Strong Match — 90.1% match
based on chemical composition and mechanical property overlap.
BS 970 (Part 3) 708M40 (BS 970 (Part 3):1991) and BS 970 (Part 1) 708A40 (BS 970 (Part 1):1983) are both steel grades.
Both fall under the Alloy Steel category.
BS 970 (Part 3) 708M40 is typically used for bright cold finished bars (cold drawn, turned or precision ground) for general engineering purposes, in straight lengths; alloy direct hardening steel (table 16), while BS 970 (Part 1) 708A40 is commonly used for through hardening steel for mechanical and allied engineering purposes; supplied in the hardened and tempered conditions of table 6..
BS 970 (Part 3) 708M40 is defined under British Standards (BS), originating from United Kingdom, while BS 970 (Part 1) 708A40 is defined under British Standards (BS), originating from United Kingdom.
As per chemical composition, BS 970 (Part 3) 708M40 vs BS 970 (Part 1) 708A40 is a 90.1% 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 90.1%.
Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Typical Applications
BS 970 (Part 3) 708M40
Bright cold finished bars (cold drawn, turned or precision ground) for general engineering purposes, in straight lengths; alloy direct hardening steel (Table 16)
BS 970 (Part 1) 708A40
Through hardening steel for mechanical and allied engineering purposes; supplied in the hardened and tempered conditions of Table 6.
Key Differences
BS 970 (Part 3) 708M40 specifies Si which is not specified for BS 970 (Part 1) 708A40.
Can BS 970 (Part 3) 708M40 Be Substituted With BS 970 (Part 1) 708A40?
BS 970 (Part 3) 708M40 and BS 970 (Part 1) 708A40 overlap closely enough on chemistry and mechanical properties that BS 970 (Part 1) 708A40 is often considered as a substitute for BS 970 (Part 3) 708M40 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 BS 970 (Part 3) 708M40 and BS 970 (Part 1) 708A40?
BS 970 (Part 3) 708M40 specifies Si which is not specified for BS 970 (Part 1) 708A40.
Can BS 970 (Part 3) 708M40 be substituted with BS 970 (Part 1) 708A40?
BS 970 (Part 3) 708M40 and BS 970 (Part 1) 708A40 overlap closely enough on chemistry and mechanical properties that BS 970 (Part 1) 708A40 is often considered as a substitute for BS 970 (Part 3) 708M40 in many applications. Always confirm the specific property range your application needs before substituting, and check with your supplier's mill certificate.