Metal Materials
EN 100CrMo7 Bearing Steel: Need to Know About Properties and Uses
When your application involves heavy-duty bearings, mining equipment, or industrial machinery that operates under high loads and elevated temperatures, you need a bearing steel that delivers exceptional fatigue resistance and toughness. EN 100CrMo7 bearing steel—a European-standard alloy with added molybdenum—offers distinct advantages over standard bearing steels.
Key takeaways
- EN 100CrMo7 achieves its superior properties through its chromium-molybdenum chemistry.
- This material is specified for bearing applications that operate under high loads, elevated temperatures, or harsh conditions.
- Producing EN 100CrMo7 requires precise control over chemistry and heat treatment to achieve its superior properties.
- Understanding the trade-offs between EN 100CrMo7 and alternative materials helps in making an informed selection.
What Makes EN 100CrMo7 Superior for Demanding Applications?
EN 100CrMo7 achieves its superior properties through its chromium-molybdenum chemistry. The molybdenum addition provides enhanced hardenability, high-temperature strength, and improved toughness compared to standard bearing steels.
The Chemistry Behind the Performance
The chemical composition of EN 100CrMo7 is specified in EN 10083-3. The molybdenum addition is the key differentiator from standard bearing steels.
| Element | Content Range (%) | Why It Matters |
|---|---|---|
| Carbon (C) | 0.95 – 1.05 | Provides hardness and forms carbides for wear resistance. |
| Chromium (Cr) | 1.50 – 1.80 | Enhances hardenability and fatigue strength. Forms chromium carbides. |
| Molybdenum (Mo) | 0.15 – 0.25 | The critical addition. Boosts high-temperature strength and toughness. Improves hardenability. |
| Manganese (Mn) | 0.25 – 0.45 | Increases tensile strength and workability. |
| Silicon (Si) | 0.15 – 0.35 | Aids deoxidation during steelmaking. |
| Nickel (Ni) | ≤ 0.30 | Trace amount for minor ductility improvement. |
| Sulfur (S) / Phosphorus (P) | ≤ 0.025 | Kept low to prevent brittleness and maintain toughness. |
Key Insight: The molybdenum addition of 0.15–0.25% is what sets EN 100CrMo7 apart from 100Cr6. Molybdenum increases the steel’s resistance to tempering, allowing it to maintain hardness at higher temperatures. It also improves hardenability, ensuring uniform properties in larger sections.
Mechanical Properties That Matter
EN 100CrMo7’s mechanical properties are achieved through quenching and tempering. The material achieves high hardness while maintaining good toughness.
| Property | Typical Value | Significance |
|---|---|---|
| Hardness | 61 – 65 HRC | Provides excellent wear resistance for rolling and sliding contact. |
| Tensile Strength | ≥ 2,100 MPa | Handles high loads without failure. |
| Yield Strength | ≥ 1,900 MPa | Resists permanent deformation under heavy loads. |
| Elongation | ≤ 7% | Limited ductility is typical for high-hardness bearing steels. |
| Impact Toughness | ≥ 18 J | Provides enough toughness to resist shock loading. |
| Fatigue Limit | ≥ 1,000 MPa | Withstands millions of load cycles. Superior to standard bearing steels. |
Case Study: A mining company faced frequent bearing failures in conveyor belt systems. Bearings made from standard 100Cr6 steel lasted only three months due to high impact and dust. They switched to EN 100CrMo7 bearings with nitriding surface treatment. Bearing life extended to 12 months—a 300% improvement. Maintenance downtime was reduced by 75%, and replacement costs were cut by 60%.
Where Does EN 100CrMo7 Deliver the Most Value?
This material is specified for bearing applications that operate under high loads, elevated temperatures, or harsh conditions.
Mining and Heavy Equipment
Mining equipment requires bearings that can withstand high impact loads, dust, and continuous operation.
- Conveyor belt bearings: Bearings that support heavy loads and operate continuously.
- Crusher bearings: Bearings that withstand high impact and vibration.
- Excavator bearings: Bearings in digging equipment that face shock loads.
- Shaker screen bearings: Bearings that handle high vibration and abrasive conditions.
Case Study: A mining operation used EN 100CrMo7 for bearings in crushers and conveyor systems. The molybdenum-enhanced steel provided the toughness needed to withstand impact loads and the wear resistance required for dusty conditions. Bearing life increased from 6 months to over 24 months.
Heavy-Duty Automotive
Heavy trucks and off-road vehicles require bearings that can handle high loads and elevated temperatures.
- Transmission bearings: Bearings that handle high torque and repeated stress.
- Wheel bearings: Bearings that support heavy vehicle loads.
- Engine bearings: Bearings that operate at elevated temperatures.
- Axle bearings: Bearings that withstand high radial and axial loads.
Industrial Machinery
Industrial equipment operating under continuous use benefits from EN 100CrMo7’s fatigue resistance.
- Gearbox bearings: Bearings that handle high torque and speed.
- Pump bearings: Bearings that operate under continuous load.
- Motor bearings: Bearings in large industrial motors that generate heat.
Case Study: A manufacturer of large industrial motors experienced bearing failures after 10,000 hours of operation due to high operating temperatures. They switched to EN 100CrMo7 bearings. The molybdenum addition provided the high-temperature strength needed, and bearing life increased to 25,000 hours. The company saved $200,000 annually in maintenance costs.
Aerospace and Precision Applications
Aerospace applications require bearings with exceptional reliability and dimensional stability.
- Engine accessory bearings: Bearings in aircraft engines that operate at high temperatures.
- Landing gear bearings: Bearings that withstand high loads during takeoff and landing.
- Instrument bearings: Precision bearings for flight control systems.
How Is EN 100CrMo7 Manufactured and Processed?
Producing EN 100CrMo7 requires precise control over chemistry and heat treatment to achieve its superior properties.
Steelmaking
EN 100CrMo7 is produced in an electric arc furnace (EAF) for small batches or a basic oxygen furnace (BOF) for large-scale production. Molybdenum is added during melting to achieve the target 0.15–0.25% range.
Rolling and Forging
- Hot rolling: Heated to 1,100–1,200°C and rolled into bars, billets, and wire.
- Cold rolling: For precision components requiring smooth surfaces and tight tolerances.
- Precision forging: For complex shapes such as large bearing rings, forging improves grain structure and enhances mechanical properties.
Heat Treatment
Heat treatment is critical for achieving EN 100CrMo7’s properties.
- Quenching: Heat to 830–870°C, then rapidly cool in oil. This hardens the steel to 62–65 HRC.
- Tempering: Reheat to 160–220°C to reduce brittleness while maintaining high hardness (61–65 HRC).
- Carburizing (optional): For parts requiring a hard outer layer such as gear teeth, carburizing adds carbon to the surface.
Machining and Finishing
- Turning: For cylindrical parts such as bearing races.
- Grinding: For ultra-smooth surfaces. Essential for bearing performance. Surface finishes as smooth as Ra 0.1 μm are achieved.
- Surface treatment: Nitriding adds a hard surface layer for additional wear resistance. Blackening provides minor rust protection.
How Does EN 100CrMo7 Compare to Other Bearing Steels?
Understanding the trade-offs between EN 100CrMo7 and alternative materials helps in making an informed selection.
| Material | Hardness (HRC) | Fatigue Limit (MPa) | High-Temp Strength | Relative Cost | Best For |
|---|---|---|---|---|---|
| EN 100CrMo7 | 61 – 65 | ≥ 1,000 | Excellent | 100% | Heavy-duty, high-temperature applications |
| 100Cr6 | 60 – 64 | ~800 | Good | 85% | General bearing applications |
| AISI 52100 | 60 – 64 | ~800 | Good | 85% | U.S. market equivalent to 100Cr6 |
| JIS SUJ2 | 60 – 64 | ~800 | Good | 85% | Japanese market standard |
| AISI 440C Stainless | 58 – 60 | ~600 | Moderate | 180% | Wet and corrosive environments |
| Silicon Nitride (Ceramic) | 75 – 80 | ~900 | Excellent | 500% | High-speed, high-temperature applications |
Key Insights:
- Compared to 100Cr6, EN 100CrMo7 offers higher fatigue strength (≥ 1,000 MPa vs. ~800 MPa) and better high-temperature performance for a 15% cost premium. For heavy-duty applications, this upgrade is essential.
- Compared to AISI 440C stainless steel, EN 100CrMo7 offers higher hardness and better fatigue strength at approximately half the cost. For corrosive environments, stainless steel or coated EN 100CrMo7 is recommended.
- Compared to ceramic bearings, EN 100CrMo7 is significantly less expensive and easier to manufacture. Ceramic is reserved for extreme high-speed or high-temperature applications.
How to write a spec that gets priced correctly
A drawing is a contract. If it leaves a number open, the shop fills that number in with its own default. The default is rarely the one you had in mind. Put these five lines on every RFQ and most of the back-and-forth disappears before it starts.
- Alloy designation and the standard behind it
- Temper or heat treatment condition
- Mechanical properties you actually need
- Mill certificate and traceability requirement
- Finish and the faces it applies to
The point is not paperwork. Each line removes a decision the shop would otherwise make for you. A complete RFQ comes back priced. An incomplete one comes back guessed.
What actually drives the price
Buyers usually push on material because it is the line they can see. In practice the material is rarely the biggest number on a quote. These five lines decide most of it:
- alloy grade and mill availability
- stock size versus finished size
- heat treatment and testing
- machinability
- certification
Ask for the quote split by line. A supplier who cannot break it down is guessing, and you will pay for the guess. The line you can usually renegotiate is the tolerance band, not the raw material.
Problems you will meet, and the fix
Every process has a failure mode it prefers. The same four show up again and again on this kind of work, and none of them are mysteries once you know what to look for.
- Substituting a similar grade without telling anyone
- Hardness that varies across a single bar
- Corrosion in a weld heat-affected zone
- Distortion after heat treatment on a thin part
Catch the fault on the first part, not the hundredth. A first-article check costs an hour. A bad batch costs the whole order. Write the check into the purchase order so nobody has to remember it.
What to check on the first article
The first article is the cheapest inspection you will ever buy. Use it properly and the rest of the run becomes boring, which is exactly what you want.
- Every dimension on the drawing, with the measured value written beside it.
- The material certificate, matched to the heat or lot number on the parts.
- The finish against the sample you approved, under the same light.
- Fit against the mating part, assembled rather than measured.
- Packaging, because parts that arrive damaged were never in tolerance.
Check in this order: datums, then mating features, then cosmetic faces. If the datums are wrong, every number after them is noise. Keep the report on file. When a problem shows up in month six, that document is the only thing that tells you what changed.
How to compare two quotes fairly
Two numbers are not comparable unless the scope matches. Line them up before you decide, because a low number with three gaps is not a low number.
Same drawing, same material, same finish, same inspection. Anything else is a different job wearing the same part number. Then look at what each quote leaves out. Freight, packaging, certificates and tooling are the usual gaps.
Ask each supplier to state their assumptions in writing. The one who does is usually the one who has run the process before.
Scaling from one part to a batch
The first part teaches you the process. The hundredth teaches you the process cost.
Watch three things as volume grows: setup amortisation, tool wear, and how much hand work the finish still needs. If the unit price barely moves between ten and a hundred, the cost sits in material or in hand work, not in setup. Ask which, because only one of them is negotiable.
Lead time behaves the same way. A one-off is scheduled around other jobs. A repeat order is scheduled around your forecast. Give the shop a forecast and the lead time gets shorter, not longer.
How to read a supplier's quote
A quote is a short document with a long shadow. Four things in it decide whether the job runs smoothly, and only one of them is the price.
- The scope line. It should name the process, the material and the finish, not just the part.
- The tolerance basis. General tolerance or the drawing, and which standard it follows.
- The exclusions. Tooling, freight, certificates and inspection are the usual omissions.
- The validity date. Material prices move, and an open-ended quote is a promise nobody can keep.
Read the exclusions before you read the total. A quote that leaves out tooling is not cheaper. It is a quote for a different job.
What to send with the first order
The first order sets the pattern for every order after it. Send a complete package once and the shop files it, and the second order takes a fraction of the time.
- A STEP or native model plus a PDF drawing carrying the same revision letter.
- The material callout by standard number, not by trade name.
- The finish and the exact faces it applies to.
- Any test the part must pass: fit, seal, drop, salt spray, dielectric.
- A contact who can answer a question inside one working day.
Then write down what was agreed. An email that confirms the material, the finish and the date is worth more than a longer purchase order that leaves them open.
What About Corrosion Resistance?
EN 100CrMo7 has moderate corrosion resistance. For dry indoor applications, no additional protection is needed. For wet or corrosive environments, surface treatment is required:
- Nitriding: Adds a hard surface layer and provides some corrosion resistance.
- Zinc plating: Provides corrosion protection for bearings in humid or wet environments.
- Blackening: Low-cost protection for minor rust prevention.
EN 100CrMo7 bearing steel is a premium material for the most demanding bearing applications. Its molybdenum addition provides superior hardenability, high-temperature strength, and enhanced toughness compared to standard bearing steels. For mining equipment, heavy-duty automotive components, industrial machinery, and aerospace applications, EN 100CrMo7 delivers the fatigue resistance, wear resistance, and reliability required for long service life under extreme conditions. When you need a bearing steel that can handle high loads, elevated temperatures, and repeated stress cycles, EN 100CrMo7 is a proven, trusted choice.
FAQ About EN 100CrMo7 Bearing Steel
Why is molybdenum added to EN 100CrMo7?
Molybdenum improves EN 100CrMo7’s high-temperature strength and toughness. It allows the steel to maintain hardness at elevated temperatures and enhances hardenability, ensuring uniform properties in larger sections. This makes it suitable for applications such as mining equipment and industrial motors that generate heat or face heavy impacts.
Can EN 100CrMo7 be used in corrosive environments?
EN 100CrMo7 has moderate corrosion resistance. For wet or corrosive environments such as marine or food processing applications, apply a surface treatment such as nitriding or zinc plating to prevent rust and extend service life. For continuous immersion in water or chemicals, stainless steel bearing grades are recommended.
How does EN 100CrMo7 compare to 100Cr6?
EN 100CrMo7 has added molybdenum (0.15–0.25%), which boosts fatigue resistance and high-temperature strength. EN 100CrMo7 is better suited for heavy-duty, high-stress applications such as mining equipment and heavy trucks. 100Cr6 is ideal for lighter-duty applications such as light machinery and small motors.
What surface treatments work best for EN 100CrMo7?
Nitriding adds a hard surface layer that enhances wear resistance and provides some corrosion protection. Zinc plating provides corrosion protection for wet environments. Blackening is a low-cost option for minor rust prevention. For bearing races and rolling elements, precision grinding to a smooth finish is essential for performance.
Our solution for EN 100CrMo7 Bearing Steel: Need
YiguProto runs metal sourcing and machining in house, from a single prototype to a production batch. We quote the process, the material and the finish as separate lines, so you can see where the money goes instead of arguing with one number.
Send a STEP file or a drawing and you get a DFM report in one to two business days. It flags the features that add cost and the features that will not hold tolerance on the process you picked.
Every order ships with an inspection report on the features you call out. If a part misses, we make it again. Ready to price a part? Start with a free quote and DFM review, or read more about our metal sourcing and machining. You can also talk to an engineer before you commit to a drawing.
FAQ about EN 100CrMo7 Bearing Steel: Need
What files do you need in order to quote?
A STEP file plus a PDF drawing that carries the same revision letter. The model carries the geometry and the drawing carries the intent. When the two disagree, the shop picks one, and it is never the one you meant.
What material should I specify?
Specify by standard, not by trade name. A trade name can change under you between two orders; a standard number cannot. Then add the one property that actually decides the part, whether that is strength, heat resistance or chemical exposure.
How much does EN 100CrMo7 Bearing Steel: Need cost?
Price comes from five lines: material, machine or tool time, setup, finishing and inspection. The material itself is usually the smallest of them. Send a drawing and we will split the quote so you can see which line is doing the damage.
How do I compare two quotes fairly?
Match the scope first: same drawing, same material, same finish, same inspection. Then read the exclusions. Freight, tooling and certificates are the usual gaps, and a low number with three gaps is not a low number.
What should I check before approving the parts?
Datums first, then the features that mate, then the cosmetic faces. Ask for a dimensional report, a material certificate and a finish sample. A part can be inside every tolerance and still not fit, so assemble one before you sign.
What is EN 100CrMo7 Bearing Steel: Need used for?
EN 100CrMo7 Bearing Steel: Need turns up wherever the part has to do a real job at a predictable cost: brackets, housings, fixtures, covers and the fittings that hold them together. The honest test is whether the properties match the load and the environment, not whether the material is fashionable.
The short version
EN 100CrMo7 Bearing Steel: Need rewards the buyer who reads the data sheet and the drawing together. Pick the option for the property that matters, not for the price per kilo.
Tighten only what mates. Test a sample before the run. Then let the process do the rest.