Both M2 and M42 high-speed steels are excellent materials, and the choice between them really depends on what you're using them for. In general, M42 has an edge over M2 in certain situations, especially when it comes to high-temperature or high-speed cutting. Here's a breakdown of the main differences:

Composition

M2 is a molybdenum-based steel, using HSS (high-speed steel) material, and it's pretty well-rounded in terms of performance. M42 using HSSE (High Cobalt High Speed Steel), its material stands out because of its higher cobalt content (around 8%), which helps it handle heat better.

Hardness & Toughness

M2 strikes a good balance between hardness and toughness, making it great for standard cutting tasks without being too brittle. M42, on the other hand, can achieve higher hardness levels (up to 68-70 HRC after heat treatment) because of the cobalt, which means it holds up better in high-stress environments.

Heat Resistance

M2 holds its hardness decently at high temperatures, but M42 is in another league when it comes to handling heat. It’s specifically designed for high-speed cutting applications, where tools get really hot.

Cutting Performance

M2 works well for general metal cutting like cast iron or low-carbon steel. It’s reliable and cost-effective. M42, though, is better suited for cutting tougher materials like stainless steel or titanium. Plus, when you’re cutting at high speeds, M42 tools tend to last longer.

Applications

You’ll typically find M2 in standard tools like drills, milling cutters, and saw blades. M42, with its high hardness and heat resistance, is preferred for more demanding tools—think high-performance drills and cutters, especially when dealing with difficult-to-machine materials.

Cost

M2 is more affordable, which makes it ideal for large-scale tool production. M42, because of the cobalt, is pricier but worth it if you're working in high-stress, high-temp applications where tool life and performance really matter.