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I Forge Iron

Beating a dead horse

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Something I’ve tried on a recent blade is soaking it at a welding temperature in a coal fire near final shape; letting it cool very slowly in the fire to decrease the likely hood of scale forming. Once at a temperature where it won’t scale I removed it and quickly wrap it in ceramic blanket to let it cool slowly. I’ve done this twice and the second time I didn’t heat it up as much or soak it as long. I’ll normalize again at least twice before heat treating. The idea behind this process is to let the edge absorb some extra carbon from the fire, while not burning carbon off or letting it flake off. Most of the surface carbonized steel will be ground off, but the edge should stay about where it is if the shaping goes as planed. This will theoretically provide the edge with a little more staying power. I’ve read a lot of different idea’s, opinions and facts about the heat treating process and some of it is very complicated, and some of it seems like folklore. But this is something I’ve come up with that seems sound to me mixing some ideas. If I was working with a known steel then I’d invest in a thermometer and follow the instructions given by folks in lab coats. But people have been making darn good tools for a very long time through trial, error, and a keen eye. I've worked these darn e-clips in the past so I've got some ground to stand on when I'm through for comparison when I'm through, but I could just have a few differently manufactured clips. I'd just like some opinions. I'm kinda just experimenting, but does the logic seem sound to you folks who've paid your dues?

Edit, sorry, this probably should have been posted over in the bladesmithing section.. I'm just used to viewing the blacksmithing forums. Apologies!

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So do you know if this alloy will refine it's grain through thermal cycling or are you growing the grain as you soak it?

I generally work with good alloys to start with an not mess with trying to change them on the fly...

Note you can turn iron into steel into cast iron levels of carbon by carburization too; if you are not careful.

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Welp, the theory craft came from me trying to refine the grain structure. These 3/E scrap clips aren't super high carbon, and are a pain to straighten out at anything other than a glowing yellow. (I've been using the step of the anvil to hold one end in place while doing this so it only takes a few heats, I'm going to try the leg vise next time I do a batch since it's new to me.) So I start off working these too hot. Steve Sells pretty much sums it up better than me. I can't really tell a few hundred degrees one way or the other so I guesstimate and just cycle it through the color spectrum best I can. When I got my gas forge going it was coincidently right about when I was running out of coal. So I gave it a few heats a bit too hot after I'd already been reducing my working temperatures. Since I needed to go through the process again, I figured what could it hurt. No one should be risking their neck with this blade, if it's not all it could be then it's a "decorative" piece. In my experience these clips don't harden well enough in oil, but do well in brine. Would a whole percent of carbon on just a few hairs of the blade increase the likelihood of nicks? A proper heat treat is a subjective thing I suppose biased on how the tool is used. I just want something someone can thwack a chuck of hard wood with, bow the blade while trying to unstick it and still have a noticeable edge and straight blade... At least thats my stress testing minimum, it's something a $20 mass produced machete often can't do.. and don't get me started on those knives and swords you normally find at flea markets.. eh I digress..
So I guess you're saying if done correctly in the right part of the fire at the right temperatures it could have some effect, while not necessarily positive?
I like making knives, but they're kinda practice for me. I prefer the hammer swinging to all the work that goes into making a quality knife. That said I've been collecting old files and have a nice pile I plan to work on once I feel I'm ready to make something sharp out of what I consider good steel if not exactly known. I know working junk steel is full of head aches, but at least you tend to remember a mistake if you ruin several hours of work. If someone wants something custom made (a lot of folks do.. until I tell them how much it cost to pull me away from my personal projects) they can pay double material cost and only a few bucks for labor. Then I'm more than happy to spend the money on some high grade steel and a thermometer. As long as I get it right the first time I might actually end up being compensated for my time. <_<
Thanks for the quick reply Thomas.

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Hmm welp I suppose I should say I've read some stuff on the subject. But the three brain cells between my ears just haven't agreed on what I may be doing right or wrong. I don't know how exactly to treat this mysterious stuff. I've read it's often somewhere between 1045 and 1065. Odds are just as good I've burned carbon off than added any. I was a little worried something could've gone wrong I decided to see how stressed the blank could have been.
I've done this before and I've been lucky at times, but I'm still trying to figure somethings out. I keep a magnet handy and I'm getting better about fire management. Maybe someone else has used those squiggly clips for knives?
I've broke 'em, bent 'em, burt 'em, hardened and tempered even the crooked ones. Most of it was on the fly. I don't keep very good records. I'm still trying to develop more organized forging habits.
Something I'm unclear on his how extended time in different types of heat effects different types of alloys. Should I be worried come heat treat time For instance this thread a while back, and a few others have just pointed me toward a few conflicting conclusions.
I apologizes for being so long winded.. I just keep finding words :huh:

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I think you're making things more complicated for yourself than need be.

Ray Kirk in Oklahoma sells 3/4" round 5160 for $2 a foot and can fit 20 feet in a medium USPS flat rate box. It'd be no harder forging from that than from a clip, and you don't have to straighten first. I turned a 3 1/2" long piece into a knife with a 5" blade and a full-length tang. I get absolutely satisfactory performance out of a very simple heat treatment that I describe and explain on my blog.

Very cheap for great performance.

If you want to stick with scrap material, try automotive leaf springs. Much less struggling with the original form, and is typically 5160 or similar, so you can train yourself on the proper heat treatment for 5160.

You're likely causing problems with grain growth weakening the blade, as Thomas said, moreso that picking up any detectible change in performance from additional carbon. The tendency in a gas forge is going to be losing carbon rather than gaining it, but it is at such a slow rate and in such tiny sections that you will typically get past the de-carbed layer when you do cleanup stock removal.

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This knife was a forging exorcise for me. I don't normally draw out my ideas and then try to forge them. I tend to plan at the anvil.. not suggested, but I do. In the past I've forged a similar blade out in only one or two forging sessions. It didn't make the cut so to speak and when it broke I noticed a very large grain structure toward the very center.
This blade took much longer but I spent a lot of time trying to avoid stressing the steel or creating an uneven/large grain structure. I did this by very slowly heating and cooling the steel during each forging session. I assumed when working with an unknown steel this was helpful.
Trying to avoid decarbonization was been a main concern, but I hadn't considered what effect carbonization could have. (I've research both a bit more and found it takes several hours in an oxidizing atmosphere to remove all the carbon from 0.01", but outside of pack case hardening I haven't found out how much carbon could be absorbed steel if any. I'm under the assumption it's nominal)

I think I've been a little too careful honestly as when referencing Machine Tool Practices 6thEdition it simply advises normalizing overheated steel once and then reheating to the correct quenching temperature and hardening. But perhaps it doesn't accounting for any reshaping done at those temperatures.
I broke up my annealed knife into several pieces and will polish and etch it later to get a better idea, but I feel better about things seeing what appears to me to be a fine (ferrite and pearlite?) grain structure
I'll use these pieces to test for the next tool of similar shape.
One book I'm referencing list the lower critical temperature in simple carbon steel as 1330f, the other states 1400f. The upper critical range for 0.00 "steel" is listed as about 1680f decreasing by about 33f every .1% of carbon until about 0.7% they both vary. Heat treating rules of thumb and suggestions are made in both books for different steels and they again vary just a bit but the lower the carbon content the higher the suggested temperature

Practically speaking as a guy playing blacksmith in a world of metallurgist.. from my research into the most basic carbon steel this means if a properly normalized tool of an unknown carbon level is to be heat treated it should be done at the lowest possible temperature. The goal is to heat the steel to the critical point and hold it there just long enough to allow the complete transformation to austenite. How far above the critical point the steel is heated seems to be a factor of how much it has a chance to cool before getting to the quenching medium to produce martensite. The higher it must be heated above the lower critical transformation the grain grows changing the durability. A change that tempering doesn't correct. If the desired results aren't achieved in air, oil or water then the temperature should be increased incrementally.. or until I break something :blink:
At least thats my plan next time, accept I'll bypass the air. I'm rather sure these aren't near the 1060 that I'd hope, but I'm seldom really sure on anything :lol:

I would like to know I'm on the right track by giving ya'll a chance to correct me. I've delved into this stuff before. But it's kinda hard for me to retain the dry reading as a whole. So I just catch bits and pieces of terminology. Writing helps me retain the knowledge and hopefully help out some folks out who're also struggling with the 'ites. Maybe I'll get around to committing those cubes to memory one day. Thanks for the advice Dave and James.

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For wot it is worth you are going to give youirself and ulcer with your concerns. All of the things youi mentioned have a time and place. but it seems to me they are going to delay your forging abilities a lot. Shop work equals forging skills. If you want a thought to work on, Get some 1084 knife steel and forge a simple shape of a blade you like then follow the directions that come with the steel. For that steel, Anneal after forging, do all of your clean up work you wish to do, leave a dimes thick edge. Normalize once, use a magnet to determine temp. Heat to non magnetic without exceeding that. REmember that color and g oright back into the fire for that color,,wont take long. Go directly into oil quench I like atf and check to make sure it is at 120f. STraight into the quench with minimal movement,,when it has lost most of i ts heat,, Test with a file,,it should not cut at all, should skate along the edges,,,then wipe oil off and into a 400f oven for 45 minutes to an hour,,,retest with file,, it shouild not skate but bite a little bit,,,if it still skates temper again. After the first 100 blades then start worrying more about the internal structures. By then you should have forging skills and a working knowledge of how all of your blades have held up through rigorous testing. And you should be keeping records of each and every blade. material type and thickness, ht procedures and how each one did in testing. Then if you move away from this steel stqaraet over with notes on that steel.

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