Can oil/water hardening steels air harden in thin sections?

weo

weo

Joined
Sep 21, 2014
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Hello all. The reason I'm asking this seemingly dumb question is that on my latest blade (1080/15N20), I forgot to drill the pin holes before heat treating. I used my buddy's induction forge to heat the pin areas, and am still unable to drill the holes, so wondering if I need to redo and immediately put in some pearlite to slow the cooling, or do I just need sharper bits?

Thanks

as always
peace and love
billyO
 
Yep, I've had it happen before (although I don't use induction). If you need to drill a semi-hard tang just get some carbide masonry/glass bits from the hardware store. I use a set I got from home depot for like ten bucks. Works fine...
 
Never had the water quenching steels do it, but O1 will do it in thin sections. Except in very thin sections it doesn't seem to achieve full hardness.
 
How hot are you heating it? If you heat it up into austenite and let cool, you're just perpetuating the problem.
Both O1 and 15N20 will harden enough in still air to kill a drill bit.
Just heat 3-4 times up to red - about 1000 degrees - and let cool for a shade-tree spherodizing anneal.
 
Thanks Karl. I used my buddy's induction forge the first try so probably got it too hot, like you said. Then I tried with my propane torch at my shop, and that only got to dull red, but I only did it once. After this one try, I was able to drill a little bit, but not all the way through. I'll try a few cycles and let y'all know how it goes.
Again, thanks.
 
weo said:
Thanks Karl. I used my buddy's induction forge the first try so probably got it too hot, like you said. Then I tried with my propane torch at my shop, and that only got to dull red, but I only did it once. After this one try, I was able to drill a little bit, but not all the way through. I'll try a few cycles and let y'all know how it goes.
Again, thanks.
Click to expand...
All that effort for nothing ??? Why you don t listen what your colleagues suggest here ? Buy glass/ceramic drill bits and you can drill hole in unibutanium not in that O1/15N20 steel !!! I drill 68 hrc HSS steel with them .In your steel that drill bit will go like in water !!

Look this thread ................

https://www.bladeforums.com/threads/sharpening-masonry-drills.1540592/
 
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I hear ya, Natlek. But for someone who lives 30-45 minutes/miles from anywhere to get said bits, a truck that's in the shop, and the truck I'm borrowing that gets 10 mpg (at $3.20/gal, that equates to ~ $20 in gas) I'll do what I can to avoid the time and extra $.
I suspect you'll suggest getting them mailed from an online source, but that'll take a few days and I'd rather continue to be productive, and finish this.
Rest assured, said bits are on my shopping list when I get my truck back and need to run into town.
 
I'd go the route suggested by Karl. If you can keep the dull red for a while it will soften to the core, otherwise repeat the procedure a few times, proceeding in small steps with your short soaks to dull red and back to black. This procedure will also set the steel in better conditions for the subsequent actual hardening, than a slow annealing in vermiculite. The vermiculite shouldn't be used for steels that have more than 0.8% carbon.
Aside partial martesnite formation (oil hardening), any hardenable steel (also water hardening ones) will get harder than annealed when cooling fairly quick from austenitization, if any even just for the finer grain and the finer pearlite structures you get, that are harder than the microstructure you have in the full annealed situation.
I won't want to use carbide drill bits if i won't have a very rigid setup in my drill press, the last thing i 'd want would be a broken carbide bit stuck into my tang ;)
 
The typical sub-critical anneal is 1200F for two hours. That should do it .
 
stezann said:
I won't want to use carbide drill bits if i won't have a very rigid setup in my drill press, the last thing i 'd want would be a broken carbide bit stuck into my tang ;)
Click to expand...

No solid carbide drill bit . Try this one and you will not regret , if you don t like them I will buy them from you for double price :)
Drill bits right on he picture are cheaper .........and no need for rigid setup , you can drill with hand drills .. .......
1TXBs4T.jpg
 
stezann said:
I'd go the route suggested by Karl. If you can keep the dull red for a while it will soften to the core, otherwise repeat the procedure a few times, proceeding in small steps with your short soaks to dull red and back to black. This procedure will also set the steel in better conditions for the subsequent actual hardening, than a slow annealing in vermiculite. The vermiculite shouldn't be used for steels that have more than 0.8% carbon.
Aside partial martesnite formation (oil hardening), any hardenable steel (also water hardening ones) will get harder than annealed when cooling fairly quick from austenitization, if any even just for the finer grain and the finer pearlite structures you get, that are harder than the microstructure you have in the full annealed situation.
I won't want to use carbide drill bits if i won't have a very rigid setup in my drill press, the last thing i 'd want would be a broken carbide bit stuck into my tang ;)
Click to expand...

The damascus, O1/15n20 should be right at the eutectoid point. So this anneal shouldn't do too many bad things to the grain structure (nothing that can't be fixed by some mormalizations and grain refinements). But I had forgotten he had already heat treated. In that case, the options listed so far are good. You could also drill/punch the hole hot. Would depend on your setup, but it isn't hard to do. Just wrap the blade in a wet paper towel. If you decide to drill hot, be prepared to sacrifice a bit to the process as it will likely detemper (unless you use a carbide end mill or similar).

For future use, a carbide end mill will drill hardened steel just fine, and the smaller end mills are DIRT cheap. Get a good drill press vise and clamp it down. Use light pressure and cutting oil. And if you ever break an 1/8 mill in a hole, just break it out with some sharp blows. The only thing I can't speak to in this process is how well it works on a crappy drill press. If you have a ton of runout in your quill it may be a problem.
 
Natlek said:
No solid carbide drill bit . Try this one and you will not regret , if you don t like them I will buy them from you for double price :)
Drill bits right on he picture are cheaper .........and no need for rigid setup , you can drill with hand drills .. .......
1TXBs4T.jpg
Click to expand...
I'll try them, i might also have them already for drilling concrete. Thank you
 
Hello all. Heating to a dull red worked, like Karl said.
Thanks

as always
peace and love
billyO
 
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