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David Farmer

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Howdy all. New to this wonderful site. Astounding amount of knowledge contained herein. All I've done since joining is reading. And of course I managed to miss a few things (well as lot more then a few) before I started forging. I've made a few simple blades before cutting blanks and heating with a torch back in the day. Nothing astounding but they kept the weeds down in our fence rows. So when my niece watched the Forged in Fire show and immediately took a huge interest I figured, oh yeah this'll be easy. Building the forge was easy being a welder. Old brake drum and a metal stand from lord knows what I found in our scrap pile on the farm. Working out how to restrict the air flow correctly running off a hair drier. Using anthracite coal which some despise but it's readily available, burns incredibly hot, and seems to work well. Small anvil (70#) and tongs were my great grandpas. Decent enough setup with basically no money involved. Now here's where the fun starts. Not wanting to waste good steel practicing I started with a 10 inch diameter, 1/4 thick steel pipe and cut blanks. Not black pipe or galvanized by the way. Started figuring out temps to work and hammer methods to shape my steel. Also doing my quench in old engine oil. No cracks or warps. Honestly I and my family were rather impressed by how the blades turned out. But.....here in lies my problem. Never heard of normalizing.  Finally came across it in one of the many stickies I somehow missed. Assuming this is like tempering? Either way I'm sure I messed this part up. To temper after the blades were cooled I set them on top of my burning coal. Safe to say my regret was rather instant as they rapidly turned blue though this did pretty much buff out with a grinder. Saw after some reading that many use a toaster oven for this step. Long winded but hopefully this gets most of the info across. So here is my question. Can I reheat treat without destroying the integrity of the steel or should I even bother? I'm assuming I messed it up once it turned blue. Thanks all.

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Mr. Farmer,

I am far from an expert on ferrous metallurgy, but I think I can help you a little bit (hopefully without muddying the waters). Normalizing is heating to the critical temp, usually when it turns nonmagnetic at a bright red heat, then air cooling to room temp. Did you test  your knife with a file to see if it hardened after the quench? If it isn't a hardenable steel, there's no point in heat treating at all. OTOH, if it did harden, a blue color is a little soft for a knife usually, but it should be very tough now, so you wont have to worry about it breaking.  I've never encountered steel pipe that would harden (not enough carbon in the steel), but you might have pipe that does. If it was good steel and you want to try again, I would normalize, harden and temper to desired temperature. Don't use old engine oil anymore, it has nasties in it; use veggie oil instead, works great.

Hope that helps some! 

Oh, almost forgot, try to check out some knifemaking/bladesmithing books at your local library; anything by Mr. Steve Sells or Mr. Jim Hrisoulas is good reading. A high school metallurgy textbook is also helpful for understanding how the heat treating thing works, did wonders for me when I started out!

  

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Welcome aboard David, glad to have you. If you'll put your general location in the header you might be surprised how many of the Iforge gang live within visiting distance.

A few things, first I'm  not a bladesmith guy, I know the dance it's just not my cup of tea. You live on a farm pick something better to forge  blades with, it's unlikely the pipe you used for stock is anything but mild steel. Have any old springs, hay rakes, mower blades, potato chain, etc. heck even a disk harrow? You want implements that need to be tough rather than hard, no bucket teeth, grader edges, track pads, etc. those aren't good blade or much of anything other than what they're made for stock.

If the steel  was hardenable running the color to blue made it a spring rather than a knife. Next time you try hardening it run a sharp file over it. If the file bits it isn't hard if it skates it is hard, proceed to tempering. Every shop should have a toaster oven, they're cheap at yard, garage, etc. sales I got my shop toaster oven at a church rummage sale for $5.00 ad it's nicer than the one in our kitchen.

About hardening, do NOT use motor oil even new motor oil first it's about as toxic as it is smelly, especially used and full of metals and other motor chemicals. Heat transfer or commercial quench oil is the better of the acceptable oils, I use used fryer oil from the local supermarket deli section, They have to change it regularly, more regularly than most places that fry food, I was hoping for oil from the doughnut fryer but my shop smells like chicken wings, burritos, egg rolls and no telling what else. It's peanut oil making it a decently predictable quenchant and much safer than it smells.

Motor oil isn't an aggressive enough quench and generally so contaminated it's not very predictable. Trying to determine how to quench in mystery quenchant is a whole different learning curve than blacksmithing, bladesmithing and such. Best to stick to learning one thing at a time.

Frosty The Lucky.

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You can redo the heat treat without problem...most likely.  I'd normalize it a few times (as described above) and then do another quench.  I've only heat treated by using residual heat after the quench or by using a torch.  Never used an oven because I like the differential heat treat (harder working end, tougher body).  Then again, I'm not super experienced and I don't really make knives that much.  The good news is that, whether it is a knife or a hot punch, you can safely redo a quench.  Just be sure to repeat the process a few times.  Everything I have learned is that you should normalize three times, quench and then temper three times.  Using an oven to temper is out of my knowledge base.  It would seem to me that a long soak in an oven at the right temp would preclude the need for additional temper sessions...but there are far wiser people than I who can chime in on that.

 

I wouldn't be shocked if JHCC jumps in here and points you to the perfect thread wherein all of this has already been covered.  He seems quite good at that.

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Thanks for all the info gentlemen. It is definitely mild steel by the way. Won't harden. Edge even looks at a file and it disappears. Good for practice at least. Good tip on the quench too. I'm sure i read that somewhere. It's a lot of info to process that's for sure. The knife class pages helped immensely as well. Little hard to read but good info. Off to work for now. Be back in touch later. My niece is ready to start practicing tonight.

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On 9/25/2016 at 9:48 PM, Lou L said:

I wouldn't be shocked if JHCC jumps in here and points you to the perfect thread wherein all of this has already been covered.  He seems quite good at that.

Well, the best thing would be the three links in the pinned post at the top of the Heat Treating section, wherein our intrepid and curmudgeonly knife sage Steven Sells has conveniently given links to an introduction to heat treatingadvanced heat treating, and advanced annealing methods.

That said, Welcome! 

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Seems like I'm always finding new material I've missed. Usually it's forgetting a step in what I've read. I really need to print this stuff out. On a side note hopefully I've found a good an inexhaustible supply of steel. Realizing that I didn't even consider all the steel we throw away at work as quite possibly useful made me feel pretty stupid. I'm having my boss check into what grades of steel now. I work refurbishing train couplers and yokes. The parts themselves are just cheap cast but wear plates and bushings are made from far harder and more durable stuff. And all that gets chucked in a scrap bin when we reweld and heat treat. Fingers crossed.

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3 hours ago, David Farmer said:

Seems like I'm always finding new material I've missed. Usually it's forgetting a step in what I've read. I really need to print this stuff out. On a side note hopefully I've found a good an inexhaustible supply of steel. Realizing that I didn't even consider all the steel we throw away at work as quite possibly useful made me feel pretty stupid. I'm having my boss check into what grades of steel now. I work refurbishing train couplers and yokes. The parts themselves are just cheap cast but wear plates and bushings are made from far harder and more durable stuff. And all that gets chucked in a scrap bin when we reweld and heat treat. Fingers crossed.

Okay, you are going to be the most popular man at QuadState 2017 if you bring a bunch of train coupler knuckles and sell them to pay for your trip. See the photos in this thread to see what I mean.

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That's a pretty xxxx good idea he had there. Of course if I could get a scrapped out E69 rail coupler I'd have a 6 foot long anvil to play with too. Those nuckles are tough. They're not very big but weigh 50 or 60 #. And they get scrapped just for being to old regardless of damage. So yes we have THOUSANDS of them laying around. Could probably start a side business just making mini anvils for beginners or traveling small projects. The pins that hold them in the coupler are also incredibly strong. If one happens to get bent inside there's no beating it out. Torch if you have time though I'd go air arc and set the molten metal to flying personally. I'd probably just weld one in for a horn myself. If you break it you're doing something incredibly wrong. Been doing this for years and I've never seen a broken knuckle or pin.

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