Se você estiver adquirindo materiais para peças de alto estresse no setor automotivo, maquinaria, ou construção, GB 35CrMo alloy steel is a reliable choice. Como aço de baixa liga padrão chinês, equilibra força excepcional, resistência, e temperabilidade - tornando-o perfeito para componentes que não podem falhar. Este guia detalha suas principais características, usos no mundo real, e como fabricá-lo, para que você possa tomar decisões seguras para seus projetos.
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 padrão (the official specification for this alloy).
1.1 Composição Química
The alloy’s elements work together to boost strength, durabilidade, e resistência ao calor. Below is the standard composition range:
| Element | Symbol | Composition Range (%) | Key Role in the Alloy |
|---|---|---|---|
| Carbon (C) | C | 0.32 – 0.40 | Enhancesresistência à tracção and surface hardness; critical for wear-resistant parts |
| Chromium (Cr) | Cr | 0.80 – 1.10 | Improvestemperabilidade eresistência à corrosão; prevents oxidation at moderate temperatures |
| Manganese (Mn) | Mn | 0.40 – 0.70 | Boostsusinabilidade and grain refinement; reduces brittleness after heat treatment |
| Silicon (E) | E | 0.17 – 0.37 | Acts as a deoxidizer during steelmaking; strengthens the alloy without losing ductility |
| Molybdenum (Mo) | Mo | 0.15 – 0.25 | Increasesresistência à fadiga and high-temperature stability; 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 Propriedades Físicas
These traits determine how GB 35CrMo behaves in real-world conditions (por exemplo, temperature changes or magnetic fields):
- Densidade: 7.85 g/cm³ (same as most ferrous alloys, so it’s easy to replace other steels in existing designs)
- Melting point: 1420 – 1450°C (high enough for high-temperature applications like industrial rollers or engine parts)
- Thermal conductivity: 43 C/(m·K) a 20ºC (retains heat well, ideal for parts that operate continuously)
- Specific heat capacity: 465 J/(kg·K) a 20ºC (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 Propriedades Mecânicas
GB 35CrMo’s full mechanical potential is unlocked throughheat treatment (typically quenching + tempering). Below are typical values for the alloy in its optimized state, tested to Chinese standards:
| Propriedade | Valor típico | Test Standard (GB) |
|---|---|---|
| Resistência à tracção | ≥ 980 MPa | GB/T 228.1 |
| Força de rendimento | ≥ 835 MPa | GB/T 228.1 |
| Alongamento | ≥ 12% | GB/T 228.1 |
| Reduction of area | ≥ 45% | GB/T 228.1 |
| Dureza (Brinell) | 229 – 286 HB | GB/T 231.1 |
| Dureza (Rockwell C.) | 23 – 30 CDH | GB/T 230.1 |
| Dureza (Vickers) | 230 – 290 HV | GB/T 4340.1 |
| Resistência ao impacto | ≥ 60 J. | GB/T 229 |
| Força de fadiga | ~520 MPa | GB/T 3075 |
1.4 Other Properties
- Resistência à corrosão: Moderado (resists mild moisture and industrial oils; use zinc plating or paint for outdoor or humid environments)
- Resistência ao desgaste: Bom (thanks to cromo (Cr) and heat treatment—suitable for moving parts like bearings or rollers)
- Usinabilidade: Fair (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: Excelente (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, resistência, and versatility makes it a top pick foraplicações de alto estresse across industries. Here are its most common uses, com exemplos do mundo real:
2.1 Automotive Industry
Cars, trucks, and commercial vehicles rely on parts that handle constant torque and impact. GB 35CrMo is used for:
- Shafts: A Chinese heavy-duty truck manufacturer uses it for drive shafts—its yield strength (≥835 MPa) handles 25-ton loads without bending.
- Gears: A domestic automaker uses it for transmission gears; the alloy’s resistência à fadiga (~520 MPa) extends gear life by 30% contra. carbon steel.
- Bolts and fasteners: High-performance pickup trucks use GB 35CrMo bolts for engine mounts—their resistência à tracção (≥980 MPa) resists vibration loosening.
2.2 Mechanical & Heavy Machinery
Industrial machines need parts that last through continuous use. GB 35CrMo is used for:
- Bearings: A manufacturing plant uses it for conveyor belt bearings—its resistência ao desgaste cuts maintenance downtime by 20%.
- Springs: 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; isso é dureza (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; deles resistência à corrosão (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, then cromo (Cr) e molibdênio (Mo) are added to hit the target composition. EAF is flexible and reduces waste, making it ideal for custom orders (por exemplo, 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 Tratamento térmico
Heat treatment is critical to unlock GB 35CrMo’s full potential. The standard process for high-stress parts is:
- Annealing: Heat to 820 – 850°C, cool slowly. Softens the alloy for easier machining (reduces tool wear by 35%).
- Têmpera: Heat to 830 – 850°C, cool rapidly in oil. Hardens the steel to reach resistência à tracção ≥980 MPa.
- Temperamento: 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 resistência ao desgaste (ideal for bearings).
3.3 Forming Processes
GB 35CrMo is shaped into parts using techniques that preserve its strength:
- Forging: Hammered or pressed at 1100 – 1200°C. Forging aligns the alloy’s grain structure, increasing resistência à tracção by 12% contra. cast parts. Used for gears, eixos, and crane components.
- Rolling: Passed through rollers to make bars, sheets, or rods. Used for basic shapes like bolts or spring blanks.
- Extrusion: Pushed through a die to make complex shapes (por exemplo, hollow shafts). Ideal for parts with tight tolerances, like automotive transmission components.
3.4 Machining Processes
After forming, parts are finished with precision machining:
- Virando: Uses a lathe to make cylindrical parts (por exemplo, eixos). Use cutting fluid (por exemplo, mineral oil) to prevent overheating and tool wear.
- Fresagem: Uses a rotating cutter to shape gear teeth or bearing races. Carbide tools are recommended for high precision (por exemplo, HRC 23–30 hardness).
- Drilling: Creates holes for bolts or fasteners. High-speed drills (900–1400 RPM) work best to avoid cracking.
- Moagem: Smooths surfaces to tight tolerances (por exemplo, ±0.01 mm for bearing inner rings). Improves resistência ao desgaste by reducing surface friction.
4. Estudo de caso: 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 months, causing costly production delays. They switched to GB 35CrMo—and solved the issue.
4.1 Challenge
The plant’s conveyors operated 24/7, moving hot steel pipes (up to 200°C) weighing 50 kg each. Carbon steel bearings had lowresistência ao desgaste eheat stability, leading to frequent seizures and replacements.
4.2 Solution
They switched to GB 35CrMo bearings, using:
- Nitriding (520°C) to add a 0.15 mm hard outer layer for better resistência ao desgaste.
- Têmpera (840°C) + tempering (530°C) to reach 850 MPa yield strength e 65 J. impact toughness.
- Chrome plating to improve corrosion resistance in the plant’s humid environment.
4.3 Results
- Service life: Bearings now last 12 months—4x longer than before.
- Cost savings: Reduced maintenance costs by ¥120,000 per year (including labor and replacement parts).
- Confiabilidade: Production downtime due to bearing failures dropped from 8 hours/month to 1 hour/month.
5. Comparative Analysis: GB 35CrMo vs. Outros materiais
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.
| Material | Tensile Strength | Resistência à corrosão | Densidade | Custo (contra. GB 35CrMo) | Best For |
|---|---|---|---|---|---|
| GB 35CrMo | ≥980 MPa | Moderado | 7.85 g/cm³ | 100% (base) | High-stress parts (eixos, rolamentos) |
| Aço inoxidável (304) | 515 MPa | Excelente | 7.93 g/cm³ | 170% | Food/chemical equipment |
| Carbon Steel (45#) | 600 MPa | Low | 7.85 g/cm³ | 55% | Low-stress parts (brackets) |
| Liga de aço (40Cr) | 980 MPa | Moderado | 7.85 g/cm³ | 85% | General machinery parts |
| Alumínio (6061) | 310 MPa | Bom | 2.70 g/cm³ | 110% | Lightweight parts (quadros automotivos) |
Key takeaway: GB 35CrMo matches 40Cr’sresistência à tracção but has betterheat stability (thanks tomolibdênio (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
Na 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 years, and itstemperabilidade eresistência à fadiga 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—itsmelting point (1420–1450°C) emolibdênio (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 highercarbono (C) contente (0.38–0.45% vs. 0.32–0.40% for GB 35CrMo), giving it 10% higherresistência à tracção. Choose GB 42CrMo for extreme-stress parts (por exemplo, 30-ton truck shafts), and GB 35CrMo for moderate-stress, cost-sensitive projects (por exemplo, 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 (por exemplo, water-miscible coolant) and reduce cutting speed to 80–100 m/min to minimize tool wear.