Si necesita un acero de aleación que destaque en la cementación, perfecto para alto desgaste, precision parts like automotive gears or machinery shafts—JIS SCM420 alloy steel es una de las mejores opciones. Como aleación de cromo-molibdeno estándar japonesa, equilibra una gran templabilidad, tenacidad, y maquinabilidad. Esta guía desglosa todo lo que necesitas saber., desde su composición química hasta usos en el mundo real, to help you use it effectively.
1. Material Properties of JIS SCM420 Alloy Steel
JIS SCM420’s performance comes from its well-balanced properties, all compliant with Japan’sJIS G4105 estándar. Let’s explore each key aspect clearly.
1.1 Composición química
The elements in JIS SCM420 work together to boost carburizing performance, fortaleza, y durabilidad. Below is the standard composition range:
| Element | Symbol | Composition Range (%) | Key Role in the Alloy |
|---|---|---|---|
| Carbón (do) | do | 0.18 – 0.23 | Low carbon content, ideal for carburizing (forms a hard outer layer while keeping the core tough) |
| Cromo (cr) | cr | 0.90 – 1.20 | Enhancestemplabilidad yresistencia al desgaste; improves carburizing depth and uniformity |
| Molibdeno (Mes) | Mes | 0.15 – 0.25 | Increasesresistencia a la fatiga y estabilidad a altas temperaturas; prevents brittleness after carburizing |
| Manganeso (Minnesota) | Minnesota | 0.60 – 0.85 | Impulsamaquinabilidad and grain refinement; strengthens the alloy without losing ductility |
| Silicio (Y) | Y | 0.15 – 0.35 | Acts as a deoxidizer during steelmaking; enhances overall strength |
| Níquel (En) | En | ≤ 0.25 | Trace amounts slightly improvedureza al impacto without raising costs |
| Sulfur (S) | S | ≤ 0.030 | Kept low to avoid cracking in carburized parts and high-stress applications |
| Phosphorus (PAG) | PAG | ≤ 0.030 | Limited to prevent cold brittleness (fracture in low-temperature environments) |
| Vanadio (V) | V | ≤ 0.03 | Tiny amounts refine grain structure, ensuring uniform hardness across the part |
1.2 Propiedades físicas
These traits show how JIS SCM420 behaves in different working conditions—like temperature changes or magnetic fields:
- Densidad: 7.85 gramos/cm³ (same as most ferrous alloys, easy to integrate into existing designs)
- Punto de fusión: 1420 – 1450°C (high enough for aplicaciones de alta temperatura like industrial rollers or engine parts)
- Conductividad térmica: 44 con/(m·K) a 20ºC (retains heat well, suitable for parts that operate continuously)
- Capacidad calorífica específica: 465 j/(kg·K) a 20ºC (absorbs heat steadily, avoiding warping from sudden temperature swings)
- Coeficiente de expansión térmica: 12.2 μm/(m·K) (low expansion, critical for precision parts like gears)
- Propiedades magnéticas: Ferromagnético (attracts magnets, useful for tools like magnetic clamps or sensors)
1.3 Propiedades mecánicas
JIS SCM420’s full mechanical strength is unlocked aftercarburación + temple + templado (its standard heat treatment). Below are typical values tested to Japanese standards:
| Propiedad | Valor típico (Carburized) | Test Standard (ÉL) |
|---|---|---|
| Resistencia a la tracción | ≥ 980 MPa | JIS Z2241 |
| Fuerza de producción | ≥ 785 MPa | JIS Z2241 |
| Alargamiento | ≥ 12% | JIS Z2241 |
| Reduction of area | ≥ 45% | JIS Z2241 |
| Dureza (Brinell) | 240 – 300 media pensión | JIS Z2243 |
| Dureza (Rockwell C) | 25 – 32 CDH (centro) / 58 – 62 CDH (superficie) | JIS Z2245 |
| Dureza (Vickers) | 245 – 305 HV | JIS Z2244 |
| Dureza al impacto | ≥ 70 J | JIS Z2242 |
| Fuerza de fatiga | ~530 MPa | JIS Z2273 |
1.4 Otras propiedades
- Resistencia a la corrosión: Moderado (resists mild moisture and oils; use zinc plating or paint for outdoor/humid environments)
- Resistencia al desgaste: Excelente (thanks to carburizing and cromo (cr); perfect for moving parts like gears or bearings)
- maquinabilidad: Bien (soft in annealed state; use high-speed steel (HSS) or carbide tools with cutting fluid to reduce wear)
- Soldabilidad: Acceptable (preheat to 250 – 300°C and post-weld heat treat to avoid cracking; use low-hydrogen electrodes)
- Templabilidad: Outstanding (carburizing penetrates deeply, creating a hard outer layer and tough core—ideal for high-wear parts)
2. Applications of JIS SCM420 Alloy Steel
JIS SCM420’s carburizing ability and toughness make it ideal forhigh-stress, aplicaciones de alto desgaste. Here are its most common uses, con ejemplos del mundo real:
2.1 Industria automotriz
Cars and trucks rely on its durability for key transmission parts:
- Engranajes: A Japanese automaker uses it for manual transmission gears—its carburized surface (HRC 58–62) gives resistencia al desgaste that extends gear life by 40% vs. acero carbono.
- Ejes: Compact SUVs use JIS SCM420 drive shafts; es resistencia a la fatiga (~530 MPa) handles constant torque without breaking.
- Ejes: Commercial vans use it for rear axles—its dureza al impacto (≥70 J) prevents bending during heavy loading.
2.2 Ingeniería Mecánica
Industrial machinery benefits from its hardenability:
- Aspectos: A manufacturing plant uses it for conveyor belt bearings—its carburized layer reduces maintenance downtime by 30%.
- Rollers: Printing machinery uses it for pressure rollers; es dureza (240–300 HB core) resists wear from paper friction.
- Bolts and fasteners: High-speed machine tools use it for critical bolts—its resistencia a la tracción (≥980 MPa) resists vibration loosening.
2.3 Maquinaria Pesada
For large-scale equipment, it provides reliable performance:
- Ballestas: Construction excavators use it for bucket springs; its elasticity (from tempering) withstands 10,000+ compression cycles.
- Componentes estructurales: Mining machinery uses it for crusher shafts—its templabilidad ensures uniform strength in thick sections.
3. Manufacturing Techniques for JIS SCM420 Alloy Steel
To maximize JIS SCM420’s performance, follow these industry-proven manufacturing steps:
3.1 Steelmaking Processes
It’s typically produced using two methods:
- Horno de arco eléctrico (EAF): Most common for medium batches. Scrap steel is melted with electrodes, entonces cromo (cr) y molibdeno (Mes) are added to reach the target composition. EAF is flexible and reduces waste, ideal for custom parts like large gears.
- Horno de oxígeno básico (BOF): Used for mass production. Molten iron is mixed with oxygen to remove impurities, then alloy elements are added. BOF is faster and cost-effective for standard parts like bolts.
3.2 Tratamiento térmico
Carburizing is the core heat treatment for JIS SCM420. The standard process is:
- Recocido: Calentar para 820 – 850°C, cool slowly. Softens the alloy for easier machining (cuts tool wear by 35%).
- Carburación: Calentar para 900 – 950°C in a carbon-rich atmosphere (p.ej., natural gas). Creates a 0.8–1.2 mm hard outer layer (carbon content 0.8–1.0%) para resistencia al desgaste.
- Temple: Cool rapidly in oil (de 830 – 850°C). Hardens the carburized surface to HRC 58–62.
- Templado: Calentar para 180 – 220°C, cool in air. Reduces brittleness while keeping the surface hard.
3.3 Forming Processes
JIS SCM420 is shaped into parts using:
- Forja: Hammered or pressed at 1100 – 1200°C. Aligns the metal’s grain, increasing resistencia a la tracción por 15% vs. cast parts. Used for gears and shafts.
- Laminación: Passed through rollers to make bars or sheets. Used for basic shapes like bolt blanks.
- Extrusión: Pushed through a die to make complex shapes (p.ej., hollow shafts). Ideal for precision parts like transmission components.
3.4 Machining Processes
After forming, parts are finished with:
- Torneado: Uses a lathe to make cylindrical parts (p.ej., ejes). Use cutting fluid to prevent overheating.
- Molienda: Uses a rotating cutter to shape gear teeth. Carbide tools work best for precision (p.ej., gear tooth tolerance ±0.02 mm).
- Perforación: Creates holes for bolts. High-speed drills (1000–1500 RPM) avoid cracking.
- Molienda: Smooths the carburized surface to tight tolerances. Mejora resistencia al desgaste by reducing surface friction.
4. Estudio de caso: JIS SCM420 in Automotive Transmission Gears
A Japanese automotive factory faced a problem: their carbon steel transmission gears failed after 150,000 km, causing costly recalls. They switched to JIS SCM420—and solved the issue.
4.1 Desafío
The factory’s compact cars were used in urban areas with frequent start-stop cycles. Carbon steel gears had lowresistencia al desgaste yresistencia a la fatiga (400 MPa), leading to tooth wear and transmission slippage. The failure rate was 5% por año, hurting brand trust.
4.2 Solución
They switched to JIS SCM420 gears, usando:
- Carburación (920°C para 4 horas) to create a 1.0 mm hard outer layer.
- Temple + templado (200°C) to reach HRC 60 on the surface and 30 HRC in the core.
- Precision grinding to smooth gear teeth, reduciendo la fricción y el desgaste.
4.3 Resultados
- Service life: Gears now last 300,000 km—double the previous lifespan.
- Ahorro de costos: Cut recall costs by ¥280,000 per year.
- Actuación: Transmission efficiency improved by 5%, reduciendo el consumo de combustible.
5. Comparative Analysis: JIS SCM420 vs. Other Materials
How does JIS SCM420 stack up against common alternatives? Here’s a side-by-side comparison:
| Material | Resistencia a la tracción | Resistencia al desgaste | Dureza al impacto | Costo (vs. JIS SCM420) | Mejor para |
|---|---|---|---|---|---|
| JIS SCM420 | ≥980 MPa | Excelente | ≥70 J | 100% (base) | High-wear, piezas de precisión (engranajes) |
| Acero inoxidable (SUS304) | 515 MPa | Bien | 60 J | 180% | Food/chemical equipment |
| Acero carbono (S45C) | 600 MPa | Bajo | 35 J | 50% | Piezas de baja tensión (paréntesis) |
| Acero aleado (SCM415) | 800 MPa | Bien | 60 J | 80% | General machinery parts |
| Titanio (Ti-6Al-4V) | 1100 MPa | Bien | 110 J | 800% | Piezas aeroespaciales ligeras |
Conclusión clave: JIS SCM420 has betterresistencia al desgaste than SCM415 or carbon steel, thanks to carburizing. It’s cheaper than stainless steel and titanium, making it the best value foralto desgaste, precision applications.
Yigu Technology’s Perspective on JIS SCM420 Alloy Steel
En Yigu Tecnología, JIS SCM420 is our top choice for carburized parts like automotive gears. We’ve supplied it to clients for 12+ años, and itstemplabilidad ymolybdenum-enhanced fatigue strength consistently meet strict standards. We optimize the carburizing process to ensure a uniform hard layer, helping clients extend part life by 2–3x. Para uso en exteriores, we pair it with anti-rust coatings. For manufacturers needing durable, cost-effective high-wear parts, JIS SCM420 is unmatched.
FAQ About JIS SCM420 Alloy Steel
1. Is JIS SCM420 the same as AISI 4120?
Yes—JIS SCM420 is nearly identical to AISI 4120 (American standard) in chemical composition and performance. They can be used interchangeably, making JIS SCM420 a great choice for global supply chains.
2. Can JIS SCM420 be used without carburizing?
It can, but carburizing is recommended for high-wear parts. Without carburizing, esresistencia al desgaste is lower (similar to mild alloy steel), so it’s only suitable for low-stress parts like non-critical shafts or brackets.
3. How to improve JIS SCM420’s corrosion resistance?
Add a protective coating: galvanizado (for outdoor parts like bolts), recubrimiento en polvo (for structural components), or chrome plating (for moving parts like bearings). These treatments extend service life in humid environments by 5–10 years.