Se stai acquistando materiali per parti ad alta sollecitazione nel settore automobilistico, macchinari, or construction, GB 35CrMo alloy steel is a reliable choice. Come acciaio bassolegato standard cinese, bilancia la forza eccezionale, tenacità, e temprabilità, rendendolo perfetto per componenti che non possono guastarsi. Questa guida ne analizza i tratti principali, usi nel mondo reale, e come produrlo, così puoi prendere decisioni sicure per i tuoi progetti.
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 Composizione chimica
The alloy’s elements work together to boost strength, durabilità, e resistenza al calore. Below is the standard composition range:
| Elemento | Simbolo | Composition Range (%) | Key Role in the Alloy |
|---|---|---|---|
| Carbonio (C) | C | 0.32 – 0.40 | Enhancesresistenza alla trazione and surface hardness; critical for wear-resistant parts |
| Cromo (Cr) | Cr | 0.80 – 1.10 | Miglioratemprabilità Eresistenza alla corrosione; prevents oxidation at moderate temperatures |
| Manganese (Mn) | Mn | 0.40 – 0.70 | Aumentalavorabilità and grain refinement; reduces brittleness after heat treatment |
| Silicio (E) | E | 0.17 – 0.37 | Acts as a deoxidizer during steelmaking; strengthens the alloy without losing ductility |
| Molibdeno (Mo) | Mo | 0.15 – 0.25 | Increasesresistenza alla fatica e stabilità alle alte temperature; ensures uniform hardness in thick parts |
| Zolfo (S) | S | ≤ 0.035 | Kept low to avoid cracking and brittleness in high-stress applications |
| Fosforo (P) | P | ≤ 0.035 | Limited to prevent cold brittleness (fracture in low-temperature environments) |
1.2 Proprietà fisiche
These traits determine how GB 35CrMo behaves in real-world conditions (per esempio., temperature changes or magnetic fields):
- Densità: 7.85 g/cm³ (same as most ferrous alloys, so it’s easy to replace other steels in existing designs)
- Punto di fusione: 1420 – 1450°C (high enough for applicazioni ad alta temperatura like industrial rollers or engine parts)
- Conduttività termica: 43 Con/(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: Ferromagnetico (attira i magneti, useful for tools like magnetic clamps or sensors)
1.3 Proprietà meccaniche
GB 35CrMo’s full mechanical potential is unlocked throughtrattamento termico (typically quenching + tempera). Below are typical values for the alloy in its optimized state, tested to Chinese standards:
| Proprietà | Valore tipico | Test Standard (GB) |
|---|---|---|
| Resistenza alla trazione | ≥ 980 MPa | GB/T 228.1 |
| Yield strength | ≥ 835 MPa | GB/T 228.1 |
| Allungamento | ≥ 12% | GB/T 228.1 |
| Reduction of area | ≥ 45% | GB/T 228.1 |
| Durezza (Brinell) | 229 – 286 HB | GB/T 231.1 |
| Durezza (Rockwell C) | 23 – 30 HRC | GB/T 230.1 |
| Durezza (Vickers) | 230 – 290 alta tensione | GB/T 4340.1 |
| Impact toughness | ≥ 60 J | GB/T 229 |
| Fatigue strength | ~520 MPa | GB/T 3075 |
1.4 Altre proprietà
- Resistenza alla corrosione: Moderare (resists mild moisture and industrial oils; use zinc plating or paint for outdoor or humid environments)
- Resistenza all'usura: Bene (grazie a cromo (Cr) and heat treatment—suitable for moving parts like bearings or rollers)
- Lavorabilità: Giusto (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)
- Temprabilità: Eccellente (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, tenacità, and versatility makes it a top pick forapplicazioni ad alto stress in tutti i settori. Ecco i suoi usi più comuni, con esempi del mondo reale:
2.1 Industria automobilistica
Cars, trucks, and commercial vehicles rely on parts that handle constant torque and impact. GB 35CrMo is used for:
- Alberi: A Chinese heavy-duty truck manufacturer uses it for drive shafts—its yield strength (≥835 MPa) handles 25-ton loads without bending.
- Ingranaggi: A domestic automaker uses it for transmission gears; the alloy’s resistenza alla fatica (~520 MPa) extends gear life by 30% contro. acciaio al carbonio.
- Bolts and fasteners: High-performance pickup trucks use GB 35CrMo bolts for engine mounts—their resistenza alla trazione (≥980 MPa) resists vibration loosening.
2.2 Meccanico & Macchinari pesanti
Industrial machines need parts that last through continuous use. GB 35CrMo is used for:
- Cuscinetti: A manufacturing plant uses it for conveyor belt bearings—its resistenza all'usura cuts maintenance downtime by 20%.
- Sorgenti: 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; suo durezza (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; loro resistenza alla corrosione (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:
- Forno ad arco elettrico (EAF): Most common for medium batches. Scrap steel is melted with electrodes, Poi cromo (Cr) E molibdeno (Mo) are added to hit the target composition. EAF is flexible and reduces waste, making it ideal for custom orders (per esempio., large shafts).
- Fornace ad ossigeno basico (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 Trattamento termico
Heat treatment is critical to unlock GB 35CrMo’s full potential. The standard process for high-stress parts is:
- Ricottura: Riscaldare a 820 – 850°C, cool slowly. Softens the alloy for easier machining (reduces tool wear by 35%).
- Tempra: Riscaldare a 830 – 850°C, cool rapidly in oil. Hardens the steel to reach resistenza alla trazione ≥980 MPa.
- Temperamento: Riscaldare a 500 – 550°C, cool in air. Reduces brittleness while retaining strength—critical for parts like gears or shafts.
- Nitrurazione (optional): Riscaldare a 500 – 550°C in a nitrogen-rich atmosphere. Adds a hard outer layer (0.1–0.2 mm thick) to boost resistenza all'usura (ideal for bearings).
3.3 Forming Processes
GB 35CrMo is shaped into parts using techniques that preserve its strength:
- Forgiatura: Hammered or pressed at 1100 – 1200°C. Forging aligns the alloy’s grain structure, increasing resistenza alla trazione di 12% contro. cast parts. Used for gears, alberi, and crane components.
- Rotolamento: Passed through rollers to make bars, fogli, or rods. Used for basic shapes like bolts or spring blanks.
- Estrusione: Pushed through a die to make complex shapes (per esempio., hollow shafts). Ideal for parts with tight tolerances, like automotive transmission components.
3.4 Machining Processes
After forming, parts are finished with precision machining:
- Girando: Uses a lathe to make cylindrical parts (per esempio., alberi). Use cutting fluid (per esempio., mineral oil) to prevent overheating and tool wear.
- Fresatura: Uses a rotating cutter to shape gear teeth or bearing races. Carbide tools are recommended for high precision (per esempio., HRC 23–30 hardness).
- Perforazione: Creates holes for bolts or fasteners. High-speed drills (900–1400 RPM) work best to avoid cracking.
- Rettifica: Smooths surfaces to tight tolerances (per esempio., ±0.01 mm for bearing inner rings). Migliora resistenza all'usura by reducing surface friction.
4. Caso di studio: 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 mesi, causing costly production delays. They switched to GB 35CrMo—and solved the issue.
4.1 Sfida
The plant’s conveyors operated 24/7, moving hot steel pipes (fino a 200°C) weighing 50 kg each. Carbon steel bearings had lowresistenza all'usura Estabilità al calore, leading to frequent seizures and replacements.
4.2 Soluzione
They switched to GB 35CrMo bearings, utilizzando:
- Nitrurazione (520°C) to add a 0.15 mm hard outer layer for better resistenza all'usura.
- Tempra (840°C) + tempera (530°C) to reach 850 MPa yield strength E 65 J impact toughness.
- Placcatura in cromo to improve corrosion resistance in the plant’s humid environment.
4.3 Risultati
- Service life: Bearings now last 12 months—4x longer than before.
- Risparmio sui costi: Reduced maintenance costs by ¥120,000 per year (including labor and replacement parts).
- Affidabilità: 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.
| Materiale | Resistenza alla trazione | Resistenza alla corrosione | Densità | Costo (contro. GB 35CrMo) | Ideale per |
|---|---|---|---|---|---|
| GB 35CrMo | ≥980 MPa | Moderare | 7.85 g/cm³ | 100% (base) | Parti ad alto stress (alberi, cuscinetti) |
| Acciaio inossidabile (304) | 515 MPa | Eccellente | 7.93 g/cm³ | 170% | Food/chemical equipment |
| Acciaio al carbonio (45#) | 600 MPa | Basso | 7.85 g/cm³ | 55% | Parti a bassa sollecitazione (parentesi) |
| Acciaio legato (40Cr) | 980 MPa | Moderare | 7.85 g/cm³ | 85% | General machinery parts |
| Alluminio (6061) | 310 MPa | Bene | 2.70 g/cm³ | 110% | Lightweight parts (telai automobilistici) |
Key takeaway: GB 35CrMo matches 40Cr’sresistenza alla trazione but has betterstabilità al calore (grazie amolibdeno (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
Alla tecnologia Yigu, 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 anni, and itstemprabilità Eresistenza alla fatica 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—itspunto di fusione (1420–1450°C) Emolibdeno (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 highercarbonio (C) contenuto (0.38–0.45% vs. 0.32–0.40% for GB 35CrMo), giving it 10% più altoresistenza alla trazione. Choose GB 42CrMo for extreme-stress parts (per esempio., 30-ton truck shafts), and GB 35CrMo for moderate-stress, cost-sensitive projects (per esempio., 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 (per esempio., water-miscible coolant) and reduce cutting speed to 80–100 m/min to minimize tool wear.