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321/321H is a titanium-stabilized stainless steel alloy known for its high-temperature strength and excellent corrosion resistance in high-temperature environments.

321/321H is a titanium-stabilized stainless steel alloy that is known for its high-temperature strength and excellent corrosion resistance in high-temperature environments. It is a variation of the standard 321 alloy, which is stabilized with titanium to improve its intergranular corrosion resistance. The H in 321H stands for "high carbon" which indicates that the alloy has a higher carbon content than standard 321 alloy.

The alloy has a high resistance to corrosion, especially in high-temperature environments, such as those found in the aerospace and petrochemical industries. It also has a good resistance to intergranular corrosion and is resistant to pitting and crevice corrosion in chloride-containing environments. The high-temperature strength of the alloy makes it suitable for use in applications such as exhaust manifolds, furnace parts, and heat exchangers.

321H alloy has a higher carbon content than standard 321 alloy which gives it a higher strength and improved high-temperature properties. It is often used for applications that require high strength and corrosion resistance at high temperatures, such as furnace parts, heat exchangers, and heavy-duty exhaust systems.

In general, 321/321H alloy is a versatile alloy that offers a combination of high strength and corrosion resistance, making it a good choice for many high-temperature applications. It is available in a variety of forms including sheet, plate, and pipe, and can be easily welded and formed to meet specific requirements.

Chemical Composition of 321/321H

  • The chemical composition of 321 stainless steel, also known as UNS S32100 or 1.4541, is as follows:

  • Carbon (C): 0.08% max

  • Manganese (Mn): 2.00% max

  • Silicon (Si): 1.00% max

  • Phosphorus (P): 0.045% max

  • Sulfur (S): 0.03% max

  • Chromium (Cr): 17.0-19.0%

  • Nickel (Ni): 9.0-12.0%

  • Titanium (Ti): 5xC min

  • Iron (Fe): balance

The chemical composition of alloy 321H (UNS S32109) and 1.4878 is as follows:

Carbon: 0.04-0.10%

Manganese: 2.00% maximum

Phosphorus: 0.045% maximum

Sulfur: 0.030% maximum

Silicon: 0.75% maximum

Chromium: 17.00-19.00%

Nickel: 9.00-12.00%

Titanium: 5x(C+N) 0.70% maximum

Nitrogen: 0.10-0.25%

Iron: balance

Additionally, alloy 321H also contains a small amount of columbium (niobium) and tantalum, typically around 0.10% each, to improve its stability in high-temperature service.

It is important to note that the composition of the alloy may vary slightly depending on the manufacturer and the specific grade of the alloy. It is always recommended to consult the manufacturer's data sheet for the exact composition of the alloy in a given application.

321 and 321H are both variations of the alloy known as stainless steel 321. They have similar chemical compositions and are often used interchangeably in industry.

The main difference between the two is that 321H has a higher carbon content, which gives it improved high temperature strength.

Physical Properties:

  • Density: 0.28 lb/in3 (7.99 g/cm3)

  • Melting point: 2550-2650°F (1399-1454°C)

Mechanical Properties:

  • Tensile strength: 90 ksi (620 MPa)

  • Yield strength: 45 ksi (310 MPa)

  • Elongation: 40%

  • Hardness: Rb 95

  • Impact strength: 20 ft-lb (27 J)

321/321H is resistant to corrosion and has good mechanical properties, making it well-suited for high-temperature applications such as furnace parts, heat exchangers, and boilers.

Physical & Mechanical Properties of 321/321H

Variants of 321

There are several variants of stainless steel 321, each with slightly different chemical compositions and properties. Some examples include:

  • 321F: This variant is a stabilized version of 321 and is used in applications where high temperatures are a concern. It is stabilized with titanium to prevent carbide precipitation.

  • 321L: This variant has lower carbon content than 321 and 321H, which makes it more resistant to intergranular corrosion. It is often used in welding applications.

  • 321H: As I mentioned before, this variant has higher carbon content than 321, which improves its high temperature strength.

  • 321Ti: This variant is similar to 321F but uses titanium instead of niobium as the stabilizing element.

  • 321LN: This variant is a low-carbon, nitrogen-strengthened version of 321. It offers improved toughness and resistance to intergranular corrosion.

Each variant of 321 is suited for different applications and environments, so it's important to select the right one based on the specific requirements of the application.


Intamet offers 321/H in a wide range of forms, including the below:

Stacked Pipes
flat brs.jpg
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