AISI Type L4 Tool Steel Sheet,Plate

AISI Type L4 Tool Steel Sheet/Plate Product Information -:- For detailed product information, please contact sales. -: AISI Type L4 Tool Steel Sheet/Plate Synonyms -:- For detailed product information, please contact sales. -:

AISI Type L4 Tool Steel Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: AISI Type L4 (UNS T61204) High-Toughness Tool Steel** ## **Overview** AISI Type L4 is a **medium-carbon, high-chromium** oil-hardening tool steel within the AISI "L-series" (Low-Alloy, Special Purpose). Distinguished by its **optimized carbon-chromium balance**, L4 provides exceptional **toughness and shock resistance** while maintaining good wear characteristics. This grade is specifically engineered for applications requiring both high hardness and the ability to withstand impact loading, bridging the gap between general-purpose tool steels and high-impact grades. **Key Advantages:** - **Superior Toughness:** Excellent resistance to chipping and fracture under impact conditions - **Good Wear Resistance:** Adequate carbide formation for moderate abrasive wear applications - **Deep Hardenability:** Through-hardening capability in substantial cross-sections - **Minimal Distortion:** Predictable dimensional stability during oil quenching - **Balanced Performance:** Optimal combination of hardness, strength, and ductility **Primary Considerations:** - Lower maximum hardness compared to higher-carbon L-series grades - Requires specific tempering protocols to optimize toughness - Best suited for applications where impact resistance is prioritized over extreme wear resistance ## **International Designations & Standards** | Standard System | Designation | Note | |----------------|-------------|------| | **AISI/SAE (USA)** | L4 | Primary specification | | **UNS (USA)** | T61204 | Unified numbering system | | **ASTM (USA)** | A681 | Governing material standard | | **DIN (Germany)** | ~1.2436 | Similar high-chromium tool steel | | **BS (UK)** | ~**BH11** | Related oil-hardening grade | | **JIS (Japan)** | ~SKS4 | Similar special purpose tool steel | | **ISO (International)** | ~**100CrMnMo8** | Closest functional equivalent | *Note: Direct international equivalents vary due to specific national composition preferences. AISI L4 is characterized by its balanced chromium content for optimal hardenability and toughness.* --- ## **1. Chemical Composition (Typical, Weight %)** The composition is carefully balanced to promote toughness while maintaining adequate hardenability and wear resistance. | Element | Content (%) | Role & Metallurgical Effect | |---------|-------------|-----------------------------| | **Carbon (C)** | 0.65 - 0.85 | Provides base hardness and strength. Lower than L3 to enhance toughness while maintaining wear resistance through carbide formation. | | **Chromium (Cr)** | 1.20 - 1.80 | Primary alloying element. Enhances hardenability depth, contributes to wear resistance through carbide formation, and provides slight corrosion resistance. | | **Manganese (Mn)** | 0.50 - 0.80 | Improves hardenability and promotes austenite stability during quenching. | | **Silicon (Si)** | 0.10 - 0.30 | Deoxidizer, provides solid solution strengthening, improves tempering resistance. | | **Molybdenum (Mo)**| 0.20 - 0.40 (Optional) | When present, enhances hardenability and toughness, particularly in thicker sections. | | **Vanadium (V)** | 0.10 - 0.20 (Optional) | Refines grain size, improves toughness and wear resistance through fine carbide precipitation. | | **Phosphorus (P)** | ≤0.025 | Harmful impurity; kept minimal to prevent temper embrittlement. | | **Sulfur (S)** | ≤0.025 | Impurity; controlled for optimal machinability without compromising transverse properties. | | **Iron (Fe)** | Balance | Matrix element. | **Grade Variations:** - **Standard L4:** Optimized for general impact applications - **Modified L4:** May include additional molybdenum or vanadium for specific applications --- ## **2. Physical & Mechanical Properties** ### **Physical Properties** | Property | Typical Value | Conditions/Notes | |----------|---------------|------------------| | **Density** | 7.82 - 7.84 g/cm³ | At 20°C (68°F) | | **Melting Range** | 1420 - 1440°C (2590 - 2625°F) | Liquidus to solidus range | | **Thermal Conductivity** | 43 - 47 W/m·K | At 20°C (68°F) | | **Specific Heat Capacity** | 470 - 490 J/kg·K | At 20°C (68°F) | | **Coefficient of Thermal Expansion** | 11.8 - 12.3 × 10⁻⁶/K | 20-200°C (68-392°F) range | | **Electrical Resistivity** | 0.28 - 0.32 μΩ·m | At 20°C (68°F) | | **Elastic Modulus** | 205 - 210 GPa (29.7 - 30.5 × 10⁶ psi) | At room temperature | ### **Mechanical Properties (Heat-Treated Condition)** | Property | Value Range | Heat Treatment Condition | |----------|-------------|--------------------------| | **Hardness (Annealed)** | 187 - 217 HB | Spheroidize annealed, ready for machining | | **Hardness (Hardened)** | 56 - 60 HRC | Oil quenched from 820-850°C, tempered at 200-300°C | | **Tensile Strength** | 1850 - 2100 MPa (268 - 305 ksi) | At 58-60 HRC | | **Yield Strength (0.2% offset)** | 1550 - 1750 MPa (225 - 254 ksi) | At 58-60 HRC | | **Compressive Strength** | 2200 - 2500 MPa (319 - 363 ksi) | At 58-60 HRC | | **Impact Toughness (Charpy)** | 18 - 25 J (13 - 18 ft·lb) | At 58-60 HRC, unnotched | | **Fatigue Endurance Limit** | 700 - 800 MPa (102 - 116 ksi) | Rotating bending, 10⁷ cycles | | **Fracture Toughness (K₁c)** | 35 - 45 MPa√m | At 58-60 HRC | ### **Hardenability Data (Jominy Test Typical)** | Distance from Quenched End (1/16 in) | 1 | 4 | 8 | 12 | 16 | 20 | 24 | |--------------------------------------|---|---|---|---|---|---|---| | **Hardness (HRC)** | 60-62 | 59-61 | 58-60 | 57-59 | 56-58 | 55-57 | 54-56 | *Through-hardening capability: Approximately 100-125mm (4-5 inches) diameter in oil quench.* --- ## **3. Product Applications** ### **Primary Application Areas** **1. Impact Tooling:** - Cold chisels and masonry tools - Pneumatic tool components (chipping hammers, rivet busters) - Blacksmith tools and hot work tooling (secondary applications) - Heavy-duty punches and shears **2. Forming and Forging Tools:** - Cold heading dies and punches (particularly for larger diameters) - Swaging dies and mandrels - Extrusion tooling for non-ferrous metals - Bending and forming dies requiring shock resistance **3. Cutting Tools (Impact-Resistant):** - Heavy-duty lathe tools for interrupted cuts - Milling cutters for tough materials - Broaches and reamers for hardened materials - Woodworking tools for dense hardwoods **4. Wear Components with Shock Loading:** - Gear blanks and sprockets - Machine tool components (slides, ways, gibs) - Agricultural implement parts - Mining and drilling tool components ### **Industry-Specific Applications** | Industry | Typical L4 Components | |----------|-----------------------| | **Fastener Manufacturing** | Large cold heading dies, thread rolling dies for high-strength fasteners | | **Forging & Stamping** | Trimming dies, hot snips, bolster plates | | **Heavy Machinery** | Wear plates, guide blocks, shear blades | | **Oil & Gas** | Valve components, drilling tool inserts | | **Construction Equipment** | Cutting edges, bucket teeth, demolition tool parts | ### **Performance in Service** | Application Condition | L4 Performance Characteristics | |----------------------|--------------------------------| | **High Impact** | Excellent resistance to chipping and fracture | | **Moderate Wear** | Good service life with proper hardening | | **Cyclic Loading** | Good fatigue resistance with proper surface finish | | **Shock Loading** | Superior energy absorption capability | | **Combined Stresses** | Good performance under complex stress states | --- ## **4. Heat Treatment Guidelines** ### **Annealing (Preparation for Machining)** - **Process:** Full annealing or spheroidize annealing - **Temperature:** 800-820°C (1475-1510°F) - **Cooling:** Slow furnace cool at ≤20°C/hr (≤36°F/hr) to 540°C (1000°F), then air cool - **Resulting Hardness:** 187-217 HB (Brinell) - **Microstructure:** Fine spheroidized carbides in ferrite matrix ### **Hardening (Austenitizing & Quenching)** 1. **Preheating:** Critical for minimizing thermal shock and distortion - Stage 1: 400-500°C (750-930°F) - Stage 2: 650-700°C (1200-1290°F) 2. **Austenitizing:** - **Temperature:** 820-850°C (1510-1560°F) - **Soaking Time:** 25-35 minutes per inch of thickness - **Atmosphere:** Neutral or slightly carburizing recommended - **Grain Size:** ASTM 8-10 (fine) achievable with proper control 3. **Quenching:** - **Medium:** Warm oil (50-80°C / 120-175°F) - **Agitation:** Moderate agitation for uniform cooling - **Quench to:** 60-80°C (140-175°F) before tempering - **Alternative:** Polymer quenchants for reduced distortion in complex shapes ### **Tempering (Optimizing Toughness)** - **Immediate Tempering:** Required within 1 hour of quenching - **Standard Cycle:** Double tempering strongly recommended - First temper: 200-300°C (400-570°F) for 2+ hours - Second temper: Same temperature, 2+ hours (minimum 1 hour longer than first temper) - **Temperature-Hardness Relationship:** - 150°C (300°F): 59-61 HRC - 200°C (400°F): 58-60 HRC - 250°C (480°F): 57-59 HRC - 300°C (570°F): 56-58 HRC - 350°C (660°F): 54-56 HRC - 400°C (750°F): 52-54 HRC ### **Stress Relieving** - After rough machining, before final hardening - **Temperature:** 600-650°C (1110-1200°F) - **Hold Time:** 1-2 hours per inch of thickness - **Cooling:** Slow furnace cool or air cool ### **Sub-Zero Treatment (Optional)** - For maximum dimensional stability and hardness - **Temperature:** -70 to -100°C (-95 to -150°F) - **Duration:** 2-4 hours after quenching, before tempering - **Effect:** Converts retained austenite, increases hardness by 1-2 HRC --- ## **5. Machining & Fabrication Notes** ### **Machinability (Annealed Condition)** - **Relative Machinability:** 70-75% (compared to 1% carbon steel = 100%) - **Recommended Cutting Parameters:** - **Turning:** 45-65 m/min (150-215 SFM) with carbide - **Milling:** 30-45 m/min (100-150 SFM) with carbide - **Drilling:** 20-30 m/min (65-100 SFM) with HSS - **Tapping:** 10-15 m/min (33-50 SFM) with HSS - **Tool Geometry:** Positive rake angles (5-10°), sharp cutting edges - **Coolant:** Soluble oil or semi-synthetic coolant recommended ### **Grinding (Hardened Condition)** - **Wheel Selection:** Aluminum oxide (A46-J8-V) or CBN for precision work - **Parameters:** Light cuts (0.01-0.03mm/pass), moderate feed rates - **Coolant:** Copious flow to prevent thermal damage - **Dressing:** Frequent dressing to maintain wheel sharpness ### **Electrical Discharge Machining (EDM)** - Suitable for both annealed and hardened conditions - **Finishing Passes:** Essential to minimize white layer (<0.005mm) - **Post-EDM Treatment:** Temper at 25-50°C below original tempering temperature - **Wire EDM:** Preferred for complex shapes; use skim cuts for best surface integrity --- ## **6. Comparative Analysis** ### **vs. Other L-Series Grades** | Property | L4 | L3 | L6 | S7 (Shock Steel) | |----------|----|----|----|------------------| | **Carbon Content** | Medium (0.65-0.85%) | High (0.95-1.10%) | Medium (0.65-0.75%) | Low (0.45-0.55%) | | **Chromium Content** | High (1.20-1.80%) | High (1.00-1.80%) | Medium (0.60-1.00%) | Low (3.00-3.50%) | | **Primary Strength** | Impact toughness | Wear resistance | Toughness | Extreme impact | | **Typical Hardness** | 56-60 HRC | 60-64 HRC | 56-60 HRC | 54-58 HRC | | **Charpy Impact** | 18-25 J | 8-15 J | 20-30 J | 40-60 J | | **Cost Factor** | 1.0x | 1.1x | 1.0x | 1.5x | ### **vs. Similar Impact-Resistant Grades** | Aspect | AISI L4 | AISI S1 | AISI H13 (Hot Work) | |--------|---------|---------|---------------------| | **Service Temperature** | <200°C | <300°C | Up to 600°C | | **Hardening Method** | Oil | Oil | Air/Oil | | **Toughness at Hardness** | Excellent at 58-60 HRC | Good at 56-58 HRC | Good at 48-52 HRC | | **Primary Application** | Cold impact | Hot/cold impact | Hot work | | **Machinability** | Good | Fair | Fair | --- ## **7. Quality Control & Inspection** ### **Material Quality Standards** - **Decarburization:** Maximum 0.10mm per side on finished tooling stock - **Non-Metallic Inclusions:** ASTM E45 Method A, Max Thin Series 2.5 - **Segregation:** Minimal banding acceptable per customer requirements - **Surface Quality:** Free from seams, laps, and other surface imperfections ### **Testing Requirements** - **Chemical Analysis:** Optical emission spectrometry with full traceability - **Hardness Testing:** Brinell, Rockwell, or microhardness as specified - **Microstructural Examination:** Per ASTM E112 for grain size, ASTM E381 for carbide distribution - **Ultrasonic Testing:** Available for detection of internal discontinuities - **Dimensional Inspection:** Per drawing specifications with appropriate GD&T ### **Certification** - Mill test certificates to ASTM A681 requirements - Heat number traceability throughout manufacturing process - Certificates of conformity for finished tools --- ## **8. Technical Recommendations** ### **Design Guidelines** 1. **Section Transitions:** Use generous radii (minimum R2mm) to reduce stress concentrations 2. **Wall Thickness:** Maintain uniform sections where possible; avoid ratios > 3:1 3. **Hardness Gradients:** Consider differential hardening for tools requiring hard surfaces with tough cores 4. **Surface Finish:** Specify 1.6μm Ra or better for critical wear surfaces ### **Storage & Handling** - **Storage Conditions:** Dry environment (<50% RH), protected from corrosion - **Identification:** Clearly mark with grade designation and heat number - **Handling:** Use appropriate lifting equipment for heavy sections - **Protection:** Apply rust preventive oil for long-term storage ### **Safety Considerations** - **Machining:** Use proper dust collection for grinding operations - **Heat Treatment:** Follow furnace safety protocols and use appropriate PPE - **Handling Hardened Tools:** Beware of sharp edges and brittle fracture risks - **Material Disposal:** Recycle as alloy steel scrap ### **Failure Analysis Indicators** | Failure Mode | Possible Causes | Corrective Actions | |--------------|----------------|-------------------| | **Chipping** | Insufficient toughness, sharp corners | Increase tempering temperature, add radii | | **Wear** | Inadequate hardness, poor lubrication | Increase carbon content, improve surface finish | | **Fracture** | Over-hardening, stress risers | Reduce hardening temperature, improve design | | **Distortion** | Uneven heating/cooling, residual stresses | Improve fixturing, add stress relief cycle | --- ## **Disclaimer** This technical datasheet provides comprehensive information about AISI Type L4 tool steel based on industry standards and typical manufacturing practices. Actual properties and performance may vary depending on: 1. **Manufacturer Variations:** Different steel producers may have slight compositional adjustments 2. **Heat Treatment Parameters:** Results are highly dependent on specific thermal cycles 3. **Application Conditions:** Service environment, loading conditions, and maintenance practices 4. **Design Factors:** Part geometry, surface finish, and manufacturing quality **For Critical Applications:** - Consult with material engineers and steel suppliers - Conduct application-specific testing and qualification - Develop detailed heat treatment specifications - Consider alternative materials for extreme conditions This information is subject to technical revisions as material science advances. Always refer to the most current standards and supplier specifications for your specific requirements. -:- For detailed product information, please contact sales. -: AISI Type L4 Tool Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6708 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 Type L4 Tool Steel Properties -:- For detailed product information, please contact sales. -:

Applications of AISI Type L4 Tool Steel Sheet,Plate -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI Type L4 Tool Steel Sheet,Plate -:- For detailed product information, please contact sales. -:

Packing of AISI Type L4 Tool Steel Sheet/Plate -:- 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 Sheet/Plate 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 3179 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