AISI Type M8 High Speed Tool Steel Rod/Bar

AISI Type M8 High Speed Tool Steel Rod Product Information -:- For detailed product information, please contact sales. -: AISI Type M8 High Speed Tool Steel Rod Synonyms -:- For detailed product information, please contact sales. -:

AISI Type M8 High Speed Tool Steel Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: AISI Type M8 High-Speed Tool Steel** ## **Overview** **AISI M8** is a **molybdenum-tungsten high-speed steel** developed as part of the early evolution of molybdenum-based HSS grades. While less commonly referenced in modern standards than mainstream grades like M2 or M7, M8 represents an important historical formulation in the transition from tungsten-dominated to molybdenum-rich high-speed steels. Characterized by a **balanced tungsten-molybdenum ratio** with moderate vanadium, it was designed to provide good hot hardness and wear resistance at a potentially lower cost than early tungsten-heavy grades. ## **1. Historical Context & Chemical Composition (Nominal %)** **Note:** AISI M8 is not officially listed in current ASTM A600 standards, and precise specifications vary among historical sources. The following represents a consensus based on historical literature and tool steel reference texts. | Element | Historical Content (%) | Primary Function | |---------|-----------------------|------------------| | **Carbon (C)** | 0.78 - 0.88 | Provides matrix hardness and carbide formation. | | **Tungsten (W)** | 5.00 - 5.75 | Contributes to hot hardness and wear resistance. | | **Molybdenum (Mo)** | 5.00 - 5.75 | Primary molybdenum hardening element; improves hardenability and hot strength. | | **Chromium (Cr)** | 3.75 - 4.25 | Enhances hardenability and wear/oxidation resistance. | | **Vanadium (V)** | 1.60 - 2.20 | Forms hard vanadium carbides for wear resistance. | | **Cobalt (Co)** | Not Present (typically) | Historical M8 was generally cobalt-free. | | **Other Elements** | Si, Mn, P, S | Typical residual/deoxidizing elements at historical levels. | | **Iron (Fe)** | Balance | Base metal. | **Key Chemistry Note:** M8's formulation features a **nearly 1:1 ratio of tungsten to molybdenum**. This was a significant development, demonstrating that molybdenum could effectively replace a substantial portion of tungsten while maintaining performance—a key economic and strategic advantage. Its composition is conceptually similar to, but distinct from, modern grades like **M1 (lower vanadium) and M2 (different W-Mo balance)**. ## **2. Physical & Mechanical Properties (Estimated)** Based on its composition, typical properties in the hardened and tempered condition would be: | Property | Estimated Typical Value / Condition | |----------|-------------------------------------| | **Density** | ~8.1 g/cm³ | | **Hardness (Annealed)** | ~220-255 HB | | **Hardness (Hardened & Tempered)** | **63-65 HRC** (when properly heat treated) | | **Red Hardness** | **Good.** Comparable to other intermediate HSS grades of its era. | | **Abrasion Resistance** | **Good to Very Good,** benefiting from its vanadium content. | | **Toughness** | **Good,** owing to its moderate carbon and balanced carbide structure. | | **Grindability** | **Fair.** Better than high-vanadium grades but more difficult than simple compositions. | ## **3. Historical & Approximate Modern Cross-References** Due to its obsolescence in formal standards, direct equivalents are not maintained. However, its compositional philosophy lives on in modern grades. | Standard / Era | Approximate Equivalent / Successor | Notes | |----------------|-----------------------------------|-------| | **Historical AISI** | M8 | Original designation. | | **Modern AISI/ASTM** | **Largely Superseded** | Not listed in current ASTM A600. Functionally replaced by more optimized grades. | | **ISO (Conceptual)** | **HS ~6-5-2 type** (ISO 4957) | Similar tungsten-molybdenum-vanadium balance, though modern HS 6-5-2 is more aligned with M2. | | **Modern Functional Successors** | **M1, M2, M7** | For general HSS applications, M2 became the dominant balanced grade. For more wear resistance, M7 (higher V, Mo) is a logical progression. | | **Common Industry Understanding** | Often considered a precursor or variant within the **M1-M7 series**. | | ## **4. Historical & Niche Applications** As a mainstream industrial material, M8 has been superseded. However, understanding its applications provides historical context: * **Primary Historical Uses:** * **General-purpose cutting tools:** Drills, taps, milling cutters, and lathe tools for machining steels and cast irons. * **Metal forming tools:** Punches, dies, and shear blades where a balance of hardness and toughness was needed. * It served as a **cost-effective alternative to pure tungsten-based T-series grades** (like T1) during periods of tungsten scarcity or high cost. * **Modern Relevance:** * **Historical Tool Restoration:** Understanding its properties is relevant for maintaining or re-treating antique machinery tools. * **Metallurgical Reference:** It remains a point of reference in the study of high-speed steel development. * **Niche Production:** May occasionally be produced for specific legacy tooling or customer specifications but is not a standard stock item. ## **5. Heat Treatment (General Guidelines for M-Type HSS of Similar Composition)** If processing a steel identified as M8, standard high-speed steel practices apply: 1. **Annealing:** Heat to 840-870°C (1550-1600°F), slow furnace cool. 2. **Hardening:** Preheat thoroughly (800-850°C). Austenitize in the range of **1200-1220°C (2190-2225°F)**, then quench in oil or salt. 3. **Tempering:** **Double or triple temper** immediately at 540-590°C (1000-1095°F) to achieve final hardness and stability. ## **Conclusion & Modern Perspective** **AISI M8 is best understood as a historical milestone in tool steel metallurgy.** Its development validated the large-scale substitution of molybdenum for tungsten, paving the way for the economical and high-performance **"M-series" steels that dominate the market today** (notably M2, M3, M4, M7, M42). For any contemporary application, a modern, standardized grade should be selected instead: * For **general-purpose high-speed steel applications**, use **AISI M2**. * For **superior abrasion resistance without cobalt**, use **AISI M7** or **M4**. * For **maximum hot hardness**, use cobalt-bearing grades like **M35** or **M42**. --- **Disclaimer:** This profile is based on historical technical literature. **AISI M8 is not a currently standardized, commercially prevalent tool steel.** The information is provided for educational and historical reference only. For any practical tooling application, consultation with a modern tool steel producer and selection of an active, standardized grade is essential. Properties and processing data for actual, legacy M8 material can vary significantly. -:- For detailed product information, please contact sales. -: AISI Type M8 High Speed Tool Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6740 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 M8 High Speed Tool Steel Properties -:- For detailed product information, please contact sales. -:

Applications of AISI Type M8 High Speed Tool Steel Rod -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI Type M8 High Speed Tool Steel Rod -:- For detailed product information, please contact sales. -:

Packing of AISI Type M8 High Speed Tool Steel Rod -:- 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 3211 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