Strong Match — 89.2% match
based on chemical composition and mechanical property overlap.
BS 970 (Part 3) 708M40 (BS 970 (Part 3):1991) and SAE J404 4140 (SAE J404:2009) 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 SAE J404 4140 is commonly used for gears, shafts, dies, bolts, crankshafts.
BS 970 (Part 3) 708M40 is defined under British Standards (BS), originating from United Kingdom, while SAE J404 4140 is defined under SAE International, originating from United States.
As per chemical composition, BS 970 (Part 3) 708M40 vs SAE J404 4140 is a 89.2% 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 89.2%.
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)
SAE J404 4140
Gears, shafts, dies, bolts, crankshafts
Can BS 970 (Part 3) 708M40 Be Substituted With SAE J404 4140?
BS 970 (Part 3) 708M40 and SAE J404 4140 overlap closely enough on chemistry and mechanical properties that SAE J404 4140 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 SAE J404 4140?
Both grades share a similar composition profile; see the specification table above for the exact chemistry and mechanical property values.
Can BS 970 (Part 3) 708M40 be substituted with SAE J404 4140?
BS 970 (Part 3) 708M40 and SAE J404 4140 overlap closely enough on chemistry and mechanical properties that SAE J404 4140 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.