EN19 (42CrMo4) Forgings
EN19 — internationally 42CrMo4 — is the workhorse alloy steel for loaded forgings. Chromium and molybdenum give it the hardenability to develop uniform properties deep into a thick section, which plain carbon steel simply cannot do.
- Carbon
- 0.36 – 0.44%
- Chromium
- 0.90 – 1.20%
- Molybdenum
- 0.15 – 0.30%
- Tensile (Q&T)
- 850 – 1000 MPa
- Hardness (Q&T)
- 280 – 320 BHN
- Equivalent
- AISI 4140, 42CrMo4, SCM440
EN19 (42CrMo4) Forgings at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- Carbon: 0.36 – 0.44%
- Chromium: 0.90 – 1.20%
- Molybdenum: 0.15 – 0.30%
- Tensile (Q&T): 850 – 1000 MPa
- Hardness (Q&T): 280 – 320 BHN
- Equivalent: AISI 4140, 42CrMo4, SCM440
Why Hardenability Matters
On a 100 mm shaft, EN8 hardens only in an outer skin while the core stays soft. EN19's chromium and molybdenum let the whole section transform, so strength quoted on the certificate is strength the core actually has.
- Deep hardening through thick sections
- Uniform core and surface properties
- High fatigue strength
- Good toughness at high hardness
Typical Heat Treatment
Quench and temper to 280–320 BHN for most drivetrain and machinery work; tempering temperature is set to land inside the customer's hardness band, with results verified on every batch.
Applications
Crankshafts, connecting rods, axle shafts, steering knuckles, gears, high-tensile bolts, hydraulic rods, mining pins and any component where fatigue governs the design.
EN19 Chemical Composition and Mechanical Properties
EN19 is a chromium-molybdenum low alloy steel, designated 709M40 in BS 970 and 42CrMo4 (material number 1.7225) in European practice, with AISI 4140 and JIS SCM440 as close counterparts. Chromium and molybdenum give it the hardenability that plain carbon steel lacks, so strength develops through the section rather than only at the surface. Note that 709M40 and 42CrMo4 specify slightly different molybdenum ranges.
| Property | Typical value |
|---|---|
| Carbon | 0.36 – 0.45% |
| Manganese | 0.60 – 1.00% |
| Chromium | 0.90 – 1.20% |
| Molybdenum | 0.15 – 0.35% (varies by standard) |
| Tensile strength, quenched and tempered | 850 – 1,000 MPa in moderate sections |
| Hardness, quenched and tempered | ≈ 280 – 320 HB |
| Nitrided surface | Very hard, shallow case |
| Quench medium | Oil or polymer, not water |
How Section Size Changes EN19's Properties
A steel's strength is not a single number — it falls as section size rises, because thick parts cool more slowly when quenched. EN 10083 tabulates this for 42CrMo4, and the pattern is what makes the grade valuable: it keeps delivering useful strength in sections where carbon steel has stopped responding at the core.
| Diameter | Tensile strength |
|---|---|
| Up to 16 mm | 1,100 – 1,300 MPa |
| 16 – 40 mm | 1,000 – 1,200 MPa |
| 40 – 100 mm | 900 – 1,100 MPa |
| 100 – 160 mm | 800 – 950 MPa |
| 160 – 250 mm | 750 – 900 MPa |
Heat Treating and Welding EN19
EN19 is normally oil or polymer quenched from about 820–860°C and tempered between roughly 540°C and 680°C, with the tempering temperature chosen to land inside the specified hardness band. Because its hardenability is high, a severe water quench is unnecessary and only raises distortion and cracking risk. The grade also responds well to induction hardening and to nitriding, which produces a very hard, shallow case with little distortion on finished parts. Welding is difficult: preheat, controlled interpass temperature and post-weld heat treatment are all required, so designs should avoid welding EN19 where possible. See can forgings be welded.
People also ask
What hardness does EN19 reach?
280 to 320 BHN quenched and tempered for most applications, with higher hardness achievable at lower tempering temperatures at some cost in toughness.
Is EN19 the same as 42CrMo4 and AISI 4140?
Effectively yes — they are the same chromium-molybdenum alloy steel designated under British, European and American standards respectively.
Topics covered on this page
- EN19 forging manufacturer India
- 42CrMo4 forged components
- alloy steel forging Rajkot
- EN19 forging supplier Gujarat
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
Is EN19 the same as 42CrMo4?
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Yes, EN19, 42CrMo4, AISI 4140 and SCM440 are effectively the same chromium-molybdenum alloy steel across different standards.
What hardness can EN19 reach?
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Quenched and tempered it commonly runs 280–320 BHN; higher hardness is achievable with lower tempering, at some cost in toughness.
Why choose EN19 over EN8?
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For thick sections, higher strength requirements and fatigue-critical parts, where EN8's shallow hardenability leaves a soft core.
Do you stock EN19?
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We procure EN19 against mill test certificates and spectro-verify every heat lot before production.