Strong Match — 86.3% match
based on chemical composition and mechanical property overlap.
ASTM A240/A240M S43100 (ASTM A240/A240M:2025) and BS 970 (Part 3) 431S29 (BS 970 (Part 3):1991) are both steel grades.
Both fall under the Stainless Steel category.
ASTM A240/A240M S43100 is typically used for pressure vessels and general applications (plate, sheet and strip), while BS 970 (Part 3) 431S29 is commonly used for bright cold finished bars (cold drawn, turned or precision ground) for general engineering purposes, in straight lengths; martensitic stainless steel (table 17).
ASTM A240/A240M S43100 is defined under ASTM International, originating from United States, while BS 970 (Part 3) 431S29 is defined under British Standards (BS), originating from United Kingdom.
As per chemical composition, ASTM A240/A240M S43100 vs BS 970 (Part 3) 431S29 is a 86.3% 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 86.3%.
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 S43100
BS 970 (Part 3) 431S29
Hardness
<=285 HB
Not specified
Condition
Plate, sheet and strip; yield by 0.2 percent offset
Not specified
Typical Applications
ASTM A240/A240M S43100
Pressure vessels and general applications (plate, sheet and strip)
BS 970 (Part 3) 431S29
Bright cold finished bars (cold drawn, turned or precision ground) for general engineering purposes, in straight lengths; martensitic stainless steel (Table 17)
Can ASTM A240/A240M S43100 Be Substituted With BS 970 (Part 3) 431S29?
ASTM A240/A240M S43100 and BS 970 (Part 3) 431S29 overlap closely enough on chemistry and mechanical properties that BS 970 (Part 3) 431S29 is often considered as a substitute for ASTM A240/A240M S43100 in many applications. Always confirm the specific property range your application needs before substituting, and check with your supplier's mill certificate.
What is the difference between ASTM A240/A240M S43100 and BS 970 (Part 3) 431S29?
Both grades share a similar composition profile; see the specification table above for the exact chemistry and mechanical property values.
Can ASTM A240/A240M S43100 be substituted with BS 970 (Part 3) 431S29?
ASTM A240/A240M S43100 and BS 970 (Part 3) 431S29 overlap closely enough on chemistry and mechanical properties that BS 970 (Part 3) 431S29 is often considered as a substitute for ASTM A240/A240M S43100 in many applications. Always confirm the specific property range your application needs before substituting, and check with your supplier's mill certificate.