M2 High Speed steel is a lower cost replacement for an earlier tungsten-carbide based high speed steel called T1. Neither of these is particularly new, but we don’t find T1 tools. M2 tools are common in turning tools, but not often seen in planes and chisel irons, leading perhaps to the notion that there is something about it that is inferior to current offerings.
The high speed steel label just simply means the steel will hold up reasonably well in “hot work”, work done at high speeds that creates a lot of heat at the tip of a tool. M2 does that well, and can be ground freely with no ill effect on a grinder at temperatures that will burn your fingers if you attempt to walk over to your stones and hone right away. Few steels used for hand tools, even the longer wearing alloys, have the same heat tolerance. V11 (CTS-XHP), for example, is slightly longer wearing, but gradually loses its temper above typical points for cold work steels (400F or so). M2 has an advantage in comparison because you can counter the slow hot grinding characteristics by just allowing the heat to occur. A2 , D2, V11 and most others should not be ground to the point that any colors appear at the cutting edge.
Unlike more modern steels that rely on powder metallurgy, M2 gets excellent abrasion resistance without having large random carbides by thoughtful composition. The result is a steel that is about as fine as A2 or V11 in terms of carbides, but with less carbide volume than V11 (more than A2), and without the expense of powder metallurgy.
M2 has the capability of attaining high hardness without losing edge stability and is excellent for planing and chiseling hardened somewhere in the neighborhood of 64 hardness on the rockwell C scale.
I’ve not observed it used in quantity and quality other than stanley’s original hobart blades, which were followed up by the now defunct Academy Saw Works. Those blades were very expensive (ASW, stanley’s blades were probably cheap) but M2 itself isn’t expensive or difficult to have heat treated and ground, so what would be considered a super alloy in a hand tool context is not on the market in volume and at a reasonable price for no reason other than lack of being offered.
Chinese high speed steel chisels and plane irons may be M2 or something close, but plan on buying more than once in some cases if the first try yields something cheap, but not good, and expect to do some of the finishing/flattening work yourself.
Excellent steel in a good hardness range, but pointless for chiseling and planing if not hardened to a reasonably hard spec.
Of Making by Hand with Wood and Steel 