321 stainless steel sheet
  • 321 stainless steel sheet

A Titanium Stabilized Austenitic Stainless Steel with Excellent Resistance to Intergranular Corrosion After Exposure to Temperatures in the Chromium Carbide Precipitation Range of 800–1500°F (427–816°C)


Alloy 321 (UNS S32100) is a titanium stabilized austenitic stainless steel with good general corrosion resistance. It has excellent resistance to intergranular corrosion after exposure to temperatures in the chromium carbide precipitation range of 800–1500°F (427–816°C). The alloy resists oxidation to 1500°F (816°C) and has higher creep and stress rupture properties than alloys 304 and 304L. It also possesses good low temperature toughness. Alloy 321H (UNS S32109) is the higher carbon (0.04–0.10) version of the alloy. It was developed for enhanced creep resistance and for higher strength at temperatures
above 1000°F (537°C). In most instances, the carbon content of the plate enables dual certification. Alloy 321 cannot be hardened by heat treatment, only by cold working. It can be easily welded and processed by standard shop fabrication practices.


Applications

• Aerospace—piston engine manifolds
• Chemical Processing
• Expansion Joints
• Food Processing—equipment and storage
• Petroleum Refining—polythionic acid service
• Waste Treatment—thermal oxidizers


Standard

  • ASTM ................. A 240

  • ASME ................. SA 240

  • AMS ................... 5510


Chemical Analysis

Weight % (all values are maximum unless a range is otherwise indicated)

Element 321 321H
Chromium 17.00 min. –19.00 max 17.00 min.–19.00 max.
Nickel 9.00 min.–12.00 max. 9.00 min.–12.00 max.
Carbon 0.08 0.04 min.– 0.10 max.
Manganese 2 2
Phosphorus 0.045 0.045
Sulfur 0.03 0.03
Silicon 0.75 0.75
Titanium 5 x (C + N) min.–0.70 max. 4 x (C + N) min.–0.70 max.
Nitrogen 0.1 0.1
Iron Balance Balance


Physical Properties

Density
0.286 lbs/in3
7.920 g/cm3
Modulus of Elasticity
28.0 x 106 psi
193 Gpa
Melting Range
2550–2635°F
1398–1446°C
Specific Heat
0.12 BTU/lb-°F (32–212°F)
500 J/kg-°K (0–100°C)
Thermal Conductivity 212°F (100°C)
9.3 BTU/hr/ ft2/ft /°F
16.0 W/m-°K
Electrical Resistivity 72 Microhm-cm at 20°C


Mean Coefficient of Thermal Expansion

Temperature Range
in/in ℉ cm/cm℃
68-212 20-100 9.2 x 10-6 16.0 x 10-6
68-1112 20-600 10.5 x 10-6 18.9 x 10-6
68-1832 20-1000 11.4 x 10-6 20.5 x 10-6


Mechanical Properties

Typical Values at 68°F (20°C)

Yield Strength
0.2% Offset
Ultimate Tensile
Strength
Elongation
in 2 in.
Hardness
psi(min.) (Mpa) psi(min.) (Mpa) %(min.) (max.)
30,000 205 75,000 515 40 217 Brinell


Corrosion Resistance

Alloy 321 exhibits good general corrosion resistance that is comparable to 304. It was developed for use in the chromium carbide precipitation range of
1800–1500°F (427–816°C) where un-stabilized alloys such as 304 are subject to intergranular attack.
The alloy can be used in most diluted organic acids at moderate temperatures and in pure phosphoric acid at lower temperatures and up to 10% diluted solutions at elevated temperatures. Alloy 321 resists polythionic acid stress corrosion cracking in hydrocarbon service. It can also be utilized in chloride or fluoride free caustic solutions at moderate temperatures. Alloy 321 does not perform well in chloride solutions, even in small concentrations, or in sulfuric acid service.

Fabrication Data

Alloy 321 can be easily welded and processed by standard shop fabrication practices.
Machining
The cold work hardening rate of 321 makes it less machinable than 410 stainless steel, but similar to 304. The table below provides relevant machining data.

OperationToolLubricationCONDITIONS



Depth-mm Depth-mm Feed-mm/t Feed-in/t Speed-mm/min Speed-ft/min
Turning
High Speed
Steel
Cutting
Oil
6 0.23 0.5 0.019 12-16 39-52
3 0.11 0.4 0.016 28-23 59-75
1 0.04 0.2 0.008 23-28 75-92
Carbide
Dry or
Cutting Oil
6 0.23 0.5 0.17 67-76 220-249
3 0.11 0.4 0.16 81-90 266-295
1 0.04 0.2 0.008 99-108 325-354



Depth of cut-m Depth of cut-in Feed-mm/t Feed-in/t Speed-mm/min Speed-ft/min
Cutting
High Speed
Steel
Cutting
Oil
1.5 0.06 0.03-0.05 0.012-0.002 16-21 52-69
3 0.11 0.04-0.06 0.016-0.024 17-22 56-72
6 0.23 0.05-0.07 0.020-0.027 18-23 59-75



Drill Ø mm Drill Ø in Feed-mm/t Feed-in/t Speed-m/min Speed-ft/min
Drilling
High Speed
Steel
Cutting
Oil
1.5 0.06 0.02-0.03 0.0007-0.0012 9-13 29-42
3 0.11 0.05-0.06 0.0020-0.0024 11-15 36-49
6 0.23 0.08-0.09 0.0031-0.0035 11-15 36-49
12 0.48 0.09-0.1 0.0035-0.0039 11-15 36-49





Feed-mm/t Feed-in/t Speed-m/min Speed-ft/min
Milling
Profiling
High Speed
Steel
Cutting
Oil


0.05-0.10 0.002-0.004 11-21 26-69


Hot Forming
Working temperatures of 2100–2300°F (1149–1260°C) are recommended for forging, upsetting and other hot working processes. Do not work this alloy
at temperatures below 1700°F (927°C). Material must be water quenched or fully annealed after working to re-attain maximum corrosion resistance.


Cold Forming
The alloy is quite ductile and forms easily.


Welding
Alloy 321 can be readily welded by most standard processes. A post weld heat treatment is not necessary.


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