AISI 81B45H Steel Sheet,Plate

AISI 81B45H Steel Sheet/Plate Product Information -:- For detailed product information, please contact sales. -: AISI 81B45H Steel Sheet/Plate Synonyms -:- For detailed product information, please contact sales. -:

AISI 81B45H Steel Product Information -:- For detailed product information, please contact sales. -: ## **Product Specification: AISI 81B45H Controlled-Hardenability Boron Steel** ### **Product Designation** * **Standard Name:** AISI 81B45H / SAE 81B45H * **UNS Number:** H50450 (with Hardenability Certification) * **Type:** Medium-Carbon, Boron-Treated Alloy Steel, Hardenability-Grade * **Primary Form:** Hot-rolled or cold-drawn bar * **Key Feature:** **Guaranteed hardenability band per ASTM A304** with boron-enhanced economics. ### **Overview** AISI 81B45H is the **hardenability-controlled ("H"-grade) variant** of standard AISI 81B45 boron-treated steel. The "H" designation signifies that the material is produced and certified to meet precise minimum and maximum hardness values at standardized distances on a Jominy end-quench test (ASTM A304). This ensures exceptional consistency in the depth and uniformity of hardening across different production lots. Combining the **cost-effectiveness of boron hardenability enhancement** with **predictable heat treatment response**, this grade is engineered for high-volume production of components where consistent core properties and minimal distortion are critical. --- ### **1. Chemical Composition (Range by Weight %, ASTM A304)** The composition is tightly controlled to achieve the specified Jominy hardenability band. It mirrors standard 81B45 but with adjusted ranges to guarantee the "H" band. | Element | 81B45H Range (%) | Role & Effect | | :--- | :--- | :--- | | **Carbon (C)** | 0.43 - 0.48 | Primary determinant of maximum achievable hardness and strength. | | **Manganese (Mn)** | 0.75 - 1.05 | Provides base hardenability; range is adjusted to control the Jominy curve slope. | | **Phosphorus (P)** | ≤ 0.030 | Impurity; controlled at low levels. | | **Sulfur (S)** | ≤ 0.035 | Impurity; low level ensures good transverse properties. | | **Silicon (Si)** | 0.15 - 0.35 | Deoxidizer and solid solution strengthener. | | **Boron (B)** | 0.0005 - 0.003 | **Core performance element.** Drastically increases hardenability by segregating to austenite grain boundaries, delaying soft phase transformation. | | **Other (Al, Ti, Zr)**| May be present to protect boron from nitrogen, ensuring its efficacy. | | **Iron (Fe)** | Balance | | ***Procurement Note:*** AISI 81B45H is purchased based on its **guaranteed hardenability band** (SAE Jominy band for 81B45H). The mill test report includes actual Jominy test results, not just chemistry. --- ### **2. Physical & Mechanical Properties** **A. Physical Properties (Annealed/Normalized State - Typical)** * **Density:** 7.85 g/cm³ (0.284 lb/in³) * **Elastic Modulus (E):** ~205 GPa (29.7 x 10⁶ psi) * **Poisson's Ratio:** 0.29 * **Thermal Conductivity:** ~48 W/m·K * **Coefficient of Thermal Expansion:** 11.5 x 10⁻⁶ /K (20-100°C) **B. Mechanical Properties (As-Supplied, Annealed)** *Typical for machinable condition.* * **Hardness (Brinell):** 179 - 217 HB * **Tensile Strength:** 585 - 725 MPa (85 - 105 ksi) * **Yield Strength:** ~415 MPa (60 ksi) min. * **Elongation:** 20% min. **C. Guaranteed Hardenability & Heat-Treated Properties** * **Governing Standard:** **ASTM A304** * **Hardenability Band:** The certified Jominy curve ensures that for a given bar diameter and quench severity, the resulting core hardness will fall within a narrow, predictable range. * **Typical Jominy Curve:** Shows a high initial hardness (J1 ~55-60 HRC) with a moderately slow decline, characteristic of boron steels, suitable for hardening medium to large sections. * **Achievable Tempered Hardness Range:** 25 - 50 HRC (via tempering between 425-650°C / 800-1200°F). * **Key Benefit:** **Reduced lot-to-lot variation** in final part strength, fatigue life, and dimensional stability after quenching and tempering. --- ### **3. Product Applications** 81B45H is specified for high-volume, cost-sensitive components where **consistent heat treatment results are mandatory** for performance, assembly, or safety. * **Automotive Powertrain (Primary Market):** * **Shafts:** Consistent axle shafts, input/output shafts for transmissions, and steering column shafts. * **Fasteners:** High-volume, high-strength bolts, wheel studs, and suspension components requiring uniform clamping force. * **Forgings:** Connecting rods, crankshafts (for certain applications), and other forged parts where uniform core strength controls weight and fatigue life. * **Agricultural & Off-Highway Equipment:** * Pivot pins, linkage arms, and drive components produced in large batches. * **Fluid Power Components:** * Hydraulic cylinder rods and piston rods where consistent hardness ensures uniform wear and seal life. * **General Machinery:** * Spindles, arbors, and tool holders manufactured in quantity. --- ### **4. International Standards & Designations** The "H"-grade concept for boron steels is primarily North American. Other systems may have similar grades but without the same standardized hardenability certification. | Standard System | Designation | Notes / Key Comparison | | :--- | :--- | :--- | | **SAE / AISI (USA)** | **SAE 81B45H** | The standard "H"-grade designation. | | **ASTM (USA)** | **ASTM A304** (H50450H) | Governing standard for H-band requirements. Also falls under **ASTM A29** for bars. | | **UNS (USA)** | **H50450** (with H spec) | Same UNS as 81B45; "H" is a procurement spec. | | **DIN / EN (Germany/EU)** | **No direct H-equivalent.** Conceptually similar to **~1.5530 (38MnB5)** with supplementary hardenability testing. | European boron steels are common, but the "H" system is not directly applied. Consistency is achieved through separate quality agreements. | | **JIS (Japan)** | **No direct equivalent.** | Similar boron-treated steels exist (e.g., **S45C-B**), but not with an "H" hardenability guarantee. | | **GB (China)** | **40MnBH or 45MnBH** | Chinese standards **do have "H" designations** for boron steels (e.g., GB/T 5216), making **40MnBH/45MnBH** the closest functional and conceptual equivalents. | --- ### **Key Advantages & Processing Guidance** 1. **Economic Consistency:** Delivers the predictable performance of higher-alloy "H" grades (like 41xxH or 86xxH) at a significantly lower material cost, thanks to boron. 2. **Heat Treatment Optimization:** The known hardenability band allows for precise design of quenching media, agitation, and tempering cycles to achieve target properties with minimal trial and error. 3. **Reduced Scrap & Rework:** Minimizes the risk of parts being out-of-specification after heat treatment due to material variability. 4. **Welding & Machining:** Similar to standard 81B45. Welding requires pre/post-heat treatment due to high hardenability. Machinability is fair to good in the annealed state. ### **Summary** **AISI 81B45H** represents the **optimized intersection of cost-efficiency and production reliability** in medium-carbon alloy steels. By leveraging boron for hardenability and incorporating ASTM A304's strict hardenability controls, it provides manufacturers with a material that ensures consistent, predictable results in high-volume heat treatment. This makes it an ideal choice for automotive and industrial components where part-to-part uniformity, fatigue performance, and overall value are paramount. Its existence underscores the advanced metallurgical control applied to commodity alloy steels for modern manufacturing. The closest global analogues are the Chinese **GB 40MnBH/45MnBH** grades. -:- For detailed product information, please contact sales. -: AISI 81B45H Steel Specification Dimensions Size： Diameter 20-1000 mm Length <4144 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 81B45H Steel Properties -:- For detailed product information, please contact sales. -:

Applications of AISI 81B45H Steel Sheet,Plate -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI 81B45H Steel Sheet,Plate -:- For detailed product information, please contact sales. -:

Packing of AISI 81B45H 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 615 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