Assab Steel Sheet,Plates,718HH Plastic Mold Material

Assab Steel Sheet/Plates 718HH Plastic Mold Material Product Information -:- For detailed product information, please contact sales. -: Assab Steel Sheet/Plates 718HH Plastic Mold Material Synonyms -:- For detailed product information, please contact sales. -:

Assab Steels 718HH Plastic Mold Material Product Information -:- For detailed product information, please contact sales. -: ### **Assab Steels 718HH: High-Hardness Premium P20-Type Plastic Mold Steel** --- #### **1. Introduction** **Assab Steels 718HH** is a premium-grade, nickel-chromium-molybdenum (Ni-Cr-Mo) alloyed **plastic mold steel**, specifically engineered to offer higher hardness and strength than standard P20-type steels. The "HH" designation stands for **"High Hardness"**. It is manufactured using advanced refining processes to ensure excellent cleanliness, homogeneity, and isotropic properties. 718HH is pre-hardened and supplied at a high and uniform hardness, eliminating the need for heat treatment by the mold maker. It is the industry benchmark for demanding injection molds requiring superior wear resistance, excellent polishability, and high precision. **Key Value Propositions:** * **High Pre-Hardened Hardness:** Supplied at ~ **340 - 380 HB** (36-40 HRC), providing significantly higher wear resistance and strength than standard P20 (~ 290-330 HB). * **Excellent Polishability & Texture Transfer:** Superior surface finish quality due to its homogeneous, fine-grained microstructure with very low sulfur content. * **Superior Machinability & EDM Performance:** Despite its high hardness, it offers good machining characteristics and consistent EDM results. * **Excellent Through-Hardening & Homogeneity:** Uniform properties throughout large cross-sections, ensuring consistent performance in deep cavities and cores. * **Good Weldability:** Can be repaired or modified with standard welding procedures, given appropriate precautions. * **Isotropic Properties:** Minimal directional variation in mechanical properties, ensuring predictable mold behavior. --- #### **2. International Standard Designations** * **Assab / Uddeholm:** 718HH * **AISI / ASTM A681:** Modified P20+Ni (Proprietary High-Hardness Grade) * **European Norm (EN):** 1.2738 (Modified / HH Quality) - Often referenced as 40CrMnNiMo8-6-4 * **DIN:** 40CrMnNiMo8-6-4 (HH) * **JIS:** PX5 (Equivalent) * **GB (China):** 3Cr2NiMo (HH) --- #### **3. Chemical Composition (Typical Weight %)** | Element | Carbon (C) | Silicon (Si) | Manganese (Mn) | Chromium (Cr) | Nickel (Ni) | Molybdenum (Mo) | | :--- | :---: | :---: | :---: | :---: | :---: | :---: | | **%** | 0.37 | 0.30 | 1.50 | 2.00 | 1.00 | 0.20 | *Key Feature: The addition of **Nickel (Ni)** enhances through-hardening capability, toughness, and homogeneity, especially in large sections.* --- #### **4. Physical & Mechanical Properties (As Supplied - Pre-Hardened)** * **Hardness (Supplied):** **340 - 380 HB** (Approx. **36 - 40 HRC**) * **0.2% Proof Strength (Yield Strength):** ≥ 1000 MPa * **Tensile Strength:** 1200-1400 MPa * **Elongation:** > 10% * **Impact Toughness (Charpy V):** Typically > 40 J (ensuring good resistance to chipping) * **Density:** 7.8 g/cm³ * **Thermal Conductivity:** ~ 36 W/m·K (at 20°C) * **Coefficient of Thermal Expansion:** 12.5 x 10⁻⁶/K (20-100°C) --- #### **5. Heat Treatment & Processing** * **Supply Condition:** Pre-hardened, ready for machining. **No further heat treatment required** for most applications. * **Nitriding/Case Hardening:** Excellent candidate for gas or plasma nitriding to achieve surface hardness up to 700 HV, further enhancing wear and corrosion resistance for molds processing abrasive or corrosive plastics. * **Stress Relieving (Optional):** For highly complex or precise molds, stress relieving at 500-550°C after rough machining and before finishing is recommended. * **If Hardening is Required (for special applications):** Austentize at 850-880°C, quench in oil or polymer, and temper to desired hardness (typically in the 540-600°C range). --- #### **6. Product Applications** 718HH is the premier choice for high-performance, long-running injection molds across all industries. 1. **High-Volume & Technical Injection Molding:** * Automotive components (bumpers, dashboards, lighting lenses, under-hood parts). * Electronic housings and connectors. * Household appliance parts. 2. **Molds Requiring Superior Surface Finish:** * Optical components (lenses, light guides). * Consumer products with Class-A surfaces (e.g., phone/computer casings). * Molds for glossy or transparent parts (e.g., PMMA, PC, SAN). 3. **Molds Processing Abrasive or Corrosive Materials:** * Glass-filled or mineral-filled plastics (PA, PBT, PPS). * PVC and other halogenated polymers (with proper surface protection like nitriding or plating). 4. **Large & Complex Mold Bases and Inserts:** * Where high pre-hardened strength prevents deflection under high injection pressures. * Deep-draw molds requiring excellent core toughness. --- #### **7. Machining & Fabrication Guide (Pre-Hardened Condition)** | Process | Recommended Tools & Parameters | | :--- | :--- | | **Turning** | Coated carbide inserts. Use positive rake geometry, moderate feeds, and good coolant. | | **Milling** | High-speed steel (HSS) or carbide end mills. Use stable set-ups, climb milling, and ample coolant. | | **Drilling** | HSS or carbide drills with sufficient coolant flow and chip evacuation. | | **Grinding** | Aluminum oxide or CBN wheels. Use light passes with ample coolant to avoid thermal stress. | | **EDM (Sinker)** | Excellent performance. Use fine-finish settings for best surface quality. A tempering (stress-relief) layer may form and should be removed by polishing. | | **Polishing** | Responds excellently to sequential abrasive polishing, capable of achieving mirror finishes (A1/A0). | --- #### **8. Quality & Supply Forms** * **Quality:** Vacuum degassed and subjected to ultrasonic testing to ensure internal soundness. * **Available Forms:** Supplied in pre-hardened, black or machined condition. * Precision ground flat stock (PGFS) * Blocks and billets * Round bars * Custom pre-machined mold plates and components --- #### **9. Comparison: 718HH vs. Standard P20** | **Property** | **718HH** | **Standard P20 (e.g., Assab 618)** | | :--- | :--- | :--- | | **Supplied Hardness** | **High (340-380 HB / 36-40 HRC)** | Medium (290-330 HB / 30-34 HRC) | | **Wear Resistance** | **Superior** | Good | | **Core Toughness** | **Higher** (due to Ni content) | Good | | **Polishability** | **Excellent** | Very Good | | **Machinability** | Good (considering its hardness) | Very Good | | **Best For** | High-volume, high-precision, abrasive materials | General-purpose, medium-volume molds | --- #### **10. Conclusion** **Assab Steels 718HH** represents the optimal balance of high pre-hardened strength, exceptional polishability, and reliable processability for the modern, high-performance plastic injection molding industry. By delivering higher hardness "off the shelf," it extends mold life, reduces polishing time, and maintains precision under high clamping forces. For mold builders and manufacturers targeting top-tier surface quality, maximum production runs, and processing of demanding engineering plastics, 718HH is the proven and trusted material of choice, justifying its premium status through superior total cost of ownership and part quality. -:- For detailed product information, please contact sales. -: Assab Steels 718HH Plastic Mold Material Specification Dimensions Size： Diameter 20-1000 mm Length <7244 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. -: Assab Steels 718HH Plastic Mold Material Properties -:- For detailed product information, please contact sales. -:

Applications of Assab Steel Sheet,Plates 718HH Plastic Mold Material -:- For detailed product information, please contact sales. -: Chemical Identifiers Assab Steel Sheet,Plates 718HH Plastic Mold Material -:- For detailed product information, please contact sales. -:

Packing of Assab Steel Sheet/Plates 718HH Plastic Mold Material -:- 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 3715 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