Si vous recherchez des matériaux pour des pièces à fortes contraintes dans le secteur automobile, machinerie, ou un chantier, GB 35CrMo alloy steel is a reliable choice. En tant qu'acier faiblement allié standard chinois, il équilibre une force exceptionnelle, dureté, et trempabilité, ce qui le rend parfait pour les composants qui ne peuvent pas tomber en panne. Ce guide détaille ses principales caractéristiques, utilisations réelles, et comment le fabriquer, afin que vous puissiez prendre des décisions en toute confiance pour vos projets.
1. Material Properties of GB 35CrMo Alloy Steel
GB 35CrMo’s performance is defined by its precise composition and inherent characteristics, all aligned with China’sGB/T 3077 standard (the official specification for this alloy).
1.1 Chemical Composition
The alloy’s elements work together to boost strength, durabilité, et résistance à la chaleur. Below is the standard composition range:
| Element | Symbol | Composition Range (%) | Key Role in the Alloy |
|---|---|---|---|
| Carbon (C) | C | 0.32 – 0.40 | Enhancesrésistance à la traction and surface hardness; critical for wear-resistant parts |
| Chromium (Cr) | Cr | 0.80 – 1.10 | Amélioretrempabilité etrésistance à la corrosion; prevents oxidation at moderate temperatures |
| Manganese (Mn) | Mn | 0.40 – 0.70 | Boosteusinabilité and grain refinement; reduces brittleness after heat treatment |
| Silicium (Et) | Et | 0.17 – 0.37 | Acts as a deoxidizer during steelmaking; strengthens the alloy without losing ductility |
| Molybdène (Mo) | Mo | 0.15 – 0.25 | Increasesrésistance à la fatigue et stabilité à haute température; ensures uniform hardness in thick parts |
| Sulfur (S) | S | ≤ 0.035 | Kept low to avoid cracking and brittleness in high-stress applications |
| Phosphorus (P.) | P. | ≤ 0.035 | Limited to prevent cold brittleness (fracture in low-temperature environments) |
1.2 Physical Properties
These traits determine how GB 35CrMo behaves in real-world conditions (par ex., temperature changes or magnetic fields):
- Densité: 7.85 g/cm³ (same as most ferrous alloys, so it’s easy to replace other steels in existing designs)
- Point de fusion: 1420 – 1450°C (high enough for applications à haute température like industrial rollers or engine parts)
- Conductivité thermique: 43 W/(m·K) at 20°C (retains heat well, ideal for parts that operate continuously)
- Specific heat capacity: 465 J/(kg·K) at 20°C (stable heat absorption, preventing warping from sudden temperature swings)
- Thermal expansion coefficient: 12.1 μm/(m·K) (low expansion, critical for precision components like gears or shafts)
- Magnetic properties: Ferromagnetic (attracts magnets, useful for tools like magnetic clamps or sensors)
1.3 Propriétés mécaniques
GB 35CrMo’s full mechanical potential is unlocked throughtraitement thermique (typically quenching + trempe). Below are typical values for the alloy in its optimized state, tested to Chinese standards:
| Propriété | Valeur typique | Test Standard (GB) |
|---|---|---|
| Résistance à la traction | ≥ 980 MPa | GB/T 228.1 |
| Yield strength | ≥ 835 MPa | GB/T 228.1 |
| Élongation | ≥ 12% | GB/T 228.1 |
| Reduction of area | ≥ 45% | GB/T 228.1 |
| Dureté (Brinell) | 229 – 286 HB | GB/T 231.1 |
| Dureté (Rockwell C) | 23 – 30 CRH | GB/T 230.1 |
| Dureté (Vickers) | 230 – 290 HV | GB/T 4340.1 |
| Impact toughness | ≥ 60 J | GB/T 229 |
| Fatigue strength | ~520 MPa | GB/T 3075 |
1.4 Other Properties
- Résistance à la corrosion: Modéré (resists mild moisture and industrial oils; use zinc plating or paint for outdoor or humid environments)
- Résistance à l'usure: Bien (grâce à chrome (Cr) and heat treatment—suitable for moving parts like bearings or rollers)
- Usinabilité: Équitable (softer in its annealed state; use high-speed steel (HSS) or carbide tools with cutting fluid to reduce tool wear)
- Weldability: Acceptable (preheat to 250 – 300°C and post-weld heat treat to avoid cracking; use low-hydrogen electrodes)
- Hardenability: Excellent (heat treatment penetrates deeply, ensuring uniform strength in thick parts like heavy machinery shafts)
2. Applications of GB 35CrMo Alloy Steel
GB 35CrMo’s mix of strength, dureté, and versatility makes it a top pick forapplications à forte contrainte dans tous les secteurs. Here are its most common uses, avec des exemples concrets:
2.1 Industrie automobile
Cars, trucks, and commercial vehicles rely on parts that handle constant torque and impact. GB 35CrMo is used for:
- Arbres: A Chinese heavy-duty truck manufacturer uses it for drive shafts—its yield strength (≥835 MPa) handles 25-ton loads without bending.
- Engrenages: A domestic automaker uses it for transmission gears; the alloy’s résistance à la fatigue (~520 MPa) extends gear life by 30% contre. acier au carbone.
- Bolts and fasteners: High-performance pickup trucks use GB 35CrMo bolts for engine mounts—their résistance à la traction (≥980 MPa) resists vibration loosening.
2.2 Mécanique & Machinerie lourde
Industrial machines need parts that last through continuous use. GB 35CrMo is used for:
- Roulements: A manufacturing plant uses it for conveyor belt bearings—its résistance à l'usure cuts maintenance downtime by 20%.
- Ressorts: A construction equipment maker uses it for excavator arm springs; the alloy’s elasticity (from tempering) withstands 8,000+ compression cycles.
- Rollers: Steel mills use it for rolling mill rollers; c'est dureté (229–286 HB) resists deformation from hot metal sheets.
2.3 Structural Components
For infrastructure and heavy-duty structures, GB 35CrMo provides reliable strength:
- Crane shafts: Port cranes use it for hoist shafts—its impact toughness (≥60 J) prevents fracture when lifting 40-ton containers.
- Bridge fasteners: Large-span highways use GB 35CrMo bolts; leur résistance à la corrosion (with anti-rust coating) ensures long-term stability in outdoor conditions.
3. Manufacturing Techniques for GB 35CrMo Alloy Steel
To maximize GB 35CrMo’s performance, follow these proven manufacturing steps—aligned with industry best practices for low-alloy steels.
3.1 Steelmaking Processes
GB 35CrMo is typically produced using two methods:
- Electric Arc Furnace (EAF): Most common for medium batches. Scrap steel is melted with electrodes, alors chrome (Cr) et molybdène (Mo) are added to hit the target composition. EAF is flexible and reduces waste, making it ideal for custom orders (par ex., large shafts).
- Basic Oxygen Furnace (BOF): Used for large-scale production. Molten iron is mixed with oxygen to remove impurities, then alloying elements are added. BOF is faster and more cost-effective for mass-produced parts like bolts.
3.2 Traitement thermique
Heat treatment is critical to unlock GB 35CrMo’s full potential. The standard process for high-stress parts is:
- Recuit: Heat to 820 – 850°C, cool slowly. Softens the alloy for easier machining (reduces tool wear by 35%).
- Trempe: Heat to 830 – 850°C, cool rapidly in oil. Hardens the steel to reach résistance à la traction ≥980 MPa.
- Tempering: Heat to 500 – 550°C, cool in air. Reduces brittleness while retaining strength—critical for parts like gears or shafts.
- Nitriding (optional): Heat to 500 – 550°C in a nitrogen-rich atmosphere. Adds a hard outer layer (0.1–0.2 mm thick) to boost résistance à l'usure (ideal for bearings).
3.3 Forming Processes
GB 35CrMo is shaped into parts using techniques that preserve its strength:
- Forgeage: Hammered or pressed at 1100 – 1200°C. Forging aligns the alloy’s grain structure, increasing résistance à la traction par 12% contre. cast parts. Used for gears, arbres, and crane components.
- Roulement: Passed through rollers to make bars, feuilles, or rods. Used for basic shapes like bolts or spring blanks.
- Extrusion: Pushed through a die to make complex shapes (par ex., hollow shafts). Ideal for parts with tight tolerances, like automotive transmission components.
3.4 Machining Processes
After forming, parts are finished with precision machining:
- Tournant: Uses a lathe to make cylindrical parts (par ex., arbres). Use cutting fluid (par ex., mineral oil) to prevent overheating and tool wear.
- Fraisage: Uses a rotating cutter to shape gear teeth or bearing races. Carbide tools are recommended for high precision (par ex., HRC 23–30 hardness).
- Forage: Creates holes for bolts or fasteners. High-speed drills (900–1400 RPM) work best to avoid cracking.
- Affûtage: Smooths surfaces to tight tolerances (par ex., ±0.01 mm for bearing inner rings). Améliore résistance à l'usure by reducing surface friction.
4. Étude de cas: GB 35CrMo in Industrial Conveyor Bearings
A Chinese manufacturing plant that produces steel pipes faced a problem: their carbon steel conveyor bearings failed every 3 mois, causing costly production delays. They switched to GB 35CrMo—and solved the issue.
4.1 Défi
The plant’s conveyors operated 24/7, moving hot steel pipes (jusqu'à 200°C) weighing 50 kg each. Carbon steel bearings had lowrésistance à l'usure etstabilité thermique, leading to frequent seizures and replacements.
4.2 Solution
They switched to GB 35CrMo bearings, en utilisant:
- Nitriding (520°C) to add a 0.15 mm hard outer layer for better résistance à l'usure.
- Trempe (840°C) + trempe (530°C) to reach 850 MPa yield strength et 65 J impact toughness.
- Chromage to improve corrosion resistance in the plant’s humid environment.
4.3 Résultats
- Service life: Bearings now last 12 months—4x longer than before.
- Économies de coûts: Reduced maintenance costs by ¥120,000 per year (including labor and replacement parts).
- Fiabilité: Production downtime due to bearing failures dropped from 8 hours/month to 1 hour/month.
5. Comparative Analysis: GB 35CrMo vs. Other Materials
How does GB 35CrMo stack up against common alternatives? Below is a side-by-side comparison of key traits—helping you choose the right material for your project.
| Matériel | Résistance à la traction | Résistance à la corrosion | Densité | Coût (contre. GB 35CrMo) | Idéal pour |
|---|---|---|---|---|---|
| GB 35CrMo | ≥980 MPa | Modéré | 7.85 g/cm³ | 100% (base) | Pièces très sollicitées (arbres, roulements) |
| Acier inoxydable (304) | 515 MPa | Excellent | 7.93 g/cm³ | 170% | Food/chemical equipment |
| Acier au carbone (45#) | 600 MPa | Faible | 7.85 g/cm³ | 55% | Pièces à faible contrainte (parenthèses) |
| Acier allié (40Cr) | 980 MPa | Modéré | 7.85 g/cm³ | 85% | General machinery parts |
| Aluminium (6061) | 310 MPa | Bien | 2.70 g/cm³ | 110% | Lightweight parts (cadres automobiles) |
Key takeaway: GB 35CrMo matches 40Cr’srésistance à la traction but has betterstabilité thermique (grâce àmolybdène (Mo)), making it better for high-temperature applications. It’s cheaper than stainless steel and aluminum, making it the best value forhigh-stress, moderate-heat parts like conveyor bearings or truck shafts.
Yigu Technology’s Perspective on GB 35CrMo Alloy Steel
Chez Yigu Technologie, GB 35CrMo is a staple in our product line for its reliability and versatility. We’ve supplied it to clients in automotive and machinery sectors for over 12 années, and itstrempabilité etrésistance à la fatigue consistently meet high-stress demands—from truck shafts to industrial bearings. We often recommend nitriding for wear-prone parts and anti-rust coatings for outdoor use, helping clients extend service life by 2–3x. For Chinese manufacturers seeking a cost-effective, high-performance alloy, GB 35CrMo remains an unbeatable choice.
FAQ About GB 35CrMo Alloy Steel
1. Can GB 35CrMo be used in high-temperature environments?
Yes—itspoint de fusion (1420–1450°C) etmolybdène (Mo) content let it perform reliably at temperatures up to 300°C. For higher temps (300–400°C), we recommend adjusting the tempering process (lower to 480–500°C) to boost heat stability.
2. What’s the difference between GB 35CrMo and GB 42CrMo?
GB 42CrMo has highercarbone (C) contenu (0.38–0.45% vs. 0.32–0.40% for GB 35CrMo), giving it 10% plus hautrésistance à la traction. Choose GB 42CrMo for extreme-stress parts (par ex., 30-ton truck shafts), and GB 35CrMo for moderate-stress, cost-sensitive projects (par ex., conveyor bearings).
3. How to improve GB 35CrMo’s machinability?
Anneal the alloy first (heat to 820–850°C, cool slowly)—this softens it to 229–250 HB, making machining easier. Use carbide tools with cutting fluid (par ex., water-miscible coolant) and reduce cutting speed to 80–100 m/min to minimize tool wear.