AISI Type A8 Tool Steel Sheet,Plate

AISI Type A8 Tool Steel Sheet/Plate Product Information -:- For detailed product information, please contact sales. -: AISI Type A8 Tool Steel Sheet/Plate Synonyms -:- For detailed product information, please contact sales. -:

AISI Type A8 Tool Steel Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: AISI Type A8 Tool Steel** ## **Overview** AISI Type A8 is a **medium-carbon, high-chromium, air-hardening tool steel** uniquely formulated to provide **exceptional dimensional stability combined with good toughness and wear resistance**. Positioned between the general-purpose A2 and high-wear A7 grades, A8 features balanced alloying that emphasizes **minimal distortion during heat treatment, reliable hardenability, and resistance to thermal fatigue**. Its distinct composition makes it particularly suitable for **precision tooling applications requiring stable dimensions under thermal cycling conditions**, such as certain die casting and plastic molding applications. --- ## **Chemical Composition (Typical Weight %)** The composition emphasizes chromium for stability and hardenability with controlled carbon. | Element | Content (%) | | :--- | :--- | | Carbon (C) | 0.50 - 0.60 | | Chromium (Cr) | 4.75 - 5.50 | | Molybdenum (Mo) | 1.15 - 1.65 | | Manganese (Mn) | 0.40 - 0.70 | | Silicon (Si) | 0.75 - 1.10 | | Vanadium (V) | ≤ 0.35 | | Sulfur (S) | ≤ 0.03 | | Phosphorus (P) | ≤ 0.03 | | **Iron (Fe)** | **Balance** | **Key Role of Elements:** * **Moderate Carbon (0.50-0.60%):** Lower than most cold work steels, providing improved toughness and reduced distortion while maintaining adequate hardness. * **High Chromium (4.75-5.50%):** Provides excellent air-hardening characteristics, good wear resistance through chromium carbide formation, and moderate corrosion resistance. * **Elevated Silicon (0.75-1.10%):** Higher than typical for tool steels; improves resistance to thermal fatigue (heat checking) and promotes graphitization in certain conditions. * **Molybdenum (1.15-1.65%):** Enhances hardenability, provides secondary hardening response during tempering, and improves high-temperature strength. * **Controlled Vanadium:** Limited to maintain machinability while providing some grain refinement. --- ## **Physical & Mechanical Properties** *Properties shown are for properly heat treated material.* | Property | Typical Value / Description | | :--- | :--- | | **Density** | 7.84 g/cm³ (0.283 lb/in³) | | **Hardness (Annealed)** | 200 - 235 HB (Brinell) | | **Hardness (Hardened & Tempered)** | **54 - 60 HRC** (Typically used at 56-58 HRC) | | **Wear Resistance** | **Good.** Better than low-alloy steels but less than high-carbon grades like A2 or D2. Suitable for moderate wear applications. | | **Toughness** | **Very Good to Excellent.** Higher than A2 at equivalent hardness due to lower carbon content. Good resistance to chipping. | | **Dimensional Stability** | **Exceptional.** Excellent for an air-hardening steel; minimal distortion and size change during heat treatment. | | **Machinability (Annealed)** | **Good** (Approx. 65-70% of 1% carbon steel). Better than higher-carbon tool steels. | | **Grindability** | **Good.** Less challenging than high-vanadium steels. | | **Thermal Fatigue Resistance** | **Good to Very Good.** The elevated silicon content improves resistance to heat checking under thermal cycling. | | **Thermal Conductivity** | ~ 28.5 W/m·K at 20°C | | **Coefficient of Thermal Expansion** | ~ 10.8 × 10⁻⁶/°C (20-100°C) | --- ## **Heat Treatment Guidelines** | Process | Parameters | | :--- | :--- | | **Annealing** | Heat to 815-845°C (1500-1550°F), slow furnace cool at ≤22°C/hour to 480°C (900°F), then air cool. Result: 200-235 HB. | | **Stress Relieving** | 650-675°C (1200-1250°F) for 1-2 hours, air cool. | | **Preheating** | Preheat at 650-760°C (1200-1400°F). | | **Austenitizing** | 955-980°C (1750-1795°F). Soak time: 20-30 minutes per inch of thickness. | | **Quenching** | **Air quench** in still or forced air. For complex shapes, forced air is recommended. | | **Tempering** | Temper immediately after quenching. Double temper at 175-540°C (350-1000°F) for minimum 2 hours per cycle. For high toughness: 425-540°C (800-1000°F). | --- ## **Product Applications** AISI A8 is particularly suited for applications requiring **dimensional stability under thermal stress and good overall mechanical balance**. ### **Primary Applications:** 1. **Die Casting Dies & Inserts:** For aluminum and zinc die casting where thermal fatigue resistance is important (though not as heat-resistant as dedicated H-series hot work steels). 2. **Plastic Injection Molds:** For abrasive or corrosive plastics where dimensional stability and moderate wear resistance are needed. 3. **Precision Gauges & Fixtures:** Where exceptional dimensional stability is required. 4. **Forming Dies & Punches:** For medium-duty forming applications requiring good toughness. 5. **Shear Blades & Cutting Tools:** For materials where a balance of wear and toughness is needed. 6. **Machine Tool Components:** Wear plates, guide rails, and cam plates requiring stability. 7. **Thread Rolling Dies:** For softer materials where dimensional precision is critical. ### **Industry Usage:** - **Tool & Die Making** - **Plastics Manufacturing** - **Light Metal Casting** - **Precision Manufacturing** --- ## **International Standards & Cross-Reference** AISI A8 has limited direct international equivalents. | Standard | Designation | Equivalent / Similar Grade | | :--- | :--- | :--- | | **AISI/SAE (USA)** | **Type A8** | - | | **UNS (USA)** | **T30108** | - | | **ASTM (USA)** | A681 | Grade A8 | | **Europe (EN)** | - | No direct common equivalent | | **Germany (DIN)** | - | No direct common equivalent | | **Japan (JIS)** | - | No direct common equivalent | | **Similar Grade** | **H12 Mod** | Modified hot work steel with similar Cr-Mo balance | **Note:** A8 is a relatively uncommon grade with few true international equivalents. Its composition shares similarities with some modified H-series hot work steels but is classified as a cold work steel. --- ## **Advantages & Considerations** ### **Advantages:** 1. **Excellent Dimensional Stability:** Minimal distortion during heat treatment. 2. **Good Toughness:** Superior to higher-carbon tool steels at equivalent hardness. 3. **Improved Thermal Fatigue Resistance:** Better than typical cold work steels due to silicon content. 4. **Reliable Hardenability:** Good through-hardening characteristics with air quenching. 5. **Balanced Performance:** Good combination of wear resistance, toughness, and stability. ### **Considerations:** 1. **Moderate Wear Resistance:** Not suitable for highly abrasive applications. 2. **Lower Maximum Hardness:** Cannot achieve the high hardness levels of A2, A7, or D2. 3. **Limited High-Temperature Capability:** Not a true hot work steel; limited to approximately 400°C (750°F) continuous service. 4. **Limited Availability:** Less commonly stocked than A2 or D2. --- ## **Technical Comparison Summary** - **vs. A2:** A8 has **better toughness and dimensional stability** but **lower wear resistance and maximum hardness**. - **vs. H13 (Hot Work):** H13 has **superior high-temperature strength and thermal fatigue resistance** but may have **lower dimensional stability** during heat treatment. - **vs. O1 (Oil-Hardening):** A8 offers **far better dimensional stability** (air vs. oil quench) and **better toughness**. --- ## **Special Considerations** ### **Thermal Fatigue Performance:** The elevated silicon content (0.75-1.10%) in A8 provides improved resistance to heat checking compared to standard cold work steels. This makes it suitable for applications involving moderate thermal cycling, though it does not match the performance of dedicated hot work steels like H13 for high-temperature applications. ### **Graphitization Potential:** The combination of moderate carbon and elevated silicon can promote graphitization under certain prolonged high-temperature exposures (above 425°C/800°F for extended periods). This should be considered for applications involving sustained elevated temperatures. --- ## **Conclusion** AISI Type A8 tool steel occupies a **specialized niche within the cold work steel family**, offering a **unique combination of dimensional stability, toughness, and moderate thermal fatigue resistance**. Its balanced composition—featuring moderate carbon, high chromium, and elevated silicon—makes it particularly valuable for **precision tooling applications that experience moderate thermal cycling** or where exceptional dimensional stability is paramount. While not as wear-resistant as A2 or as thermally resistant as H13, A8 provides an **optimal compromise for applications requiring stability under varying thermal conditions** with good overall mechanical performance. It represents a thoughtful engineering solution for tooling applications that fall between traditional cold work and hot work steel requirements, particularly where the dimensional predictability of air hardening is essential for manufacturing accuracy. -:- For detailed product information, please contact sales. -: AISI Type A8 Tool Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6668 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 Type A8 Tool Steel Properties -:- For detailed product information, please contact sales. -:

Applications of AISI Type A8 Tool Steel Sheet,Plate -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI Type A8 Tool Steel Sheet,Plate -:- For detailed product information, please contact sales. -:

Packing of AISI Type A8 Tool 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 3139 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