Stainless Steel 321

Type 321 is a standard austenitic 18/8 chromium nickel alloy with the addition of Titanium making it an excellent choice in elevated temperature environments.

Used in particular applications within 450-850 degrees centigrade, 321 combines high strength with resistance to scaling and phase stability, Some typical areas of application are, furnace components, superheater and afterburner parts, compensators and expansion bellows.

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Stainless steel 321 is a 18Cr-9Ni austenitic stainless steel stabilised with some titanium additions.

This kind of steel is one of the basic grades of the stainless steels range. Titanium bearing (carbide forming element) avoids intergranular corrosion, even on welded pieces without ulterior water quenching.

Alloys stainless steel 321 exhibit austenitic microstructures free of deleterious carbide precipitations but with CNTi precipitations at the grain boundaries. The grade contains some residual ferrite (≈4%) after solution annealing (1000-1100°C - 1832-2012°F) and water quenching.

The main properties are:

  • Basic corrosion resistance
  • Resistance against intergranular corrosion
  • Heat resistant alloy (medium temperature)
  • High ductility

Standards

EURONORM 1.4541 X6CrNiTi 18-10
AFNOR Z6 CNT 18-10
DIN W1.4541
ASTM A 240 - TP 321 UNS S32100

Chemical Analysis

Typical values (weight %)
C Cr NI Mo N Others
0.050 17.5 9.2 - - =5x%C ; up to 0.70
PREN (=%Cr+3.3%Mo+16%N) ≥ 18

Mechanical Properties

Tensile properties after water quenching
°C °F Minimum guaranteed values * Typical values El %
Y.S. 0.2% Y.S. 1% UTS Y.S. 0.2% Y.S. 1% UTS
MPa Ksi MPa Ksi MPa Ksi MPa Ksi MPa Ksi MPa Ksi
20 68 200 29 240 35 500/
700		 73/
102		 280 40 310 45 600 89 45
100 212 176 25 208 30 460 67 238 34 260 38 550 82 40
200 392 157 23 186 27 410 60 200 29 230 33 450 66 35
300 572 136 20 167 24 390 57 168 26 210 30 435 64 35
400 752 125 18 156 23 390 57 175 25 200 29 420 61 30
500 932 119 17 149 22 310 45 168 24 195 28 340 50 30

* Following EN 10088 hot rolled plates.
The EN guaranteed values are valid for a thickness from 5-75mm.

Impact values
°C -269 -196 +20
°F -452 -320 68
KCV (J*cm²) Minimum 62 100 150
KCV (J*cm²) Typical 138 160 25

Physical Properties

 
Interval
temper
°C		 Thermal
expansion
αx10-6K-1		 °C °F Resistivity
(µΩ cm)		 Thermal
conductivity
(W.m-1.K-1)		 Specific
heat
(J.kg-1.K-1)		 Young
modulus
E
(GPa)		 Shear
modulus
G
(GPa)
20-100 16 20 68 73 15 500 200 77
20-200 16.5 100 212 77 16 500 194 75
20-300 17 200 392 84 17.5 520 186 71
20-400 17.5 300 572 91 19 530 179 68
20-500 18 400 752 97 20.5 540 172 65
    500 932 102 22 540 165 62

Corrosion Resistance

Quality corrosion tests guaranteed (special request may be discussed)
TEST Other name Corrosion (1) Results
ASTM A 262 A   Intergranular Step or dual structure
ASTM A 262 B STREICHER Intergranular Not recommended
ASTM A 262 C HUEY Intergranular Not recommended
ASTM A 262 E
DIN 50914
RCCM		 STRAUSS Intergranular No cracking after bending
ASTM G48 A   Pitting Not recommended
(typical CPT = 5°C-41°F)
ASTM G48 B ASTM G78 Crevice Not recommended
(typical CCT ≤ 0°C-32°F)

(1) kind of corrosion mechanism investigated

Applications

Stainless steel 321 is corrosion resistant in:

  • Urban media
  • Most of diluted organic acids at moderate temperatures
  • Most of food and pharmaceutical products
  • Pure phosphoricM
    • Whatever concentration in cold solution
    • Up to 10% diluted hot solution
  • Caustic solutions free of chlorides or fluorides at medium temperatures

The alloys is not corrosion resistant in chloride containing solutions, even diluted, and in sulphuric acid media.

So, the main applications are:

  • Food processing and storage
  • Chemical industry
  • High temperature