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ASTM A240/A240M S34700 vs BS 970 (Part 3) 321S31

Strong Match — 91.3% match based on chemical composition and mechanical property overlap.

ASTM A240/A240M S34700 (ASTM A240/A240M:2025) and BS 970 (Part 3) 321S31 (BS 970 (Part 3):1991) are both steel grades. Both fall under the Stainless Steel category. ASTM A240/A240M S34700 is typically used for pressure vessels and general applications (plate, sheet and strip), while BS 970 (Part 3) 321S31 is commonly used for bright cold finished bars (cold drawn, turned or precision ground) for general engineering purposes, in straight lengths; austenitic stainless and heat resisting steel (table 18). ASTM A240/A240M S34700 is defined under ASTM International, originating from United States, while BS 970 (Part 3) 321S31 is defined under British Standards (BS), originating from United Kingdom.

As per chemical composition, ASTM A240/A240M S34700 vs BS 970 (Part 3) 321S31 is a 91.3% match. Mechanical property data is not available for both grades, so this factor could not be scored. Combined, this makes them a strong match overall at 91.3%.

Frequently Compared With ASTM A240/A240M S34700:
EN 10088-1 1.4301 ASTM A959 .- EN 10088-1 1.4006 IS 1570 (Part 7) 12Cr12MoH IS 1570 (Part 7) 12Cr12Ni2Mo GB/T 3280 06Cr19Ni10 GOST 5632 06Kh23N28 GOST 5632 08X18H10 EN 10088-1 1.4401 EN 10088-1 1.4845 IS 1570 (Part 7) 11Cr17Ni13W3TiH IS 1570 (Part 7) 12Cr12MoVH
Match Breakdown
CHEMISTRY MATCH
91.3%
MECHANICAL MATCH
No shared data
OVERALL
91.3%
Specifications
Property ASTM A240/A240M S34700 BS 970 (Part 3) 321S31
Standard ASTM A240/A240M:2025 BS 970 (Part 3):1991
Category Stainless Steel Stainless Steel
C (%) <=0.08 <=0.08
Mn (%) <=2.00 <=2.0
P (%) <=0.045 <=0.045
S (%) <=0.030 <=0.030
Si (%) <=0.75 <=1.0
Cr (%) 17.0-19.0 17.0-19.0
Ni (%) 9.0-13.0 9.0-12.0
Nb (%) <=1.00 Not specified
Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Mechanical Properties
Property ASTM A240/A240M S34700 BS 970 (Part 3) 321S31
Tensile Strength >=515 MPa Not specified
Yield Strength >=205 MPa Not specified
Elongation >=40% Not specified
Hardness <=201 HB Not specified
Condition Plate, sheet and strip; yield by 0.2 percent offset Not specified
Typical Applications
ASTM A240/A240M S34700
Pressure vessels and general applications (plate, sheet and strip)
BS 970 (Part 3) 321S31
Bright cold finished bars (cold drawn, turned or precision ground) for general engineering purposes, in straight lengths; austenitic stainless and heat resisting steel (Table 18)
Key Differences
Can ASTM A240/A240M S34700 Be Substituted With BS 970 (Part 3) 321S31?
ASTM A240/A240M S34700 and BS 970 (Part 3) 321S31 overlap closely enough on chemistry and mechanical properties that BS 970 (Part 3) 321S31 is often considered as a substitute for ASTM A240/A240M S34700 in many applications. Always confirm the specific property range your application needs before substituting, and check with your supplier's mill certificate.
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ASTM A240/A240M S34700
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BS 970 (Part 3) 321S31
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Frequently Asked Questions
What is the difference between ASTM A240/A240M S34700 and BS 970 (Part 3) 321S31?
ASTM A240/A240M S34700 specifies Nb which is not specified for BS 970 (Part 3) 321S31.
Can ASTM A240/A240M S34700 be substituted with BS 970 (Part 3) 321S31?
ASTM A240/A240M S34700 and BS 970 (Part 3) 321S31 overlap closely enough on chemistry and mechanical properties that BS 970 (Part 3) 321S31 is often considered as a substitute for ASTM A240/A240M S34700 in many applications. Always confirm the specific property range your application needs before substituting, and check with your supplier's mill certificate.