AISI Type A4 Tool Steel

AISI Type A4 Tool Steel Product Information -:- For detailed product information, please contact sales. -: AISI Type A4 Tool Steel Synonyms -:- For detailed product information, please contact sales. -:

AISI Type A4 Tool Steel Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: AISI Type A4 Tool Steel** ## **Overview** AISI Type A4 is a distinctive **medium-alloy, air-hardening cold work tool steel** notable for its **lower carbon content and unique combination of good toughness, dimensional stability, and moderate wear resistance**. Positioned as the most **shock-resistant grade** within the A-series air-hardening family, A4 offers superior toughness compared to other air-hardening grades while maintaining the characteristic minimal distortion of air-hardening steels. This balanced property profile makes it particularly valuable for applications where impact resistance and dimensional precision are prioritized alongside wear resistance. --- ## **Chemical Composition (Typical Weight %)** The composition is characterized by lower carbon content and strategic alloying for toughness and hardenability. | Element | Content (%) | | :--- | :--- | | Carbon (C) | 0.95 - 1.05 | | Manganese (Mn) | 1.80 - 2.20 | | Chromium (Cr) | 0.90 - 1.20 | | Molybdenum (Mo) | 0.90 - 1.40 | | Silicon (Si) | 0.15 - 0.50 | | Nickel (Ni) | 0.90 - 1.40 | | Vanadium (V) | ≤ 0.25 | | Sulfur (S) | ≤ 0.03 | | Phosphorus (P) | ≤ 0.03 | | **Iron (Fe)** | **Balance** | **Key Role of Elements:** * **Moderate Carbon:** Provides a foundation for hardness while prioritizing toughness over extreme wear resistance. * **High Manganese & Nickel:** The defining feature of A4. These elements significantly enhance **toughness, hardenability, and core strength**, allowing it to withstand substantial impact without fracturing. * **Chromium & Molybdenum:** Provide adequate hardenability for air quenching and contribute to wear resistance through carbide formation. * **Low Vanadium:** Minimizes hard carbide formation to preserve toughness; primarily serves as a grain refiner. --- ## **Physical & Mechanical Properties** *Note: Properties depend on heat treatment condition.* | Property | Typical Value / Description | | :--- | :--- | | **Density** | 7.86 g/cm³ (0.284 lb/in³) | | **Hardness (Annealed)** | 200 - 241 HB (Brinell) | | **Hardness (Hardened & Tempered)** | **54 - 60 HRC** (Typically used at 56-58 HRC for optimal toughness/wear balance) | | **Wear Resistance** | **Fair to Good.** Lower than other A-series grades (A2, A3) due to lower carbon and alloy content. Suitable for moderate wear conditions. | | **Toughness** | **Excellent (for an air-hardening grade).** The highest among standard A-series steels (A2-A10), approaching that of dedicated shock-resistant steels (S-series). Its primary advantage. | | **Dimensional Stability** | **Excellent.** Air-hardening provides minimal distortion and size change, making it ideal for precision tools. | | **Machinability (Annealed)** | **Good** (Approx. 70% of 1% carbon steel). Better than higher-carbon tool steels due to its lower carbide volume. | | **Grindability** | **Good.** Less challenging than high-vanadium or high-chromium steels, reducing fabrication time and cost. | | **Thermal Conductivity** | ~ 32.0 W/m·K (Slightly higher than higher-alloy tool steels) | | **Coefficient of Thermal Expansion** | ~ 11.5 × 10⁻⁶/°C (20-100°C) | --- ## **Heat Treatment Guidelines** | Process | Parameters | | :--- | :--- | | **Annealing** | Heat to 790-815°C (1450-1500°F), slow furnace cool at ≤22°C/hour to 480°C (900°F), then air cool. Result: 200-241 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** | 830-870°C (1525-1600°F). The relatively low austenitizing temperature preserves toughness. | | **Quenching** | **Air quench** in still or forced air. Its good hardenability allows through-hardening of moderate sections. | | **Tempering** | Temper immediately at 150-540°C (300-1000°F). For high toughness: temper at 425-540°C (800-1000°F) to achieve 54-56 HRC. | --- ## **Product Applications** AISI A4 is selected for applications where **impact resistance, dimensional stability, and moderate wear are critical**. It bridges the gap between general-purpose cold work steels and dedicated shock-resistant steels. ### **Primary Applications:** 1. **Master Hubs, Master Dies, and Die Models:** Where high toughness and precision are required for reproducing tooling. 2. **Punches, Forming Dies, and Trimming Tools:** Subject to intermittent shock or heavy loading. 3. **Shear Blades and Knives:** For cutting materials that cause high shock loads (e.g., thick paper, rubber, certain composites). 4. **Chisels, Cold Cutting Tools, and Hand Tools:** Requiring good edge strength under impact. 5. **Gauges, Jigs, and Precision Fixtures:** Where dimensional stability is paramount and wear is moderate. 6. **Machine Tool Components:** Cam plates, wear plates, and guide rails in heavy machinery. 7. **Rolls and Arbors:** For forming applications where toughness prevents spalling or chipping. ### **Industry Usage:** - **Tool and Die Making** (for master tooling) - **Metal Forming and Stamping** - **Heavy Machinery Manufacturing** - **Gauge and Precision Manufacturing** --- ## **International Standards & Cross-Reference** AISI A4 is a less common grade with limited direct international equivalents. | Standard | Designation | Equivalent / Similar Grade | | :--- | :--- | :--- | | **AISI/SAE (USA)** | **Type A4** | - | | **UNS (USA)** | **T30104** | - | | **ASTM (USA)** | A681 | Grade A4 | | **Europe (EN)** | **~1.2516** (*approximate*) | 55NiCrMoV7 (Closest functional match, but not identical) | | **Germany (DIN)** | **~1.2516** | 55NiCrMoV7 | | **Japan (JIS)** | - | No direct common equivalent | | **Sweden (SS)** | **~2710** | - | **Important Note:** True, chemically identical equivalents to A4 are rare outside North America. The European 1.2516 (55NiCrMoV7) is often used as a functional substitute due to its similar high-manganese, high-nickel composition aimed at toughness. --- ## **Advantages & Considerations** ### **Advantages:** 1. **Superior Toughness:** Best impact resistance in the A-series, suitable for shock-loaded tools. 2. **Excellent Dimensional Stability:** Maintains shape and size during air hardening. 3. **Good Machinability and Grindability:** Easier to fabricate than higher-alloy steels. 4. **Reliable Hardenability:** Consistent through-hardening in moderate sections with simple air quenching. 5. **Balanced Performance:** Provides a practical compromise where both wear and shock are factors. ### **Considerations:** 1. **Limited Wear Resistance:** Not suitable for highly abrasive applications or long production runs on abrasive materials. 2. **Lower Maximum Hardness:** Cannot achieve the high hardness (62+ HRC) of A2, A3, or D2. 3. **Lower Hot Hardness:** Not suitable for elevated temperature applications. 4. **Limited Availability:** Less commonly stocked than A2 or O1; may require longer lead times. --- ## **Technical Comparison Summary** - **vs. A2:** A4 has **significantly higher toughness** but **lower wear resistance and maximum hardness**. Choose A4 for shock, A2 for wear. - **vs. O1 (Oil-Hardening):** A4 offers **better dimensional stability** (air vs. oil quench) and **slightly better toughness**, but may be less readily available. - **vs. S7 (Shock Steel):** S7 has **even higher toughness** and is the definitive choice for extreme impact, but A4 offers **better machinability and dimensional stability** for less severe applications. ## **Availability Forms** - Round and Flat Bars - Plates - Blocks (less common) --- **Conclusion:** AISI Type A4 tool steel is a **specialist grade designed for toughness and precision**. Its unique high-manganese, high-nickel, medium-carbon composition fills an important niche for **tools that must withstand significant impact while maintaining dimensional accuracy after heat treatment**. While not as wear-resistant as other A-series steels, its exceptional shock resistance within the air-hardening family makes it the ideal choice for master tooling, heavily loaded punches, and precision components where failure by chipping or fracture is a greater concern than gradual abrasive wear. It represents a prudent engineering solution when the application demands a balance skewed towards resilience and stability. -:- For detailed product information, please contact sales. -: AISI Type A4 Tool Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6661 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 A4 Tool Steel Properties -:- For detailed product information, please contact sales. -:

Applications of AISI Type A4 Tool Steel -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI Type A4 Tool Steel -:- For detailed product information, please contact sales. -:

Packing of AISI Type A4 Tool 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 3132 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