ASTM A439 Austenitic Ductile Iron Rod/Bar type D2B

ASTM A439 Austenitic Ductile Iron Rod type D2B Product Information -:- For detailed product information, please contact sales. -: ASTM A439 Austenitic Ductile Iron Rod type D2B Synonyms -:- For detailed product information, please contact sales. -:

ASTM A439 Austenitic Ductile Iron type D2B Product Information -:- For detailed product information, please contact sales. -: # **Product Technical Data Sheet: ASTM A439 Austenitic Ductile Iron – Type D-2B** --- ## **1. Product Overview** **ASTM A439 Type D-2B Austenitic Ductile Iron** is a **high-nickel, chromium-alloyed, boron-modified austenitic spheroidal graphite iron**. It is a direct derivative of the standard Type D-2 grade, with the intentional addition of **boron (B)** to significantly enhance its **as-cast hardness, wear resistance, and elevated-temperature strength** while retaining the core benefits of the austenitic matrix: **superior corrosion resistance, non-magnetic properties, and excellent thermal stability**. Type D-2B is engineered for applications that demand not only the environmental resistance of an austenitic ductile iron but also improved resistance to abrasion, galling, and deformation under load at moderate temperatures. --- ## **2. Governing Standards & Specifications** This alloy is a specialized variant within the ASTM A439 standard, often specified for its enhanced mechanical properties. * **Primary Standard:** * **ASTM A439** - *Standard Specification for Austenitic Ductile Iron Castings* (Includes Type D-2 and D-2B). * **International & Commercial Equivalents:** * While ISO 2892 does not have a direct 1:1 equivalent, D-2B fits within the broader **Ni-Resist®** family of austenitic ductile irons and is sometimes referenced in proprietary specifications. * **Common Trade Name:** **Ni-Resist® Type D-2B**. * **Key Referenced Testing Standards:** * **ASTM E8:** Tensile Testing * **ASTM E10/E18:** Hardness Testing (Brinell/Rockwell) * **ASTM A247:** Microstructure Evaluation * **ASTM G65:** Dry Sand/Rubber Wheel Abrasion Test (for wear comparison) --- ## **3. Chemical Composition Requirements (per ASTM A439)** The composition is identical to Type D-2, with the critical addition of boron. | Element | Composition Range (wt.%, ASTM A439) | Functional Role & Rationale for D-2B | | :--- | :--- | :--- | | **Carbon (C)** | 2.60 - 3.00 | Provides graphite; controlled to balance strength and castability. | | **Silicon (Si)** | 1.50 - 2.50 | Graphitizer and solid solution strengthener. | | **Nickel (Ni)** | **18.00 - 22.00** | **Primary Austenite Stabilizer.** Ensures a fully austenitic matrix, providing ductility, toughness, and non-magnetic properties. | | **Chromium (Cr)** | **1.75 - 2.50** | **Key for Corrosion & Heat Resistance.** Forms a protective passive layer. Strengthens the matrix. | | **Manganese (Mn)** | 0.50 - 1.50 | Austenite stabilizer and sulfur control. | | **Copper (Cu)** | **≤ 0.50** | Low, as in Type D-2. | | **Boron (B)** | **0.010 - 0.030** | **The Defining Addition.** Boron segregates to cell boundaries and promotes the formation of very fine, hard **boron carbides (e.g., (Fe,Cr,Mo)₂₃(C,B)₆)** and borides. This **significantly increases the as-cast hardness and wear resistance** without requiring heat treatment. | | **Magnesium (Mg)** | ≥ 0.07 (min., residual) | Ensures spheroidal graphite formation. | | **Phosphorus (P)** | ≤ 0.08 | Kept low. | | **Sulfur (S)** | ≤ 0.03 | Kept low. | --- ## **4. Physical & Mechanical Properties** The boron addition shifts the property balance towards higher strength and wear resistance, with a slight trade-off in ductility compared to Type D-2. | Property | Typical Value / Range for D-2B | Comparison & Significance vs. Type D-2 | | :--- | :--- | :--- | | **Tensile Strength, min.** | **414 MPa (60,000 psi)** | Similar minimum, but typical values are often **higher (450-550 MPa)**. | | **Yield Strength (0.2% offset), min.** | **207 MPa (30,000 psi)** | Similar minimum, but typical values are **higher (240-300 MPa)** due to dispersion strengthening from borides/carbides. | | **Elongation, min.** | **15%** | **Reduced from 20% in D-2.** Still good ductility, but the hard phases slightly reduce the ability to deform plastically. | | **Hardness (Brinell, HBW)** | **180 - 250 HBW** | **Significantly higher** than D-2 (140-190 HBW). This is the primary benefit, leading to improved wear and deformation resistance. | | **Modulus of Elasticity** | **~110 - 125 GPa** | Similar to D-2; the austenitic matrix dominates this property. | | **Impact Resistance** | **Good.** Slightly lower than D-2 due to harder microstructure, but still maintains useful toughness for most engineering applications. | | **Wear & Abrasion Resistance** | **Very Good.** **Superior to Type D-2.** The fine, hard boride/carbide network provides excellent resistance to adhesive wear (galling), abrasive wear, and cavitation erosion. | | **Elevated Temperature Strength** | **Improved.** Retains a higher percentage of its room-temperature strength up to ~500°C compared to D-2, due to the stabilizing effect of boron on the microstructure. | | **Corrosion Resistance** | **Excellent.** Comparable to Type D-2. The boron addition does not significantly detract from the excellent corrosion resistance in alkalis, seawater, and many organic and dilute mineral acids. | | **Non-Magnetic Property** | **Maintained.** The austenitic matrix remains stable; permeability remains low (µᵣ ~1.05 - 1.10). | | **Machinability** | **Fair to Good.** More challenging than D-2 due to higher hardness and abrasive phases. Requires carbide tooling and appropriate parameters. | --- ## **5. Product Applications** Type D-2B is specified where the corrosion/heat resistance of an austenitic ductile iron is required alongside improved mechanical durability. * **Corrosive & Abrasive Slurry Handling:** * **Pump casings, impellers, and wear plates** for chemical process, mining, and dredging applications handling abrasive slurries in corrosive media. * **Valves for Severe Service:** * **Valve bodies, trim components, and seats** in applications involving particulate-laden or slightly abrasive corrosive fluids. * **Marine & Offshore (Wear-Critical):** * **Bearing housings, bushings, and seals** in seawater pumps and systems where both corrosion and wear are factors. * **Food & Chemical Processing Equipment:** * **Mixer blades, agitators, and conveyor components** subject to moderate abrasion in corrosive environments. * **General Engineering:** * **Gears, cams, and guides** requiring non-magnetic properties, corrosion resistance, and better wear performance than standard D-2. --- ## **6. Fabrication & Processing Notes** * **Condition:** Supplied **as-cast**. The enhanced properties are achieved directly from the casting process via the boron addition; no subsequent hardening heat treatment is used or typically required. * **Casting Considerations:** Boron can slightly reduce ductility and impact toughness at very high levels. Foundry practice must carefully control the boron content within the specified range to optimize the hardness/ductility balance. It may have a slight effect on fluidity and feeding characteristics. * **Machinability:** **Fair to Good, but more demanding than D-2.** The increased hardness and presence of hard phases make it more abrasive on tools. **Carbide tooling is recommended.** Speeds and feeds should be adjusted accordingly. * **Weldability:** **Fair (with caution).** Similar to Type D-2 but requires even greater care. The HAZ may exhibit altered properties due to boron redistribution. Use matching or over-alloyed Ni-Cr-Mo filler metals (e.g., ENiCrFe-3). **Pre-heat (~200-300°C) and post-weld stress relief are strongly recommended.** Welding should be limited to repair, not fabrication. --- ## **7. Ordering Information** **Specify:** **"Austenitic Ductile Iron Castings, ASTM A439 Type D-2B (Ni-Resist D-2B equivalent)."** **Critical Details to Provide:** * **Applicable Standard & Grade** (ASTM A439 D-2B). * **Part Drawing & Specification.** * **Key Performance Requirements** (e.g., minimum hardness, wear resistance needs alongside corrosion service environment). * **Certification Requirements:** Mill Test Report (MTR) with full chemical analysis (must include **Boron content**) and mechanical properties. Hardness should be explicitly called out. * **Special Requirements:** If wear resistance is critical, specifying a **minimum hardness** (e.g., 200 HBW) is advisable. Non-magnetic certification if required. --- ## **8. Summary: D-2 vs. D-2B Selection Guide** | **Criterion** | **Choose ASTM A439 Type D-2 when:** | **Choose ASTM A439 Type D-2B when:** | | :--- | :--- | :--- | | **Primary Need** | Maximum ductility, impact toughness, and formability. | Higher as-cast hardness, wear resistance, and load-bearing ability are required. | | **Mechanical Focus** | Superior elongation and toughness for shock/vibration loads. | Improved yield strength and resistance to abrasion/galling are paramount. | | **Hardness** | Standard hardness (140-190 HBW) is acceptable. | A higher, more consistent as-cast hardness (180-250 HBW) is needed. | | **Machinability** | Easier machinability is a priority. | Slightly more difficult machining can be accommodated for property gain. | | **Application** | General corrosion-resistant castings, complex shapes, cryogenic parts. | Corrosion-resistant parts subject to wear, sealing surfaces, or requiring better dimensional stability under load. | **ASTM A439 Type D-2B is the engineered solution for applications that must withstand the dual challenges of a corrosive environment and mechanical wear, offering a unique and valuable property set within the austenitic ductile iron family.** -:- For detailed product information, please contact sales. -: ASTM A439 Austenitic Ductile Iron type D2B Specification Dimensions Size： Diameter 20-1000 mm Length <6552 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. -: ASTM A439 Austenitic Ductile Iron type D2B Properties -:- For detailed product information, please contact sales. -:

Applications of ASTM A439 Austenitic Ductile Iron Rod type D2B -:- For detailed product information, please contact sales. -: Chemical Identifiers ASTM A439 Austenitic Ductile Iron Rod type D2B -:- For detailed product information, please contact sales. -:

Packing of ASTM A439 Austenitic Ductile Iron Rod type D2B -:- 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 3023 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