AISI 4150H Steel, normalized

AISI 4150H Steel, normalized at 870°C (1600°F), air cooled Product Information -:- For detailed product information, please contact sales. -: AISI 4150H Steel, normalized at 870°C (1600°F), air cooled Synonyms -:- For detailed product information, please contact sales. -:

AISI 4150H Steel, normalized at 870°C (1600°F), air cooled Product Information -:- For detailed product information, please contact sales. -: # **AISI 4150H Steel (Hardenability Grade, Normalized Condition) Product Specification** ## **1. PRODUCT IDENTIFICATION & THERMAL PROCESS** **Product:** AISI 4150H High-Carbon Chromium-Molybdenum Alloy Steel **Material State:** Normalized Condition - Hardenability Controlled Grade **Specified Normalizing Process:** - **Austenitizing:** 870°C (1600°F) with complete soak - **Cooling:** Still air cooling to room temperature **Metallurgical Significance:** Normalization at 870°C refines the grain structure, homogenizes the microstructure, and eliminates the thermal history from prior manufacturing processes for this high-carbon alloy. For AISI 4150H, the higher normalization temperature (compared to annealing) ensures complete dissolution of carbides and formation of a uniform austenitic structure prior to air cooling. This produces a fine, uniform ferrite-pearlite microstructure with improved strength and toughness compared to the annealed condition, while maintaining the guaranteed hardenability characteristics of the "H" grade. This condition represents an optimal balance for components requiring both good machinability and a robust starting structure for subsequent heat treatment. ## **2. CHEMICAL COMPOSITION (Hardenability Controlled)** The composition is engineered to satisfy both the high-carbon 4150 chemistry and strict hardenability band requirements. | Element | Composition Range (% by weight) | Role in Normalized Condition & Hardenability Control | | :--- | :--- | :--- | | **Carbon (C)** | **0.48 - 0.53** | **Highest in 41xx-H series.** Forms increased pearlite content (~65-75%) during air cooling, providing higher normalized strength. Carbon content is tightly controlled to maintain consistent hardenability response. | | **Manganese (Mn)** | 0.75 - 1.10 | **Primary hardenability adjuster.** Expanded range allows precise Jominy curve positioning. Promotes fine pearlite formation during air cooling and enhances normalized strength. | | **Phosphorus (P)** | ≤ 0.030 | Tighter than standard 4150 (≤0.035) for consistent impact properties in normalized state. | | **Sulfur (S)** | ≤ 0.030 | Controlled for improved transverse properties and machinability consistency. | | **Silicon (Si)** | 0.15 - 0.35 | Deoxidizer; provides solid solution strengthening in ferrite. | | **Chromium (Cr)** | 0.80 - 1.10 | Refines pearlite spacing significantly and promotes fine carbide formation. Major contributor to hardenability and wear resistance potential. | | **Molybdenum (Mo)** | 0.15 - 0.25 | **Critical for microstructural control.** Enhances grain refinement during normalization and prevents abnormal grain growth at 870°C. Ensures consistent hardenability response. | **Carbon Equivalent (CE) for Weldability:** ~0.85-0.95 (indicates very poor weldability) ## **3. CERTIFIED HARDENABILITY (SAE J1268)** The material carries certified hardenability data that defines its predictable through-hardening characteristics. **Standard Hardenability Band for 4150H:** | Jominy Distance (1/16 in.) | As-Quenched Hardness Range, HRC (Min - Max) | | :--- | :--- | | **J1.5** | 58 - 64 | | **J5** | 50 - 58 | | **J10** | 42 - 52 | | **J15** | 36 - 46 | | **J20** | 32 - 42 | **Engineering Significance:** This certification is particularly valuable for normalized 4150H as it guarantees that the refined, uniform microstructure will respond predictably to subsequent quenching. For a 100mm diameter component normalized at 870°C, then later austenitized and oil quenched, the core hardness will be predictable within a 5 HRC range across all production lots. ## **4. MICROSTRUCTURE & METALLURGY** **Microstructural Features:** - **Matrix:** Fine, uniform mixture of ferrite and pearlite - **Pearlite Content:** 65-75% (higher than lower-carbon steels due to 0.48-0.53% C) - **Pearlite Spacing:** Very fine (0.1-0.3 μm) due to chromium's refining effect - **Grain Size:** ASTM 7-9 (fine, refined by 870°C treatment) - **Carbide Morphology:** Fine lamellar cementite within pearlite colonies - **Band Segregation:** Minimized by normalization process **Normalizing Transformation:** - **Ac₁:** ~735°C - **Ac₃:** ~780°C - **Soak Time:** 30-45 minutes per inch at 870°C - **Cooling Rate:** Still air (~0.5-2°C/second depending on section size) - **Transformation Products:** Fine pearlite (major) + polygonal ferrite (minor) ## **5. PHYSICAL & MECHANICAL PROPERTIES (Normalized Condition)** * **Physical Properties:** * **Density:** 7.85 g/cm³ * **Melting Point:** ~1405°C (2560°F) * **Modulus of Elasticity:** 205 GPa (29,700 ksi) * **Thermal Conductivity:** 40.5 W/m·K @ 100°C * **Coefficient of Thermal Expansion:** 11.1 µm/m·°C (20-100°C) * **Specific Heat Capacity:** 460 J/kg·K * **Mechanical Properties (Typical for Normalized Condition):** * **Tensile Strength:** 750 - 900 MPa (109,000 - 131,000 psi) * **Yield Strength (0.2% Offset):** 500 - 650 MPa (73,000 - 94,000 psi) * **Elongation (in 50mm):** **16% - 20%** * **Reduction of Area:** **40% - 50%** * **Hardness:** **240 - 290 HB** (Approx. 100-108 HRB) * **Charpy V-Notch Impact (21°C):** 25 - 45 J (18 - 33 ft-lb) * **Machinability Rating:** **Fair to Good (60-65% of B1112 standard)** * **Fatigue Strength:** ~300-350 MPa (polished specimens) * **Fracture Toughness:** 60-80 MPa√m (estimated) ## **6. PRODUCT APPLICATIONS (Normalized Condition)** This condition serves as an **excellent intermediate state** for high-performance components requiring a balance of strength, machinability, and predictable heat treatment response. * **Heavy Component Pre-Machining:** - **Large gear blanks** for wind turbine, mining, and marine applications - **Shaft pre-forms** for heavy machinery and power generation - **Die blocks** and **tooling pre-forms** requiring subsequent hardening * **Forging & Casting Conditioning:** - Post-forging treatment for **large crankshafts** and **axle shafts** - **Cast component normalization** for grain refinement and property uniformity - **Weldment normalizing** for stress relief and HAZ refinement in heavy fabrications * **Direct Application (Non-Hardened) Components:** - **Structural components** in heavy equipment requiring good toughness - **Fixtures**, **jigs**, and **tooling plates** for manufacturing - **Agricultural equipment parts** not requiring maximum hardness - **Non-critical gears** and **sprockets** for moderate service conditions * **Substrate for Selective Hardening:** - Ideal for components to be **induction hardened**, **flame hardened**, or **carburized** - **Bearing races** and **gear teeth** for subsequent case hardening - **Wear surfaces** requiring localized hardening only ## **7. INTERNATIONAL STANDARDS & EQUIVALENT GRADES** | Standard / Country | Designation | Equivalent Status | Critical Notes | | :--- | :--- | :--- | :--- | | **AISI/SAE** | **4150H** | Primary Standard | SAE J1268 governs hardenability | | **ASTM** | **A304 Grade 4150H** | US Standard | For bars with hardenability requirements | | **UNS** | **H41500** | Unified Numbering | | | **DIN/EN** | **50CrMo4H (1.7228+H)** | **True equivalent** | 50CrMo4 (0.47-0.55%C) matches carbon range | | **JIS** | **SCM445H** | Japanese H-grade | Specify high carbon range | | **GB** | **50CrMoH / 55CrMoH** | Chinese H-grades | 50CrMoH preferred (0.47-0.54%C) | | **ISO** | **ISO 683-18 Type 50CrMo4** | International | Can specify hardenability requirements | ## **8. PROCESSING & FABRICATION** **Normalizing Process Control:** - **Temperature Uniformity:** ±10°C (±20°F) throughout load - **Soak Time:** 45 minutes per inch minimum at 870°C - **Cooling Conditions:** Still air on racks with adequate spacing - **Atmosphere:** Air or slightly protective to minimize excessive scaling - **Loading:** Avoid stacking to ensure uniform air cooling **Machinability:** - **Tooling:** Carbide grade C2-C3 recommended for production - **Cutting Speed:** 60-85 m/min (200-280 SFM) for turning with carbide - **Feed Rate:** 0.15-0.25 mm/rev (0.006-0.010 in/rev) - **Depth of Cut:** Up to 4mm (0.16") for roughing operations - **Coolant:** Highly recommended for tool life and chip control - **Chip Formation:** Continuous chips typical; chip breakers helpful **Forming & Bending:** - **Moderate cold formability** - **Minimum bend radius:** 4-5 × material thickness - **Hot forming preferred** for complex shapes - **Springback allowance:** 3-4° required for precision bending **Welding Characteristics:** - **Very poor weldability** due to high carbon equivalent - **Not recommended** without specialized procedures - **If absolutely necessary:** Preheat to 300-350°C, use specialized low-hydrogen electrodes, post-heat immediately to 650°C and slow cool - **Best practice:** Avoid welding; design as one-piece construction or use mechanical fastening ## **9. SUBSEQUENT HEAT TREATMENT** **Recommended Manufacturing Sequence:** 1. Receive in normalized condition (240-290 HB) 2. Rough machine (leave 1.5-2.5mm per side for finish) 3. Stress relieve at 600-650°C for 1-2 hours/inch (highly recommended) 4. Finish machine to near-final dimensions 5. Harden: Austenitize at 815-830°C, oil quench 6. Temper: 450-600°C based on final property requirements 7. Final grinding (minimal stock removal) **Heat Treatment Response:** - **Excellent hardenability:** Can through-harden sections >125mm diameter - **Uniform response:** Normalized structure ensures consistent transformation - **Reduced distortion:** Compared to as-forged or annealed starting conditions - **Predictable growth:** 0.08-0.12% dimensional increase during hardening **Stress Relieving (After Machining):** - Temperature: 600-650°C (1110-1200°F) - Time: 1-2 hours per inch of thickness - Cooling: Slow furnace cool (100°C/hour) to 300°C, then air cool ## **10. QUALITY ASSURANCE** **Mandatory Certification:** 1. **Hardenability Test Report** (Jominy curve per SAE J1268) 2. **Chemical Analysis Certificate** (complete analysis including trace elements) 3. **Mechanical Test Report** for normalized condition 4. **Microstructure Report** (grain size, pearlite content, uniformity) 5. **Heat Treatment Certificate** with temperature records **Standard Testing:** - Tensile testing per ASTM A370 - Hardness testing (Brinell scale preferred) - Impact testing if specified - Macro-etch examination for soundness (ASTM A381) - Grain size determination (ASTM E112) **Acceptance Criteria:** - **Hardness:** 240-290 HB (properly normalized) - **Grain Size:** ASTM 7-9 - **Microstructure Uniformity:** Consistent throughout cross-section - **Decarburization:** ≤0.25mm total depth - **Surface Quality:** Free from seams, laps, and rolling defects ## **11. COMPARATIVE ANALYSIS** **vs. Normalized 4140H:** - +40-60 HB higher hardness in normalized state - +15-20% higher tensile and yield strength - Lower impact toughness (25-45J vs 35-65J) - Significantly greater hardenability depth - Higher final hardness potential (up to 60+ HRC) **vs. Annealed 4150H:** - Harder (240-290 HB vs 185-225 HB) - Better strength and fatigue resistance - More consistent response to final heat treatment - Less machinable (60-65% vs 65-70% of B1112) - Better dimensional stability during heat treatment **vs. As-Forged/Hot-Rolled 4150:** - More uniform microstructure and properties - Consistent throughout cross-section - Reduced residual stresses - Better machinability and predictability **Value of "H" Designation in Normalized State:** - **Critical** for predictable through-hardening of large sections - Eliminates heat treatment variability concerns - Guarantees consistent core properties after quenching - Essential for safety-critical and high-value components ## **12. DESIGN & SELECTION GUIDELINES** **When to Specify Normalized 4150H:** - Components 50-150mm diameter requiring predictable through-hardening - Parts requiring good strength and toughness before final heat treatment - Applications where heat treatment distortion must be minimized - Components with complex geometries requiring uniform response to hardening - Safety-critical parts where material certification and predictability are essential **Design Considerations:** - **Section transitions:** Minimum radius = 5mm or 0.5× section thickness - **Machining allowances:** 1.5-2.5mm per side for finish grinding after heat treatment - **Stress concentrations:** Avoid sharp corners and sudden changes in cross-section - **Symmetry:** Design symmetrical parts to minimize heat treatment distortion **Manufacturing Best Practices:** - Perform all heavy machining before final heat treatment - Stress relieve after rough machining to minimize distortion - Use sharp carbide tools with positive rake angles - Consider normalized condition for components that may be used without further hardening - Specify final grinding after tempering for precision components **Economic Considerations:** - Higher material cost than standard 4150 (due to H-grade certification) - Reduced risk of heat treatment failures and scrap - Better machinability than as-forged material - Optimal for high-value components where reliability justifies cost --- **TECHNICAL SUMMARY:** **AISI 4150H steel normalized at 870°C (1600°F)** represents a **strategically optimized intermediate condition** for manufacturing the most demanding high-performance components. This treatment provides the ideal balance of sufficient strength for handling and machining, excellent microstructural uniformity for predictable heat treatment response, and the certified hardenability guarantee that is critical for large-section components. The normalized condition is particularly valuable for parts that require extensive machining operations before final hardening, as it offers better dimensional stability than annealed material while maintaining adequate machinability. When specified for critical applications in energy, heavy machinery, transportation, or defense, normalized 4150H provides engineers with the material certainty needed for reliable design, predictable manufacturing, and consistent performance in service. This condition embodies the principle of "right material, right condition, right certification" for components where failure is not an option. -:- For detailed product information, please contact sales. -: AISI 4150H Steel, normalized at 870°C (1600°F), air cooled Specification Dimensions Size： Diameter 20-1000 mm Length <6231 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 4150H Steel, normalized at 870°C (1600°F), air cooled Properties -:- For detailed product information, please contact sales. -:

Applications of AISI 4150H Steel, normalized at 870°C (1600°F), air cooled -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI 4150H Steel, normalized at 870°C (1600°F), air cooled -:- For detailed product information, please contact sales. -:

Packing of AISI 4150H Steel, normalized at 870°C (1600°F), air cooled -:- 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 2702 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