Se você está procurando um custo-benefício, high-strength alloy steel for mechanical parts like gears or shafts—JIS SCR440 alloy steel is an excellent choice. Como aço de liga de cromo padrão japonês, equilibra a temperabilidade sólida, resistência ao desgaste, e usinabilidade. Este guia detalha tudo o que você precisa saber, desde sua composição química até usos no mundo real, to help you make informed decisions for your projects.
1. Material Properties of JIS SCR440 Alloy Steel
JIS SCR440’s performance is rooted in its well-balanced properties, all compliant with Japan’sJIS G4105 padrão. Let’s explore each key aspect clearly.
1.1 Composição Química
The elements in JIS SCR440 work together to boost strength, dureza, e durabilidade. Below is the standard composition range:
| Elemento | Símbolo | Composition Range (%) | Key Role in the Alloy |
|---|---|---|---|
| Carbono (C) | C | 0.38 – 0.45 | Enhancesresistência à tracção and surface hardness; critical for wear-resistant parts |
| Cromo (Cr) | Cr | 0.90 – 1.20 | Melhoratemperabilidade eresistência à corrosão; prevents oxidation at moderate temperatures |
| Manganês (Mn) | Mn | 0.60 – 0.90 | Impulsosusinabilidade and grain refinement; reduces brittleness after heat treatment |
| Silício (E) | E | 0.15 – 0.35 | Acts as a deoxidizer during steelmaking; strengthens the alloy without losing ductility |
| Molybdenum (Mo) | Mo | ≤ 0.15 | Trace amounts slightly enhance high-temperature stability; not a primary alloying element |
| Níquel (Em) | Em | ≤ 0.25 | Minimal content; small amounts slightly improveimpact toughness |
| Enxofre (S) | S | ≤ 0.030 | Kept low to avoid cracking and brittleness in high-stress applications |
| Fósforo (P) | P | ≤ 0.030 | Limited to prevent cold brittleness (fracture in low-temperature environments) |
| Vanadium (V) | V | ≤ 0.03 | Tiny amounts refine grain structure for uniform strength across the part |
1.2 Propriedades Físicas
These traits determine how JIS SCR440 behaves in different working conditions—like temperature changes or magnetic fields:
- Densidade: 7.85 g/cm³ (consistent with most ferrous alloys, easy to integrate into existing designs)
- Ponto de fusão: 1430 – 1450°C (high enough for aplicações de alta temperatura like industrial rollers or engine parts)
- Condutividade térmica: 45 C/(m·K) a 20ºC (retains heat well, suitable for parts that operate continuously)
- Specific heat capacity: 470 J/(kg·K) a 20ºC (absorbs heat steadily, avoiding warping from sudden temperature swings)
- Thermal expansion coefficient: 12.0 μm/(m·K) (low expansion, critical for precision parts like gears or shafts)
- Magnetic properties: Ferromagnético (atrai ímãs, useful for tools like magnetic clamps or sensors)
1.3 Propriedades Mecânicas
JIS SCR440’s full mechanical strength is unlocked aftertêmpera + têmpera (its standard heat treatment). Below are typical values tested to Japanese standards:
| Propriedade | Valor típico | Test Standard (ELE) |
|---|---|---|
| Resistência à tracção | ≥ 1000 MPa | JIS Z2241 |
| Força de rendimento | ≥ 800 MPa | JIS Z2241 |
| Alongamento | ≥ 12% | JIS Z2241 |
| Reduction of area | ≥ 45% | JIS Z2241 |
| Dureza (Brinell) | 229 – 286 HB | JIS Z2243 |
| Dureza (Rockwell C.) | 23 – 30 CDH | JIS Z2245 |
| Dureza (Vickers) | 230 – 290 Alta tensão | JIS Z2244 |
| Resistência ao impacto | ≥ 50 J. | JIS Z2242 |
| Força de fadiga | ~520 MPa | JIS Z2273 |
1.4 Outras propriedades
- Resistência à corrosão: Moderado (resists mild moisture, óleos, and industrial chemicals; use zinc plating or paint for outdoor/humid environments)
- Resistência ao desgaste: Bom (graças a cromo (Cr) e tratamento térmico; suitable for moving parts like bearings or rollers)
- Usinabilidade: Justo (softer in 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)
- Temperabilidade: Excelente (heat treatment penetrates deeply, ensuring uniform strength in thick parts like heavy machinery shafts)
2. Applications of JIS SCR440 Alloy Steel
JIS SCR440’s mix of strength, acessibilidade, and versatility makes it ideal foraplicações de alto estresse em todos os setores. Aqui estão seus usos mais comuns, com exemplos do mundo real:
2.1 Indústria Automotiva
Cars and commercial vehicles rely on its durability for key mechanical parts:
- Engrenagens: A Japanese automaker uses it for manual transmission gears—its resistência ao desgaste extends gear life by 30% contra. aço carbono.
- Eixos: Compact trucks use JIS SCR440 drive shafts; isso é yield strength (≥800 MPa) handles 20-ton loads without bending.
- Bolts and fasteners: High-performance sedans use it for engine mount bolts—their resistência à tracção (≥1000 MPa) resist vibration loosening.
2.2 Engenharia Mecânica
Industrial machines need parts that last through continuous use:
- Rolamentos: A manufacturing plant uses it for conveyor belt bearings—its dureza (229–286 HB) cuts maintenance downtime by 20%.
- Rollers: Printing machinery uses it for pressure rollers; isso é resistência à fadiga (~520 MPa) withstands repeated contact with paper.
- Molas: Small construction tools (like jackhammers) use it for compression springs; its elasticity (from tempering) alças 8,000+ ciclos.
2.3 Máquinas Pesadas
For large-scale equipment, it provides reliable strength:
- Crane shafts: Small port cranes use it for hoist shafts—its impact toughness (≥50 J) prevents fracture when lifting 25-ton containers.
- Structural fasteners: Agricultural machinery (like tractors) uses JIS SCR440 bolts; deles resistência à corrosão (with anti-rust coating) stands up to mud and rain.
3. Manufacturing Techniques for JIS SCR440 Alloy Steel
To maximize JIS SCR440’s performance, follow these industry-proven manufacturing steps:
3.1 Steelmaking Processes
It’s typically produced using two methods:
- Forno Elétrico a Arco (EAF): Most common for medium batches. Scrap steel is melted with electrodes, então cromo (Cr) is added to reach the target composition. EAF is flexible and reduces waste, ideal for custom parts like large gears.
- Forno de oxigênio 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 Tratamento térmico
Heat treatment is critical to unlock JIS SCR440’s full potential. The standard process for high-stress parts is:
- Recozimento: Aqueça até 820 – 850°C, cool slowly. Softens the alloy for easier machining (cuts tool wear by 30%).
- Têmpera: Aqueça até 840 – 860°C, cool rapidly in oil. Hardens the steel to reach resistência à tracção ≥1000 MPa.
- Temperamento: Aqueça até 500 – 550°C, cool in air. Reduces brittleness while retaining strength—critical for parts like gears or shafts.
- Carburização (optional): Aqueça até 900 – 950°C in a carbon-rich atmosphere. Adds a hard outer layer (0.8–1.0 mm thick) to boost resistência ao desgaste (ideal for bearings).
3.3 Forming Processes
JIS SCR440 is shaped into parts using:
- Forjamento: Hammered or pressed at 1100 – 1200°C. Aligns the metal’s grain structure, increasing resistência à tracção por 12% contra. cast parts. Used for gears, eixos, and crane components.
- Rolando: Passed through rollers to make bars, folhas, or rods. Used for basic shapes like bolt blanks or spring stock.
- Extrusão: Pushed through a die to make complex shapes (por exemplo, hollow shafts). Ideal for precision parts 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 work best for high precision (por exemplo, gear tooth tolerance ±0.02 mm).
- Perfuração: Creates holes for bolts or fasteners. High-speed drills (900–1400 RPM) avoid cracking.
- Moagem: Smooths surfaces to tight tolerances (por exemplo, ±0.01 mm for bearing inner rings). Melhora resistência ao desgaste by reducing surface friction.
4. Estudo de caso: JIS SCR440 in Automotive Transmission Gears
A Japanese automotive parts supplier faced a problem: their carbon steel transmission gears failed after 160,000 quilômetros, leading to customer complaints. They switched to JIS SCR440—and solved the issue.
4.1 Desafio
The supplier’s gears were used in compact cars with frequent city driving (start-stop cycles). Carbon steel gears had lowresistência à fadiga (400 MPa) eresistência ao desgaste, leading to tooth wear and transmission slippage. The failure rate was 6% per year, hurting the supplier’s reputation.
4.2 Solução
They switched to JIS SCR440 gears, usando:
- Forjamento (1150°C) to align grain structure and boost strength.
- Têmpera (850°C) + têmpera (530°C) to reach 820 MPa yield strength e 55 J. impact toughness.
- Precision grinding to smooth gear teeth, reduzindo o atrito e o desgaste.
4.3 Resultados
- Service life: Gears now last 320,000 km—double the previous lifespan.
- Economia de custos: Reduced replacement part costs by ¥240,000 per year.
- Confiabilidade: Failure rate dropped from 6% para 1%, restoring customer trust.
5. Comparative Analysis: JIS SCR440 vs. Outros materiais
How does JIS SCR440 stack up against common alternatives? Below is a side-by-side comparison of key traits:
| Material | Resistência à tracção | Resistência ao Impacto | Resistência à corrosão | Custo (contra. JIS SCR440) | Melhor para |
|---|---|---|---|---|---|
| JIS SCR440 | ≥1000 MPa | ≥50 J | Moderado | 100% (base) | High-stress, cost-sensitive parts |
| Aço inoxidável (SUS304) | 515 MPa | 60 J. | Excelente | 170% | Food/chemical equipment |
| Aço carbono (S45C) | 600 MPa | 35 J. | Baixo | 50% | Peças de baixo estresse (colchetes) |
| Liga de aço (SCM440) | 1080 MPa | 60 J. | Moderado | 110% | Peças de alto desempenho (eixos do motor) |
| Alumínio (A6061) | 310 MPa | 110 J. | Bom | 120% | Lightweight parts (car frames) |
Key takeaway: JIS SCR440 offers betterresistência à tracção than carbon steel and aluminum, while being cheaper than SCM440 or stainless steel. It’s the best value forhigh-stress, cost-sensitive applications like standard transmission gears or medium-duty shafts.
Yigu Technology’s Perspective on JIS SCR440 Alloy Steel
Na tecnologia Yigu, JIS SCR440 is a go-to for clients needing reliable, affordable high-strength parts. We’ve supplied it for automotive gears and machinery shafts for 10+ anos, and itstemperabilidade eresistência ao desgaste consistently meet mid-range performance needs. We often recommend annealing for easier machining and anti-rust coatings for outdoor use, helping clients cut maintenance costs by 25%. For manufacturers balancing performance and budget, JIS SCR440 is an unbeatable choice.
FAQ About JIS SCR440 Alloy Steel
1. Can JIS SCR440 be used in cold temperatures?
Yes—itsimpact toughness (≥50 J) lets it perform reliably at temperatures down to -15°C. For colder climates (-20°C or below), adjust the tempering process (lower to 480–500°C) to boost toughness to ≥60 J.
2. What’s the difference between JIS SCR440 and SCM440?
SCM440 containsmolibdênio (Mo) (0.15–0.25%), giving it 8% mais altoresistência à tracção and better high-temperature stability than SCR440. Choose SCM440 for extreme stress; SCR440 for cost-sensitive, medium-stress parts.
3. How to improve JIS SCR440’s corrosion resistance?
Add a protective coating: zincagem (for outdoor bolts), revestimento em pó (for structural components), or chrome plating (for moving parts like bearings). These treatments extend service life in humid environments by 5–8 years.