ASTM A276 Alloy 321F Stainless Steel Round Bar Bright Polishing H6 H7 H9 H11 H13 Tolerance

Products Specification

ASTM A276 Alloy 321F Stainless Steel Round Bar Bright Polishing H6 H7 H9 H11 H13 Tolerance

Introduction to ASTM A276 Alloy 321F Stainless Steel

ASTM A276 Alloy 321F Stainless Steel Round Bars are widely used in applications requiring high temperature and corrosion resistance. Alloy 321F is a titanium-stabilized version of Type 304 stainless steel, making it ideal for use in harsh environments. The alloy exhibits excellent resistance to oxidation and intergranular corrosion, especially at elevated temperatures. This makes it an ideal material for industries such as aerospace, chemical processing, and power generation.

ASTM A276 is the standard specification for stainless steel bars used in general industrial applications. The round bar product typically comes in various grades of stainless steel, including the popular 321F grade. The "F" designation indicates that the material has been specially designed to be more resistant to stress corrosion cracking and sensitization, especially in welding applications.

In this product description, we will explore the properties, applications, specifications, and tolerances of ASTM A276 Alloy 321F stainless steel round bars.

Alloy 321F Stainless Steel Composition

The chemical composition of ASTM A276 Alloy 321F stainless steel is designed to provide excellent resistance to high-temperature oxidation and carburization. Below is the typical composition of 321F stainless steel:

As indicated, the alloy contains significant amounts of chromium and nickel, which provide corrosion resistance, while the titanium content is added to prevent sensitization during welding. This ensures the stainless steel retains its properties even when exposed to high temperatures.

Properties of ASTM A276 Alloy 321F Stainless Steel

Mechanical Properties

1. Tensile Strength: 515 – 690 MPa (75,000 – 100,000 psi)

2. Yield Strength: 205 – 350 MPa (30,000 – 50,000 psi)

3. Elongation: 40% min (in 50 mm)

4. Hardness: Rockwell B (HRB) 90 max

These properties make the 321F stainless steel round bar highly suitable for critical applications where high strength and durability are required. Its ability to resist mechanical wear and tear also contributes to its longevity in industrial applications.

Thermal Properties

1. Maximum Service Temperature: 870°C (1600°F)

2. Thermal Conductivity: 15.1 W/m·K at 100°C

3. Specific Heat Capacity: 500 J/kg·K at 25°C

4. Coefficient of Thermal Expansion: 17.3 µm/m·K at 20–100°C

With its excellent high-temperature properties, ASTM A276 Alloy 321F is particularly suitable for use in applications where components are subject to temperature fluctuations or sustained heat, such as in the aerospace, petrochemical, and power generation sectors.

Corrosion Resistance

One of the standout features of ASTM A276 Alloy 321F stainless steel is its outstanding resistance to corrosion. The alloy offers superior protection against:

• Oxidation: Ideal for high-temperature environments, 321F stainless steel can resist oxidation in conditions up to 870°C (1600°F).

• Intergranular Corrosion: Titanium stabilizes the alloy by binding carbon and prevents chromium carbide precipitation, which can cause intergranular corrosion.

• Acid Resistance: It has resistance to many acidic environments, especially at elevated temperatures.

Applications of Alloy 321F Stainless Steel Round Bar

Alloy 321F stainless steel round bars are used across a wide range of industries due to their superior performance at elevated temperatures and resistance to corrosion. Common applications include:

• Aerospace: For engine components, exhaust systems, and airframes due to its high temperature and corrosion resistance.

• Chemical Processing: In the production of tanks, heat exchangers, and reactors exposed to corrosive chemicals.

• Petrochemical: For use in refineries, boilers, and piping systems where high temperatures and corrosion resistance are critical.

• Power Generation: In steam turbines, exhaust systems, and heat exchangers used in power plants.

• Marine: For parts exposed to seawater and other corrosive environments.

• Food Processing: In high-temperature food processing equipment that requires resistance to oxidation.

Bright Polishing of 321F Stainless Steel Round Bars

Bright polishing refers to the surface finish of the stainless steel round bars, which are treated to achieve a smooth, glossy surface. This process not only enhances the aesthetic appeal of the material but also provides improved corrosion resistance. The bright polished finish is commonly used in decorative applications or where a clean, sanitary surface is required, such as in the food processing and pharmaceutical industries.

Tolerances: H6, H7, H9, H11, H13

The dimensional tolerances of ASTM A276 Alloy 321F stainless steel round bars are defined by specific standards that ensure the bars fit precisely in industrial applications. These tolerances are categorized by tolerance classes:

• H6 Tolerance: Suitable for highly precise applications, such as in components that must fit together very tightly.

• H7 Tolerance: Standard tolerance for medium-precision components. Common in mechanical and automotive applications.

• H9 Tolerance: Looser tolerances, suitable for general industrial use.

• H11 and H13 Tolerances: These are even looser and often applied where minor deviations in dimension will not affect the performance of the component.

Selecting the correct tolerance depends on the intended application. For highly critical components requiring precise fitment and performance, H6 or H7 tolerances are ideal. For more general industrial uses, H9, H11, or H13 may suffice.

Advantages of ASTM A276 Alloy 321F Stainless Steel Round Bar

1. High Temperature Resistance: The material performs well in temperatures up to 870°C (1600°F), making it ideal for high-temperature applications like aerospace and industrial furnaces.

2. Corrosion Resistance: Excellent resistance to a wide range of corrosive environments, particularly in high-temperature conditions.

3. Weldability: Titanium stabilization allows for easier welding without the risk of sensitization or intergranular corrosion.

4. Durability: High mechanical strength and resistance to wear and tear ensure long-lasting performance in demanding environments.

5. Versatility: It can be used in a variety of industries including aerospace, chemical processing, and power generation, making it a highly versatile material.

Conclusion

ASTM A276 Alloy 321F Stainless Steel Round Bar is a top-tier material designed for demanding applications where high-temperature and corrosion resistance are critical. With its titanium stabilization, bright polished finish, and precise tolerance classifications (H6, H7, H9, H11, H13), it provides superior performance in industries such as aerospace, petrochemical, marine, and power generation.