Steel Grade Datasheet
42CrMo4/ 1.7225 / 4140
Chrome-Molybdenum Q&T Steel
What is 42CrMo4 (4140) steel?
42CrMo4 (Werkstoff No. 1.7225, equivalent to AISI 4140) is a chromium-molybdenum alloy steel for quenching and tempering per EN 10083-3. It contains 0.38–0.45% carbon, 0.90–1.20% chromium and 0.15–0.30% molybdenum. In the quenched and tempered (+QT) condition it delivers a 650–900 MPa yield strength and 900–1300 MPa tensile strength depending on section size. It is the default choice for shafts, gears and high-strength bolting that demand fatigue strength and toughness.
Chemical Composition
Cast analysis, % by weight (per the applicable EN standard)
| Element | Range (%) |
|---|---|
| C | 0.38–0.45 |
| Si | ≤ 0.40 |
| Mn | 0.60–0.90 |
| P | ≤ 0.025 |
| S | ≤ 0.035 |
| Cr | 0.90–1.20 |
| Mo | 0.15–0.30 |
Mechanical Properties (+QT)
Values depend on ruling section / thickness (d).
| Section (mm) | Yield Re min (MPa) | Tensile Rm (MPa) | Elongation A min (%) |
|---|---|---|---|
| d ≤ 16 | 900 | 1100–1300 | 10 |
| 16 < d ≤ 40 | 750 | 1000–1200 | 11 |
| 40 < d ≤ 100 | 650 | 900–1100 | 12 |
| 100 < d ≤ 160 | 550 | 800–950 | 13 |
| 160 < d ≤ 250 | 500 | 750–900 | 14 |
Hardness: +A (annealed): ≤ 241 HB · +QT: typically 260–320 HB · Induction-hardened surface: 50–55 HRC
42CrMo4 / AISI 4140 properties and use
International Equivalents
Values marked ≈ are nearest matches, not exact equivalents. Always confirm against the governing standard.
| System | Grade |
|---|---|
| EN | 42CrMo4 |
| W.-Nr. (DIN) | 1.7225 |
| AISI/SAE | 4140 |
| ASTM | A29 / A322 (4140) |
| JIS | SCM440 |
| GOST | ≈ 38ХМ (38KhM) |
| BS 970 (UK) | 708M40 (EN19) |
| GB (China) | 42CrMo |
Detailed comparison: 42CrMo4 vs 4140
Applications
- Gears, shafts and axles
- Crankshafts and eccentric shafts
- High-strength bolting, property classes 8.8–12.9
- Hydraulic piston rods (pre-chrome blanks)
- Tool holders and machine components
- Oil & gas forged components
Available Product Forms
Frequently Asked Questions
Can 42CrMo4 / 4140 be welded?+
Only with precautions. Its high carbon equivalent creates cold-cracking risk, so 200–300 °C preheat, low-hydrogen consumables and post-weld stress relief (around 550–650 °C) are required. For weld-heavy fabrications, structural grades such as S355J2 are the better choice.
What is the hardness of 42CrMo4?+
In the quenched and tempered (+QT) delivery condition it is typically 260–320 HB (about 26–34 HRC). As-quenched it reaches 54–59 HRC but is brittle; working hardness is set by the tempering temperature. Induction hardening produces 50–55 HRC at the surface.
What does +QT mean?+
QT stands for quenched and tempered. For 42CrMo4 the typical process is oil quenching from 840–880 °C followed by tempering at 540–680 °C, giving high strength combined with toughness. Bars are most commonly ordered in this condition.
Are 42CrMo4 and AISI 4140 the same steel?+
For practical purposes yes — 42CrMo4 is the European (EN) designation and 4140 the American (AISI/SAE) one, and they are used interchangeably. Minor range differences exist: 4140 allows slightly more manganese and a slightly narrower carbon window. For critical work, follow the ranges of the standard governing the order.
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References & Standards
Values on this page are reference data compiled from the applicable EN standard; certified material properties are defined by the mill test certificate (EN 10204 3.1).