Edge hardness Question

[Steve Nuckels]

I recently forged a SW Bowie from an Farriers rasp.  I did a spark test on the rasp before forging and was satisfied it was high carbon steel.

I hardened (quenched) the blade and was not satisfied with the outcome (filed the edge},and rehardened this morning.  When I filed the edge one side was hard, the other not as hard (file bit a little more}.  The edge is as thick as a penny.

Is it possable that different hardness on one side to the other?

Steve
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Potomac Forge
Member, W.F. Moran Jr. Museum & Foundation

[Lin Rhea]

Steve, first of all, I dont know if your rasp is an old one or a new one and even if I did, I dont know what steel it is, for sure. Some new files are case hardened low carbon. But let's assume it's high carbon.

This is just a suggestion of what might be happening. There may be some carbon loss on the edge and you might "read" it as being soft. If you file back a couple of good strokes, it might be hard. In this case you would have to allow some extra material to be removed to reach the hardened material. This will take place more when the piece has been in and out of the fire a lot during the forging procedure. Lots of heats.

When using an unknown steel, you are also having to accept some other "unknowns" that follow. Such as, Which is the proper quenchant, drawback temperatures, etc.?

[Lin Rhea]

Steve, Have you any report on the results of this knife discussion? Just checking.  

[Steve Nuckels]

Lin, I have worked on the knife and it seems the second heat treat worked out!  I did some finish grinding and the edge seems hard.  After I put the final edge on I will do a performance test.

I will post a photo then.

Thanks for the follow up.

Steve
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Potomac Forge
Member, W.F. Moran Jr. Museum & Foundation