Description
M42 Tool Steel: Detailed Overview
M42 tool steel is a high-speed steel (HSS) known for its outstanding hardness, wear resistance, and red hardness, meaning it retains its hardness even at high temperatures. M42 is designed for cutting tools that require superior heat and wear resistance, making it ideal for high-speed cutting and machining of tough materials.
Introduction to M42 Tool Steel
M42 is a cobalt-based high-speed tool steel, classified as a “super high-speed” grade. The addition of cobalt (typically 8%) significantly enhances its hardness, red hardness, and wear resistance compared to other high-speed steels. M42 is often used in tools designed to cut through hard materials at elevated temperatures, maintaining its sharpness and cutting edge.
Key Features of M42 Tool Steel:
- Exceptional Red Hardness: M42 retains its hardness at high temperatures, making it ideal for high-speed machining.
- High Wear Resistance: Outstanding resistance to wear, abrasion, and deformation.
- Superior Edge Retention: M42 holds a sharp cutting edge for longer periods, even in tough materials.
- High Hardness: M42 can be hardened to extremely high levels for maximum cutting performance.
Applications of M42 Tool Steel
M42 tool steel is used in a wide range of cutting applications that demand extreme hardness, wear resistance, and the ability to maintain cutting performance at high temperatures. Commonly, it is used in the manufacturing of cutting tools, particularly for hard materials and difficult machining operations.
Typical Applications Include:
- Cutting Tools: Drill bits, milling cutters, taps, reamers, and broaches.
- End Mills: High-performance end mills used for machining hardened materials.
- Saw Blades: Industrial saw blades and circular saws for cutting tough materials.
- Gear Cutting Tools: Hobs and gear shaper cutters.
- Forming Tools: Punches and dies that require excellent wear resistance and toughness.
- Woodworking Tools: High-end tools used for precise cutting and shaping.
Equivalent Grades of M42 Tool Steel
M42 tool steel is recognized under different standards, ensuring compatibility across regions and industries.
| Standard | Equivalent Grade |
|---|---|
| AISI/SAE | M42 |
| DIN | 1.3247 |
| EN | HS2-9-1-8 |
| JIS | SKH59 |
Chemical Composition of M42 Tool Steel
The chemical composition of M42 is carefully designed to balance high hardness, red hardness, and wear resistance, mainly through the addition of cobalt, tungsten, and molybdenum. The typical composition is as follows:
| Element | Composition (%) |
|---|---|
| Carbon (C) | 1.05 – 1.15 |
| Chromium (Cr) | 3.75 – 4.50 |
| Molybdenum (Mo) | 9.00 – 10.00 |
| Tungsten (W) | 1.50 – 2.00 |
| Vanadium (V) | 1.00 – 1.30 |
| Cobalt (Co) | 7.75 – 8.50 |
The high levels of cobalt, molybdenum, and tungsten contribute to M42’s superior red hardness and cutting performance under high temperatures.
Mechanical Properties of M42 Tool Steel
M42 offers high mechanical strength, especially in high-temperature applications. Its toughness, hardness, and wear resistance make it suitable for high-performance cutting tools.
| Property | Value (Typical) |
|---|---|
| Tensile Strength (MPa) | 1300 – 1700 |
| Yield Strength (MPa) | 1000 – 1200 |
| Elongation (%) | ≥ 8 |
| Impact Toughness (J) | ≥ 20 (at room temp) |
| Hardness (HB) | 260 – 300 |
M42 is primarily known for its high hardness and ability to retain these properties even in extreme conditions, such as high-speed cutting.
Heat Treatment of M42 Tool Steel
Heat treatment is critical for maximizing the performance of M42 tool steel. The proper heat treatment processes allow M42 to achieve optimal hardness, toughness, and red hardness for its applications.
- Hardening: Heat to 1180 – 1230°C (2156 – 2246°F), followed by oil or air quenching.
- Tempering: Tempering is performed at temperatures between 510 – 595°C (950 – 1100°F) to reduce brittleness and improve toughness while maintaining hardness.
- Annealing: Heat to 870 – 900°C (1598 – 1652°F) followed by slow furnace cooling to soften the steel and improve machinability.
These heat treatments ensure M42 achieves its characteristic hardness and toughness for demanding cutting applications.
Hardness of M42 Tool Steel
M42 tool steel can achieve extremely high hardness, making it highly suitable for cutting and machining tough materials. Typical hardness values are:
- Annealed Condition: 260 – 300 HB
- After Hardening and Tempering: Up to 67 HRC
The hardness levels of M42 are among the highest for high-speed steels, contributing to its excellent performance in cutting applications.
Physical Properties of M42 Tool Steel
M42’s physical properties play a significant role in its ability to withstand extreme conditions, such as high heat and wear.
| Property | Value |
|---|---|
| Density (g/cm³) | 8.10 |
| Melting Point (°C) | 1425 – 1500 |
| Thermal Conductivity (W/m·K) | 25 – 30 |
| Specific Heat Capacity (J/kg·K) | 420 – 460 |
These properties contribute to M42’s stability and performance in high-speed machining operations where heat buildup is a concern.
Forging Properties of M42 Tool Steel
M42 can be forged at temperatures ranging from 1050 – 1150°C (1920 – 2100°F). Post-forging, slow cooling is recommended to avoid cracking and internal stresses.
Stress Relieving for M42 Tool Steel
Stress relieving is performed by heating the steel to 600 – 650°C (1110 – 1200°F) to remove residual stresses from machining or forming operations. This helps maintain dimensional stability and prevent warping during service.
Machinability of M42 Tool Steel
M42 is moderately machinable in its annealed condition. Due to its high hardness, care must be taken during machining, especially after hardening, to avoid excessive tool wear. M42 responds well to grinding and other finishing processes.
Welding of M42 Tool Steel
Welding M42 is generally not recommended due to its high carbon content and tendency to crack. If welding is necessary, preheating and post-weld heat treatment must be carefully controlled to minimize the risk of cracking and to maintain mechanical properties.
Supply Cities:
Mumbai Ahmedabad, Amaravathi, Ambattur, Bangalore, Belgaum, Chennai, Chittoor, Coimbatore, Dindigul, Mysore, Nellore, Hyderabad, Kochi, Mangalore, Tirupur, Tuticorin, Madurai, Andhra Pradesh, Karnataka, Puducherry, Kerala, Tamil Nadu, Telangana, Visakhapatnam, Kochi, Kerala, Hubli-Dharwad, Karnataka, Ghaziabad Kolkata.
