EN24 (817M40) Forgings
EN24 adds nickel to the chromium-molybdenum recipe, buying toughness at high strength levels that EN19 cannot quite reach. It is the grade specified when a part must be both very strong and resistant to shock.
- Carbon
- 0.36 – 0.44%
- Nickel
- 1.30 – 1.80%
- Chromium
- 1.00 – 1.40%
- Tensile (Q&T)
- 925 – 1075 MPa
- Hardness (Q&T)
- 300 – 350 BHN
- Equivalent
- AISI 4340, 817M40, SNCM439
EN24 (817M40) Forgings at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- Carbon: 0.36 – 0.44%
- Nickel: 1.30 – 1.80%
- Chromium: 1.00 – 1.40%
- Tensile (Q&T): 925 – 1075 MPa
- Hardness (Q&T): 300 – 350 BHN
- Equivalent: AISI 4340, 817M40, SNCM439
Nickel's Contribution
Nickel refines grain and improves low-temperature toughness, so EN24 keeps its impact resistance at hardness levels where EN19 begins to turn brittle. That combination is what heavy gearboxes and drilling components need.
- Excellent toughness at high strength
- Deep, uniform hardenability
- Good impact resistance
- Suited to large sections
Heat Treatment Practice
Oil quench and temper to 300–350 BHN typically. Because hardenability is high, even sections above 150 mm develop consistent properties from surface to core.
Where It Earns Its Cost
Heavy-duty gears, large crankshafts, drilling components, aircraft-adjacent ground equipment, high-load pins and shafts. EN24 costs more than EN19, so it is specified where the load case actually demands it.
People also ask
When is EN24 worth the extra cost over EN19?
On very large sections above roughly 150 mm, under severe shock loading, or where low-temperature toughness is specified.
Can EN24 be welded?
Only with preheat and post-weld heat treatment. Design to avoid welding this grade wherever possible.
Topics covered on this page
- EN24 forging manufacturer India
- 817M40 forged components
- nickel chrome moly forging
- EN24 forging supplier Rajkot
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
What is EN24 equivalent to?
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AISI 4340, BS 817M40 and JIS SNCM439 are the standard equivalents.
EN24 or EN19 — how do I choose?
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EN24 when sections are very large or shock loading is severe; EN19 when the load case is well within its capability, since it costs less.
What section size can EN24 harden through?
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Its hardenability supports uniform properties in sections above 150 mm, which is why it is specified for large shafts and gears.
Is EN24 weldable?
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It is difficult to weld and requires preheat and post-weld heat treatment. Design to avoid welding EN24 wherever possible.