Inconel 601 (UNS N06601) – Nickel-Chromium Alloy with Aluminum for Extreme Oxidation Resistance

Short Description:

Inconel 601 (UNS N06601 / W.Nr. 2.4851 / NS313 / GH3600) is a nickel-chromium-aluminum solid-solution strengthened alloy specifically designed for extreme high-temperature oxidation resistance up to 1204°C (2200°F). Womic Steel supplies Inconel 601 in multiple product forms including seamless pipe, welded pipe, steel bar, steel plate, steel coil, strip, flanges, fittings, forgings, wire, and valves for heat treating, petrochemical processing, furnace manufacturing, aerospace, and power generation applications.

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Product Overview

The alloy was developed in the 1960s as an improved version of Inconel 600, with aluminum additions (1.0-1.7%) to enhance oxidation resistance by forming a protective Al₂O₃ oxide scale. This provides significantly superior oxidation resistance compared to Inconel 600 at temperatures above 1000°C. Today, Inconel 601 is the preferred material for industrial furnace components, radiant tubes, petrochemical reformers, and automotive exhaust systems requiring reliable performance under severe thermal cycling and oxidizing conditions.

What is Inconel 601?

Inconel 601 is a nickel-chromium-aluminum alloy with controlled carbon content that provides excellent high-temperature strength and oxidation resistance. Unlike Inconel 600, which relies solely on Cr₂O₃ for oxidation protection, Inconel 601 develops a tightly adherent, hard oxide layer of Cr₂O₃ and Al₂O₃. This dual oxide scale provides exceptional resistance to scaling and spalling, even under severe thermal cycling conditions, carburizing, and oxidizing atmospheres.

The aluminum addition improves resistance to oxidation at temperatures above 1000°C (1830°F), making it suitable for service up to 1204°C (2200°F). The alloy maintains its structural integrity through numerous thermal cycles without significant oxidation-induced material loss, delivering service life 2-4 times longer than heat-resistant stainless steels in many applications.

Key characteristics include:

Superior oxidation resistance up to 1204°C (2200°F) with excellent resistance to scaling and spalling
Outstanding resistance to carburization in carbon-rich high-temperature environments
Excellent resistance to thermal cycling and thermal fatigue
Good high-temperature creep-rupture strength up to 1038°C
Excellent resistance to sulfur-containing atmospheres
Good weldability and fabricability

Chemical Composition

Element	Content (%)	Role
Nickel (Ni)	58.0 – 63.0	Base element, provides corrosion and oxidation resistance
Chromium (Cr)	21.0 – 25.0	Forms Cr₂O₃ oxide scale, provides oxidation resistance
Aluminum (Al)	1.0 – 1.7	Forms Al₂O₃ scale, enhances oxidation resistance and prevents spalling
Iron (Fe)	Balance	Balances cost and improves thermal conductivity
Manganese (Mn)	≤ 1.0	Deoxidizer, improves hot workability
Carbon (C)	≤ 0.10	Controlled to optimize creep strength and workability
Silicon (Si)	≤ 0.50	Deoxidizer, improves oxidation resistance
Copper (Cu)	≤ 0.50	Residual element
Sulfur (S)	≤ 0.015	Tightly controlled to avoid hot shortness

Mechanical Properties

Property	Annealed Condition	Cold Drawn
Tensile Strength	585 – 650 MPa (85 – 94 ksi)	800 – 950 MPa
Yield Strength (0.2% Offset)	≥ 205 MPa (30 ksi)	≥ 350 MPa
Elongation	≥ 30%	≥ 8%
Hardness	150 – 220 HB	—
Density	8.11 g/cm³
Melting Range	1360 – 1411°C
Thermal Conductivity	11.2 W/m·K at 20°C
Coefficient of Thermal Expansion (20-100°C)	12.0 × 10⁻⁶/°C
Elastic Modulus	206 GPa
Maximum Service Temp (Oxidation)	1204°C (2200°F)
Maximum Service Temp (Structural)	1038°C (1900°F)

Key Advantages of Inconel 601

Superior Oxidation Resistance – Inconel 601 develops a tightly adherent oxide layer of Cr₂O₃ and Al₂O₃ that provides exceptional protection up to 1204°C (2200°F). This dual oxide scale is significantly more stable and spallation-resistant than the Cr₂O₃ scale formed on Inconel 600, making it ideal for severe thermal cycling applications. Even after extended exposure at 1200°C, the oxide layer remains adherent and protects the underlying metal.

Outstanding Resistance to Carburization – In environments rich in carbon (e.g., ethylene cracking furnaces, carbon black production), Inconel 601 resists carburization better than most other nickel-based alloys. The aluminum addition creates a protective scale that hinders carbon diffusion, preventing metal dusting and embrittlement.

Excellent Thermal Fatigue Resistance – The alloy's high ductility and thermal stability provide excellent resistance to thermal fatigue and thermal shock. Components subjected to repeated heating and cooling cycles (such as radiant tubes and furnace rollers) maintain their integrity significantly longer than stainless steel alternatives.

Good Creep-Rupture Strength – Inconel 601 maintains useful structural strength up to 1038°C. The creep-rupture strength at 1000°C is 25 MPa for 1000-hour life, making it suitable for load-bearing furnace components operating at elevated temperatures.

Resistance to Sulfur-Containing Atmospheres – The alloy performs well in sulfur-containing oxidizing atmospheres, making it suitable for combustion and waste incineration applications where sulfur compounds are present.

Good Workability and Weldability – Inconel 601 can be readily welded using TIG, MIG, and resistance welding processes with matching filler metal. It can be hot worked at 900-1200°C and cold worked using standard techniques.

Inconel 601 vs Inconel 600: Comparison

Property	Inconel 600	Inconel 601
Nickel Content	≥ 72%	58 – 63%
Chromium Content	14 – 17%	21 – 25%
Aluminum Content	None	1.0 – 1.7%
Oxidation Resistance	Excellent up to 1093°C	Superior up to 1204°C
Scale Adhesion	Good	Excellent (Al₂O₃ + Cr₂O₃)
Carburization Resistance	Good	Superior
Chloride SCC Resistance	Outstanding	Good
Temperature Limit	1093°C	1204°C
Creep Strength	Good	Better at high temperature
Preferred Applications	Chemical processing, nuclear power, chloride environments	Furnaces, petrochemical reformers, high-temperature oxidation

When to choose Inconel 600: Applications where chloride stress corrosion cracking is a concern, nuclear power, chemical processing with aggressive chlorides, and moderate high-temperature service up to 1093°C where higher nickel content is beneficial.

When to choose Inconel 601: Applications involving extreme oxidation at temperatures above 1093°C, thermal cycling, sulfur-containing atmospheres, carburizing environments, and furnace components requiring long service life.

Heat Treatment of Inconel 601

Inconel 601 is a solid-solution strengthened alloy and does not respond to precipitation hardening heat treatment. The standard heat treatment is solution annealing:

Standard Solution Annealing:

Temperature: 1100 – 1200°C (2010 – 2190°F)
Soaking Time: 10 – 20 minutes (depending on thickness)
Cooling: Water quench or forced air
Purpose: Dissolve carbides, refine grain structure, achieve optimal corrosion resistance

Stress Relief Annealing:

Temperature: 800 – 900°C (1470 – 1650°F)
Soaking Time: 2 – 4 hours
Cooling: Air cool

Available Product Forms from Womic Steel

Seamless Pipe & Seamless Tube

Outside Diameter: 6mm – 350mm (1/4" – 14")
Wall Thickness: 1mm – 40mm (Schedule 5S to XXS)
Length: Up to 12m
End Finish: Plain End, Beveled End, Threaded
Standards: ASTM B167, ASME SB-167
Applications: Radiant tubes, furnace tubes, heat exchanger tubes, process piping, thermowells
Keywords: Inconel 601 seamless pipe, 2.4851 pipe, N06601 tube, nickel alloy high temperature tube

Welded Pipe

Outside Diameter: 50mm – 1200mm (2" – 48")
Wall Thickness: 1.0mm – 30mm
Standards: ASTM B517, ASTM B516
Applications: Large-diameter furnace components, retorts, process piping
Keywords: Inconel 601 welded pipe, large diameter nickel pipe, furnace pipe

Steel Bar (Round, Square, Flat)

Diameter: 6mm – 500mm
Surface: Hot rolled, Bright, Ground
Standards: ASTM B166, AMS 5715
Applications: Valve stems, fasteners, shafts, furnace rollers, studs, bolts
Keywords: Inconel 601 round bar, N06601 bar, nickel alloy bar, high temperature bar

Steel Plate & Sheet

Thickness: 1mm – 150mm
Width: Up to 2500mm
Standards: ASTM B168, AMS 5870
Applications: Furnace hearth plates, vessel shells, muffles, baffles, structural components
Keywords: Inconel 601 plate, Inconel 601 sheet, nickel alloy plate

Steel Coil & Strip

Thickness: 0.5mm – 6.0mm
Width: 10mm – 1500mm
Standards: ASTM B168
Applications: Formed components, expansion joints, bellows, thin-walled tubing
Keywords: Inconel 601 coil, nickel alloy strip

Flanges & Fittings

Types: Weld Neck, Slip-On, Blind, Socket Weld, Threaded
Sizes: 1/2" – 48"
Pressure Rating: Class 150 – Class 2500
Standards: ASTM B564, ASME B16.5, ASME B16.47
Keywords: Inconel 601 flanges, nickel alloy fittings

Forgings

Types: Rings, disks, rollers, valve bodies, shafts
Weight: Up to 5,000kg
Standards: ASTM B564, AMS 5715

Applications of Inconel 601

Industrial Furnaces and Heat Treating – Inconel 601 is the industry standard for radiant tubes, retorts, muffles, trays, baskets, furnace rollers, and hearth plates. Its outstanding oxidation and carburization resistance extends component life 2-4 times longer than stainless steel alternatives in heat treating applications with thermal cycling up to 1150°C.

Petrochemical Processing – The alloy is widely used in ethylene cracking furnace tubes, catalytic reformers, hydrogen reformer tubes, and ammonia synthesis plant components. Its resistance to carburization and high-temperature oxidation ensures reliable service in critical petrochemical applications, significantly reducing maintenance downtime and replacement costs.

Power Generation – Inconel 601 is used in superheater tubing, boiler components, gas turbine transition ducts, and heat recovery steam generators. Its high-temperature strength and oxidation resistance make it suitable for combined cycle power plants operating at elevated temperatures.

Aerospace and Automotive – The alloy is used in aircraft engine combustion chambers, exhaust system components, turbocharger housings, diesel engine glow plugs, and automotive exhaust systems. Its ability to withstand severe thermal cycling and oxidation makes it ideal for exhaust gas recirculation systems and diesel particulate filters.

Chemical Processing – Inconel 601 is used in nitric acid plant equipment, ammonia oxidizers, and high-temperature chemical reactors. Its resistance to nitric acid and high-temperature corrosion makes it suitable for specialty chemical manufacturing.

Environmental and Waste Incineration – The alloy is used in waste incineration plants, flue gas desulfurization systems, and pollution control equipment. Its resistance to SO₂, HCl, and other corrosive combustion gases ensures long service life in harsh environmental applications.

Glass and Ceramic Manufacturing – Inconel 601 is used in glass melting furnace components, ceramic kiln furniture, and lehr rolls. Its thermal stability and resistance to glass corrosion make it suitable for the glass and ceramics industries.

Standards & Specifications

Product Form	ASTM Standard	ASME Standard	AMS Standard
Seamless Pipe/Tube	ASTM B167	ASME SB-167	—
Welded Pipe	ASTM B517, ASTM B516	ASME SB-517, SB-516	—
Bar/Rod	ASTM B166	ASME SB-166	AMS 5715
Plate/Sheet/Strip	ASTM B168	ASME SB-168	AMS 5870
Forgings	ASTM B564	ASME SB-564	AMS 5715
Fittings	ASTM B366	ASME SB-366	—
UNS Designation	N06601
Werkstoff Number	2.4851
DIN Designation	NiCr23Fe
Chinese Equivalent	NS313 / GH3600

Frequently Asked Questions

Q: What is the main difference between Inconel 601 and Inconel 600?

A: Inconel 601 contains 1.0-1.7% aluminum, which forms a protective Al₂O₃ oxide scale providing superior oxidation resistance up to 1204°C. Inconel 600 relies solely on Cr₂O₃ scale and is rated for 1093°C. Inconel 601 is the preferred choice for extreme high-temperature oxidation and carburizing environments.

Q: Is Inconel 601 readily weldable?

A: Yes. Inconel 601 can be welded using TIG, MIG, and resistance welding processes. Matching filler metal (ERNiCr-3 or ERNiCrFe-3) is recommended. Preheating is generally not required, and post-weld heat treatment is not necessary for most applications.

Q: What is the maximum continuous service temperature for Inconel 601?

A: For oxidation resistance: continuous service up to 1204°C (2200°F). For structural strength: recommended maximum continuous service is approximately 1038°C (1900°F). Short-term excursions above 1200°C are possible but reduce service life.

Q: What is the Chinese equivalent of Inconel 601?

A: The Chinese equivalent grade is NS313 (耐蚀合金) and GH3600 (高温合金). These grades conform to GB/T 15007 and GB/T 2882 standards.

Q: What product forms are available for Inconel 601?

A: Womic Steel supplies Inconel 601 in seamless pipe, welded pipe, steel bar, steel plate, steel coil, strip, flanges, pipe fittings, forgings, and valves. Complete product specifications and size ranges are listed in the product availability section.

Contact Womic Steel

Website: www.womicsteel.com

E-mail: sales@womicsteel.com

Tel / WhatsApp / WeChat:

Victor: +86 15575100681

Jack: +86 18390957568

Womic Steel – Your reliable partner for Inconel 601 seamless pipe, welded pipe, steel bar, steel plate, steel coil, flanges, fittings, forgings, and valves for industrial furnaces, heat treating, petrochemical processing, power generation, and high-temperature oxidation-resistant applications worldwide. Full traceability, classification society certification (CCS, ABS, BV, DNV, LR), and EN 10204 Type 3.1/3.2 documentation available.