Introduction: Navigating Global Steel Standards
International engineers and procurement managers sourcing steel from China often face the challenge of navigating different material grading systems. This guide provides a clear cross-reference for the most common Chinese steel grades, detailing their international equivalents from SAE/AISI (USA), EN (Europe), and JIS (Japan). For each grade, we will outline the chemical composition, key performance properties, and typical applications to facilitate accurate material selection and substitution.
Alloy Structural Steels: The Foundation of Mechanical Engineering
These steels are valued for their excellent balance of strength, toughness, and wear resistance, which are achieved after appropriate heat treatment.
40Cr (Equivalent to SAE 5140 / EN 41Cr4)
| Grade | C (%) | Si (%) | Mn (%) | Cr (%) | Mo (%) | P (≤%) | S (≤%) |
| 40Cr | 0.37-0.44 | 0.17-0.37 | 0.50-0.80 | 0.80-1.10 | ≤0.10 | 0.025 | 0.025 |
| SAE 5140 | 0.38-0.43 | 0.15-0.35 | 0.60-0.90 | 0.70-0.90 | – | 0.035 | 0.040 |
Key Properties
• Good Overall Performance: A well-balanced combination of strength, toughness, and plasticity.
• Good Hardenability: Superior to carbon steel, capable of hardening through sections up to 40mm in diameter.
• Excellent Machinability: Known for its good cutting performance.
• Post-Heat Treatment Hardness: Achieves a hardness of HRC25-32 after quenching and tempering.
• Weldability: Requires preheating before welding to prevent cracking.
Common Applications
• Machine tool spindles
• Automotive half-shafts and connecting rods
• Gears and spline shafts
• High-strength bolts
42CrMoA (Equivalent to SAE 4140 / EN 42CrMo4)
The ‘A’ in 42CrMoA signifies a high-quality grade with stricter control over impurities.
| Grade | C (%) | Si (%) | Mn (%) | Cr (%) | Mo (%) | P (≤%) | S (≤%) |
| 42CrMoA | 0.38-0.45 | 0.17-0.37 | 0.50-0.80 | 0.90-1.20 | 0.15-0.25 | 0.020 | 0.020 |
Key Properties
• High Strength: Achieves tensile strengths in the range of 1000-1200 MPa.
• High Hardenability: The addition of Molybdenum (Mo) significantly improves hardenability and tempering stability.
• Excellent Fatigue Resistance: Possesses a high fatigue limit and resistance to stress corrosion.
• Good High-Temperature Strength: Retains its strength well at elevated temperatures, making it suitable for high-load engine components or downhole drilling tools.
Common Applications
• Heavy machinery drive shafts and connecting rods
• Oil drilling equipment and coal mining machinery
• Large gears and high-strength fasteners
SCM435 (Japanese Grade, approx. 35CrMoA / SAE 4135)
This is a common Japanese standard (JIS) alloy structural steel.
| Grade | C (%) | Si (%) | Mn (%) | Cr (%) | Mo (%) | P (≤%) | S (≤%) |
| SCM435 | 0.33-0.38 | 0.15-0.35 | 0.60-0.90 | 0.90-1.20 | 0.15-0.30 | 0.030 | 0.030 |
Key Properties
• Excellent Balance of Strength and Toughness: Known for its optimal combination of mechanical properties.
• Good Fatigue Performance: Exhibits reliable performance under cyclic loading.
• Good Processability: Responds well to machining and various heat treatment processes.
Common Applications
• Critical bolts for automotive and tractor applications
• Machine tool shafts
• Oil machinery parts
Case Hardening & Gear Steels: Engineered for Surface Durability
These low-carbon alloy steels are designed for carburizing or carbonitriding to create a very hard, wear-resistant surface (case) while maintaining a tough, ductile core.
22CrMoH (Equivalent to SAE 4120H / EN 18CrMo4)
The ‘H’ designation signifies that the steel is produced to a guaranteed hardenability band, ensuring a predictable response to heat treatment.
| Grade | C (%) | Si (%) | Mn (%) | Cr (%) | Mo (%) | P (≤%) | S (≤%) |
| 22CrMoH | 0.20-0.25 | 0.17-0.37 | 0.60-0.95 | 0.90-1.20 | 0.20-0.30 | 0.025 | 0.025 |
| SAE 4120H | 0.19-0.24 | 0.15-0.35 | 0.70-1.00 | 0.90-1.20 | 0.20-0.30 | 0.035 | 0.040 |
Key Properties
• Guaranteed Hardenability: Strict control over the Jominy hardenability curve.
• Medium Strength with Good Toughness: Offers a robust core to support the hardened case, with a hardness of HRC28-35 after quenching and tempering.
• Excellent Fatigue Resistance: Ideal for components under high cyclic stress.
• Good Machinability: Can be machined effectively before case hardening. Note: Welding requires preheating.
Common Applications
• Automotive gearbox gears
• Rear axle gears
• Heavy machinery drive shafts
• Oil drilling equipment parts
20CrMnTiH (Equivalent to EN 20MnCr5; approx. SAE 8620H)
The ‘H’ signifies guaranteed hardenability. The inclusion of Titanium (Ti) is a key differentiator from many international grades, offering specific benefits during heat treatment.
| Grade | C (%) | Si (%) | Mn (%) | Cr (%) | Ti (%) | P (≤%) | S (≤%) |
| 20CrMnTiH | 0.18-0.23 | 0.17-0.37 | 0.90-1.20 | 1.00-1.30 | 0.04-0.10 | 0.025 | 0.025 |
Key Properties
• Grain Refinement: Titanium (Ti) refines the grain structure and prevents overheating during the carburizing process, leading to a more consistent and higher-quality case.
• High Surface Fatigue Strength: Achieves high contact fatigue strength after carburizing, which is critical for extending gear life in high-torque applications.
• Good Dimensional Stability: Exhibits relatively small distortion during heat treatment.
Common Applications
• Transmission gears for automobiles and tractors
• Critical gears for construction machinery
• Important gear components for machine tools
High-Strength Structural Steels: For Maximum Load-Bearing Capacity
These steels are specified for applications where a high strength-to-weight ratio and exceptional reliability are critical design requirements.
30CrMnSiA-1 (Russian Equivalent: 30ХГСА)
| Grade | C (%) | Si (%) | Mn (%) | Cr (%) | Mo (%) | P (≤%) | S (≤%) |
| 30CrMnSiA-1 | 0.28-0.34 | 0.90-1.20 | 0.80-1.10 | 0.80-1.10 | – | 0.025 | 0.025 |
Key Properties
• Very High Tensile Strength: Can reach 1100-1400 MPa after heat treatment.
• Good Impact Toughness: Offers an excellent combination of strength and toughness.
• Relatively Good Weldability: Can be welded successfully with appropriate preheating procedures.
Common Applications
• Aerospace structural parts
• Aircraft landing gear components
• High-strength fasteners and connectors
Q355D (Equivalent to EN S355J2 / ASTM A572 Gr. 50)
Q355D is a low-alloy high-strength (LAHS) steel with a specified minimum yield strength of 355 MPa. The ‘D’ quality grade indicates specific impact toughness requirements at a test temperature of -20°C.
Key Properties
• High Strength: Minimum yield strength of 355 MPa.
• Excellent Low-Temperature Toughness: Guaranteed impact properties at -20°C.
• Good Weldability: The chemical composition and carbon equivalent are controlled to ensure good performance during welding.
• Atmospheric Corrosion Resistance: Offers some improvement in corrosion resistance over plain carbon steels.
Common Applications
• Bridges and building structures
• Ships and vehicle frames
• Pressure vessels and construction machinery
Specialized Performance Steels: Bearings, Springs & Tools
This group includes steels engineered for unique and highly specific performance characteristics, such as extreme hardness, high elasticity, or enhanced corrosion resistance.
GCr15 (Equivalent to AISI 52100 / EN 100Cr6)
GCr15 is a high-carbon chromium bearing steel, the most common material for precision rolling bearings.
| Grade | C (%) | Si (%) | Mn (%) | Cr (%) | P (≤%) | S (≤%) |
| GCr15 | 0.95-1.05 | 0.15-0.35 | 0.25-0.45 | 1.40-1.65 | 0.025 | 0.025 |
| AISI 52100 | 0.98-1.10 | 0.15-0.35 | 0.25-0.45 | 1.30-1.60 | 0.025 | 0.025 |
Key Properties
• High Hardness: Achieves a very high hardness of HRC61-65 after heat treatment.
• High Wear Resistance: The high carbon and chromium content provides excellent resistance to abrasive wear.
• High Contact Fatigue Strength: A critical property for ensuring long bearing life under high cyclic loads.
• Excellent Dimensional Stability: Exhibits minimal size and shape changes after heat treatment, which is crucial for precision components.
• High Purity: Produced with strict controls on non-metallic inclusions to maximize performance.
Common Applications
• Rolling bearing races (rings) and rolling elements (balls, rollers)
• Precision measuring tools and molds
• Machine tool lead screws
65Mn (Approx. Equivalent to SAE 1065)
This is a high-carbon manganese spring steel.
| Grade | C (%) | Si (%) | Mn (%) | P (≤%) | S (≤%) |
| 65Mn | 0.62-0.70 | 0.17-0.37 | 0.90-1.20 | 0.035 | 0.035 |
Key Properties
• High Elastic Limit: Possesses excellent elasticity after proper heat treatment.
• Long Fatigue Life: Designed to withstand a high number of load cycles without failure.
• Good Hardenability: The manganese content provides better hardenability than plain carbon steels, and it can be through-hardened for diameters under 12mm.
• Decarburization Tendency: Requires careful atmosphere control during heat treatment to prevent surface carbon loss.
Common Applications
• Flat and round coil springs
• Spring washers and circlips
• Agricultural plowshares and machine tool collets
The Workhorses: Medium-Carbon Steels (40, 45, 50)
This series of carbon structural steels offers a gradient of properties, with strength and hardness increasing with carbon content. 45 steel is the most widely used and versatile grade in this family for general machinery parts.
| Grade | C (%) | Si (%) | Mn (%) | P (≤%) | S (≤%) |
| 45 (GB) | 0.42-0.50 | 0.17-0.37 | 0.50-0.80 | 0.035 | 0.035 |
| 1045 (SAE) | 0.43-0.50 | 0.15-0.35 | 0.60-0.90 | 0.040 | 0.050 |
| S45C (JIS) | 0.42-0.48 | 0.15-0.35 | 0.60-0.90 | 0.030 | 0.030 |
Key Characteristics
• Strength and hardness increase with carbon content, while plasticity and toughness decrease.
• They offer excellent machinability (especially 45 steel).
• Low hardenability makes them suitable for smaller section sizes or surface hardening.
Applications by Grade
• 40 Steel: Medium-strength parts like shafts, bolts, and connecting rods.
• 45 Steel: The most common grade, used for machine tool spindles, gears, and piston pins.
• 50 Steel: Higher-strength parts requiring greater wear resistance, such as rollers, springs, and other wear-resistant components.
Quick Reference Chart: Chinese Steel Grade Equivalents
| Chinese Grade | USA (SAE/AISI) | Europe (EN) | Japan (JIS) | Key Feature | Typical Application |
| 22CrMoH | 4120H | 18CrMo4 | SCM420H | Guaranteed Hardenability | Automotive Gears |
| 20CrMnTiH | 8620H (approx.) | 20MnCr5 | SMF420H | Case Hardening Gear Steel | Gearbox Gears |
| 30CrMnSiA-1 | 4130 (approx.) | 30CrMnSi5 (approx.) | – | High Strength | Aerospace Structural Parts |
| 40Cr | 5140 | 41Cr4 | SCr440 | General Purpose Alloy Steel | Shaft Components |
| 42CrMoA | 4140 (approx.) | 42CrMo4 | SCM440 | High Strength | Heavy Machinery |
| 45 | 1045 | C45 | S45C | Quality Carbon Steel | Widely Used General Parts |
| 65Mn | 1065 (approx.) | 66Si7 (Functional Equiv.) | SUP2 (approx.) | Spring Steel | Various Springs |
| Q355D | A572 Gr. 50 (approx.) | S355J2 | SM490B | Low Alloy High Strength | Building Structures |
| 27SiMn | – | 28Mn6 (approx.) | – | Wear Resistance | Wear-Resistant Parts |
| X30CrMoA | 420 (approx.) | X30Cr13 (approx.) | SUS420J2 | Martensitic Stainless Steel | Medical Instruments |
| GCr15 | 52100 | 100Cr6 | SUJ2 | Bearing Steel | Rolling Bearings |
| SCM435 | 4135 (approx.) | 34CrMo4 | SCM435 | Alloy Structural Steel | Critical Bolts |
Key Considerations for Sourcing and Material Substitution
1. Principle of Substitution: While similar chemical composition is the starting point for material substitution, it is essential to verify the final mechanical properties, heat treatment response, and in-service performance.
2. Understand Standard Differences: Different national standards may have varying requirements for impurity levels (e.g., P, S), hardenability bands, and specified testing methods. For example, as seen in the reference chart, many grades are ‘approximate’ equivalents, differing in allowable impurity levels or the presence of micro-alloying elements (like Ti in 20CrMnTiH vs. SAE 8620H), which can significantly affect performance in critical applications.
3. Verify Certifications: Critical industries like automotive (requiring IATF 16949 compliance) and aerospace demand specific material certifications and traceability that must be confirmed with the supplier.
4. Establish Clear Technical Agreements: In international trade, it is advisable to use mutually recognized international standards (like ISO) as the basis for technical agreements to avoid ambiguity and ensure quality.
For critical components, it is always recommended that full experimental validation be performed on the substitute material to confirm it meets all design and performance requirements.
Understanding these cross-references between Chinese and international steel grades is crucial for successful international trade, engineering design, and procurement. This guide serves as a practical starting point for navigating the complexities of global material standards. For detailed technical specifications or assistance in selecting the right material for your project, contact our engineering team.
Frequently Asked Questions (FAQ)
1. What is the difference between 42CrMo and 42CrMoA?
The “A” in 42CrMoA designates it as a high-quality grade, which typically implies stricter control over impurities like phosphorus (P) and sulfur (S), resulting in better overall performance.
2. Is Q355D a direct equivalent to S355J2?
They are very close functional equivalents. Q355D (Chinese standard) and S355J2 (European standard) both have a minimum yield strength of 355 MPa and similar low-temperature impact requirements, making them interchangeable in most structural applications.
3. What does the ‘H’ in steel grades like 22CrMoH mean?
The ‘H’ stands for “Hardenability.” It indicates that the steel is produced to a specific hardenability band (Jominy curve), guaranteeing a more predictable and consistent response to heat treatment compared to standard grades.
4. Why is GCr15 (AISI 52100) used for bearings?
GCr15 is used for bearings due to its high hardness (HRC 61-65 after heat treatment), excellent wear resistance, and high contact fatigue strength. It is also produced to high purity standards to minimize non-metallic inclusions, which is critical for long bearing life.
5. Can I substitute 40Cr with 42CrMoA?
While they are both alloy steels, they are not direct substitutes. 42CrMoA contains Molybdenum (Mo), which significantly increases its hardenability, strength (especially at high temperatures), and fatigue resistance compared to 40Cr. The choice depends on the specific performance requirements of the part.
6. Why is 20CrMnTiH a popular choice for automotive gears?
The combination of Chromium, Manganese, and Titanium in 20CrMnTiH provides a great balance of properties for gears. The Titanium (Ti) refines the grain structure, preventing overheating during the carburizing process. This results in a hard, wear-resistant surface and a tough core with high fatigue strength, ideal for transmission gears.
7. What’s the main difference between 45 steel and 50 steel?
The main difference is the carbon content. 50 steel has a higher carbon content (0.47-0.55%) than 45 steel (0.42-0.50%). This makes 50 steel harder and stronger after heat treatment but less ductile and more difficult to weld. 50 steel is chosen for applications requiring higher strength and wear resistance.
8. Is 65Mn steel difficult to work with?
65Mn has good elasticity and fatigue resistance, making it ideal for springs. However, its high carbon content means it has a tendency to decarburize during heat treatment, which requires careful process control. Welding is also challenging and generally not recommended.
9. Which Chinese steel is best for high-strength aerospace parts?
30CrMnSiA-1 is a high-strength alloy structural steel commonly used for critical applications like aircraft structural components and landing gear parts, thanks to its excellent tensile strength (up to 1400 MPa) and good toughness.
10. What are the international equivalents for the common bearing steel GCr15?
GCr15 has direct equivalents in all major international standards. It is known as AISI 52100 in the USA, EN 100Cr6 in Europe, and JIS SUJ2 in Japan.
English