Help with HT of larger pieces of steel

D

deker

Joined
Nov 14, 2005
Messages
3,496
So, I've built a file guide (similar to the one in the Sheffield catalog) out of O-1 (2 pieces, 5/8"x1"x5"). Yesterday I went over to Butch's place to do the HT properly since he has an evenheat. We heated to 1550 in a foil packet, soaked for ~10 minutes, pulled it out, cut the foil and dumped into oil. Everything seemed OK, but after some use today my file definitely gouged the guide.

Clearly it's not hard enough.

Our only theory is that due to the large cross-section the heat from the core of the steel effectively tempered the steel out while it was in the oil. Does that seem reasonable? Any suggestions for ways to make sure we get it properly hardened the next time? The guide saved me all kinds of time today, but it won't be straight and even for long at this rate :(

-d
 
1. What Leon said.

2. Leave it in the oil long enough so that there is not enough residual heat left to temper/soften it.

3. Temper it slightly, maybe 350 F, just to reduce the chances of it snapping when you tighten it down.

4. Have it surface ground once you have it assembled, as it is likely both to have surface decarb and to warp very slighty in HT.

John
 
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