What Is the Yield Strength of 42CrMo4 Steel?
📑 Table of Contents
- 📌 What Is the Yield Strength of 42CrMo4 Steel?
- 📊 Yield Strength Values by Section Size
- ⚙️ Yield Strength vs. Tensile Strength
- 🔥 How Heat Treatment Changes Yield Strength
- 📏 Why Steel Thickness Matters
- 🔬 Chemical Composition and Strength
- 🏭 Applications That Depend on Yield Strength
- 🧾 How Buyers Should Verify 42CrMo4 Yield Strength
- 🔍 42CrMo4 vs. Similar Alloy Steel Grades
- 🏢 Company Advantages
- ❓ Frequently Asked Questions
📌 What Is the Yield Strength of 42CrMo4 Steel?
42CrMo4 yield strength is not one fixed value. It depends on the delivery condition, heat treatment, product form, and governing standard. For quenched and tempered (+QT) 42CrMo4 steel, commonly published EN 10083-3 reference values show minimum yield strengths ranging from approximately 900 MPa for small round sections to 500 MPa for round sections measuring 160–250 mm in diameter. The applicable limits for flat products follow thickness-based classes and should not be assumed to match the round-bar values exactly.
42CrMo4, also known as material number 1.7225, is a chromium-molybdenum alloy steel widely used for components that require a combination of strength, toughness, and hardenability. Engineers often specify it for shafts, gears, pins, heavy machinery components, and other parts that experience torsion, cyclic loads, or substantial mechanical stress.
For procurement teams, the most important question is not simply how strong 42CrMo4 can become. Instead, buyers should establish the minimum yield strength required for the actual component and confirm that the ordered product can meet it in its specified delivery condition.
What does yield strength mean?
Yield strength describes the stress at which a material begins to deform plastically. Below this point, a steel component generally returns to its original shape after the load is removed, assuming it remains within its elastic range. Once stress exceeds the yield point, permanent deformation may occur.
Technical documents may identify this property as ReH, the upper yield strength, or Rp0.2, the 0.2% proof strength. The correct parameter depends on the material’s stress-strain behaviour and the applicable test standard. Therefore, when comparing certificates or technical datasheets, buyers should check the exact property reported rather than treating every strength figure as interchangeable.
Why the delivery condition matters
A 42CrMo4 bar supplied in a soft-annealed condition is not equivalent, mechanically, to a bar supplied in a quenched and tempered condition. Heat treatment changes the microstructure and therefore changes the achievable strength, hardness, and toughness.
For this reason, a datasheet value without a delivery condition is incomplete for purchasing decisions. Always confirm whether the order calls for annealed, normalized, as-rolled, or quenched and tempered material.
📊 Yield Strength Values by Section Size
Section size is one of the key factors affecting the minimum mechanical properties specified for 42CrMo4. In the quenched and tempered condition, commonly published EN 10083-3 tables distinguish round products by diameter and flat products by thickness. Larger sections generally require different mechanical-property limits because heat treatment does not produce identical conditions throughout every cross-section.
The following round-product values provide a useful reference for preliminary material selection. They are not a substitute for the current standard, the agreed purchase specification, or the inspection certificate for the actual shipment.
| Round section diameter | Minimum yield strength | Tensile strength reference |
|---|---|---|
| d ≤ 16 mm | 900 MPa | 1100–1300 MPa |
| 16 mm < d ≤ 40 mm | 750 MPa | 1000–1200 MPa |
| 40 mm < d ≤ 100 mm | 650 MPa | 900–1100 MPa |
| 100 mm < d ≤ 160 mm | 550 MPa | 800–950 MPa |
| 160 mm < d ≤ 250 mm | 500 MPa | 750–900 MPa |
Reference note: These figures represent commonly published minimum yield-strength requirements and tensile-strength ranges for quenched and tempered round products under EN 10083-3. Verify the applicable edition and product specification before using them for design or contractual acceptance. Flat-product thickness classes use different section limits.
How buyers should interpret the table
Suppose a project requires 42CrMo4 with a minimum yield strength of 650 MPa. A round bar in the 40–100 mm diameter class may meet that reference requirement under the specified +QT condition. However, a larger section may have a lower minimum requirement under the same standard. Buyers should not assume that a supplier can guarantee 650 MPa for every diameter merely because the grade is 42CrMo4.
Similarly, a strength figure listed for small-diameter round bar should not automatically be applied to a thick plate or forged block. Product form, ruling section, heat-treatment practice, and the applicable specification all matter.
Minimum values versus actual test results
A standard’s minimum yield strength is an acceptance threshold, not a prediction of the exact result for every batch. Actual test results may exceed the minimum. For purchasing purposes, the material test certificate (MTC) should report the measured value for the supplied heat or lot, as applicable, and the buyer should compare it against the agreed requirements.
⚙️ Yield Strength vs. Tensile Strength
Yield strength and tensile strength are both essential mechanical properties, but they describe different stages of a tensile test. Confusing them can lead to incorrect material selection or inaccurate technical comparisons.
| Property | Meaning | Why it matters |
|---|---|---|
| Yield strength (ReH or Rp0.2) | Stress associated with the onset of plastic deformation or the specified proof strain. | Helps assess whether a component will deform permanently under its working load. |
| Tensile strength (Rm) | Maximum engineering stress reached during a tensile test. | Indicates the maximum tensile stress recorded before the specimen progresses toward fracture. |
| Elongation (A) | Percentage increase in gauge length after fracture, measured according to a defined method. | Provides an indication of ductility. |
| Impact energy (KV) | Energy absorbed in a specified notched impact test. | Helps evaluate toughness under the specified test temperature and orientation. |
Why a high tensile strength does not tell the whole story
Two steel products can report similar tensile strength while having different yield strength, elongation, hardness, or impact performance. Consequently, buyers should not approve a material solely because its tensile strength falls within a published range.
For a shaft that must resist torsional loading without permanent twist, yield strength may be particularly important. For a component exposed to shock or impact, toughness also matters. In a fatigue-loaded part, surface condition, geometry, residual stress, and manufacturing quality can influence service life alongside the tensile properties.
Read the mechanical-property set together
When evaluating 42CrMo4, review yield strength, tensile strength, elongation, impact energy where specified, and hardness as a group. These properties describe different aspects of performance. A material that meets one requirement does not automatically satisfy the others.
Also check the test method and specimen orientation. Longitudinal and transverse results may differ, and the contract may specify particular test locations or acceptance criteria. The MTC should match the technical conditions agreed in the purchase order.
🔥 How Heat Treatment Changes Yield Strength
42CrMo4 is designed for applications that benefit from chromium-molybdenum alloying and controlled heat treatment. Quenching and tempering are especially important when a component needs high strength combined with useful toughness. However, the steel grade alone does not guarantee a specific yield strength: the delivered condition must also meet the purchase specification.
Quenched and tempered (+QT)
During hardening, the steel is heated to an appropriate austenitizing temperature and then cooled using a specified quenching process. Tempering follows to balance strength, hardness, and toughness. The final properties depend on the treatment parameters, section size, cooling conditions, and the required property range.
For many demanding mechanical components, +QT is the relevant condition because it can provide substantially higher strength than a soft-annealed state. Nevertheless, buyers should confirm whether the material must arrive already quenched and tempered or whether the component manufacturer plans to perform the heat treatment after machining.
Soft-annealed (+A)
Soft annealing reduces hardness and improves machinability. This condition can be useful when a manufacturer needs to remove substantial material or carry out extensive machining before final hardening. It should not be treated as mechanically equivalent to +QT material.
If a purchase specification requires a minimum yield strength for the finished component, an annealed supply condition may be suitable only when the downstream heat-treatment process is clearly defined and validated. Otherwise, the material may not meet the required mechanical performance at delivery.
Normalized or as-rolled material
Normalized and as-rolled products have their own property profiles, which may not match the guaranteed requirements of a quenched and tempered product. Published values for these conditions are often presented as typical data rather than as the same contractual minimums provided for +QT products.
Therefore, do not combine mechanical-property figures from different delivery conditions in one comparison without identifying the differences. A supplier quotation should specify the grade, product dimensions, delivery condition, standard, and required inspection documents.
Should buyers specify a heat-treatment recipe?
When purchasing finished +QT steel, buyers generally need to define the required condition and mechanical properties rather than impose an arbitrary heat-treatment cycle. The processing route should be suitable for the section size and the required combination of strength and toughness.
If the buyer intends to heat-treat the steel after delivery, the supplier and the component manufacturer should clarify the initial condition, machining sequence, final-property requirements, and verification method. This reduces the risk of receiving a material that is chemically correct but unsuitable for the intended manufacturing route.
📏 Why Steel Thickness Matters
Section size affects the relationship between heat treatment and mechanical performance. The surface and core of a large section do not necessarily experience identical cooling rates during quenching. As a result, the final microstructure and achievable strength can vary with the product’s dimensions and the effectiveness of the heat-treatment process.
That is why standards use different dimensional classes when specifying mechanical properties. For round products, the reference dimension is commonly the diameter. For flat products, the applicable thickness class and product-specific requirements must be checked. Buyers should not simply copy a round-bar yield-strength value into a plate specification.
Plate thickness and round-bar diameter are not interchangeable
A 50 mm thick plate and a 50 mm diameter round bar have different geometries. Their cooling behaviour and the relevant standard provisions may also differ. Even when both products carry the designation 42CrMo4, the minimum mechanical properties can depend on the applicable dimensional category and testing rules.
For example, a buyer ordering thick 42CrMo4 plate should request the applicable flat-product specification and confirm whether the material is supplied in the annealed, as-rolled, normalized, or +QT condition. If a particular minimum yield strength is essential, that value should appear clearly in the technical requirements and be supported by the agreed test documentation.
Machining allowance can affect material planning
Purchasing teams should also consider the final dimensions of the component. If a part requires substantial machining, the starting stock may need to be larger than the finished part. However, the dimensional allowance should not be confused with the reference section used to determine mechanical-property requirements.
Discuss the intended final geometry and the required test basis with the supplier before placing the order. This is especially important for thick sections, forged components, and parts where core properties matter as much as surface properties.
What to confirm on a quotation
- Exact product form: plate, bar, forged stock, or another form.
- Nominal dimensions and the applicable dimensional class.
- Required delivery condition, including +QT where specified.
- Minimum yield strength and any associated tensile, elongation, hardness, or impact requirements.
- Applicable standard and edition, together with required inspection documentation.
Clear specifications help buyers compare offers on an equivalent basis. Without them, two quotations for “42CrMo4 steel” may cover products that are not mechanically equivalent.
🔬 Chemical Composition and Strength
42CrMo4 obtains its hardenability and strength potential from its alloy composition, particularly its carbon, chromium, and molybdenum content. Nevertheless, chemical composition does not establish the finished product’s yield strength by itself. Heat treatment, section size, and testing remain essential.
The following ranges are commonly listed for 42CrMo4 under EN 10083-3:2006. Buyers should verify the applicable edition and purchase specification, since standards and agreed requirements may change.
| Element | Commonly published range or limit (wt.%) | Contribution |
|---|---|---|
| Carbon (C) | 0.38–0.45 | Supports hardness and strength after hardening. |
| Silicon (Si) | ≤ 0.40 | Contributes to deoxidation and steel processing. |
| Manganese (Mn) | 0.60–0.90 | Contributes to hardenability and strength. |
| Chromium (Cr) | 0.90–1.20 | Improves hardenability and wear-related performance. |
| Molybdenum (Mo) | 0.15–0.30 | Supports hardenability and tempering response. |
| Phosphorus (P) | ≤ 0.025 | Controlled as a residual element. |
| Sulfur (S) | ≤ 0.035 | Controlled to manage cleanliness and processing behaviour. |
Standard limits, typical analysis, and MTC results
When reviewing chemistry data, distinguish three types of information. First, standard composition limits define the permitted range or maximum for each element. Second, a mill’s typical analysis describes representative production and does not replace the standard’s requirements. Third, the actual heat analysis on the material test certificate reports measured chemistry for the supplied steel heat.
For procurement, the actual MTC and the applicable standard are more important than a generic chemistry table on a website. Buyers should confirm traceability between the certificate and the delivered material, especially when the steel will be used in a safety-critical or highly loaded component.
Why chemistry alone is insufficient
Two heats can both comply with the same chemical composition limits yet deliver different mechanical test results after processing. For that reason, buyers should not estimate yield strength directly from carbon or chromium content. Use composition to verify grade identity and use the specified mechanical tests to verify performance.
🏭 Applications That Depend on Yield Strength
42CrMo4 is often selected for mechanical components that need high strength, hardenability, and toughness. The required yield strength depends on the design loads, geometry, fatigue conditions, operating environment, and safety factors established by the component designer.
| Application | Key performance consideration | Purchasing focus |
|---|---|---|
| Drive shafts and axles | Torsional loading, fatigue, and resistance to permanent deformation. | Confirm +QT condition, section size, and specified mechanical properties. |
| Gears and transmission components | Core strength, toughness, fatigue resistance, and any required surface treatment. | Check the core-property requirements and any additional hardening process. |
| Pins and connecting components | Load-bearing capacity and resistance to impact or cyclic stress. | Review yield strength, tensile strength, and impact requirements where applicable. |
| Heavy machinery parts | Strength across the section, machinability, and service durability. | Specify the final dimensions, stock allowance, delivery condition, and test documentation. |
| Hydraulic and industrial equipment | Mechanical loading, dimensional accuracy, and surface requirements. | Confirm strength, machining requirements, and any specified surface treatment. |
Choose properties for the actual load case
A higher yield strength can improve resistance to permanent deformation, but it does not automatically make a component safer or more durable. The designer must also account for fatigue, stress concentrations, toughness, temperature, corrosion exposure, and manufacturing quality where relevant.
For example, a rotating shaft may experience repeated stress cycles even when its nominal working stress remains below the specified yield strength. In that situation, fatigue performance and surface condition deserve attention alongside static yield strength.
Likewise, a component subject to sudden impact may require an explicit Charpy impact-energy requirement at a defined temperature. A tensile-strength result alone cannot demonstrate that the material satisfies the impact requirement.
Match the specification to the manufacturing route
Before buying 42CrMo4, confirm whether the steel will be machined in its supplied condition, heat-treated after rough machining, or used after delivery in a specified +QT condition. This decision influences the required condition, inspection plan, processing allowance, and final verification.
When the application has critical mechanical requirements, have the responsible engineer approve the material specification and acceptance criteria. A supplier can provide material and inspection evidence, but the component’s suitability must be assessed against its design and service conditions.
🧾 How Buyers Should Verify 42CrMo4 Yield Strength
For industrial purchasing, the most reliable approach is to define the required mechanical properties before requesting quotations. A generic grade description may not be enough to ensure that different suppliers quote comparable material.
1. State the applicable standard and grade
Identify 42CrMo4, material number 1.7225, and the applicable product standard and edition. Do not rely only on a grade name or a supplier’s claim that a material is equivalent to another alloy. If the project allows alternatives, review chemistry, mechanical properties, dimensions, and delivery conditions before approval.
2. Specify product form and dimensions
State whether you need plate, round bar, forged stock, or another form. Include the nominal thickness or diameter, dimensional tolerances, and any machining allowance. These details help the supplier identify the relevant property requirements and confirm whether the requested size can be supplied.
3. Define the delivery condition and acceptance criteria
If the component requires quenched and tempered steel, specify +QT rather than simply writing “42CrMo4.” State the minimum yield strength and any required tensile strength, elongation, hardness, or impact properties. If a particular test temperature or specimen orientation is necessary, include it in the purchase specification.
4. Review the material test certificate
Check the certificate for the grade, heat or lot identification, chemical composition, delivery condition, dimensions or product reference, and mechanical test results required by the contract. Confirm that the reported yield-strength value meets the agreed acceptance threshold and that the documentation can be traced to the delivered material.
Where the project requires EN 10204 inspection documentation, specify the required document type in advance. Third-party inspection may also be appropriate when the contract, customer, or risk level calls for independent verification.
5. Compare suppliers on equivalent terms
A low quotation may not represent the same supply scope as a higher quotation. One supplier may quote annealed material while another quotes +QT material; one may include cutting and inspection documents while another may not. Compare delivery condition, property guarantees, tolerances, testing, packaging, lead time, and total landed cost.
Before issuing the purchase order, confirm these details in writing:
- Grade and applicable standard.
- Product form, dimensions, tolerances, and quantity.
- Delivery condition and minimum mechanical-property requirements.
- Required MTC and inspection documentation.
- Cutting, packaging, shipment, and delivery arrangements.
This process reduces the risk of receiving material that matches the grade name but does not satisfy the component’s actual mechanical requirements.
🔍 42CrMo4 vs. Similar Alloy Steel Grades
Buyers may compare 42CrMo4 with AISI 4140, JIS SCM440, or other chromium-molybdenum steels when sourcing material internationally. These grades are often described as related or approximate equivalents, but their standards and detailed requirements are not identical in every respect.
42CrMo4 and AISI 4140
42CrMo4 and AISI/SAE 4140 have similar alloying systems and are commonly considered close counterparts. However, each belongs to a different standards system. The permitted chemistry ranges, product requirements, dimensional classes, and mechanical-property guarantees may differ depending on the governing specification.
If a drawing specifies 42CrMo4, a buyer should not substitute 4140 solely because a website lists them as equivalent. First confirm that the customer or design authority accepts the alternative and that the actual product meets the specified performance requirements.
42CrMo4 and SCM440
SCM440 is a Japanese chromium-molybdenum alloy steel commonly compared with 42CrMo4. Their intended applications overlap, but the chemistry limits and mechanical-property requirements should be checked against the relevant JIS and EN specifications.
When sourcing across markets, compare the applicable standard, product form, heat-treatment condition, section size, inspection requirements, and certificate data. This is more reliable than comparing grade names alone.
Use a performance-based comparison
For procurement decisions, compare the properties required by the finished component rather than selecting the grade with the highest advertised yield strength. The best choice must meet the design requirements while supporting the planned machining route, availability, inspection needs, and total cost.
If an alternative grade is under consideration, obtain written technical approval before ordering. The supplier should identify the proposed grade and provide documentation that demonstrates compliance with the agreed requirements.
🏢 Company Advantages
- Established export experience: Otai has supplied steel to customers in more than 54 countries since 1999.
- Stock and supply capability: More than 10,000 tons of stock across the company’s steel range. Confirm the current availability, condition, dimensions, and quantity of the specific 42CrMo4 product before ordering.
- Cutting capacity: 20 saw-cutting machines support stock cutting and preparation according to confirmed requirements.
- Custom dimensions: Cutting, CNC machining, grinding, and dimensional tolerance services can support different manufacturing needs, subject to product and order confirmation.
- Quality documentation: Material testing and MTC documentation can be discussed according to the agreed specification; ultrasonic testing and third-party inspection support are available when required and confirmed for the order.
- Packaging and export service: Anti-rust protection, bundled packaging, wooden cases, and shipment arrangements can be coordinated according to product and transport requirements.
- One-stop service: Customers can discuss material selection, cutting, processing, inspection, and export requirements within one supply arrangement.
For 42CrMo4, buyers should provide the required dimensions, delivery condition, yield-strength target, applicable standard, and inspection requirements when requesting a quotation. This helps the supply team confirm the appropriate material and documentation rather than relying on a generic grade description.
❓ Frequently Asked Questions
1. What is the yield strength of 42CrMo4 steel?
For quenched and tempered round products under commonly published EN 10083-3 reference tables, the minimum yield strength ranges from 900 MPa for diameters up to 16 mm to 500 MPa for diameters above 160 mm and up to 250 mm. The applicable value depends on section size, product form, condition, and the governing specification.
2. Is 42CrMo4 yield strength always 900 MPa?
No. The 900 MPa figure applies to a specific small-section class in the quenched and tempered condition. Larger sections have different minimum values, and other delivery conditions may have different properties. Always verify the exact requirement for the product being purchased.
3. What is the difference between 42CrMo4 yield strength and tensile strength?
Yield strength indicates the stress associated with the onset of permanent deformation or a specified proof strain. Tensile strength is the maximum engineering stress recorded during a tensile test. Both values matter, and neither replaces requirements for elongation, impact toughness, or hardness.
4. Does heat treatment increase the yield strength of 42CrMo4?
Quenching and tempering can produce a high-strength condition suitable for demanding mechanical applications. However, the final yield strength depends on the treatment process, section size, and specified properties. Soft-annealed or as-rolled material should not be assumed to meet the same requirements as +QT steel.
5. What should buyers check before ordering 42CrMo4 steel?
Confirm the grade and applicable standard, product form, thickness or diameter, delivery condition, minimum yield strength, other required mechanical properties, and inspection documentation. Review the MTC against the purchase specification and confirm traceability, dimensions, and current availability before shipment.
