Overview
Grades 321 and 347 are the basic austenitic 18/8 steel (Grade 304) stabilised by Titanium (321) or Niobium (347) additions. These grades are used because they are not sensitive to intergranular corrosion after heating within the carbide precipitation range of 425-850°C. Grade 321 is the grade of choice for applications in the temperature range of up to about 900°C, combining high strength, resistance to scaling and phase stability with resistance to subsequent aqueous corrosion.
A limitation with 321 is that titanium does not transfer well across a high temperature arc, so is not recommended as a welding consumable. In this case grade 347 is preferred - the niobium performs the same carbide stabilisation task but can be transferred across a welding arc. Grade 347 is therefore the standard consumable for welding 321. Grade 347 is only occasionally used as parent plate material.
ASTM A213 Grade321 steel tubes have excellent forming and welding characteristics, which are readily brake or roll formed. Post-weld annealing is not required. The tubes also have excellent toughness, even down to cryogenic temperatures. It is more readily available in most product forms, therefore generally used in preference to 321 if the requirement is simply for resistance to intergranular corrosion after welding. However 304L has lower hot strength than 321 and so is not the best choice if the requirement is resistance to an operating environment over about 500°C.
Specification
ASTM A213/A213M-21a Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes.
321 Stainless Steel Pipe & Tubes Specification | ASTM A269, ASTM A213, ASTM A312, ASME SA269, ASME SA213, ASME SA312 |
321 Stainless Steel Pipe & Tubes Grades | 202, 304, 304L, 304H, 304LN, 309S, 310S, 316, 316L, 316H, 316Ti, 316LN, 317L, 321, 321H, 347, 347H, 904L, SMO 254, ALLOY 254, 6MO, 6MOLY, UNS S31254 ETC. |
321 Stainless Steel Pipe & Tubes Type | Seamless / Welded / ERW / EFW / Cold Draw / Hot Finish / Cold Finish |
321 Stainless Steel Pipe & Tubes Outer Diameter Size | Seamless - 1/2"NB TO 18"NB |
321 Stainless Steel Pipe & Tubes Wall Thickness | Schedule 10 to Schedule 160 (3 mm to 100 mm Thickness) |
321 Stainless Steel Pipe & Tubes Length | 01 Meter to 12.5 Meters, Single Random Length, Double Random Length And Customize Size. |
321 Stainless Steel Pipe & Tubes Delivery Conditions | As Rolled, Formed, Stress Relieved, Annealed, Hardened, Tempered, Cold Draw |
321 Stainless Steel Pipe & Tubes Coating | Electropolish, Mechanical Polish, Satin Finish, Passivated |
321 Stainless Steel Pipe & Tubes Other Testing | Product Analysis, Transverse Tension Test, Flattening Test, Etching Test, Radiograph HIC Examination, Stabilizing Heat Treatment, Intergranular Corrosion Test, Weld Decay Test, Magnetic Particle Detection, Grain Size Test, NACE 0175, Dual Grade, PWHT (POST WELD HEAT TREATMENT), Flare Test, Bend Test, Hardness Test, Tensile Test etc |
321 Stainless Steel Pipe & Tubes Value Added Services | Draw / Expansion / Machining / Sand Blasting / Shot Blasting / Heat Treatment |
321 Stainless Steel Pipe & Tubes Material Test Certificate | Manufacturer Test Certificate As Per EN10204 3.1, 3.2 / Laboratory Test Certificate From NABL Approved Lab. / Under Third Party Inspection Agency Like SGS, TUV, DNV, LLOYDS, ABS ETC |
Chemical Composition
Grade | C | Mn | Si | P | S | Cr | Mo | Ni | N | Other | |
321 | min. | - | 2.00 | 0.75 | 0.045 | 0.030 | 17.0 | - | 9.0 | 0.10 | Ti=5(C+N) |
321H | min. | 0.04 | 2.00 | 0.75 | 0.045 | 0.030 | 17.0 | - | 9.0 | - | Ti=4(C+N) |
Physical Properties
Grade | Density | Elastic Modulus | Mean Coefficient of | Thermal Conductivity | Specific Heat | Electrical Resistivity | |||
0-100°C | 0-315°C | 0-538°C | at 100°C | at 500°C | |||||
321 | 8027 | 193 | 16.6 | 17.2 | 18.6 | 16.1 | 22.2 | 500 | 720 |
Mechanical Properties
Grade | Tensile Strength | Yield Strength | Elongation | Hardness | |
Rockwell B | Brinell | ||||
321 | 515 | 205 | 40 | 95 | 217 |
321H | 515 | 205 | 40 | 95 | 217 |
Applications
1. Food preparation equipment particularly in chloride environments.
2. Laboratory benches & equipment.
3. Coastal architectural panelling, railings & trim.
4. Boat fittings.
5. Chemical containers, including for transport.
6. Heat Exchangers.
7. Woven or welded screens for mining, quarrying & water filtration.
8. Threaded fasteners.
9. Springs.
