1. Incoloy 800H Round Bar Heat-Resistant Alloy Rod for Furnace Parts & Chemical Processing

Products Specification

Incoloy 800H Round Bar: Heat-Resistant Alloy Rod for Furnace Parts & Chemical Processing

Product Introduction

Incoloy 800H is a high-performance iron-nickel-chromium alloy specifically designed for extreme temperature and corrosive environments. This austenitic solid solution-strengthened alloy offers exceptional creep rupture strength, outstanding resistance to oxidation and carburization, and excellent stability in high-temperature applications. With its controlled carbon content and optimized titanium-to-carbon ratio, Incoloy 800H round bars maintain superior mechanical properties even under continuous exposure to temperatures up to 1500°F (815°C) and intermittent service up to 1800°F (982°C).

The round bar form of Incoloy 800H is particularly valued in industrial applications for its machining characteristics and structural integrity. Available in diameters ranging from 6mm to 500mm, these round bars can be supplied in various conditions including hot-worked, annealed, or ground finishes to meet specific application requirements. The alloy's versatility makes it suitable for fabricating components for furnace systems, chemical processing equipment, heat exchangers, and nuclear power installations where reliability under thermal stress is paramount.

Material Characteristics and Properties

Chemical Composition

Incoloy 800H's exceptional properties stem from its carefully balanced chemical composition, which provides optimal performance in high-temperature and corrosive environments:

Table 1: Standard Chemical Composition of Incoloy 800H

The elevated chromium content provides outstanding resistance to oxidation and sulfidation, while the nickel content ensures structural stability and resistance to chloride stress corrosion cracking. The controlled carbon content (0.05-0.10%) is crucial for enhanced creep rupture strength at elevated temperatures compared to standard Alloy 800. The addition of aluminum and titanium further strengthens the alloy through precipitation hardening mechanisms -2.

Physical & Mechanical Properties

Incoloy 800H demonstrates a unique combination of physical and mechanical properties that make it ideal for demanding high-temperature applications:

Table 2: Physical & Mechanical Properties of Incoloy 800H

The alloy possesses a face-centered cubic crystal structure that contributes to its excellent high-temperature strength and ductility. Its non-magnetic nature and good thermal expansion characteristics make it suitable for applications involving thermal cycling -1. The mechanical properties remain stable even after prolonged exposure to high temperatures, with minimal sensitization or sigma phase formation.

Corrosion Resistance

Incoloy 800H offers comprehensive corrosion resistance in various aggressive environments:

• Oxidizing Environments: The high chromium content provides exceptional resistance to nitric acid, oxidizing salts, and other strongly oxidizing media

• High-Temperature Gases: Excellent resistance to oxidation, carburization, and sulfidation in furnace atmospheres and combustion gases

• Aqueous Corrosion: Good resistance to stress corrosion cracking in chloride-containing environments, high-purity water, and alkaline solutions

• Organic Acids: Suitable for handling formic, acetic, and other organic acids across a wide concentration and temperature range

Research has demonstrated that Incoloy 800H maintains excellent surface stability even in alkaline high-temperature high-pressure water environments at 300°C/10MPa, forming a protective multi-layered oxide film that acts as an effective diffusion barrier -7. The outer layer consists of Fe₂O₃ or NiFe₂O₄, while the inner layer is a dense, continuous amorphous or nanocrystalline oxide rich in chromium with minimal iron content.

Applications

Incoloy 800H round bars are specified across multiple industries where high temperature strength and corrosion resistance are critical:

1. Chemical Processing Industry

Incoloy 800H round bars are extensively used for manufacturing reactor components, heat exchanger tubes, baffles, and support structures in chemical plants. The material demonstrates particular effectiveness in nitric acid production facilities, where it serves in condenser units -8. The alloy's resistance to stress corrosion cracking makes it suitable for equipment handling chlorides and caustic solutions.

2. Heat Treatment & Industrial Furnaces

The alloy's carburization resistance and high-temperature strength make it ideal for radiant tubes, muffles, retorts, heat treatment fixtures, and basket assemblies in heat treating operations -3. Components fabricated from Incoloy 800H round bars can withstand repeated thermal cycling while maintaining structural integrity under mechanical load at temperatures up to 2100°F (1150°C).

3. Power Generation

Incoloy 800H finds extensive application in power generation systems, including superheater and reheater tubes, header assemblies, outlet piping, and heating element sheaths -3. Its performance in high-temperature high-pressure water environments makes it suitable for nuclear reactor components, particularly in high-temperature gas-cooled reactors -7.

4. Petrochemical Industry

The alloy serves in ethylene production facilities, specifically in convection and transfer line exchangers, quench systems, and cracking tube assemblies. Its resistance to carburization extends service life in hydrocarbon processing environments at elevated temperatures.

Processing and Heat Treatment

Machining and Fabrication

Hot Working:
Incoloy 800H can be readily hot-formed using conventional equipment. The recommended hot-working temperature range is 1600°F to 2200°F (870°C to 1200°C). For heavy forming operations, temperatures above 1850°F (1010°C) are recommended. The material should not be worked between 1200°F to 1600°F (650°C to 870°C) due to reduced ductility in this temperature range. Post-hot working, rapid cooling is recommended to minimize time spent in the 1000°F to 1400°F (540°C to 760°C) range where sensitization can occur -3.

Cold Working:
Cold forming operations should be performed on annealed material using power-assisted equipment due to the alloy's high work hardening rate. Intermediate annealing may be necessary for severe forming operations. Stress relief annealing at 1000°F to 1600°F (540°C to 870°C) is recommended for cold-worked parts, particularly for applications involving elevated temperature service.

Welding

Incoloy 800H exhibits good weldability using common fusion welding techniques. For service temperatures below 787°C, recommended filler metals include ERNiCr-3 (AWS A5.14 ERNiCr-3). For maximum mechanical strength at elevated temperatures, ERNiCrCoMo-1 or ENiCrCoMo-1 electrodes are preferred -2.

To prevent grain boundary cracking in welded components operating above 538°C due to stress relaxation, post-weld heat treatment at 1650°F (899°C) is recommended. The holding time should be approximately 25 hours per 25 mm of thickness, followed by air cooling -2.

Heat Treatment

Proper heat treatment is essential for optimizing the performance of Incoloy 800H:

Table 3: Heat Treatment Guidelines for Incoloy 800H

The annealing process produces a recrystallized microstructure with optimal grain size distribution for high-temperature service. Solution annealing at 2050-2150°F (1120-1175°C) followed by rapid cooling ensures that carbides remain in solution, maximizing corrosion resistance -3.

Quality Assurance and Standards

Incoloy 800H round bars are manufactured under strict quality control protocols to ensure consistent performance. The material complies with various international standards:

• ASTM: B408 (Bar)

• ASME: SB-408

• DIN: 2.4660 (N08810)

• EN: 1.4958, 1.4876

Reputable manufacturers implement complete traceability from melt to final product, with comprehensive documentation including material test certificates and heat treatment records. The alloy is recognized by the ASME Boiler and Pressure Vessel Code Section VIII, Division 1 for pressure vessel applications -3.

Non-destructive testing methods including ultrasonic testing, liquid penetrant examination, and eddy current testing are employed to ensure material integrity. Chemical composition and mechanical properties are verified through certified laboratory testing.

Conclusion

Incoloy 800H round bars represent an engineered solution for demanding high-temperature applications where conventional materials prove inadequate. The alloy's balanced composition delivers an exceptional combination of creep strength, corrosion resistance, and fabricability that extends equipment service life in aggressive environments. From chemical processing components to furnace fixtures and power generation equipment, Incoloy 800H continues to demonstrate its value across industrial sectors.

When sourcing Incoloy 800H round bars, it is essential to partner with reputable suppliers who can provide proper material certification and technical support. The material's performance heavily depends on correct processing and heat treatment, making supplier expertise a critical factor in application success. With proper selection, fabrication, and installation, components manufactured from Incoloy 800H round bars deliver reliable long-term performance even in the most challenging operating conditions.