319 Stainless Steel: Properties and Key Applications

Table Of Content

Table Of Content

319 Stainless Steel is classified as an austenitic stainless steel, notable for its high chromium and nickel content, which contributes to its excellent corrosion resistance and mechanical properties. This grade is primarily alloyed with approximately 19% chromium and 9% nickel, along with small amounts of manganese, silicon, and carbon. The austenitic structure of 319 stainless steel provides it with superior toughness and ductility, making it suitable for various applications in challenging environments.

Comprehensive Overview

319 Stainless Steel is recognized for its exceptional resistance to oxidation and corrosion, particularly in high-temperature applications. Its high chromium content enhances its ability to withstand corrosive environments, while the nickel content contributes to its toughness and ductility. The steel's unique combination of properties makes it particularly advantageous in applications requiring high strength and resistance to thermal fatigue.

Advantages:
- Corrosion Resistance: Excellent resistance to a wide range of corrosive media, including acids and chlorides.
- High-Temperature Stability: Maintains mechanical properties at elevated temperatures, making it suitable for applications in heat exchangers and furnace components.
- Ductility and Toughness: Offers good formability and weldability, allowing for various fabrication processes.

Limitations:
- Cost: Higher alloy content can lead to increased material costs compared to lower-grade stainless steels.
- Work Hardening: Can be challenging to machine due to its tendency to work harden during processing.

319 Stainless Steel holds a significant position in the market, often used in industries such as aerospace, chemical processing, and food manufacturing due to its robust performance in demanding environments.

Alternative Names, Standards, and Equivalents

Standard Organization Designation/Grade Country/Region of Origin Notes/Remarks
UNS S31900 USA Closest equivalent to AISI 304 but with higher silicon content.
AISI/SAE 319 USA Similar to 304 but with improved high-temperature properties.
ASTM A240 USA Standard specification for chromium and chromium-nickel stainless steel plate, sheet, and strip.
EN 1.4301 Europe Equivalent to AISI 304, with minor compositional differences.
JIS SUS 304 Japan Closely related but with different mechanical properties.

The table highlights the various standards and designations associated with 319 Stainless Steel. Notably, while it shares similarities with AISI 304, the higher silicon content in 319 enhances its resistance to oxidation at elevated temperatures, making it a preferable choice in specific applications.

Key Properties

Chemical Composition

Element (Symbol and Name) Percentage Range (%)
Cr (Chromium) 18.0 - 20.0
Ni (Nickel) 8.0 - 10.0
Si (Silicon) 2.0 - 3.0
Mn (Manganese) 1.0 - 2.0
C (Carbon) 0.08 max
Fe (Iron) Balance

The primary alloying elements in 319 Stainless Steel play crucial roles in defining its properties:
- Chromium (Cr): Enhances corrosion resistance and forms a protective oxide layer.
- Nickel (Ni): Improves toughness and ductility, contributing to the steel's ability to withstand deformation.
- Silicon (Si): Increases oxidation resistance and improves high-temperature strength.

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 520 - 750 MPa 75 - 109 ksi ASTM E8
Yield Strength (0.2% offset) Annealed Room Temp 210 - 310 MPa 30 - 45 ksi ASTM E8
Elongation Annealed Room Temp 40 - 50% 40 - 50% ASTM E8
Hardness (Rockwell B) Annealed Room Temp 80 - 90 HRB 80 - 90 HRB ASTM E18
Impact Strength (Charpy) Annealed -20°C 40 J 29.5 ft-lbf ASTM E23

The mechanical properties of 319 Stainless Steel make it suitable for applications that require high strength and ductility. Its tensile and yield strengths indicate its ability to withstand significant loads, while the elongation percentage reflects its capacity for deformation without fracture. The impact strength is particularly important in applications exposed to dynamic loads or impacts.

Physical Properties

Property Condition/Temperature Value (Metric) Value (Imperial)
Density Room Temp 7.93 g/cm³ 0.286 lb/in³
Melting Point/Range - 1400 - 1450 °C 2552 - 2642 °F
Thermal Conductivity Room Temp 16 W/m·K 92 BTU·in/h·ft²·°F
Specific Heat Capacity Room Temp 500 J/kg·K 0.12 BTU/lb·°F
Electrical Resistivity Room Temp 0.72 µΩ·m 0.00000072 Ω·m
Coefficient of Thermal Expansion Room Temp 16.5 x 10⁻⁶/K 9.17 x 10⁻⁶/°F

Key physical properties such as density and thermal conductivity are significant for applications in heat exchangers and other thermal management systems. The relatively high melting point indicates its suitability for high-temperature applications, while the coefficient of thermal expansion is crucial for applications involving temperature fluctuations.

Corrosion Resistance

Corrosive Agent Concentration (%) Temperature (°C) Resistance Rating Notes
Chlorides 3-10 20-60 Good Risk of pitting corrosion.
Sulfuric Acid 10-30 20-40 Fair Susceptible to stress corrosion cracking.
Acetic Acid 5-20 20-60 Excellent Resistant to localized corrosion.
Sea Water - 20-30 Good Suitable for marine applications.

319 Stainless Steel exhibits excellent resistance to various corrosive agents, making it suitable for applications in chemical processing, marine environments, and food manufacturing. Its performance in chloride environments is noteworthy, although caution is advised due to the risk of pitting. Compared to other stainless steels like 304 and 316, 319 offers improved oxidation resistance at elevated temperatures but may not perform as well in highly acidic environments.

Heat Resistance

Property/Limit Temperature (°C) Temperature (°F) Remarks
Max Continuous Service Temp 800 1472 Suitable for prolonged exposure.
Max Intermittent Service Temp 900 1652 Can withstand short-term spikes.
Scaling Temperature 1000 1832 Begins to lose mechanical properties.
Creep Strength considerations 600 1112 Creep resistance begins to decline.

319 Stainless Steel maintains its mechanical properties at elevated temperatures, making it ideal for applications in heat exchangers and furnace components. However, care must be taken to avoid prolonged exposure to temperatures above 800 °C, as this can lead to scaling and loss of strength.

Fabrication Properties

Weldability

Welding Process Recommended Filler Metal (AWS Classification) Typical Shielding Gas/Flux Notes
TIG ER309L Argon Good for thin sections.
MIG ER308L Argon + CO2 Suitable for thicker sections.
SMAW E309L - Requires preheat for thicker materials.

319 Stainless Steel is generally considered to have good weldability, particularly with TIG and MIG processes. Preheating may be required for thicker sections to avoid cracking. Post-weld heat treatment can enhance the mechanical properties of the weld.

Machinability

Machining Parameter 319 Stainless Steel AISI 1212 Notes/Tips
Relative Machinability Index 40 100 Moderate machinability.
Typical Cutting Speed (Turning) 30 m/min 60 m/min Use carbide tools for best results.

319 Stainless Steel presents moderate machinability challenges due to its work-hardening characteristics. Utilizing carbide tools and optimizing cutting speeds can improve performance during machining operations.

Formability

319 Stainless Steel exhibits good formability, allowing for cold and hot forming processes. However, care must be taken to avoid excessive work hardening, which can lead to cracking during bending operations. Recommended bend radii should be adhered to for optimal results.

Heat Treatment

Treatment Process Temperature Range (°C/°F) Typical Soaking Time Cooling Method Primary Purpose / Expected Result
Annealing 1000 - 1100 / 1832 - 2012 1 - 2 hours Air Relieve stresses, improve ductility.
Solution Treatment 1050 - 1100 / 1922 - 2012 1 hour Water Enhance corrosion resistance.

Heat treatment processes such as annealing and solution treatment are essential for optimizing the microstructure of 319 Stainless Steel. These treatments enhance ductility and corrosion resistance, making the material suitable for demanding applications.

Typical Applications and End Uses

Industry/Sector Specific Application Example Key Steel Properties Utilized in this Application Reason for Selection
Aerospace Engine components High strength, corrosion resistance Performance at high temperatures.
Chemical Processing Heat exchangers Oxidation resistance, thermal stability Durability in corrosive environments.
Food Manufacturing Processing equipment Non-reactive surface, ease of cleaning Compliance with hygiene standards.

Other applications include:
- Marine components
- Pharmaceutical equipment
- Oil and gas industry applications

319 Stainless Steel is chosen for these applications due to its ability to withstand harsh environments while maintaining structural integrity and performance.

Important Considerations, Selection Criteria, and Further Insights

Feature/Property 319 Stainless Steel AISI 304 AISI 316 Brief Pro/Con or Trade-off Note
Key Mechanical Property High strength Moderate High 319 offers better high-temp performance.
Key Corrosion Aspect Good in chlorides Fair Excellent 316 is superior in marine environments.
Weldability Good Excellent Good 319 requires more care in welding.
Machinability Moderate Good Fair 319 is more challenging to machine.
Formability Good Excellent Good 319 may require more attention to avoid cracking.
Approx. Relative Cost Higher Moderate Higher Cost considerations may affect selection.
Typical Availability Moderate High High 304 is more commonly available.

When selecting 319 Stainless Steel, considerations such as cost, availability, and specific application requirements must be evaluated. Its unique properties make it suitable for specialized applications, particularly where high-temperature performance and corrosion resistance are critical.

Back to blog

Leave a comment