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BS 970 EN24 vs SAE J404 4340

Close Alternative — 70.6% match based on chemical composition and mechanical property overlap.

BS 970 EN24 (BS 970:1955) and SAE J404 4340 (SAE J404:2009) are both steel grades. Both fall under the Alloy Steel category. BS 970 EN24 is typically used for heavy duty gears, shafts, connecting rods, while SAE J404 4340 is commonly used for aircraft parts, heavy duty gears, crankshafts. BS 970 EN24 is defined under British Standards (BS), originating from United Kingdom, while SAE J404 4340 is defined under SAE International, originating from United States.

As per chemical composition, BS 970 EN24 vs SAE J404 4340 is a 70.6% match. Mechanical property data is not available for both grades, so this factor could not be scored. Combined, this makes them a close alternative overall at 70.6%.

Frequently Compared With BS 970 EN24:
GOST 4543 12HN3A NF A35-565 100C6 UNI 11234 100Cr6 GB/T 3077 12Cr2Ni4A IS 1570 (Part 4) 105Cr5 IS 4367 07Cr4Mo6 IS 1570 (Part 4) 103Cr4 IS 1570 (Part 4) 10Cr20Mo6 IS 1570 (Part 7) 10Cr36Mo10H IS 1570 (Part 4) 07Cr4Mo6 IS 4367 10Cr9Mo10 IS 1570 (Part 4) 103Cr6
Match Breakdown
CHEMISTRY MATCH
70.6%
MECHANICAL MATCH
No shared data
OVERALL
70.6%
Specifications
Property BS 970 EN24 SAE J404 4340
Standard BS 970:1955 SAE J404:2009
Category Alloy Steel Alloy Steel
C (%) 0.35-0.45 0.38-0.43
Si (%) 0.10-0.35 0.15-0.35
Mn (%) 0.45-0.70 0.60-0.80
Ni (%) 1.30-1.80 1.65-2.00
Cr (%) 0.90-1.40 0.70-0.90
Mo (%) 0.20-0.35 0.20-0.30
S (%) <=0.050 <=0.040
P (%) <=0.050 <=0.030
Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Mechanical Properties
Property BS 970 EN24 SAE J404 4340
Tensile Strength ≥772 MPa (50 tons/sq in, converted) Not specified
Yield Strength ≥587 MPa (38 tons/sq in, converted) Not specified
Elongation ≥20% Not specified
Hardness 223-277 HB Not specified
Condition Hardened and tempered S, ruling section 6 in (lowest-strength condition of the standard) Not specified
Typical Applications
BS 970 EN24
Heavy duty gears, shafts, connecting rods
SAE J404 4340
Aircraft parts, heavy duty gears, crankshafts
Can BS 970 EN24 Be Substituted With SAE J404 4340?
BS 970 EN24 and SAE J404 4340 are a close alternative rather than a direct substitute. Some properties overlap well, but check the specific chemistry and mechanical rows above against your application's requirements before treating them as interchangeable.
Forms & Sizes Available on M-EX
BS 970 EN24
Round Bar → (26 listings)
Diameter: 50–130 mm (1.97–5.12 in)
Length: 4800–7000 mm (188.98–275.59 in)
Flat Bar → (6 listings)
Thickness: 25–40 mm (0.98–1.57 in)
Width: 200–200 mm (7.87–7.87 in)
Length: 2500–3900 mm (98.43–153.54 in)
Hex Bar → (4 listings)
Across Flats: 45–50 mm (1.77–1.97 in)
Length: 2500–3900 mm (98.43–153.54 in)
SAE J404 4340
Round Bar → (25 listings)
Diameter: 50–100 mm (1.97–3.94 in)
Length: 3800–7000 mm (149.61–275.59 in)
Forging → (4 listings)
Diameter: 150–200 mm (5.91–7.87 in)
Length: 500–1500 mm (19.69–59.06 in)
Flat Bar → (3 listings)
Thickness: 30–30 mm (1.18–1.18 in)
Width: 120–120 mm (4.72–4.72 in)
Length: 2500–3000 mm (98.43–118.11 in)
On M-EX Right Now
BS 970 EN24
36 active listings and RFQs →
SAE J404 4340
32 active listings and RFQs →
Frequently Asked Questions
What is the difference between BS 970 EN24 and SAE J404 4340?
Both grades share a similar composition profile; see the specification table above for the exact chemistry and mechanical property values.
Can BS 970 EN24 be substituted with SAE J404 4340?
BS 970 EN24 and SAE J404 4340 are a close alternative rather than a direct substitute. Some properties overlap well, but check the specific chemistry and mechanical rows above against your application's requirements before treating them as interchangeable.