0.1 ASTM A240 Overview of the Standard
ASTM A240 is a standard established by ASTM International, specifying requirements for chromium and chromium-nickel stainless steel plate, sheet, and strip used in various fields such as pressure vessels, architectural applications, food processing, automotive, and medical devices. The standard defines the chemical composition, mechanical properties, surface finishes, sampling methods, and certification requirements for different stainless steel grades in plate, strip, or coil form.
Resources:
1.0 M A240 Types of Stainless Steel Covered
ASTM A240 covers a wide range of stainless steel types, including but not limited to:
- Austenitic stainless steels: 304, 304L, 316, 316L, 321, 310S
- Ferritic stainless steels: 409, 430
- Martensitic stainless steels: 410, 420
- Duplex stainless steels: 2205, 2507
- High molybdenum or super duplex alloys
Grades
| Type | Raw Material |
| 304 | 18-8 Chromium Nickel Austenitic Stainless Steel |
| 316L | Low Carbon, Chromium Nickel Molybdenum Austenitic Stainless Steel |
| 321 | Titanium Stabilized 18-8 Chromium-Nickel Austenitic Stainless Steel |
| 410 | 12% Straight Chromium Martensitic Stainless Steel |
| 904L | High Nickel Molybdenum Super Austenitic Stainless Steel |
| UNS S31803 | Ferritic / Austenitic Duplex Stainless Steel |
| UNS S32750 | Ferritic / Austenitic Super Duplex Stainless Steel |
| UNS S31254 | High Moly Austenitic Stainless Steel |
2.0 ASTM A240 Product Forms and Delivery Conditions
Product forms covered under ASTM A240 include:
- Plate: Generally with a thickness greater than 3 mm
- Strip: Thinner material, usually delivered in coils
- Coil: Rolled material supplied in coil form for further processing
Common surface finishes include:
- 1: Hot rolled, annealed, and pickled
- 2B: Cold rolled, annealed, and passivated with light skin pass
- BA: Bright annealed, mirror-like finish under controlled atmosphere
3.0 ASTM A240 Key Technical Requirements
Chemical Composition:Each stainless steel grade must meet strict chemical composition limits (C, Cr, Ni, Mo, Mn, etc.) to ensure proper physical properties and corrosion resistance.
Chemical Composition
| Element | 304 | 316 | 321 | 410 | 904L | S31803 | S32750 | S31254 |
| Carbon | 0.07 | 0.08 | 0.08 | 0.08 – 0.15 | 0.02 | 0.03 | 0.03 | 0.02 |
| Manganese, max | 2.00 | 2.00 | 2.00 | 1.00 | 2.00 | 2.00 | 1.20 | 1.00 |
| Phosphorus, max | 0.045 | 0.045 | 0.045 | 0.040 | 0.045 | 0.030 | 0.035 | 0.030 |
| Sulfur, max | 0.030 | 0.030 | 0.030 | 0.030 | 0.035 | 0.020 | 0.020 | 0.010 |
| Silicon | 0.75 | 0.75 | 0.75 | 1.00 | 1.00 | 1.00 | 0.80 | 0.80 |
| Chromium | 17.50 – 19.50 | 16.00 – 18.00 | 17.00 – 19.00 | 11.50 – 13.50 | 19.00 – 23.00 | 21.00 – 23.00 | 24.00 – 26.00 | 19.50 – 20.50 |
| Nickel | 8.00 – 10.50 | 10.00 – 14.00 | 9.00 – 12.00 | 0.75 | 23.00 – 28.00 | 4.50 – 6.50 | 6.00 – 8.00 | 17.50 – 18.50 |
| Molybdenum | – | 2.00 – 3.00 | – | – | 4.00 – 5.00 | 2.50 – 3.50 | 3.00 – 5.00 | 6.00 – 6.50 |
| Nitrogen | 0.10 max | 0.10 max | 0.10 max | – | 0.10 max | 0.08 – 0.20 | 0.24 – 0.32 | 0.18 – 0.25 |
| Copper, max | – | – | – | – | 1.00 – 2.00 | – | 0.50 | 0.50 – 1.00 |
| Titanium | – | – | 5 x (C+N) – 0.70 | – | – | – | – | – |
3.1 Mechanical Properties
Typical values include:
- Tensile strength (MPa)
- Yield strength (MPa)
- Elongation (%)
3.2 Dimensions and Tolerances
Tolerances for thickness, width, and flatness are generally referenced to ASTM A480.
3.3 Testing Methods
- Tensile test
- Hardness test (HB, HRB, HV)
- Impact test (required for certain applications)
3.4 Identification and Traceability
Each batch must have clear markings, including the standard number, steel grade, heat number, dimensions, and other traceability data.
Mechanical Properties
| Type | Tensile Strength, ksi, min |
Yield Strength, ksi, min |
Elongation, % min |
Hardness, maxA |
| 304 | 75 | 30 | 40 | 201 HBW or 92 HRB |
| 316 | 75 | 30 | 40 | 217 HBW or 95 HRB |
| 321 | 75 | 30 | 40 | 217 HBW or 95 HRB |
| 410 | 65 | 30 | 20 | 217 HBW or 96 HRB |
| 904L | 71 | 31 | 35 | 95 HRB |
| UNS S31803 | 90 | 65 | 25 | 293 HBW or 31 HRC |
| UNS S32750 | 116 | 80 | 15 | 310 HBW or 32 HRC |
| UNS S31254 | 100 | 45 | 35 | 223 HBW or 96 HRB |
3.5 Related ASTM Stainless Steel Standards
| Standard No. | Description |
| ASTM A240/A240M | Plates, sheets, and strips for pressure vessels and general use |
| ASTM A276/A276M | Stainless steel bars and shapes |
| ASTM A313/A313M | Stainless steel spring wire |
| ASTM A314 | Stainless steel billets and bars for forging |
| ASTM A473 | Stainless steel forgings |
| ASTM A479/A479M | Stainless steel bars and shapes for boilers and pressure vessels |
| ASTM A580/A580M | Stainless steel wire |
| ASTM A666 | Annealed or cold-worked austenitic stainless steel flat products |
| ASTM A959 | Standard guide for stainless steel compositions |
| SAE J405 | Chemical compositions for SAE stainless forging materials |
3.6 Common Stainless Steel Grades (Type / UNS) and Applications
| Grade | Typical Applications |
| 304/304L | Chemical containers, kitchen equipment, drinking water piping |
| 316/316L | Desalination systems, chemical process equipment, heat exchangers |
| 321 | High-temperature equipment, heat exchange systems |
| 410/420 | Cutlery, mechanical parts, wear-resistant components |
| 430 | Indoor decorations, appliance panels |
| 2205 | Marine environments, oil & gas, structural components |
4.0 Typical Application Areas
ASTM A240 materials are widely used due to their excellent corrosion resistance, mechanical properties, and formability, including:
- Pressure vessels: Suitable for high-pressure and corrosive environments
- Chemical processing equipment: Pipes, tanks, heat exchangers
- Food processing: Work surfaces, containers, cleaning equipment
- Architecture and decoration: Facades, railings, interior structures
- Automotive parts: Exhaust systems, trims
- Medical devices: Surgical instruments, housings
- Petrochemical and energy: Steam turbines, nuclear power, pipelines
- Desalination and flue gas desulfurization systems
4.1 Example Chemical Composition (S30400)
- Chromium (Cr): 17.5% – 5%
- Nickel (Ni): 8.0% – 5%
- Carbon (C): ≤ 07%
- Manganese (Mn): ≤ 00%
- Phosphorus (P): ≤ 045%
- Sulfur (S): ≤ 030%
- Silicon (Si): ≤ 75%
- Iron (Fe): Balance