy 800 is guided by its austenitic microstructure, which grants good ductility but also leads to work hardening during cold working. The key processing methods are categorized as follows:

(1) Hot Working

Hot working is the primary processing method for shaping Incoloy 800 into rough product forms, with the following core parameters and requirements:

Temperature Range: Optimal hot working temperature is 925–1150°C. Below 925°C, the alloy exhibits high deformation resistance; above 1150°C, grain coarsening may occur, impairing mechanical properties.

Common Processes:

Hot Forging: Used to produce forgings and bar blanks. The alloy should be uniformly heated through its cross-section to ensure consistent deformation and avoid internal cracks.

Hot Rolling: Applied to manufacture plates, sheets, and seamless tube blanks. Controlled rolling at the lower end of the hot working temperature range helps refine grains and enhance strength.

Post-processing Requirement: Hot-worked components must undergo annealing treatment (925–1100°C, followed by air cooling) to eliminate internal stresses, homogenize the microstructure, and restore ductility for subsequent processing.

(2) Cold Working

Cold working is employed to achieve precise dimensions and improve surface quality of Incoloy 800 products, with attention to work hardening characteristics:

Common Processes:

Cold Rolling: Used for producing thin sheets, precision tubes, and strips with tight tolerance requirements. The alloy's work hardening rate is moderate, allowing for a certain degree of cold deformation before intermediate annealing is needed.

Cold Drawing: Applied to bars and seamless tubes to reduce diameter and improve dimensional accuracy. Intermediate annealing is required when the cold deformation rate exceeds 20%–30% to eliminate work hardening and prevent cracking during further processing.

Bending and Forming: Incoloy 800 can be bent, flanged, or deep-drawn at room temperature for fabricating components like heat exchanger tube sheets and pipeline elbows. For complex forming operations, warm forming (at 200–400°C) is recommended to reduce deformation resistance.

Key Note: Cold-worked components require final annealing to restore the desired combination of ductility and corrosion resistance, unless enhanced strength from work hardening is specifically required for the application.

(3) Welding

Incoloy 800 possesses excellent weldability and can be joined using most conventional welding methods, with considerations for avoiding intergranular corrosion:

Suitable Welding Methods:

Gas Tungsten Arc Welding (GTAW/TIG): Preferred for thin-walled components (e.g., tubes, sheets) due to its precise heat control and low weld spatter.

Gas Metal Arc Welding (GMAW/MIG): Used for thick plates and large structural components to achieve high welding efficiency.

Submerged Arc Welding (SAW): Applied for heavy-duty welding projects such as pressure vessel fabrication.

Welding Consumables: Matching filler metals such as ERNiCr-3 (for GTAW/GMAW) and ENiCr-3 (for SMAW) are recommended to ensure the weld joint has mechanical properties and corrosion resistance equivalent to the base metal.

Post-weld Treatment: For components serving in corrosive environments, post-weld annealing (870–925°C, slow cooling) is advisable to relieve residual stresses and reduce the risk of stress corrosion cracking (SCC).

(4) Machining

Incoloy 800 has moderate machinability, with challenges stemming from its toughness and tendency to adhere to cutting tools. The following practices are recommended:

Tool Selection: Use high-speed steel (HSS) tools with cobalt additions or carbide tools to improve wear resistance.

Cutting Parameters: Adopt low cutting speeds, high feed rates, and sufficient coolant to prevent tool overheating and workpiece work hardening.

Key Note: Machining should be performed on annealed Incoloy 800 components to minimize cutting resistance; machining cold-worked components is not recommended due to their high hardness and strength.

3. Key Processing Notes

Avoid Sensitization Temperature Range: During heating and cooling processes, minimize holding time in the 600–800°C range to prevent precipitation of chromium carbides at grain boundaries, which would increase intergranular corrosion sensitivity.

Cleanliness Requirements: Ensure the workpiece surface is free of oil, grease, and scale before processing, as contaminants can cause defects such as porosity and cracking during welding or heat treatment.

Controlled Cooling: For heat treatment processes such as solution annealing, rapid cooling (water quenching) is required to suppress precipitate formation; slow cooling is only used for post-weld annealing to relieve residual stresses.

In summary, Incoloy 800 is highly adaptable to various processing methods and can be manufactured into a full range of product forms. By selecting the appropriate processing parameters and post-treatment processes, the alloy's performance can be optimized to meet the requirements of different application scenarios.