Post Stock Login Register

UNI 7845 42CrMo4 vs BS 970 (Part 3) 709M40

Strong Match — 85.3% match based on chemical composition and mechanical property overlap.

UNI 7845 42CrMo4 (UNI 7845:1978) and BS 970 (Part 3) 709M40 (BS 970 (Part 3):1991) are both steel grades. Both fall under the Alloy Steel category. UNI 7845 42CrMo4 is typically used for shafts,gears,axles,studs,forgings,machine components,automotive parts,hydraulic parts, while BS 970 (Part 3) 709M40 is commonly 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). UNI 7845 42CrMo4 is defined under Ente Nazionale Italiano di Unificazione (UNI), originating from Italy, while BS 970 (Part 3) 709M40 is defined under British Standards (BS), originating from United Kingdom.

As per chemical composition, UNI 7845 42CrMo4 vs BS 970 (Part 3) 709M40 is a 85.3% 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 85.3%.

Frequently Compared With UNI 7845 42CrMo4:
NF A35-565 100C6 UNI 11234 100Cr6 GOST 4543 12HN3A IS 1570 (Part 4) 103Cr6 IS 4367 07Cr4Mo6 IS 4367 10Cr9Mo10 IS 1570 (Part 4) 105Cr5 IS 1570 (Part 4) 10Mo6 IS 1570 (Part 4) 103Cr4 IS 1570 (Part 7) 10Cr36Mo10H IS 1570 (Part 4) 07Cr4Mo6 IS 1570 (Part 4) 10Cr20Mo6
Match Breakdown
CHEMISTRY MATCH
85.3%
MECHANICAL MATCH
No shared data
OVERALL
85.3%
Specifications
Property UNI 7845 42CrMo4 BS 970 (Part 3) 709M40
Standard UNI 7845:1978 BS 970 (Part 3):1991
Category Alloy Steel Alloy Steel
C (%) 0.38-0.45 0.36-0.44
Si (%) <=0.40 0.10-0.40
Mn (%) 0.60-0.90 0.70-1.00
P (%) <=0.025 <=0.035
S (%) <=0.035 <=0.040
Cr (%) 0.90-1.20 0.90-1.20
Mo (%) 0.15-0.30 0.25-0.35
Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Mechanical Properties
Property UNI 7845 42CrMo4 BS 970 (Part 3) 709M40
Tensile Strength 900-1100 MPa Not specified
Yield Strength 700-900 MPa Not specified
Elongation 11-16 % Not specified
Hardness 248-320 HB Not specified
Typical Applications
UNI 7845 42CrMo4
shafts,gears,axles,studs,forgings,machine components,automotive parts,hydraulic parts
BS 970 (Part 3) 709M40
Bright cold finished bars (cold drawn, turned or precision ground) for general engineering purposes, in straight lengths; alloy direct hardening steel (Table 16)
Can UNI 7845 42CrMo4 Be Substituted With BS 970 (Part 3) 709M40?
UNI 7845 42CrMo4 and BS 970 (Part 3) 709M40 overlap closely enough on chemistry and mechanical properties that BS 970 (Part 3) 709M40 is often considered as a substitute for UNI 7845 42CrMo4 in many applications. Always confirm the specific property range your application needs before substituting, and check with your supplier's mill certificate.
Forms & Sizes Available on M-EX
UNI 7845 42CrMo4
Round Bar → (2 listings)
Diameter: 50–50 mm (1.97–1.97 in)
Length: 5000–6300 mm (196.85–248.03 in)
BS 970 (Part 3) 709M40
No active listings currently.
On M-EX Right Now
UNI 7845 42CrMo4
2 active listings and RFQs →
BS 970 (Part 3) 709M40
0 active listings and RFQs →
Frequently Asked Questions
What is the difference between UNI 7845 42CrMo4 and BS 970 (Part 3) 709M40?
Both grades share a similar composition profile; see the specification table above for the exact chemistry and mechanical property values.
Can UNI 7845 42CrMo4 be substituted with BS 970 (Part 3) 709M40?
UNI 7845 42CrMo4 and BS 970 (Part 3) 709M40 overlap closely enough on chemistry and mechanical properties that BS 970 (Part 3) 709M40 is often considered as a substitute for UNI 7845 42CrMo4 in many applications. Always confirm the specific property range your application needs before substituting, and check with your supplier's mill certificate.