AISI 8720H Steel

AISI 8720H Steel Product Information -:- For detailed product information, please contact sales. -: AISI 8720H Steel Synonyms -:- For detailed product information, please contact sales. -:

AISI 8720H Steel Product Information -:- For detailed product information, please contact sales. -: ### **Product Introduction: AISI 8720H Steel** #### **1. Overview** AISI 8720H is a **hardenability-controlled (H-grade) boron-modified nickel-chromium-molybdenum alloy steel**, representing the premium, consistency-guaranteed variant of the standard AISI 8720. This steel combines the **cost-effective hardenability enhancement of boron** with the **stringent batch-to-batch consistency** of the H-grade certification system. Engineered for high-volume manufacturing, it delivers **reliable and predictable core properties** after carburizing heat treatment, ensuring uniform performance across production lots. AISI 8720H provides an optimal balance of **deep hardenability, good core strength, and economic alloy design**, making it a preferred choice for cost-conscious yet quality-critical applications requiring guaranteed material consistency. #### **2. International Standards & Designations** This H-grade boron steel conforms to standards that govern both its composition and its guaranteed hardenability range. | Region/System | Standard Designation | Title / Purpose | | :--- | :--- | :--- | | **USA (AISI/SAE)** | **AISI 8720H, SAE J404 & SAE J1268** | Chemical Composition & Hardenability Bands | | **USA (ASTM)** | **ASTM A304** | Standard Specification for Steel Bars Subject to End-Quench Hardenability Requirements | | **USA (ASTM)** | **ASTM A914/A914M** | Steel Bars Subject to Restricted Hardenability Bands | | **UNS Number** | **H87200** | Unified Numbering System for H-Steels | | **Europe (EN)** | **20NiCrMoS2-2H (+B)** | Hardenability-controlled Boron-Treated Equivalent | | **Boron Steel Specific** | **SAE J406** | Hardenability Bands for Boron Steels | | **Heat Treatment** | **SAE AMS-H-6875** | Heat Treatment of Steel, General Requirements | #### **3. Chemical Composition & Hardenability Guarantee** The composition is tightly controlled, with boron as the key differentiating element and the entire chemistry optimized to meet precise H-band specifications. **Core Composition (% by Weight, AISI 8720H):** | Element | Content Range | Metallurgical Significance | | :--- | :--- | :--- | | **Carbon (C)** | 0.17 - 0.23 | Provides base core strength; tightly controlled for H-band consistency. | | **Manganese (Mn)** | 0.70 - 0.95 | Enhances hardenability; range adjusted for predictable Jominy curve. | | **Phosphorus (P)** | ≤ 0.035 | Impurity control. | | **Sulfur (S)** | ≤ 0.040 | Impurity control; sometimes optimized for machinability. | | **Silicon (Si)** | 0.15 - 0.35 | Deoxidizer and solid solution strengthener. | | **Nickel (Ni)** | 0.35 - 0.75 | Enhances core toughness; content stabilized for hardenability consistency. | | **Chromium (Cr)** | 0.35 - 0.65 | Increases hardenability; promotes wear-resistant carbides. | | **Molybdenum (Mo)** | 0.20 - 0.30 | Strong hardenability element; suppresses temper embrittlement. | | **Boron (B)** | **0.0005 - 0.003** | **Critical Hardenability Intensifier:** Significantly boosts hardenability at low cost. Its effect is maximized and stabilized through precise control of protecting elements (e.g., Ti, Al). | | **Titanium (Ti)** | Often added (~0.02%) | **Essential for Boron Efficacy:** Forms TiN, protecting soluble boron and ensuring consistent hardenability response. | **Key Feature: Guaranteed Hardenability Band (with Boron Effect)** The steel is supplied with certified Jominy end-quench test results guaranteed to fall within a specified narrow band. This certification **includes the potent effect of boron**, guaranteeing a predictable and uniformly deep hardening response. It ensures core hardness after heat treatment will have minimal lot-to-lot variation, typically within ±3 HRC for a given section size. #### **4. Mechanical & Physical Properties** *Properties are process-dependent. The following represents typical achievable ranges.* **As-Supplied (Annealed) Properties:** * **Hardness:** **149 - 197 HB** (Brinell) * **Tensile Strength:** **520 - 690 MPa** (75 - 100 ksi) * **Machinability:** **~60%** of B1112 steel. **Properties After Case Hardening (Carburized & Hardened):** * **Surface (Case) Properties:** * **Hardness:** **58 - 63 HRC** * **Effective Case Depth:** Can achieve greater depths more consistently than non-H grades due to guaranteed hardenability. * **Core Properties (H-Grade Advantage):** * **Hardness:** **32 - 45 HRC** (Predictable within narrow range). * **Tensile Strength:** **950 - 1300 MPa** (138 - 189 ksi) * **Yield Strength:** **750 - 1100 MPa** (109 - 160 ksi) * **Impact Toughness:** Good, maintained by nickel content. * **Section Size Capability:** The boron-enhanced, H-guaranteed hardenability allows reliable hardening of larger sections than possible with 8620H of similar alloy base. **Physical Properties (Core):** * **Density:** **7.85 g/cm³** * **Modulus of Elasticity:** **205 GPa** * **Coefficient of Thermal Expansion:** **12.5 × 10⁻⁶/°C** #### **5. Product Applications** AISI 8720H is specified for high-volume, cost-sensitive components where guaranteed core consistency and good hardenability are required without the expense of higher nickel/chromium grades. * **High-Volume Automotive Gearing:** Transmission gears, differential gears, and pinions for passenger cars and light trucks where production consistency is critical. * **Agricultural & Off-Highway Equipment:** Gears, shafts, and drive components for tractors, combines, and utility vehicles. * **Industrial Gearboxes:** Medium-duty gears for conveyors, pumps, and general industrial machinery produced in large batches. * **Bearing Components:** Races and rollers for mass-produced, medium-duty bearings. * **Hydraulic Components:** Gears and shafts in high-volume hydraulic pump and motor production. * **Fasteners:** High-strength, case-hardened bolts and pins for automotive and machinery assembly. #### **6. Key Characteristics & Advantages** * **Cost-Effective, Guaranteed Hardenability:** The **primary value proposition.** Boron provides deep hardenability at low alloy cost, while the H-grade certification ensures this benefit is delivered consistently in every production lot. * **Superior Production Consistency:** Eliminates the risk of hardenability variation common in standard boron steels, leading to uniform core hardness, predictable distortion, and stable heat treatment processes. * **Reduced Quality Risk & Scrap:** The guaranteed H-band virtually eliminates rejects due to insufficient core hardness in finished parts, offering significant savings in high-volume production. * **Excellent Value for Performance:** Delivers a hardenability profile often comparable to more expensive alloy grades (e.g., 8620H/8622H) but at a lower material cost, optimized for cost-driven designs. * **Good Machinability:** In the annealed condition, it offers good productivity in high-volume CNC machining operations. * **Design Flexibility:** The reliable hardenability allows for the design of larger or more complex sections with confidence in achieving target core properties. **Process Considerations:** * **Boron Protection:** Consistent response relies on adequate titanium/aluminum to protect boron from forming ineffective oxides/nitrides. * **Quenching:** Requires adequate quench severity (typically oil) to realize the full boron hardenability benefit. * **Not for Nitriding:** Boron can lead to brittle nitrided cases; not recommended for nitriding processes. * **Weldability:** Requires caution; preheat and low-hydrogen processes are essential to avoid cracking in the heat-affected zone. **Conclusion:** **AISI 8720H is a strategically engineered material that maximizes value through intelligent metallurgy and guaranteed quality control.** It successfully marries the **economic efficiency of boron hardenability** with the **production reliability of H-grade certification.** This makes it an ideal choice for manufacturers who must balance stringent performance and consistency requirements with aggressive cost targets. For high-volume applications in the automotive, agricultural, and general industrial sectors, where every component must perform identically and production yields are paramount, AISI 8720H provides a dependable, high-value solution. It exemplifies how modern steelmaking can deliver premium consistency in a cost-optimized alloy, ensuring quality and predictability without unnecessary material expense. -:- For detailed product information, please contact sales. -: AISI 8720H Steel Specification Dimensions Size： Diameter 20-1000 mm Length <5748 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 8720H Steel Properties -:- For detailed product information, please contact sales. -:

Applications of AISI 8720H Steel -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI 8720H Steel -:- For detailed product information, please contact sales. -:

Packing of AISI 8720H Steel -:- 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 2219 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