42CrMo4 vs 39NiCrMo3: Both mainstream QT steels — different alloy strategies
42CrMo4 vs 39NiCrMo3
Side-by-side chemical composition and mechanical property comparison.
Overview
42CrMo4
1.7225
High-strength quenched and tempered chromium-molybdenum steel. Widely used for shafts, gears, crankshafts, connecting rods, and high-strength bolts. Excellent hardenability and good fatigue resistance.
39NiCrMo3
1.6510
Nickel-chromium-molybdenum quench & temper steel. Similar to AISI 4340 but with lower Ni — more economical. Good hardenability for sections up to ~80mm. Excellent balance of strength, toughness, and fatigue resistance. High white-point sensitivity — hydrogen control required. Used for crankshafts, connecting rods, gear shafts, landing gear components, and heavy-duty machinery parts.
| 42CrMo4 | 39NiCrMo3 | |
|---|---|---|
| Material Number | 1.7225 | 1.6510 |
| Category | Alloy Steel | Alloy Steel |
| Standard | EN 10083-3 | EN 10083-3 |
Chemical composition (wt%)
| Element | 42CrMo4 | 39NiCrMo3 | Overlap |
|---|---|---|---|
| C | 0.38–0.45% | 0.35–0.43% | Partial |
| Si | 0–0.4% | 0–0.4% | OK |
| Mn | 0.6–0.9% | 0.5–0.8% | Partial |
| P | 0–0.025% | 0–0.025% | OK |
Mechanical properties
| Property | 42CrMo4 | 39NiCrMo3 | Unit |
|---|---|---|---|
| tensile_strength | 900–1100 | 900–1200 | MPa |
| yield_strength | ≥ 650 | 600–800 | MPa |
| elongation | ≥ 12 | 10–16 | % |
Compatibility Assessment
42CrMo4 uses Cr+Mo (no Ni) with higher Cr for wear resistance. 39NiCrMo3 uses Ni+Cr+Mo with lower Cr but added Ni for better toughness. Similar strength range. 42CrMo4 is more available and cheaper. 39NiCrMo3 is better for low-temperature applications.
Frequently Asked Questions
Is 42CrMo4 the same as 39NiCrMo3?
42CrMo4 and 39NiCrMo3 have a 70% composition overlap. Both mainstream QT steels — different alloy strategies
Can I replace 42CrMo4 with 39NiCrMo3?
In many cases, yes. The compositions overlap significantly (70%). However, always verify mechanical property requirements and heat treatment compatibility for your specific application.
What is the difference between 42CrMo4 and 39NiCrMo3?
The main differences are in the following elements: C, Mn, Cr. 42CrMo4 is a Alloy Steel grade, while 39NiCrMo3 is a Alloy Steel grade.
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Data provided for reference only. Always verify against the applicable specification for critical applications.
All data is for reference only. Equivalents indicate similarity, not identity. Always verify against the applicable specification for safety-critical applications. materialref.com accepts no liability for decisions based on this data.