M2 and M42 are two widely used high speed tool steel grades for manufacturing drills, taps, milling cutters, reamers, broaches and other precision cutting tools. Both provide high hardness, wear resistance and the ability to retain cutting performance at elevated temperatures.
The principal difference is cobalt. M2 is a general-purpose tungsten-molybdenum high speed steel, while M42 contains approximately 8% cobalt. This addition gives M42 higher achievable hardness and better resistance to softening under high cutting temperatures.
M2 is generally selected for balanced performance and cost. M42 is preferred for difficult-to-machine materials and applications where edge retention is more important than maximum toughness.
What Is M2 High Speed Steel?
M2 is a tungsten-molybdenum high speed steel containing tungsten, molybdenum, chromium and vanadium. Its balanced alloy composition provides:
- High hardness
- Good red hardness
- Strong wear resistance
- Good toughness
- Reliable grindability
- Broad cutting-tool applications
After appropriate heat treatment, M2 commonly achieves hardness above 63 HRC. It is widely used for general-purpose cutting tools because it offers a practical balance between performance, manufacturability and material cost.
Common applications include:
- Twist drills
- Taps
- End mills
- Reamers
- Broaches
- Gear cutters
- Saw blades
- Form tools
What Is M42 High Speed Steel?
M42 is a cobalt-alloyed molybdenum high speed steel developed for high-temperature and high-wear cutting conditions.
Its cobalt content improves resistance to tempering softening and helps the steel maintain edge hardness as cutting temperature rises. Properly heat-treated M42 can commonly reach approximately 67–70 HRC.
M42 is used for:
- High-performance drills
- Taps for difficult materials
- Milling cutters
- Reamers
- Broaches
- Precision cutting blades
- Form cutters
- High-wear punches
M2 vs M42 Comparison
| Property | M2 | M42 |
|---|---|---|
| Steel type | Tungsten-molybdenum HSS | Cobalt-molybdenum HSS |
| Cobalt | No principal cobalt addition | Approximately 8% |
| Typical hardness | Above 63 HRC | Approximately 67–70 HRC |
| Red hardness | Good | Excellent |
| Wear resistance | High | Very high |
| Toughness | Generally higher | Moderate |
| Grindability | Better | More difficult |
| Relative cost | Lower | Higher |
| Main use | General machining | Difficult materials |
The values above are general references. Actual hardness and performance depend on the applicable standard, section size and heat-treatment process.
Hardness and Edge Retention
M42 generally achieves higher hardness than M2. This allows an M42 cutting edge to resist abrasive wear and deformation during demanding machining.
The higher hardness can extend tool life when cutting stainless steel, high-strength steel, titanium or nickel-based alloys.
However, higher hardness is not always better. A tool exposed to impact, vibration or interrupted cutting may require greater toughness. Under these conditions, M2 can offer more reliable resistance to chipping.
Red Hardness
Red hardness is the ability of tool steel to retain hardness at elevated temperatures.
M2 provides sufficient red hardness for most general industrial machining. M42 performs better when cutting temperatures rise because cobalt increases its resistance to softening.
M42 should be considered when:
- Cutting speeds are high
- The workpiece generates substantial heat
- Coolant access is limited
- Long edge life is required
- Heat-resistant alloys are being machined
Toughness and Grindability
M2 generally provides better toughness and easier grinding. It is suitable for tools with complicated geometries and applications involving interrupted cutting.
M42 offers greater wear resistance but requires more careful grinding. Excessive grinding heat may produce surface damage or residual stress, so suitable grinding wheels and cooling should be used.
Which Grade Should You Choose?
Choose M2 when:
- General-purpose machining is required
- Toughness and grindability are important
- Cutting temperatures are moderate
- Material cost must be controlled
- Tools experience vibration or interrupted cutting
Choose M42 when:
- Stainless steel or heat-resistant alloys are machined
- Cutting temperatures are high
- Maximum edge retention is required
- Tool wear causes costly production downtime
- Higher material cost can be justified by longer tool life
M2 is a versatile and economical HSS grade for general cutting tools. M42 provides higher hardness, red hardness and wear resistance for demanding materials and elevated cutting temperatures.
Huangshi Xiri supplies M2 and M42 high speed tool steel in round bars, flat bars and custom-cut sizes. Contact us with your required grade, dimensions, quantity and application for a quotation.
FAQs
Is M42 harder than M2?
Yes. M42 generally achieves higher hardness than M2 after appropriate heat treatment.
Does M2 contain cobalt?
Standard M2 does not normally contain cobalt as a principal alloying element. M42 contains approximately 8% cobalt.
Is M42 tougher than M2?
M2 generally provides greater toughness, while M42 prioritises hardness, hot hardness and wear resistance.
Which grade is better for stainless steel?
M42 is often preferred for demanding stainless steel machining because it maintains edge hardness under higher cutting temperatures.
