AISI 4142 Steel, Quenched and Tempered

AISI 4142 Steel, Quenched and Tempered to 380 HB Product Information -:- For detailed product information, please contact sales. -: AISI 4142 Steel, Quenched and Tempered to 380 HB Synonyms -:- For detailed product information, please contact sales. -:

AISI 4142 Steel, Quenched and Tempered to 380 HB Product Information -:- For detailed product information, please contact sales. -: # **AISI 4142 Steel (Quenched and Tempered to 380 HB) Product Specification** ## **1. PRODUCT DEFINITION & HEAT TREATMENT** **Product:** AISI 4142 Alloy Steel, Heat Treated Condition **Target Hardness:** 380 HB (Approximately 40.5 HRC) **Standard Heat Treatment:** - **Austenitizing:** 830 - 850°C (1525 - 1560°F) - **Quenching:** Oil quench (agitated) - **Tempering:** 525 - 575°C (975 - 1070°F), air cooled **Material State:** This product is supplied in its final quenched and tempered condition, achieving a Brinell hardness of 380 HB. This specific hardness level represents an optimal balance between high tensile strength and good toughness, making it suitable for a wide range of demanding structural and mechanical applications. ## **2. CHEMICAL COMPOSITION** The elevated carbon content relative to AISI 4140 provides enhanced hardenability and strength potential. | Element | Composition Range (% by weight) | Metallurgical Role at 380 HB | | :--- | :--- | :--- | | **Carbon (C)** | 0.40 - 0.45 | **Key differentiator from 4140.** Provides higher as-quenched hardness and greater tempering resistance, allowing higher strength to be maintained at elevated tempering temperatures. Forms fine alloy carbides during tempering. | | **Manganese (Mn)** | 0.75 - 1.00 | Ensures complete through-hardening in oil for moderate sections. Contributes to solid solution strengthening in the tempered martensite matrix. | | **Phosphorus (P)** | ≤ 0.035 | Strictly controlled to maintain impact toughness at this strength level. | | **Sulfur (S)** | ≤ 0.040 | Kept low for good transverse ductility and fatigue properties. | | **Silicon (Si)** | 0.15 - 0.35 | Provides solid solution strengthening and improves tempering resistance. | | **Chromium (Cr)** | 0.80 - 1.10 | Enhances hardenability and forms stable (Cr,Fe)₇C₃ carbides during tempering, contributing significantly to secondary hardening and wear resistance. | | **Molybdenum (Mo)** | 0.15 - 0.25 | Critical for suppressing temper embrittlement in the 525-575°C range. Forms fine Mo₂C carbides that enhance creep resistance and strength. | ## **3. MICROSTRUCTURE & HARDENABILITY** **Microstructure:** Uniform, fine **tempered martensite** with a dispersion of fine alloy carbides (predominantly Mo₂C and Cr₇C₃). The microstructure is free of bainite or pearlite due to the alloy's high hardenability. **Hardenability:** Excellent (Dᵢ ~ 100-120mm in oil). The combination of higher carbon and alloy content gives 4142 approximately 15-20% greater hardenability than 4140, ensuring full martensitic transformation in sections up to approximately 100mm (4 inches) diameter when oil quenched. ## **4. MECHANICAL PROPERTIES AT 380 HB** | Property | Typical Value / Range | Test Standard / Note | | :--- | :--- | :--- | | **Hardness** | 370 - 390 HB (40 - 41 HRC) | Primary specification; Brinell preferred for consistency | | **Ultimate Tensile Strength** | 1250 - 1350 MPa (181,000 - 196,000 psi) | Direct correlation to 380 HB | | **Yield Strength (0.2% Offset)** | 1100 - 1200 MPa (160,000 - 174,000 psi) | High yield-to-tensile ratio (~0.87) | | **Elongation (in 50mm)** | 12% - 16% | Good for this strength level | | **Reduction of Area** | 40% - 50% | | | **Modulus of Elasticity** | 205 GPa (29,700 ksi) | | | **Charpy V-Notch Impact (21°C)** | 25 - 40 J (18 - 30 ft-lb) | Good toughness at this hardness | | **Fatigue Endurance Limit** | ~550 - 600 MPa (80,000 - 87,000 psi) | For polished specimens, R=-1 | | **Shear Strength** | ~750 - 800 MPa (109,000 - 116,000 psi) | Approx. 60% of UTS | ## **5. PHYSICAL PROPERTIES** | Property | Value / Condition | | :--- | :--- | | **Density** | 7.85 g/cm³ (0.284 lb/in³) | | **Thermal Conductivity** | 41.5 W/m·K @ 100°C | | **Coefficient of Thermal Expansion** | 11.4 µm/m·°C (20-100°C) | | **Specific Heat Capacity** | 460 J/kg·K @ 20°C | | **Electrical Resistivity** | 0.23 µΩ·m @ 20°C | ## **6. PRIMARY APPLICATIONS** The 380 HB condition is ideal for components subject to high cyclic loading, wear, and moderate impact, where maximum reliability is required. * **Heavy-Duty Gearing:** - Mining and construction equipment gears - Heavy vehicle transmission gears - Industrial gearbox components * **Oil & Gas Equipment:** - Drill collars and tool joints - Valve bodies and stems - Wellhead components * **Hydraulic & Power Transmission:** - High-pressure hydraulic piston rods - Shafts and axles for off-road vehicles - Couplings and universal joints * **Tooling & Die Applications:** - Die blocks for hot and cold forging - Plastic injection mold bases - Machine tool components (spindles, ways) * **Agricultural & Forestry Equipment:** - Drive shafts and PTO components - Harvesting and cutting components - Track links and rollers ## **7. INTERNATIONAL STANDARDS & EQUIVALENTS** | Standard | Designation | Equivalent Status | Notes for 380 HB Condition | | :--- | :--- | :--- | :--- | | **AISI/SAE** | 4142 | Primary Standard | | | **ASTM** | A322 Grade 4142 | U.S. Standard for Q&T Bars | Typically specifies tensile properties, not hardness | | **UNS** | G41420 | Unified Numbering | | | **DIN/EN** | 42CrMo4 / 1.7225 | Close Equivalent | Same designation as 4140; chemistry overlap | | **JIS** | SCM440 | Japanese Equivalent | Covers similar carbon range | | **GB** | 42CrMo | Chinese Equivalent | GB/T 3077 | | **ISO** | 42CrMo4 | International | ISO 683-18 | ## **8. FABRICATION & PROCESSING** **Machinability:** - **Condition:** Fair to Difficult - **Recommended:** Carbide tooling - **Cutting Speed:** 60-90 m/min (200-300 SFM) for turning with carbide - **Feed:** 0.15-0.30 mm/rev (0.006-0.012 in/rev) - **Coolant:** Essential for heat dissipation and tool life **Grinding:** - Well-suited to precision grinding - Use aluminum oxide or CBN wheels - Maintain adequate coolant flow to prevent thermal damage **Welding:** - **Not recommended** in heat-treated condition - If unavoidable: Preheat to 300-400°C (575-750°F) - Use low-hydrogen electrodes exclusively - Post-weld heat treatment required (re-tempering at 550-600°C) **Straightening:** - Limited cold straightening possible (<0.5% strain) - Hot straightening at 300-400°C preferred ## **9. QUALITY ASSURANCE** **Standard Testing:** - Hardness verification (Brinell preferred) - Tensile testing from representative samples - Microstructure examination (tempered martensite verification) **Non-Destructive Testing (Available):** - Magnetic particle inspection (ASTM E709) - Ultrasonic testing for internal defects - Dye penetrant for surface cracks **Certification:** - Mill test certificate to EN 10204 3.1 or equivalent - Heat treatment records with temperature charts - Chemical analysis certificate ## **10. COMPARATIVE ADVANTAGES** **vs. AISI 4140 at Same Hardness:** - Higher core hardenability for larger sections - Better wear resistance due to higher carbon content - Slightly higher tensile and yield strength - Better retention of properties at elevated temperatures **vs. Lower Hardness Conditions:** - Superior wear and abrasion resistance - Higher load-carrying capacity - Better fatigue resistance - Greater dimensional stability under load **vs. Higher Hardness Conditions:** - Better impact toughness - Reduced notch sensitivity - Improved machinability (relative) - Lower risk of brittle fracture ## **11. DESIGN & APPLICATION CONSIDERATIONS** **Optimal Use Conditions:** - Components with generous fillet radii (R > 2mm) - Polished or ground surfaces for fatigue applications - Operating temperatures below 250°C (480°F) - Environments where corrosion protection is applied **Limitations:** - Moderate corrosion resistance – requires protection - Not suitable for high-temperature service (>400°C) - Avoid sharp notches and stress concentrators - Not recommended for welded assemblies without PWHT --- **Summary:** AISI 4142 steel quenched and tempered to 380 HB represents a premium-grade engineering material offering an exceptional balance of strength (1250+ MPa UTS), toughness (25-40 J impact), and wear resistance. Its higher carbon content relative to 4140 makes it particularly suitable for larger cross-sections and applications where maximum reliability under heavy cyclic loading is essential. This condition is specified for critical components in mining, energy, heavy equipment, and power transmission industries where component failure carries significant safety or economic consequences. -:- For detailed product information, please contact sales. -: AISI 4142 Steel, Quenched and Tempered to 380 HB Specification Dimensions Size： Diameter 20-1000 mm Length <6214 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 4142 Steel, Quenched and Tempered to 380 HB Properties -:- For detailed product information, please contact sales. -:

Applications of AISI 4142 Steel, Quenched and Tempered to 380 HB -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI 4142 Steel, Quenched and Tempered to 380 HB -:- For detailed product information, please contact sales. -:

Packing of AISI 4142 Steel, Quenched and Tempered to 380 HB -:- 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 2685 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