How far do you go before heat treating?

On carbon steel blade about 50 percent finished but on stainless steel blade about 90%.
Stan
 
Everybody i know, and i also, leave about 1mm on the edge. But in width, i go relatively close of the final grinding... mostly cause i don't like grinding lines, in fact, and convex the grind so that we see no difference between the flat side and the grind. But a friend who grinds well, and make really nice grinding arcs at the ricasso, always leave some space to do the finer grinding and finish... maybe about 3-4mm from the final grinding line. But the most important is to have a regular and symetrical line on both sides... And a straight edge!

Edit: does everybody see what a milimeter makes? Or have i to convert in your X/Y" measure?
 
I take my edges to 1/32" before heat treating. I have an oven and can accurately and evenly control temperature. If it's a longer, thinner blade, or if you have poor temperature control or uniformity, you may go a tad thicker, say the thickness of a dime. You'll just have to work a bit more on the grinder after heat treating. Be carfeul not to overheat, and dunk in water frequently.

For plate quenched stainless, you can go much closer to finished, but I take both stainless and carbon steels very close to final grind. You'll have less warping with carbon steels by leaving more metal on, but for the size I most commonly work in (7" OAL), I haven't had much probelms in warping going to 90% on oil quenched steels.

--nathan
 
Thanks for the info. I have a A2 blade that I am working on and was worried about it cracking or warping. Looks like Im ok.
 
silver_pilate said:
I take my edges to 1/32" before heat treating. I have an oven and can accurately and evenly control temperature. If it's a longer, thinner blade, or if you have poor temperature control or uniformity, you may go a tad thicker, say the thickness of a dime. You'll just have to work a bit more on the grinder after heat treating. Be carfeul not to overheat, and dunk in water frequently.

For plate quenched stainless, you can go much closer to finished, but I take both stainless and carbon steels very close to final grind. You'll have less warping with carbon steels by leaving more metal on, but for the size I most commonly work in (7" OAL), I haven't had much probelms in warping going to 90% on oil quenched steels.

--nathan
Click to expand...


. I thought that if you take the edge to thin that the two or three seconds that it takes pull the knife out of the oven and put it in the oil that the edge can cool down. I don't know if this has any effect on the blade but I always wondered if this was bad.
 
I work mostly O-1/L-6 damascus and my blades are ground in at 60 grit prior to HT mostly full bevels and edges down to .010(or if you like .25mm) and tapered tangs on most of them. I basically want it so that I can just take the scratches out after HT.

Del
 
Delbert, you and I think alike. I work with 01. All I want to have to do is final clean up, assemble, and sharpen. I have never had problems running them this way. Any warp I get is the blade in it's whole, not just the edge, and I am usually able to correct that immediately out of the quench. I have never yet had a blade crack in quench in 20 years of doing my own HT. That cannot be just luck. I do accept the possibilty, but I also see it as extremely remote, and simply ignore it. I will say though, it can depend on the steel, and the quench.
 
J-saih, the mass of the blade behind the edge acts as the opposite of a heat sink in this instance. If the full blade is up to temperature (I don't do any torch heat treating), the heat in the thicker spine will radiate down and keep the edge hot enough.

Anoher thing to consider, you don't have to keep the edge at critical temperature all the way to the quench. It will cool down, and as long as you don't dilly-dally, you'll be fine. What you have to do is cool as fast as possible through the phases of pearlite and bainite formation to get to the point of martensite formation. The steel needs to cool through these stages very quickly. In a 10XX series steel, it needs to happen in less than a second or so through the pearlite range (1000- ~900F) and then continue throug the bainite range (~800-500F). The trick isn't to get a 1084 steel, 1450F degree blade to 400-500F in less than a second, the trick is to get a hot *enough* blade that is fully austenite (i.e. a 1084 steel blade that has been soaked at proper temperature (1450F) for a long enough period of time and hasn't cooled enough to form other structures) to cool through the temperature ranges of just above 1000F to around 500F in a short enough period of time to avoid pearlite and bainite formation. Now that being said, you don't want to just wave around a 1400-1200F blade in the air as you also have to worry about decarb. Go smoothly from the critical temperature in your oven or forge straight into the quench. It doesn't matter if you blade is at exactly 1450F when it hits the quench. As long as the quenchant is fast enough to cool it through the peralite and bainite ranges without undo stress once it reaches the martensite range, you'll be fine.

--nathan
 
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