AISI 4340 Round Bar
AISI 4340 Round Bar is a high-strength alloy steel product widely utilized in heavy-duty industrial applications due to its excellent mechanical properties and toughness. Known for its balanced combination of strength, hardness, and wear resistance, this alloy is specifically engineered to meet stringent performance standards in demanding environments. The material composition typically includes nickel, chromium, and molybdenum, which contribute to enhanced fatigue resistance and improved hardenability.
Manufactured as a precision-machined cylindrical rod, the bar is available in various diameters and lengths to accommodate diverse engineering requirements. Its robust tensile strength and superior impact resistance make it an ideal choice for components such as gears, shafts, crankshafts, and structural parts subjected to high stress. Heat treatment processes like quenching and tempering further optimize the microstructure, ensuring consistent performance under cyclic loads.
Industries such as aerospace, automotive, oil and gas, and heavy machinery heavily rely on this grade for critical applications where reliability and durability are paramount. Its ability to maintain mechanical integrity at elevated temperatures and under corrosive conditions expands its usability across challenging operational settings. Additionally, the alloy's machinability and weldability allow for flexible fabrication options, facilitating customized solutions for complex assemblies.
From an export perspective, the product adheres to international quality certifications and standards, ensuring compatibility with global industrial requirements. Supply chain partners can expect thorough documentation, traceability, and compliance with material specifications, making it suitable for worldwide distribution. Packaging and logistics are optimized to preserve the integrity of the bars during transit, supporting timely delivery and seamless integration into manufacturing workflows.
Our Approvals | Third Party Inspection
Lead Time
2–7 weeks depending on size
Delivery Terms
FOB, CIF, DDP
Shipping Modes
Sea / Air / Express
Why AISI 4340 Round Bar Are Preferred by Global Buyers
- ✔ Factory Pricing: Direct manufacturer rates with bulk stock
- ✔ Certified Quality: ISO & 3rd-party tested, EN 10204 certified
- ✔ Export-Ready: Sea-worthy packaging for on-time delivery
- ✔ Fast RFQs: Quick quotes for custom sizes & quantities
- ✔ Traceability: 100% heat number tracking from raw material to finished product
Trusted by industries like oil & gas, petrochemicals, power, marine, and heavy engineering.
- Manufacturing Capacity: 500 MT / Month
- Export Experience: 50+ Years
- Countries Served: 50+
- Annual Export Volume: 5,500 MT
Table of Contents
- 1. What is AISI 4340 Round Bar
- 2. How to Choose the Right Manufacturer
- 3.Comparison of AISI 4340 Round Bar
- 4. Why Global Buyers Source from Super Metal Manufacturing Co.
- 5. Features
- 6. Technical Overview
- 7. Specifications
- 8. Available Grades
- 9. Available Sizes
- 10. Chemical Properties
- 11. Mechanical Properties
- 12. Physical & Thermal Properties
- 13. Electrical Resistivity
- 14. Equivalent Grades
- 15. Manufacturing Process & Heat Treatment
- 16. Various Types
- 17. Applications & Uses
- 18. Industries We Serve
- 19. Latest Price List
- 20. MOQ & Payment Terms
- 21.Export Packaging & Shipping
- 22. Cities We Supply in India
- 23. Countries We Export Worldwide
- 24. Our Certifications
- 25. Quality Inspection & Testing
- 26. Our Other Product Types
- 27. People Also Search For
- 28. Frequently Asked Questions
- 29. About Super Metal Manufacturing Co.
How to Choose the Right AISI 4340 Round Bar
India is home to hundreds of manufacturers ranging from small job shops to large ISO-certified exporters. International and domestic buyers typically evaluate manufacturers based on quality compliance, production capacity, export experience, and pricing transparency.
- Certification & international standards (ASME, ASTM, EN)
- Manufacturing capability vs trading activity
- Export documentation & inspection support
- Stock availability & lead time reliability
- Past supply experience in oil & gas, EPC & heavy industries
Comparison Factors Among AISI 4340 Round Bar
| Evaluation Factor | Small Local Suppliers | Trading Companies | ISO-Certified Manufacturers |
|---|---|---|---|
| Manufacturing Control | Limited | None | Full in-house / audited partners |
| International Standards | Basic | Depends on source | ASME / ASTM / EN |
| Inspection & MTCs | Limited | Inconsistent | EN 10204 3.1 / 3.2 |
| Export Experience | Low | Medium | 50+ countries |
| Risk for EPC Projects | High | Medium | Low |
International buyers typically prefer ISO-certified manufacturers for large-scale or critical applications due to better quality control, documentation, and lower project risk.
Why Global Buyers Choose Super Metal Manufacturing Co.
Super Metal Manufacturing Co. is a trusted ISO 9001:2015 certified manufacturer and global exporter of ferro alloys and metal products, supplying consistent, high-quality materials to customers across USA, UK, Europe, Middle East, Africa, and Asia-Pacific. Our focus on quality assurance, cost efficiency, and on-time delivery makes us a preferred sourcing partner for international buyers.
| Key Advantage | Buyer Benefit |
|---|---|
| ISO 9001:2015 Certified Manufacturing | Consistent quality with documented QA systems and process control |
| ASME / ASTM / EN Compliant Products | Globally accepted standards with EN 10204 3.1 / 3.2 MTCs |
| Lower Manufacturing & Sourcing Costs | Save up to 15–20% compared to European suppliers |
| Favorable Exchange Rate Advantage | Reduced landed cost for international importers |
| In-House Testing & Inspection Facilities | Strict chemical, mechanical & dimensional quality checks |
| Bulk Stock & High Production Capacity | Fast order fulfillment and stable supply for large projects |
| Custom Sizes & Drawing-Based Manufacturing | Products manufactured exactly to buyer specifications |
| Export-Grade Packaging & Global Logistics | Sea-worthy packing, palletization & worldwide shipping support |
| Faster Global Shipping Routes | Optimized logistics for Middle East, Africa & Southeast Asia |
| Technical & After-Sales Support | Project assistance, documentation & responsive RFQ handling |
| Trusted by Global Steel & EPC Companies | Proven export experience across 50+ countries |
Features of AISI 4340 Round Bar
- ✔ High tensile strength, providing excellent resistance to deformation under load.
- ✔ Good toughness, ensuring durability and resistance to impact.
- ✔ Excellent wear resistance, ideal for demanding applications in automotive and aerospace industries.
- ✔ Superior machinability, facilitating easy fabrication and shaping.
- ✔ Versatile heat treatment capabilities, allowing for tailored mechanical properties.
- ✔ Corrosion resistance when properly treated, extending the lifespan of components.
Technical Overview of AISI 4340 Round Bar
| Product | Composition | Usage | Standards |
|---|---|---|---|
| AISI 4340 Round Bar | Carbon: 0.38-0.43%, Manganese: 0.60-0.90%, Phosphorus: ≤0.035%, Sulfur: ≤0.040%, Chromium: 0.70-0.90%, Nickel: 1.65-2.00%, Molybdenum: 0.15-0.25% | Used in high-stress applications such as gears, shafts, and heavy-duty machinery components due to its high strength and toughness. | ASTM A29, ASTM A322, SAE J403 |
| AISI 4340 Round Bar | Carbon: 0.38-0.43%, Manganese: 0.60-0.90%, Phosphorus: ≤0.035%, Sulfur: ≤0.040%, Chromium: 0.70-0.90%, Nickel: 1.65-2.00%, Molybdenum: 0.15-0.25% | Commonly used in the aerospace industry for components that require high fatigue resistance and toughness. | AMS 6345, ASTM A304 |
| AISI 4340 Round Bar | Carbon: 0.38-0.43%, Manganese: 0.60-0.90%, Phosphorus: ≤0.035%, Sulfur: ≤0.040%, Chromium: 0.70-0.90%, Nickel: 1.65-2.00%, Molybdenum: 0.15-0.25% | Ideal for manufacturing high-performance automotive parts, including crankshafts and connecting rods. | ISO 683-1, DIN 17200 |
Specifications Table
| Material | AISI 4340 |
|---|---|
| Grades | 4340 |
| Standard | ASTM A29/A29M |
| Size Range | 0.25" to 10.0" diameter |
| Length | Up to 20 feet |
| Form | Round Bar |
Available Grades Table
| Product | Composition | Applications |
|---|---|---|
| AISI 4340 Round Bar | C: 0.38-0.43, Mn: 0.60-0.90, Si: 0.15-0.40, Ni: 1.65-2.00, Cr: 0.70-0.90, Mo: 0.15-0.25 | Automotive components, aerospace applications, heavy machinery, and high-stress structural components. |
| AISI 4340 Quenched and Tempered Round Bar | C: 0.38-0.43, Mn: 0.60-0.90, Si: 0.15-0.40, Ni: 1.65-2.00, Cr: 0.70-0.90, Mo: 0.15-0.25 | High-strength applications requiring improved toughness and fatigue resistance, such as gears and shafts. |
| AISI 4340 Cold Drawn Round Bar | C: 0.38-0.43, Mn: 0.60-0.90, Si: 0.15-0.40, Ni: 1.65-2.00, Cr: 0.70-0.90, Mo: 0.15-0.25 | Used in precision machining applications and components requiring excellent surface finish. |
| AISI 4340 Hot Rolled Round Bar | C: 0.38-0.43, Mn: 0.60-0.90, Si: 0.15-0.40, Ni: 1.65-2.00, Cr: 0.70-0.90, Mo: 0.15-0.25 | Fabrication of large components where toughness and strength are essential, such as in construction and mining equipment. |
| AISI 4340 Stress Relieved Round Bar | C: 0.38-0.43, Mn: 0.60-0.90, Si: 0.15-0.40, Ni: 1.65-2.00, Cr: 0.70-0.90, Mo: 0.15-0.25 | Used in high-stress applications to minimize residual stresses and improve dimensional stability. |
Available Sizes of AISI 4340 Round Bar (MM)
| Size (MM) | Size (MM) |
|---|---|
| 20 | 30 |
| 25 | 35 |
| 28 | 40 |
| 32 | 45 |
| 36 | 50 |
| 40 | 55 |
| 45 | 60 |
| 50 | 65 |
| 60 | 70 |
| 75 | 80 |
Chemical Properties of AISI 4340 Round Bar
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.38 - 0.43 |
| Manganese (Mn) | 0.60 - 0.90 |
| Phosphorus (P) | 0.035 max |
| Sulfur (S) | 0.040 max |
| Silicon (Si) | 0.15 - 0.40 |
| Nickel (Ni) | 1.65 - 2.00 |
| Chromium (Cr) | 0.70 - 0.90 |
| Molybdenum (Mo) | 0.15 - 0.25 |
Mechanical Properties of AISI 4340 Round Bar
| Property | Value |
|---|---|
| Tensile Strength (MPa) | 745 |
| Yield Strength (MPa) | 655 |
| Elongation (%) | 20 |
| Hardness (HB) | 250 |
| Modulus of Elasticity (GPa) | 210 |
AISI 4340 Round Bar – Physical & Thermal Properties
Density of AISI 4340 Round Bar
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.85 g/cm³ | 0.284 lb/in³ |
Melting Point of AISI 4340 Round Bar
| Property | Metric | Imperial |
|---|---|---|
| Melting Point | 1420 - 1460 °C | 2600 - 2660 °F |
Specific Heat of AISI 4340 Round Bar
| Specific Heat of AISI 4340 Round Bar | ||
|---|---|---|
| Specific Heat (J/kg·K) | Temperature Range (°C) | Condition |
| 500 | 20 - 100 | Room Temperature |
| 600 | 100 - 300 | Annealed |
| 700 | 300 - 600 | Tempered |
Electrical Resistivity of AISI 4340 Round Bar
| Electrical Resistivity | ||
|---|---|---|
| Value (µΩ·m) | Temperature (°C) | Treatment or Condition |
| 75 | 20 | Normalized |
| 85 | 100 | |
| 95 | 200 | |
| 105 | 300 | |
| 115 | 400 | |
Equivalent of AISI 4340 Round Bar
| Standard | Werkstoff Nr. | UNS |
|---|---|---|
| ASTM A829 | 34CrNiMo6 | G43400 |
| EN 10083-3 | 34CrNiMo6 | 1.6582 |
Manufacturing Process & Heat Treatment of AISI 4340 Round Bar
Annealing
AISI 4340 round bars undergo a full annealing process to relieve internal stresses and improve machinability. The material is heated to a temperature range of 850-900°C and held for a specified duration before being slowly cooled in the furnace. This process enhances the ductility and toughness of the steel, making it easier to work with in subsequent manufacturing steps.
Forging
The forging of AISI 4340 involves heating the steel to approximately 1100-1200°C, followed by deformation under high pressure. This process refines the grain structure, resulting in improved strength and toughness. The forged bars are then allowed to cool gradually to avoid cracking and distortion.
Hardening & Tempering
| Process | Temperature Range (°C) | Quenching Medium | Purpose |
|---|---|---|---|
| Hardening | 830-870 | Oil | To increase hardness and strength |
| Tempering | 400-600 | Air | To reduce brittleness and improve toughness |
| Stress Relieving | 600-650 | Air | To eliminate residual stresses |
The heat treatment processes of hardening and tempering are crucial in achieving the desired mechanical properties of AISI 4340 round bars, ensuring they meet the stringent requirements for various industrial applications.
Various Types
AISI 4340 Round Bar - Standard
- Diameter: 10mm to 250mm
- Condition: Hot Rolled, Annealed
- Applications: Aerospace, Automotive, Structural Components
AISI 4340 Round Bar - Heat Treated
- Diameter: 20mm to 200mm
- Condition: Heat Treated, Quenched and Tempered
- Applications: High Strength Components, Gears, Shafts
AISI 4340 Round Bar - Cold Drawn
- Diameter: 5mm to 100mm
- Condition: Cold Drawn
- Applications: Precision Parts, Fasteners
AISI 4340 Round Bar - Customized
- Diameter: Custom Sizes Available
- Condition: Varies Based on Customer Requirements
- Applications: Specialized Engineering Applications
Applications & Uses
- Oil & Gas Industry
- Petrochemical Plants
- Water Treatment Plants
- Pharmaceutical Industry
- Food & Beverage Industry
- Automobile Industry
Industries We Serve
Our alloys are widely used across:
- Steel Plants
- Foundries & Casting Units
- Automobile Industry
- Shipbuilding & Marine
- Oil & Gas
- Engineering Components
- Heavy Industrial Machinery
latest Price List of AISI 4340 Round Bar
| Material Grade | Thickness | Price (USD / Kg) | Price (INR / Kg) |
|---|---|---|---|
| AISI 4340 Round Bar | 3 mm | $5.00 – $5.50 | ₹410 – ₹450 |
| AISI 4340 Round Bar | 6 mm | $4.80 – $5.30 | ₹395 – ₹440 |
| AISI 4340 Round Bar | 10 mm | $4.60 – $5.10 | ₹380 – ₹425 |
Note: Prices are indicative and may vary based on size, quantity, raw material cost, and delivery location. Contact us for the latest quotation for AISI 4340 Round Bar.
MOQ & Payment Terms
Minimum Order Quantity: 25–100 Kg depending on part size and grade.
Payment Terms: Depending On Grade and Quantity Size
Export Packaging & Shipping
- Seaworthy, fumigated wooden crates with waterproof inner lining
- Palletised packing with clear shipping marks and heat number identification
- Container stuffing supervision with loading photographs available on request
Cities We Suppllied In India
| Supply Cities | |||||
|---|---|---|---|---|---|
| Mumbai | Delhi | Pune | Chennai | Hyderabad | Bengaluru |
| Ahmedabad | Rajkot | Coimbatore | Kolkata | Bhopal | Surat |
We exported to 50+ countries worldwide.
| Exported Countries | |||||
|---|---|---|---|---|---|
| USA | UK | UAE | Germany | South Africa | Australia |
| Italy | Canada | Netherlands | Qatar | Saudi Arabia | Malaysia |
Our Certifications
We are a certified manufacturer and exporter, committed to strict quality control and international compliance standards.
Quality Inspection & Testing
At Super Metal Manufacturing Co., all products are checked through strict quality inspection and testing to meet international standards such as ASTM, ASME, EN, and DIN. This ensures consistent quality, accurate dimensions, and full material traceability.
- ✔ Chemical composition testing
- ✔ Mechanical tests such as tensile and hardness
- ✔ Dimensional inspection as per standard tolerances
- ✔ PMI, ultrasonic, and visual inspection (if required)
- ✔ EN 10204 3.1 / 3.2 test certificates
- ✔ Third-party inspection by SGS, TUV, BV, or Lloyd’s
Our quality systems support reliable supply for oil & gas, petrochemical, power, marine, and heavy engineering projects.
People Also Search For
- AISI 4140 Round Bar
- AISI 4130 Round Bar
- AISI 1045 Round Bar
- AISI 8620 Round Bar
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Frequently Asked Questions
About Super Metal Manufacturing Co.
Super Metal Manufacturing Co. is a trusted name in the metal industry since 1965, specializing in the manufacturing and export of high-quality 4140, EN19, and 42CrMo4 round bars. With decades of experience, we have built a strong reputation for delivering precision-engineered, durable, and high-performance steel products to industries worldwide.
Our company is committed to excellence through a robust quality management system and strict quality control at every stage of production. From sourcing premium raw materials from reputed suppliers like SAIL and JSW to final delivery, every product undergoes rigorous testing including tensile testing, bend and rebend tests, chemical analysis, and ultrasonic testing to ensure superior performance and reliability.
We are accredited with ISO 9001 certification and are TUV certified, reflecting our commitment to international quality standards. Our state-of-the-art manufacturing facilities, advanced machinery, and skilled workforce enable us to deliver customized solutions tailored to client requirements.
- ✔ 50+ years of industry experience in alloy steel and round bar manufacturing
- ✔ Specialized in 4140, EN19, and 42CrMo4 high-performance round bars
- ✔ ISO certified and TUV approved quality standards
- ✔ Strict quality testing including ultrasonic and chemical analysis
- ✔ Premium raw material sourcing from SAIL and JSW
- ✔ Advanced manufacturing infrastructure with modern machinery
- ✔ Custom-engineered solutions as per drawings and specifications
- ✔ Global export capability with reliable delivery
- ✔ Trusted by industries for critical and high-performance applications
Our Mission
Our mission is to deliver the highest-quality alloy steel round bars while maintaining excellence in precision, innovation, and customer satisfaction. We aim to empower industries worldwide by providing reliable and durable products that meet evolving manufacturing needs.
Our Vision
Our vision is to become a global leader in the manufacturing and export of premium-quality round bars, recognized for our product excellence, innovation, and commitment to exceeding customer expectations.