EN19 vs EN24
EN19 and EN24 are both deep-hardening alloy steels, and EN24 is not simply the better one. Its nickel buys toughness at high hardness — valuable when shock loading or very large sections are involved, and wasted money when they are not.
EN19 is a chromium-molybdenum steel; EN24 adds nickel for greater toughness at high hardness and hardenability in very large sections. EN24 is the better choice above roughly 150 mm section or under severe shock loading, and unnecessary cost below that.
- EN19 alloying
- Cr-Mo
- EN24 alloying
- Ni-Cr-Mo
- EN19 hardness (Q&T)
- 280 – 320 BHN
- EN24 hardness (Q&T)
- 300 – 350 BHN
- EN19 section limit
- ≈150 mm
- EN24 section limit
- Beyond 150 mm
EN19 vs EN24 at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- EN19 alloying: Cr-Mo
- EN24 alloying: Ni-Cr-Mo
- EN19 hardness (Q&T): 280 – 320 BHN
- EN24 hardness (Q&T): 300 – 350 BHN
- EN19 section limit: ≈150 mm
- EN24 section limit: Beyond 150 mm
| Factor | EN19 (42CrMo4) | EN24 (34CrNiMo6) |
|---|---|---|
| Alloying | Cr-Mo | Ni-Cr-Mo |
| Toughness at high hardness | Good | Excellent |
| Uniform hardening limit | Up to ~150 mm | Beyond 150 mm |
| Typical Q&T hardness | 280–320 BHN | 300–350 BHN |
| Relative cost | Baseline | Noticeably higher |
| Choose it for | Most loaded shafts and gears | Large crankshafts, heavy gearboxes, shock duty |
What Nickel Actually Buys
Nickel refines grain and improves toughness, particularly at low temperature and at high hardness. Where EN19 starts to turn brittle as hardness climbs, EN24 keeps useful impact resistance — the property that matters when a part is shock loaded rather than steadily stressed.
- Better toughness at equal hardness
- Improved low-temperature performance
- Hardens uniformly in very large sections
- Costs meaningfully more
Section Size Decides Again
EN19 handles most sections well. Beyond roughly 150 mm, its hardenability is stretched and core properties fall away; EN24 keeps developing uniform properties in genuinely large forgings, which is why heavy gearboxes and large crankshafts specify it.
Where the Upgrade Is Wasted
On a 60 mm shaft at moderate load, EN24 delivers nothing EN19 does not, at a real cost premium and with worse weldability. We regularly recommend customers step back down to EN19 after reviewing the actual load case.
Topics covered on this page
- EN19 vs EN24
- 42CrMo4 vs 34CrNiMo6
- EN24 or EN19 which is stronger
- difference EN19 EN24
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
Is EN24 always better than EN19?
+
No. It is tougher at high hardness and hardens larger sections, but on moderate sections at moderate load it adds cost without adding capability.
What is EN24 equivalent to?
+
AISI 4340, BS 817M40 and JIS SNCM439.
Which is more weldable?
+
Neither welds easily; EN24 is the harder of the two, requiring preheat and post-weld heat treatment.
When should I upgrade to EN24?
+
Very large sections, severe shock loading, or low-temperature toughness requirements.