Nitronic 60 Stainless Steel: Properties and Key Applications

Nitronic 60 stainless steel is classified as an austenitic stainless steel, notable for its high strength and excellent corrosion resistance. It is primarily alloyed with chromium, nickel, and manganese, which contribute to its unique properties. The addition of nitrogen enhances its strength and resistance to pitting corrosion, making it suitable for demanding environments.

Comprehensive Overview

Nitronic 60 is recognized for its exceptional mechanical properties and corrosion resistance, particularly in marine and chemical processing applications. Its alloying elements play a crucial role in defining its characteristics:

• Chromium (Cr): Enhances corrosion resistance and provides a protective oxide layer.
• Nickel (Ni): Improves ductility and toughness, contributing to the steel's overall strength.
• Manganese (Mn): Increases hardenability and enhances resistance to wear and abrasion.
• Nitrogen (N): Increases strength and improves resistance to pitting and crevice corrosion.

The primary advantages of Nitronic 60 include its high tensile strength, excellent resistance to stress corrosion cracking, and good weldability. However, it can be more expensive than other stainless steels and may require specialized machining techniques due to its strength.

Historically, Nitronic 60 has found applications in various industries, including aerospace, marine, and chemical processing, where its unique properties provide significant benefits. Its market position is strong, particularly in applications requiring high performance under corrosive conditions.

Alternative Names, Standards, and Equivalents

Standard Organization	Designation/Grade	Country/Region of Origin	Notes/Remarks
UNS	S21800	USA	Closest equivalent to AISI 316 but with improved properties.
AISI/SAE	60	USA	Notable for its high strength and corrosion resistance.
ASTM	A240/A240M	USA	Standard specification for chromium and chromium-nickel stainless steel plate, sheet, and strip.
EN	1.3964	Europe	Equivalent grade with similar properties.
JIS	SUS 316L	Japan	Similar corrosion resistance but lower strength.

While Nitronic 60 is often compared to AISI 316 and 316L, it offers superior performance in terms of strength and resistance to pitting corrosion, making it a preferred choice in highly corrosive environments.

Key Properties

Chemical Composition

Element (Symbol and Name)	Percentage Range (%)
Cr (Chromium)	14.0 - 16.0
Ni (Nickel)	8.0 - 10.0
Mn (Manganese)	5.0 - 7.0
N (Nitrogen)	0.1 - 0.3
Fe (Iron)	Balance

The primary role of chromium is to enhance corrosion resistance, while nickel contributes to ductility and toughness. Manganese increases hardenability, and nitrogen significantly improves strength and resistance to pitting.

Mechanical Properties

Property	Condition/Temper	Test Temperature	Typical Value/Range (Metric)	Typical Value/Range (Imperial)	Reference Standard for Test Method
Tensile Strength	Annealed	Room Temp	620 - 750 MPa	90 - 109 ksi	ASTM E8
Yield Strength (0.2% offset)	Annealed	Room Temp	310 - 450 MPa	45 - 65 ksi	ASTM E8
Elongation	Annealed	Room Temp	40 - 50%	40 - 50%	ASTM E8
Hardness (Rockwell B)	Annealed	Room Temp	85 - 95 HB	85 - 95 HB	ASTM E18
Impact Strength	Annealed	-196 °C	40 J	29.5 ft-lbf	ASTM E23

The combination of high tensile and yield strength makes Nitronic 60 suitable for applications requiring structural integrity under mechanical loading, such as in marine environments and chemical processing.

Physical Properties

Property	Condition/Temperature	Value (Metric)	Value (Imperial)
Density	Room Temp	7.9 g/cm³	0.285 lb/in³
Melting Point	-	1400 - 1450 °C	2552 - 2642 °F
Thermal Conductivity	Room Temp	25 W/m·K	17.3 BTU·in/h·ft²·°F
Specific Heat Capacity	Room Temp	500 J/kg·K	0.12 BTU/lb·°F
Electrical Resistivity	Room Temp	0.73 µΩ·m	0.00000073 Ω·m

Key physical properties such as density and melting point are crucial for applications involving high-temperature environments, while thermal conductivity affects heat dissipation in various engineering applications.

Corrosion Resistance

Corrosive Agent	Concentration (%)	Temperature (°C/°F)	Resistance Rating	Notes
Chlorides	3.5	25/77	Excellent	Risk of pitting in stagnant conditions.
Sulfuric Acid	10	25/77	Good	Limited resistance; requires careful handling.
Hydrochloric Acid	5	25/77	Fair	Not recommended for high concentrations.
Sea Water	-	25/77	Excellent	Ideal for marine applications.

Nitronic 60 exhibits excellent resistance to a variety of corrosive environments, particularly in marine applications. It is less susceptible to pitting corrosion compared to standard stainless steels like 316, making it a preferred choice in environments with high chloride concentrations. However, it can still be vulnerable to certain acids, necessitating careful selection based on specific application conditions.

Heat Resistance

Property/Limit	Temperature (°C)	Temperature (°F)	Remarks
Max Continuous Service Temp	800	1472	Suitable for high-temperature applications.
Max Intermittent Service Temp	900	1652	Can withstand short-term exposure.
Scaling Temperature	1000	1832	Begins to lose strength above this temperature.

At elevated temperatures, Nitronic 60 maintains its strength and oxidation resistance, making it suitable for applications in high-temperature environments. However, care must be taken to avoid prolonged exposure to temperatures above its maximum continuous service limit to prevent degradation.

Fabrication Properties

Weldability

Welding Process	Recommended Filler Metal (AWS Classification)	Typical Shielding Gas/Flux	Notes
TIG	ER308L	Argon	Good results with proper technique.
MIG	ER308L	Argon/CO2	Requires careful control of heat input.

Nitronic 60 is known for its good weldability, particularly with TIG and MIG processes. Pre- and post-weld heat treatment can enhance the quality of welds and reduce the risk of cracking. However, care must be taken to control heat input to avoid distortion and maintain mechanical properties.

Machinability

Machining Parameter	Nitronic 60	AISI 1212	Notes/Tips
Relative Machinability Index	50	100	Requires specialized tooling.
Typical Cutting Speed (Turning)	30 m/min	60 m/min	Use carbide tools for best results.

Machining Nitronic 60 can be challenging due to its strength. Optimal conditions include using carbide tooling and adjusting cutting speeds to prevent tool wear.

Formability

Nitronic 60 exhibits good formability, suitable for both cold and hot forming processes. However, due to its strength, it may require larger bend radii to avoid cracking during cold forming.

Heat Treatment

Treatment Process	Temperature Range (°C/°F)	Typical Soaking Time	Cooling Method	Primary Purpose / Expected Result
Solution Annealing	1040 - 1100 / 1900 - 2012	30 minutes	Air or Water	Dissolve carbides and improve ductility.
Stress Relieving	600 - 700 / 1112 - 1292	1 hour	Air	Reduce residual stresses.

Heat treatment processes such as solution annealing enhance the microstructure of Nitronic 60, improving its mechanical properties and ensuring uniformity in performance.

Typical Applications and End Uses

Industry/Sector	Specific Application Example	Key Steel Properties Utilized in this Application	Reason for Selection (Brief)
Marine	Boat fittings	Corrosion resistance, strength	Excellent performance in seawater.
Chemical	Pump components	High strength, resistance to chemicals	Durability in harsh environments.
Aerospace	Fasteners	High strength, lightweight	Critical for safety and performance.

Other applications include:

• Food processing equipment
• Oil and gas industry components
• Pharmaceutical manufacturing

Nitronic 60 is chosen for applications requiring high strength and corrosion resistance, particularly in environments where traditional stainless steels may fail.

Important Considerations, Selection Criteria, and Further Insights

Feature/Property	Nitronic 60	AISI 316	Duplex 2205	Brief Pro/Con or Trade-off Note
Key Mechanical Property	High Strength	Moderate	High Strength	Nitronic 60 offers superior strength.
Key Corrosion Aspect	Excellent	Good	Excellent	Comparable to Duplex but with different applications.
Weldability	Good	Excellent	Fair	Nitronic 60 requires careful welding techniques.
Machinability	Moderate	Good	Poor	More challenging to machine than 316.
Formability	Good	Excellent	Fair	Easier to form than Duplex grades.
Approx. Relative Cost	Higher	Moderate	Higher	Cost may be a consideration for large projects.
Typical Availability	Moderate	High	Moderate	316 is more commonly available.

When selecting Nitronic 60, consider its high strength and corrosion resistance against the potential challenges in machining and cost. Its unique properties make it ideal for specialized applications, particularly in marine and chemical environments.