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Stainless Steel Plate 321 321H ASTM A240

321 and 321H Stainless Steel Plate Overview

Processing 321 321H ASTM A240 Plate

321 and 321H stainless steel plate are basic austenitic materials. These grades are stabilized by the addition of Titanium. These grades are often utilized for applications in temperatures up to 1,650 ℉. These grades of plate combine high strength, resistance to scaling, and phase stability, with resistance to subsequent aqueous corrosion. 304L plate is more readily available in most product forms, and so is generally used in preference to 321 or 321H if the requirement is simply for resistance to intergranular corrosion after welding. However, 304L has lower heat strength than 321 and 321H plate and so may not be the best choice if the requirement is resistance to an operating environment over about 932 ℉.

Penn Stainless Products stocks these grades of stainless steel plate in plate mill plate. These plate grades are typically available for purchase in sizes between 0.188” to 2.0”. Other thicknesses are available as well; consult with a member of the Penn Stainless team. It is also available for purchase in a variety of lengths and widths.

Chemical Composition of 321 and 321H Stainless Steel Plate

The difference between 321 and 321H grades lies in the amount of carbon contained within each metal. 321 has at most 0.08% while 321H contains between 0.04% and 0.10% carbon. They both contain at most 2.0% manganese, 0.75% silicon and 0.045% phosphorous. This grade is also made up of at most 0.03% sulfur, between 17.0% and 19.0% chromium, and at most 0.10% nitrogen. The addition of titanium is what gives 321 and 321H stainless steel plate its unique properties. It can also include up to 0.70% titanium.

Mechanical Properties of 321 and 321H Stainless Steel Plate

Both grades have a tensile strength of 75 ksi and a yield strength at 0.2% of 30 ksi. They both have an elongation of 40% as well. On the Brinell hardness scale they both have a hardness of 217 and on the Rockwell B scale both 321 and 321H stainless steel have a hardness of 95.

Physical Properties

This stainless steel has a density of 0.289 Ibm/in^3 and the elastic modulus is 193 Gpa. The mean coefficient of thermal expansion between 32℉ and 212℉ is 9.22in x10-6, between 32 and 599 the coefficient of thermal expansion is 9.56in X10^-6. The coefficient of thermal expansion of 321 plate between 32℉ and 1,000℉ is 1.03in x10^-5. The specific heat of 321 stainless steel plate is 0.194 BTU/IBM.


UNS S32100UNS S32109
ASME 240ASME 240

Applications and Usage

There are many uses for these grades of stainless steel plate, especially in environments which require higher temperatures. These grades of stainless steel plate are commonly used in heat exchangers, bellows, expansion joints, heating element tubing, spiral welded tubes for burner pipes and flues, as well as furnace parts. This grade of stainless steel plate also has applications in woven or welded metal screens for use in high temperature mineral processing. It also has applications in the aerospace industry, specifically in aircraft exhaust and piston engine manifolds. These grades are useful in chemical and food processing industries, specifically in equipment and storage. Petroleum refining, and the chemical industry and in waste treatment processes, are also good applications for these grades. They are more commonly used in Europe than in North America.

Processing and Fabrication Options


What is the difference between these grades?

The difference between 321 and 321H is the amount of Carbon present within each stainless steel plate. 321 stainless steel plate contains less carbon than 321H.

Can these grades of stainless steel be polished?

Yes, these grades of stainless steel plate can be polished to some degree but is not recommended for decorative applications.

How much heat resistance does this stainless steel plates have?

This plate has suggested use between 800℉ and 1,500℉.

Can stainless steel plate be purchased that meets the requirements of both grades?

Yes, it is possible to purchase dual certified stainless steel plate in grades 321 and 321H.

What are the effects of titanium in the chemical and mechanical properties in these grades?

321 and 321H is stabilized with titanium which results in excellent resistance to intergranular corrosion following exposure to temperatures in the chromium carbide precipitation range from 800 to 1500°F. 321 and 321H stainless steel plate is also stabilized against chromium carbide formation by the addition of titanium. It is also advantageous for high temperature service because of its mechanical properties. 321 and 321H stainless steel plate offers higher creep and stress rupture properties than 304 ad 304L stainless steel plate.