AISI Type L6 Low Alloy Tool Steel Rod/Bar (UNS T61206)

AISI Type L6 Low Alloy Tool Steel Rod (UNS T61206) Product Information -:- For detailed product information, please contact sales. -: AISI Type L6 Low Alloy Tool Steel Rod (UNS T61206) Synonyms -:- For detailed product information, please contact sales. -:

AISI Type L6 Low Alloy Tool Steel (UNS T61206) Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: AISI Type L6 (UNS T61206) High-Toughness Tool Steel** ## **Overview** AISI Type L6 is a **nickel-chromium alloyed** oil-hardening tool steel within the AISI "L-series" (Low-Alloy, Special Purpose). Distinguished by its **significant nickel content (approximately 1.50%)**, L6 offers exceptional **toughness and shock resistance** while maintaining good wear characteristics. This grade is specifically engineered for applications requiring maximum resistance to chipping and fracture under severe impact conditions, making it particularly valuable for cold work tooling subjected to heavy loading. **Key Advantages:** - **Exceptional Toughness:** Superior impact resistance and resistance to brittle fracture - **Good Wear Resistance:** Adequate carbide formation for moderate abrasive conditions - **Deep Hardenability:** Reliable through-hardening in substantial sections via oil quenching - **Minimal Distortion:** Predictable dimensional stability during heat treatment - **Versatile Machinability:** Good machinability in annealed condition **Primary Considerations:** - Lower maximum hardness compared to higher-carbon tool steels - Requires specific tempering protocols to optimize toughness - Higher cost than standard low-alloy tool steels due to nickel content - Best suited for applications where impact resistance is the primary requirement ## **International Designations & Standards** | Standard System | Designation | Note | |----------------|-------------|------| | **AISI/SAE (USA)** | L6 | Primary specification | | **UNS (USA)** | T61206 | Unified numbering system | | **ASTM (USA)** | A681 | Governing material standard | | **DIN (Germany)** | ~1.2713 | Similar nickel-chromium tool steel | | **BS (UK)** | ~**BH21** | Related oil-hardening grade | | **JIS (Japan)** | ~SKS4 | Similar special purpose tool steel | | **ISO (International)** | ~**55NiCrMoV7** | Closest functional equivalent | *Note: AISI L6 is unique among L-series steels due to its nickel content. Exact international equivalents may vary in specific alloy balances.* --- ## **1. Chemical Composition (Typical, Weight %)** The distinctive feature is the significant nickel content, which substantially enhances toughness. | Element | Content (%) | Role & Metallurgical Effect | |---------|-------------|-----------------------------| | **Carbon (C)** | 0.65 - 0.75 | Provides base hardness and strength while maintaining good toughness. Balanced to prevent excessive brittleness. | | **Nickel (Ni)** | 1.25 - 1.75 | **Key alloying element.** Dramatically improves toughness, ductility, and hardenability. Enhances resistance to impact and fatigue. | | **Chromium (Cr)** | 0.60 - 1.00 | Improves hardenability, wear resistance, and provides moderate corrosion resistance. | | **Manganese (Mn)** | 0.25 - 0.80 | Enhances 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. | | **Iron (Fe)** | Balance | Matrix element. | **Composition Note:** The nickel content is the defining characteristic that sets L6 apart from other L-series grades and provides its exceptional toughness. --- ## **2. Physical & Mechanical Properties** ### **Physical Properties** | Property | Typical Value | Conditions/Notes | |----------|---------------|------------------| | **Density** | 7.83 - 7.85 g/cm³ | At 20°C (68°F) | | **Melting Range** | 1420 - 1440°C (2588 - 2624°F) | Liquidus to solidus range | | **Thermal Conductivity** | 42 - 46 W/m·K | At 20°C (68°F) | | **Specific Heat Capacity** | 460 - 480 J/kg·K | At 20°C (68°F) | | **Coefficient of Thermal Expansion** | 11.5 - 12.0 × 10⁻⁶/K | 20-200°C (68-392°F) range | | **Electrical Resistivity** | 0.30 - 0.35 μΩ·m | At 20°C (68°F) | | **Elastic Modulus** | 200 - 205 GPa (29.0 - 29.7 × 10⁶ psi) | At room temperature | ### **Mechanical Properties (Heat-Treated Condition)** | Property | Value Range | Heat Treatment Condition | |----------|-------------|--------------------------| | **Hardness (Annealed)** | 183 - 217 HB | Spheroidize annealed, ready for machining | | **Hardness (Hardened)** | 55 - 59 HRC | Oil quenched from 830-860°C, tempered at 200-400°C | | **Tensile Strength** | 1800 - 2000 MPa (261 - 290 ksi) | At 57-59 HRC | | **Yield Strength (0.2% offset)** | 1500 - 1700 MPa (218 - 247 ksi) | At 57-59 HRC | | **Compressive Strength** | 2150 - 2400 MPa (312 - 348 ksi) | At 57-59 HRC | | **Impact Toughness (Charpy)** | 30 - 45 J (22 - 33 ft·lb) | At 57-59 HRC, unnotched – **Exceptional for this hardness level** | | **Fatigue Endurance Limit** | 700 - 800 MPa (102 - 116 ksi) | Rotating bending, 10⁷ cycles | | **Fracture Toughness (K₁c)** | 45 - 60 MPa√m | At 57-59 HRC – **Excellent fracture resistance** | ### **Hardenability Data (Jominy Test Typical)** | Distance from Quenched End (1/16 in) | 1 | 4 | 8 | 12 | 16 | 20 | 24 | |--------------------------------------|---|---|---|---|---|---|---| | **Hardness (HRC)** | 59-61 | 58-60 | 57-59 | 56-58 | 55-57 | 54-56 | 53-55 | *Through-hardening capability: Approximately 100-150mm (4-6 inches) diameter in oil quench – excellent for a low-alloy steel.* --- ## **3. Product Applications** ### **Primary Application Areas** **1. High-Impact Tooling:** - Cold chisels and pneumatic hammer tools - Demolition tools and concrete breakers - Blacksmith tools and hot work applications (limited temperature) - Heavy-duty punches and shear blades **2. Forming and Forging Tools:** - Cold heading dies and punches (particularly for high-strength materials) - Swaging dies and mandrels - Extrusion tooling for non-ferrous metals - Bending and forming dies requiring maximum shock resistance **3. Cutting Tools (Severe Service):** - Heavy-duty lathe tools for interrupted cuts - Milling cutters for tough, abrasive materials - Broaches and reamers for hardened steels - Woodworking tools for exotic hardwoods **4. Critical Wear Components:** - Gear blanks and transmission components - Machine tool components (spindles, arbors, collets) - Agricultural and construction equipment parts - Mining and drilling tool components ### **Industry-Specific Applications** | Industry | Typical L6 Components | |----------|-----------------------| | **Metal Stamping** | Heavy-duty punches, forming dies, bolster plates | | **Fastener Manufacturing** | Cold heading dies for high-strength fasteners, thread rolling dies | | **Forging** | Trimming dies, hot snips, die inserts | | **Heavy Machinery** | Wear plates, guide blocks, shear pins | | **Aerospace** | Forming tools for titanium and high-strength alloys | ### **Service Performance Summary** | Service Condition | L6 Performance | Recommended Hardness | |-------------------|----------------|----------------------| | **Severe Impact** | Excellent | 55-57 HRC | | **Impact with Moderate Wear** | Very Good | 57-59 HRC | | **Fatigue Loading** | Excellent | 56-58 HRC | | **Combined Stresses** | Very Good | 56-58 HRC | | **Precision Applications** | Good | 58-59 HRC | --- ## **4. Heat Treatment Guidelines** ### **Annealing (Preparation for Machining)** - **Process:** Full annealing or spheroidize annealing - **Temperature:** 790-810°C (1455-1490°F) - **Cooling:** Slow furnace cool at ≤20°C/hr (≤36°F/hr) to 540°C (1000°F), then air cool - **Resulting Hardness:** 183-217 HB (Brinell) - **Microstructure:** Fine spheroidized carbides in ferrite matrix ### **Hardening (Austenitizing & Quenching)** 1. **Preheating:** Essential for this grade - Stage 1: 400-500°C (750-930°F) - Stage 2: 650-700°C (1200-1290°F) 2. **Austenitizing:** - **Temperature:** 830-860°C (1525-1580°F) - **Soaking Time:** 25-35 minutes per inch of thickness - **Atmosphere:** Neutral or slightly carburizing recommended - **Grain Size:** ASTM 8-10 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 - **Note:** Can also be quenched in polymer solutions for complex shapes ### **Tempering (Critical for Optimal Toughness)** - **Immediate Tempering:** Required within 1 hour of quenching - **Standard Cycle:** Double tempering strongly recommended - First temper: 200-400°C (400-750°F) for 2+ hours - Second temper: Same temperature, 2+ hours (minimum 1 hour longer than first) - **Temperature-Hardness Relationship:** - 150°C (300°F): 58-60 HRC - 200°C (400°F): 57-59 HRC - 250°C (480°F): 56-58 HRC - 300°C (570°F): 55-57 HRC - 350°C (660°F): 54-56 HRC - 400°C (750°F): 52-54 HRC - 450°C (840°F): 50-52 HRC ### **Special Heat Treatment Options** 1. **Austempering:** Can be austempered for exceptional toughness at lower hardness 2. **Marquenching:** Interrupted oil quenching for minimal distortion 3. **Cryogenic Treatment:** Optional for maximum dimensional stability --- ## **5. Machining & Fabrication** ### **Machinability (Annealed Condition)** - **Relative Machinability:** 65-70% (compared to 1% carbon steel = 100%) - **Recommended Cutting Parameters:** - **Turning:** 40-60 m/min (130-200 SFM) with carbide - **Milling:** 25-40 m/min (80-130 SFM) with carbide - **Drilling:** 15-25 m/min (50-80 SFM) with HSS - **Tool Geometry:** Positive rake angles, sharp cutting edges - **Coolant:** Soluble oil or semi-synthetic recommended ### **Grinding (Hardened Condition)** - **Wheel Selection:** Aluminum oxide (A46-J8-V) or CBN - **Parameters:** Light cuts (0.01-0.03mm/pass) - **Coolant:** Ample flow to prevent thermal damage - **Note:** Grinds well but requires care due to toughness --- ## **6. Comparative Analysis** ### **vs. Other Toughness-Oriented Grades** | Property | L6 | L4 | S7 | 4340 (Alloy Steel) | |----------|----|----|----|-------------------| | **Nickel Content** | High (1.25-1.75%) | None | None | Medium (1.65-2.00%) | | **Toughness at 57 HRC** | Excellent | Good | Excellent | Good | | **Wear Resistance** | Good | Very Good | Fair | Fair | | **Distortion Control** | Very Good | Good | Good | Good | | **Relative Cost** | 1.2x | 1.0x | 1.5x | 0.8x | ### **Application Selection Guide** | Application Priority | Recommended Grade | Rationale | |---------------------|-------------------|-----------| | **Maximum Impact Resistance** | L6 or S7 | L6 for cost, S7 for extreme impact | | **Balance of Wear & Impact** | L4 | Better wear than L6 | | **High Production Wear** | D2 or A2 | Superior wear resistance | | **General Purpose** | O1 or A2 | Cost-effective for most applications | --- ## **7. Technical Recommendations** ### **Design Guidelines** 1. **Section Transitions:** Minimum radius 2mm 2. **Hardness Selection:** Choose based on primary failure mode 3. **Surface Finish:** Critical surfaces 1.6μm Ra or better 4. **Quality Verification:** Require impact testing for critical applications ### **Failure Analysis Indicators** | Failure Mode | Likely Cause | Corrective Action | |--------------|--------------|-------------------| | **Chipping** | Too high hardness | Increase tempering temperature | | **Excessive Wear** | Too low hardness | Lower tempering temperature | | **Fracture** | Design stress risers | Increase radii, improve design | | **Fatigue Failure** | Insufficient toughness | Verify heat treatment, consider L6 | --- ## **Disclaimer** This technical datasheet provides general information about AISI Type L6 tool steel. Actual properties may vary based on: 1. **Manufacturer-specific compositions** 2. **Heat treatment parameters and equipment** 3. **Application conditions and loading** 4. **Design and manufacturing quality** **For critical applications:** - Consult with materials engineering specialists - Conduct application-specific testing - Specify detailed heat treatment requirements - Consider alternative grades for extreme conditions Always refer to current standards and supplier specifications. This information is subject to revision as technology advances. -:- For detailed product information, please contact sales. -: AISI Type L6 Low Alloy Tool Steel (UNS T61206) Specification Dimensions Size： Diameter 20-1000 mm Length <6710 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 L6 Low Alloy Tool Steel (UNS T61206) Properties -:- For detailed product information, please contact sales. -:

Applications of AISI Type L6 Low Alloy Tool Steel Rod (UNS T61206) -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI Type L6 Low Alloy Tool Steel Rod (UNS T61206) -:- For detailed product information, please contact sales. -:

Packing of AISI Type L6 Low Alloy Tool Steel Rod (UNS T61206) -:- 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 Rod 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 3181 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