Why Choose Stainless Steel Grade 321? (UNS S32100)

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Austenitic 321 stainless steel is also known as UNS S32100. It is also named niobium nitrogen alloy. It is a highly stabilized chromium-titanium steel. And has strong oxidation resistance properties with creep strength. In this blog, we will take a look at why one should choose grade ss321 stainless steel. Read on to learn more about SS321.

Composition of Stainless Steel Grade 321

Stainless steel grade 321 is composed of several elements. It consists of 17%-19% chromium, 9% to 12% nickel, 0.08% carbon, 2% manganese, 0.045% phosphorous, 0.75% silicon, 0.7 titanium, and 0.03% sulfur. It also has 0.1% nitrogen which stabilizes it. Following is the SS 321 chemical composition:

Element % Present
Cr 17-19
Ni 9-12
C 0.08
Mn 2
P 0.045
Si 0.75
Ti 0.7
Fe Balanced
S 0.03
N 0.1


About SS 321

SS 321 is a stabilized version of SS304. It has titanium present in it to keep it stable. While welding in high temperatures, the titanium content present in this alloy prevents carbide precipitation. This grade of stainless steel is highly resistant to oxidation and corrosion. It also possesses good creep strength.

Stainless steel 321 is ready to form and draw at normal temperatures. When compared to carbon and ferritic stainless steel, it requires high pressure. At moderate temperatures, alloy SS321 is used in diluted organic acid. This usually takes place at lower temperatures. At elevated temperatures, alloy 321 SS can be used in 10% diluted solutions. This version of stainless steel has great resistance to intergranular corrosion. This happens after exposure to temperatures in chromium carbide precipitation. This alloy of iron resists oxidation to 816 degrees Celcius. It has higher creep properties. It also has high stress rupture properties than other alloys like SS 304 and SS 304L. This alloy also possesses good low-temperature toughness.

Alloy 321H, also known as UNS S32109, is a higher carbon version of SS 321 alloy. This alloy was made for enhanced creep resistance. It was also made for higher strength at temperatures above 537 degrees Celcius. According to reports, the carbon content of this alloy enables dual certification. SS 321 can not be hardened by the process of heat treatment.

Applications of SS 321

Alloy SS 321 has a wide range of applications. It is used in the Aerospace industry for piston engine manifolds. This alloy is also used in chemical processing plants. SS 321 is also used for making expansion joints. This alloy of iron is also used in the processing industry where food is involved. This alloy is used for making storage tanks and equipment. SS 321 is used in petroleum refining and waste treatment as a thermal oxidizer. These are some of the applications of SS 321. To know more about the applications of SS 321, visit the Shalco Industries website.

SS321 stainless steel reportedly doesn’t perform well in chloride solutions, even in small concentrations. It also doesn’t perform well in sulfuric acid service. Due to these reasons and applications, ss321 is widely used and preferred.

Hot Forming

For forging and other hot working processes, working temperatures of 1149-1260 °C are recommended. It is recommended that one should not work this alloy at temperatures below 927 degrees Celsius. It is also recommended that the material must be quenched with water or fully annealed after working to re-attain maximum corrosion resistance.

Cold Forming

Alloy 321 SS is quite ductile and forms easily. This alloy of iron can be welded readily by most standard processes.

If you want to know more about the physical properties and general specifications of SS321, visit the Shalco Industries website.

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