ASTM A240 VS A666
When sourcing stainless steel sheets, plates, or strips, buyers often encounter two key ASTM standards - ASTM A240 and ASTM A666. Although both cover austenitic stainless steels, they apply to different product forms and processing conditions. Understanding their differences is essential for selecting the right material for your application and ensuring compliance with project specifications.
What is ASTM A240?
ASTM A240 is the standard specification for chromium and chromium-nickel stainless steel plate, sheet, and strip for pressure vessels and general applications.It is mainly used for hot-rolled and annealed stainless steel products.
Typical Grades Covered:
304, 304L, 316, 316L, 310S, 321, 347, 904L, etc.
Key Applications:
Pressure vessels and boilers
Chemical processing equipment
Heat exchangers and storage tanks
Architectural and structural components
What is ASTM A666?
ASTM A666 specifies annealed or cold-worked austenitic stainless steel sheet, strip, plate, and flat bar.It emphasizes mechanical properties after cold working or annealing, making it ideal for applications requiring higher strength or specific temper conditions.
Typical Grades Covered:
201, 202, 301, 304, 304L, 316, 316L, 317L, 321, 347
Key Applications:
Springs, fasteners, and formed components
Medical and food equipment
Automotive and aerospace parts
Decorative and structural applications requiring specific tempers (1/8 Hard, 1/4 Hard, etc.)
ASTM A240 vs ASTM A666 Comparison Table
| Property / Feature | ASTM A240 | ASTM A666 |
|---|---|---|
| Product Form | Plate, sheet, and strip (mainly hot-rolled) | Sheet, strip, plate, and flat bar (cold-worked or annealed) |
| Main Purpose | Pressure vessel and general service | Structural and formed components with defined mechanical properties |
| Mechanical Condition | Typically annealed | May be annealed or cold-worked (1/8 Hard to Full Hard) |
| Thickness Range | Typically thicker (≥ 3 mm) | Includes thinner sheet and strip forms (≤ 3 mm) |
| Mechanical Strength | Moderate | Can be increased by cold working |
| Surface Finish | 2B, No.1, No.4, BA | 2B, BA, and cold-worked finishes (e.g., spring temper) |
| Common Grades | 304/304L, 316/316L, 321, 904L | 201, 301, 304/304L, 316/316L, 321, 347 |
| Typical Use Cases | Pressure vessels, tanks, industrial equipment | Springs, automotive parts, appliances, decorative panels |
Can ASTM A666 replace ASTM A240 in all applications?
Not necessarily. ASTM A240 is pressure-vessel certified, while A666 focuses on mechanical temper control. For high-pressure or elevated temperature environments, A240 is required.
Are the chemical compositions the same?
Yes, both standards cover similar austenitic stainless steel grades, so chemical composition is typically identical - the difference lies in processing and mechanical condition.
Does ASTM A666 include 904L?
No, 904L is usually covered under ASTM A240 due to its use in pressure vessels and chemical processing applications.
Global demand for austenitic stainless steel sheets and strips under ASTM A240 and A666 has grown steadily due to increasing use in chemical, food, and architectural sectors.
In 2025, average prices for 304/316 grades range from USD 2,400–3,000 per ton, while high-alloy grades like 904L may exceed USD 6,000 per ton, depending on thickness and finish.
Buyers prefer suppliers offering:
Full traceability and Mill Test Certificates (EN 10204 3.1)
Surface customization (2B, BA, No.4, mirror)
Fast lead times and export packaging standards
Why Choose Gnee Stainless Steel
Gnee supplies a wide range of ASTM A240 and A666 stainless steel sheets, plates, and strips with global certifications.
Our products meet ASTM, ASME, EN, and JIS standards, offering:
Thickness: 0.3 mm – 80 mm
Width: up to 2000 mm
Surface finish: 2B, BA, No.4, Mirror, Hairline
Materials: 304/304L, 316/316L, 310S, 321, 347, 904L
Cut-to-size and polishing services
We provide competitive pricing, reliable export packaging (wooden crates/pallets), and fast delivery (7–15 days) to meet your project timelines.
