Hand Tools Archive

Reason for PM

Patrick Chase
The reason for PM isn't so much to achieve compositions that are impossible as to allow compositions that would otherwise have unacceptable downsides.

For example the most popular PM alloy for woodworking (CTS-XHP, aka PM-V11) is similar to 440C and D2 in composition. It would unquestionably be feasible as a eutectoid alloy, but it would have huge grain/carbides like 440C/D2. The old joke that D2 "takes a crappy edge and holds it forever" is referring to exactly this downside. In contrast PM-V11 takes a pretty keen edge (but still holds it for a long time).

The situation is similar for other PM tool alloys: HAP-40 is simply a PM version of M4-HSS, and CPM-3V would also be realizable with conventional processing (though it would be very difficult to sharpen).

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