AISI 8640H Steel, cold drawn

AISI 8640H Steel, cold drawn, 25 mm (1 in.) round Product Information -:- For detailed product information, please contact sales. -: AISI 8640H Steel, cold drawn, 25 mm (1 in.) round Synonyms -:- For detailed product information, please contact sales. -:

AISI 8640H Steel, cold drawn, 25 mm (1 in.) round Product Information -:- For detailed product information, please contact sales. -: # Technical Data Sheet: AISI 8640H Alloy Steel ## Cold Drawn & Stress-Relieved Round Bar ### 1. Product Identification **Designation:** AISI 8640H / UNS H86400 **Condition:** Cold Drawn, Stress Relieved (CD-SR) **Form:** Round Bar **Diameter:** 25.0 mm (1.00 inch) ±0.08 mm (±0.003 inch) **Material Classification:** Nickel-Chromium-Molybdenum (Ni-Cr-Mo) Hardenability-Controlled Alloy Steel **Processing State:** Manufactured to be machined in the "soft" state, followed by heat treatment to final hardness/strength **Key Attributes:** This product represents AISI 8640H alloy steel that has undergone cold drawing at room temperature after hot rolling and annealing. This process significantly improves dimensional accuracy, surface finish, straightness, and strength through strain hardening. The material is supplied in a stress-relieved condition to optimize machinability and dimensional stability for subsequent manufacturing operations. ### 2. Standards & Specifications **International Standards:** - **ASTM:** - A311/A311M: Standard Specification for Cold-Drawn, Stress-Relieved Carbon and Alloy Steel Bars Subject to Mechanical Property Requirements - A29/A29M: Standard Specification for Steel Bars, Carbon and Alloy, Hot-Wrought and Cold-Finished - **SAE/AISI:** - SAE J1268: Hardenability Bands for H-Grade Steels - SAE J404: Chemical Composition - **UNS:** H86400 - **ISO:** - 683-11: Heat-treatable steels, alloy steels and free-cutting steels - 286-2: Geometrical tolerances for cold-drawn products - **EN (European):** 1.6546 (34CrNiMo6) - similar composition, not exact equivalent ### 3. Chemical Composition (H-Grade Controlled) **Guaranteed Composition (Weight %):** | Element | H-Grade Range | Typical Value | Purpose | |---------|---------------|---------------|---------| | **Carbon (C)** | 0.37 - 0.44% | 0.40% | Provides base hardenability for final heat treatment | | **Manganese (Mn)** | 0.70 - 1.05% | 0.85% | Enhances hardenability and strength | | **Silicon (Si)** | 0.15 - 0.35% | 0.25% | Deoxidizer, improves cleanliness | | **Nickel (Ni)** | 0.35 - 0.75% | 0.55% | Improves toughness and hardenability | | **Chromium (Cr)** | 0.35 - 0.65% | 0.50% | Increases hardenability depth | | **Molybdenum (Mo)** | 0.15 - 0.25% | 0.20% | Refines grain structure, improves hardenability | | **Phosphorus (P)** | ≤ 0.035% | 0.020% | Residual (minimized) | | **Sulfur (S)** | ≤ 0.040% | 0.025% | Residual (standard grade); higher sulfur versions available for improved machinability | | **Iron (Fe)** | Balance | Balance | Base element | **H-Grade Significance:** The "H" designation ensures controlled composition within specified ranges to guarantee consistent hardenability response after final heat treatment, as verified by Jominy end-quench testing. ### 4. Manufacturing Process & Condition **Production Sequence:** 1. **Hot Rolling:** Initial reduction from billet to approximate size 2. **Annealing:** Full anneal to achieve soft, uniform microstructure (typically 165-187 BHN) 3. **Cold Drawing:** Reduction of 10-20% in cross-sectional area at room temperature 4. **Stress Relieving:** Heat treatment at 595-650°C (1100-1200°F) to relieve internal stresses from cold working 5. **Final Processing:** Straightening, cutting to length, surface inspection **Key Process Characteristics:** - **Cold Reduction:** Typically 10-15% area reduction for 25 mm diameter - **Surface Finish:** Significantly improved over hot-rolled material - **Dimensional Control:** Tighter tolerances than hot-finished products - **Straightness:** Superior straightness for automated machining applications ### 5. Mechanical Properties (As Cold Drawn & Stress Relieved) **Typical Properties in Supplied Condition:** | Property | Typical Value | Test Standard | Notes | |----------|---------------|---------------|-------| | **Tensile Strength** | 700 - 850 MPa | ASTM A370 | 102 - 123 ksi | | **Yield Strength (0.2% offset)** | 515 - 655 MPa (minimum) | ASTM A370 | 75 - 95 ksi min | | **Elongation (in 50 mm)** | 12 - 18% | ASTM A370 | - | | **Reduction of Area** | 45 - 55% | ASTM A370 | - | | **Hardness** | 197 - 241 HB | ASTM E10 | Brinell hardness | | | 93 - 100 HRB | ASTM E18 | Rockwell B scale | | | 17 - 25 HRC | ASTM E18 | Rockwell C scale | | **Charpy V-Notch Impact** | 20 - 35 J | ASTM E23 | At room temperature | | **Machinability Rating** | 65% | - | Compared to 100% for B1112 steel | **Geometric & Surface Properties:** - **Diameter Tolerance:** ±0.08 mm (±0.003 inch) per ASTM A311 - **Straightness:** ≤ 1 mm per meter length - **Surface Roughness (Ra):** 3.2 - 1.6 μm (125 - 63 μinch) - **Surface Condition:** Free of scale, with smooth, clean finish - **Decarburization:** ≤ 0.25 mm (0.010 inch) maximum depth ### 6. Physical Properties | Property | Value | Units | Conditions | |----------|-------|-------|------------| | **Density** | 7.85 | g/cm³ | At 20°C | | **Melting Range** | 1425 - 1475 | °C | - | | **Thermal Conductivity** | 42.6 | W/m·K | At 100°C | | **Specific Heat Capacity** | 460 | J/kg·K | At 100°C | | **Coefficient of Thermal Expansion** | 11.5 × 10⁻⁶ | /°C | 20-100°C | | **Modulus of Elasticity** | 205 | GPa | 29.7 × 10⁶ psi | | **Shear Modulus** | 80 | GPa | 11.6 × 10⁶ psi | | **Poisson's Ratio** | 0.29 | - | - | ### 7. Characteristics & Advantages **Cold Drawn Benefits:** 1. **Improved Dimensional Accuracy:** Tighter diameter and roundness tolerances 2. **Enhanced Surface Finish:** Smoother surface for improved bearing surfaces and reduced friction 3. **Increased Yield Strength:** Strain hardening provides higher strength in the "as-supplied" condition 4. **Better Straightness:** Minimizes straightening operations before machining 5. **Consistent Properties:** Uniform mechanical properties throughout length **Stress Relieved Advantages:** 1. **Dimensional Stability:** Reduced tendency for distortion during machining 2. **Improved Machinability:** Softer than as-drawn condition, better chip formation 3. **Stress Relief:** Minimizes residual stresses that could cause warping 4. **Predictable Behavior:** Consistent performance during manufacturing **H-Grade Specific Advantages:** 1. **Predictable Heat Treatment Response:** Guaranteed hardenability within SAE J1268 bands 2. **Consistent Final Properties:** Minimal variation in hardened properties across production lots 3. **Reduced Testing:** Less extensive quality control required after heat treatment 4. **Design Confidence:** Engineers can design closer to material limits ### 8. Typical Applications **Automotive Components (High Volume Production):** - Transmission shafts and gears (machined before carburizing or through-hardening) - Axle shafts for passenger vehicles and light trucks - Steering components (tie rods, rack and pinion parts) - Suspension components requiring precision machining - Engine components (crankshafts, camshafts in softer state) **Industrial Machinery:** - Hydraulic cylinder rods (machined before hardening and chrome plating) - Pump shafts and impellers - Gear blanks for custom gear manufacturing - Machine tool components (spindles, arbors, shafts) - Conveyor system components **Fastener & Hardware Manufacturing:** - High-strength bolt blanks - Special fastener stock for aerospace and automotive - Custom pin and dowel stock - Stud and threaded rod stock **General Precision Components:** - Linear motion shafts and guides - Valve stems and components - Bearing journals and races (before final hardening) - Custom shafting for OEM applications - Coupling and universal joint components ### 9. Heat Treatment Response (Post-Machining) **Typical Heat Treatment Cycle:** 1. **Austenitizing:** 845°C ± 15°C (1550°F ± 25°F) 2. **Quenching:** Oil quench (fast oil, 40-80°C) 3. **Tempering:** Depending on required final properties: - 425°C (800°F): High strength, moderate toughness - 540°C (1000°F): Balanced strength and toughness (most common) - 650°C (1200°F): High toughness, moderate strength **Expected Final Properties (after 540°C temper):** - **Tensile Strength:** 1035-1170 MPa (150-170 ksi) - **Yield Strength:** 930-1070 MPa (135-155 ksi) - **Hardness:** 34-40 HRC - **Impact Toughness:** 40-60 J (30-44 ft-lb) ### 10. Machining Recommendations **Tooling & Parameters:** - **Tool Material:** Carbide or coated carbide recommended for production - **Cutting Speed:** 70-110 m/min (230-360 SFM) for turning operations - **Feed Rate:** 0.15-0.30 mm/rev (0.006-0.012 inch/rev) - **Depth of Cut:** Up to 3 mm (0.120 inch) depending on setup rigidity - **Coolant:** Recommended for optimal tool life and surface finish **Special Considerations:** - **Work Hardening:** Material may work-harden during machining; maintain consistent feed rates - **Chip Control:** Produces continuous chips; chip breakers may be necessary - **Surface Finish:** Can achieve Ra 0.8-1.6 μm (32-63 μinch) with proper tooling and parameters ### 11. Quality Control & Testing **Mandatory Testing for H-Grade:** 1. **Jominy Hardenability Test:** Per ASTM A255 on each heat 2. **Chemical Analysis:** Full spectrographic analysis 3. **Mechanical Testing:** Tensile and hardness testing per lot 4. **Dimensional Inspection:** Diameter, roundness, straightness 5. **Surface Inspection:** Visual and dimensional checks **Optional Testing:** - Ultrasonic testing for internal defects - Magnetic particle inspection for surface defects - Microstructural examination - Decarburization depth measurement **Certification Requirements:** - Mill Test Certificate EN 10204 3.1 or 3.2 - Hardenability test report - Heat treatment records (for stress relief) - Dimensional inspection report ### 12. Comparative Analysis **Vs. Hot-Rolled 8640H:** - Improved surface finish and dimensional accuracy - Higher yield strength in supplied condition - Better straightness and roundness - Higher cost (typically 15-25% premium) **Vs. Cold Drawn Standard 8640:** - More consistent heat treatment response - Predictable hardenability depth - Reduced property variation lot-to-lot - Slightly higher cost (5-10% premium) **Alternative Materials for Similar Applications:** - **4140H:** Lower cost, slightly lower hardenability - **4340H:** Higher strength potential, higher cost - **ETD150/ETD180:** Lower alloy content, lower hardenability ### 13. Storage & Handling **Storage Recommendations:** - Store in dry, covered area with controlled humidity (<60%) - Apply rust preventive oil for storage exceeding 30 days - Stack on level supports to prevent bending - Rotate stock (FIFO) to minimize storage time **Handling Guidelines:** - Use appropriate lifting equipment (non-metallic slings recommended) - Avoid impact damage to bar ends and surfaces - Protect machined surfaces during transport - Maintain identification and traceability markings **Shelf Life:** - 12 months with proper storage conditions - Inspect for surface corrosion before use if stored for extended periods - Surface rust can typically be removed by light polishing or machining ### 14. Procurement Specifications **Example Purchase Specification:** ``` MATERIAL: AISI 8640H Alloy Steel FORM: Cold Drawn, Stress Relieved Round Bar DIAMETER: 25.0 mm ±0.08 mm LENGTH: 3000-6000 mm random lengths CONDITION: CD-SR per ASTM A311 MECHANICAL PROPERTIES: Yield ≥ 515 MPa, Tensile 700-850 MPa HARDNESS: 197-241 HB (as supplied) SURFACE FINISH: ≤ 3.2 μm Ra STRAIGHTNESS: ≤ 1 mm/m CERTIFICATION: EN 10204 3.2 with Jominy Report PACKAGING: Bundled, protected ends, rust preventive ``` ### 15. Technical Support **Available Services from Qualified Suppliers:** - Material selection assistance - Machining parameter recommendations - Heat treatment process development - Failure analysis and troubleshooting - Just-in-time delivery programs - Custom cutting to specified lengths --- **Disclaimer:** This technical data sheet provides characteristic values and general guidelines for AISI 8640H cold drawn round bar. Actual properties may vary based on specific manufacturing processes. For critical applications, conduct appropriate testing and validation. This information does not constitute a material specification or warranty. Consult with qualified materials engineers for application-specific recommendations. --- **Document Control** - **Document Number:** TDS-8640H-CD25 - **Revision:** 1.0 - **Effective Date:** March 2024 - **Prepared By:** Materials Engineering Department - **Approved By:** Quality Assurance Manager - **Quality System:** ISO 9001:2015 Certified -:- For detailed product information, please contact sales. -: AISI 8640H Steel, cold drawn, 25 mm (1 in.) round Specification Dimensions Size： Diameter 20-1000 mm Length <6352 mm Size:We can customized as required Standard： Per your request or drawing We can customized as required Properties（Theoretical） Chemical Composition -:- For detailed product information, please contact sales. -: AISI 8640H Steel, cold drawn, 25 mm (1 in.) round Properties -:- For detailed product information, please contact sales. -:

Applications of AISI 8640H Steel, cold drawn, 25 mm (1 in.) round -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI 8640H Steel, cold drawn, 25 mm (1 in.) round -:- For detailed product information, please contact sales. -:

Packing of AISI 8640H Steel, cold drawn, 25 mm (1 in.) round -:- For detailed product information, please contact sales. -: Standard Packing: -:- For detailed product information, please contact sales. -: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 2823 gallon liquid totes Special package is available on request. E FORUs’ is carefully handled to minimize damage during storage and transportation and to preserve the quality of our products in their original condition