Foil Wrap Blade Stress Relief

johnnyjump

johnnyjump

Well-Known Member
I have a set of 1084 blades that are in need of stress relief prior to heat treat. I plan on foil wrapping them to minimize carbonization, as my blade tolerances don't allow for much more steel to be removed following heat treat. To relieve stress, I follow a three step process of bringing the blade to critical temperature, letting it soak for five minutes, and cooling it in air as the blade color changes from red to black. I am new to foil wrapping, and am unsure how how the blade would be cooling in the foil wrap. Can I assume the blade is cool as the wrap cools, or should I give it more time for the blade inside to cool before I repeat the process? Thanks for your help!
 
You could just give it a "super temper" for like an hour at like 1250F. My understanding is that stress relief is done below austenizing temps.What you are doing sounds more like normalizing, not stress relieving.
 
jmforge said:
You could just give it a "super temper" for like an hour at like 1250F. My understanding is that stress relief is done below austenizing temps.What you are doing sounds more like normalizing, not stress relieving.
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My understanding for stress relief, you bring it up to critical temperature, at least from what I've heard. Thanks
 
Couple minutes maybe? I never time how long it takes to air cool. I usually put them between plates after a few minutes to make sure their done.
 
johnnyjump said:
My understanding for stress relief, you bring it up to critical temperature, at least from what I've heard. Thanks
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No. if you look it up, most places say do the lower temp. You are relieving the stress of "machining" which is to say any uneven grinding, etc. you might have done, not the damage you did while forging, etc. I have been doing the 1250F routine for years and it pretty much eliminated any warping, And I am forging, not doing stock removal. The only reason for getting hotter than 1250 would be if you have some steel that has been heavily spherodized to the point where it is difficult to harden without being normalized first. Some stuff like the 52100 from certain places in New Jersey has supposedly had that problem. But that is once again not stress relieving.
 
I've never done hi carbon steel in my oven other than to H/T it. When doing SS the SS literally glows thru the foil wrap. I can't say how long it would take. Maybe get a infrared thermometer?
 
check out..Knife Steel Nerds article on heat Treat/tempering, stress relief section. They recommended 1200 f for 2 hours. Dr. Larrin Thomas in his book.. Knife Engineering recommends 1200f for 1 hour.
 
I think I'm experiencing information overload! I guess I need to define my terms and perhaps rethink my Heat Treatment procedures. I have watched videos and read articles/posts that would suggest normalizing grain structure is a good practice prior to hardening (Austenizing), for forged blades, but also stock removal blades that experience some stress from grinding. Some use the terms, "Normalization" and "Stress Relief" synonymously, and vary somewhat in the times and temperatures. But basically, you heat the blade to critical temperature (Austenize) or higher, and allow to air cool for one or a number of times. Once the grain structure has been normalized, you are ready for Austenize and quench, followed by tempering of the blade at different temperatures and times, depending on the desired Rockwell Hardness. Am I off or what? Am I missing something? I know 1084 is one of the easier steels to heat treat, and I have had success with it in the past. I am stuck on the "normalizing" or "stress relieving" steps. Or is that step necessary for 1084? Your experienced opinions would be much appreciated!
 
vlegski said:
check out..Knife Steel Nerds article on heat Treat/tempering, stress relief section. They recommended 1200 f for 2 hours. Dr. Larrin Thomas in his book.. Knife Engineering recommends 1200f for 1 hour.
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1200 f for an hour?? Hmm, never heard that before. Interesting.
 
Dont get too twisted up. Treat stress relief like you would a "high" temper. You can do the same thing to "soften" steel up after forging, normalizing, etc so that it drills and ginds more easily. Remember than all thermal treatments other than hardening are designed to fix things that you screwed up. I say that even about tempering by you screwed up by dunking that steel in oil, etc to harden it and now yo must fix it. ;)
 
johnnyjump said:
1200 f for an hour?? Hmm, never heard that before. Interesting.
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He also does that cycle as a "temper anneal" IIRC. That is for after forging and normalizinf to get you steel in a "rlaxed" softer state so you can grind, drill, etc and also to have the steel in a condition whee it is ready to harden. For the stress releif, you just do the last 1200F cycle over again. As for foil, I used foil with carbon steel for all cycles in the oven other than austenizing (anti-scale compound) and tempering.
 
Follow Jmforges advice. Don't get twisted around the axel on this stuff. Terminology, and when or what u do to metal before the quench has caused more internet disputes than any topic I've ever read. If u think that youve done something to cause internal stress and it needs a stress relief, do it. Otherwise, ur 3 step process which come people call thermal cycling for grain refinement should relief any stresses. But then , gain I'm no scientist and I didn't sleep in a holiday Inn iast night.
 
I am curious as to why you would think that you have to stress relief 1084......wuz up?
 
tmr said:
I am curious as to why you would think that you have to stress relief 1084......wuz up?
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So it is less likely to warp in the quench. What I call stress relief is done after and grinding, machining, etc. that you do before quenching.
 
I have been making knives for a very long time and have decided long time ago to harden and quench before grinding.......especially with thin blades such as filleting knives......i do all profiling and drilling and filing before hardening and grind post heat treat with ceramic belts.......costs a bit more for belts but never a warped blade.....I always grind without gloves so over heating is never a problem........quenching an unground blade never results in a warp in my experience......if it did i would press it in the hydraulic press while still hot to straighten
 
tmr said:
I have been making knives for a very long time and have decided long time ago to harden and quench before grinding.......especially with thin blades such as filleting knives......i do all profiling and drilling and filing before hardening and grind post heat treat with ceramic belts.......costs a bit more for belts but never a warped blade.....I always grind without gloves so over heating is never a problem........quenching an unground blade never results in a warp in my experience......if it did i would press it in the hydraulic press while still hot to straighten
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Profiling is grinding. ;) I grind kitchen knives post heat treat and I have had one warp at the tip after grinding.
 
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