321 Stainless Steel: Composition, Physical Properties and Application

Introduction to 321 Stainless Steel

321 stainless steel is made by adding titanium element on the basis of 304 composition.

Its performance is very similar to 304 stainless steel.

Titanium has excellent resistance to acid and alkali corrosion.

When added to stainless steel, it only takes about 1% to greatly improve its rust resistance.

Austenitic stainless steel is easily sensitized when exposed to 450 ℃~850 ℃.

During sensitization, carbides (mainly C23C6 chromium carbide) precipitate along grain boundaries and twin boundaries, and the neighborhood of these boundaries of alloy elements is damaged.

In a specific corrosion environment, intergranular corrosion occurs.

321 can resist the formation of chromium carbide at 426C~815 ℃ due to the addition of stabilized element titanium, so it has better intergranular corrosion resistance and high temperature performance, and has higher creep resistance and stress fracture resistance than 304 and 304L.

In addition, 321 also has good low-temperature toughness, excellent formability and welding properties, and no annealing is required after welding.

321 Stainless steel composition

StandardGB/T20878ASTM A276JIS G4303DIN EN10088-3
Grade  06Cr18Ni11Ti(0Cr18Ni10Ti)S32100321SUS 321X6CrNiTi18-101.4541
C≤0.08≤0.08≤0.080.08
Si1.001.00≤1.001.00
Mn≤2.00≤2.002.00≤2.00
P0.0450.0450.0450.045
S≤0.030≤0.030≤0.0300.030
Ni9.00~12.009.00~12.009.00~13.009.00~12.00
Cr17.0~19.017.0~19.017.0~19.017.0~19.0
Ti5C~0.705(C+N)~0.70>5×C%5×C~0.70

Physical property

Density (g/cm3) 20 ℃

8.03

Melting point (℃)

1398~1427

Specific heat capacity [kJ/(kgK)] 0~100 ℃

0.50

Thermal conductivity [W/(m-K)]

100℃

16.3

500℃

22.2

Linear expansion coefficient (10-6/K)

0~100℃

16.6

0~500℃

18.6

Resistivity (Ωmm2/m) 20 ℃

0.72

Longitudinal elastic modulus (kN/mm2) 20 ℃

193

Magnetic

Slightly magnetic after cold deformation

321 stainless steel application scenario

The titanium added in 321 makes it more suitable for high temperature applications, and is suitable for 304 with sensitization reaction and 304L with insufficient high temperature strength.

Typical applications of 321 stainless steel plate and tube products: thermal expansion joint, corrugated pipe, aircraft exhaust system components, heating element casing, furnace body components and heat exchanger, etc.

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