February 1, 201214 yr Does anyone know if High Speed Tool Steel makes a good knife? I have some tines from a Rotary-tiller that I just repaired today, spark test makes me think that they're HSS Tool Steel. They're already in a rough shape of a knife, but I want to know if there is anything I ought to know about forging, quenching and tempering before I attempt. Thanks! ~RidgewayForge
February 1, 201214 yr sure it makes a good knife. HSS can be M-2 its a bit red hard, have fun, if you really want a challange try pattern welding with it
February 1, 201214 yr Yes, there are a few things you should know: (1) HSS is tricky to forge; (2) it's air-hardening; (3) you need a temperature controlled oven (furnace) to HT it properly; (4) it's expensive and brittle, so they do not use HSS for roto-tiller tines
February 1, 201214 yr What Matt said. HSS rototiller tines would cost many times what plain steel ones do and wouldn't like rocks. As for blades, without the high tech heat treat you get an inferior blade to one from a steel you can heat treat well with "blacksmith methods"
February 1, 201214 yr Author So in general these blades are not HSS? Would they be high carbon steel? I just know that these blades have taken a beating over the last 18+ years, so I know its good steel, just not sure exactly what it is. Thanks for all the input, its a great help!
February 1, 201214 yr Show us a spark test. It is very unlikely that these are high speed steel. You can also try to draw the temper to a deep blue or gray. If this softens the steel considerably, it is not HSS. Then, go for a quench test, say with water. HSS will crack, but a med-hi carbon will probably not. You know how to heat treat simple carbon steels, right?
February 1, 201214 yr Take a look at AR Abrasion Resistant steels; what I'd go for if I didn't use plain old 4340 or other medium carbon steel. Higher carbon does increase wear resistance but also increases brittleness so it's a trade off on what they use. The virtue of high speed steels is that they keep their hardness at high temperatures---not something you get in rototilling; but something you want in drill bits and lathe tools and other things expected to cut at high speeds..
February 2, 201214 yr Author Well it was hard, whatever it was. I didn't try as hard as I should have (I was more interested in making myself a fork), so some other time I'll have to try it again. Seemed pretty darn hard, though.
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