help with CruForge V normalizing temps

S

samuraistuart

Well-Known Member
I recently acquired a stick of CruForge V, and I have a couple of questions I'm hoping you can help me with. I'm stock removal only, so no forging is done. Steel comes annealed and is quite soft and machinable. There is information online (not a whole lot) about the heat treat for this particular steel, so I have an idea of what I'm going to do, but I need some advice on normalizing/grain refining. I suppose I should add that I am using a homemade forge, I'm not able to be exact, but I like to think I can get close.

Carbon - 1.05% Chromium - .50% Vanadium - .75% Manganese - .75%

How high of a temperature should that first normalizing step be, and for how long? I was thinking that 1550 would be sufficient, with a hold of about 5-10 minutes. However, after a brief exchange with a fellow knifemaker, he suggested to treat it like you would Adlo's super spherodized 52100 (requiring an initial heat of 1650F for 5-10 minutes, up to 30minutes?)

After normalizing is done, and I'm about to austenitize at 1500, should I hold it at 1500 for 10 minutes as well, or can I quench once it's up to temp?

Thank you so much.

Stuart Davenport
 
My first idea is that you shouldn't be using that steel at all with just a forge to heat treat with but you have what you have already. The person who told you that it heat treated a lot like 52100 is about right on but lets tackle things one at a time.

Normalization: 1600°, 1500°, and 1400° would be nice and not much of a problem if you had a regulated heat source like a kiln but you don't. What you could to is get some Temple-Stiks or another temperature sensitive "crayon" and use those to spot the temperature. You can get them online or at a welding supply shop. I've tried that once but didn't quite get it right. The other thing is that you can forget about the descending temperatures and just do it by catching the decalessence as the steel heats. If you have ever heard of anyone talking about the shadow passing across the steel as they heat it that's what you are looking for. As the steel heats it will get red to an orange-red and then you will see the steel darken slightly and then get brighter again. That's decallesence and is caused by the energy going from making the steel brighter to changing the phase of the iron crystals. The same thing happens as the steel cools and is called recallesence. You could heat the steel above decallesence and hold it for a few seconds to make sure that it's heated through and then just let it air cool to a black heat and repeat two more times.

Hardening is a bit different. You can use a magnet, decallesense, or a temperature crayon to make sure that you have austinized the steel. You will need to hold it at between 1450-1500° for 10-15 minutes. Remember that if the steel gets too hot not only do you run the risk of growing the grain again you could also dissolve too much of the carbon into the austinite which will produce too much retained austinite upon quenching. Too much austinite will give you a soft blade plus it might convert to untempered martinsite after tempering and create a brittleness problem, depending on the amount of RA. Of course not holding it hot enough for enough time will also produce a softer blade. Temperature is the most critical factor here. Now you may be able to get some of that retained austinite to convert to untempered martinsite with triple tempering. This is just a problem when you start using steels up to about 1% carbon. You can produce a good blade with high carbon in a forge but it is really difficult to do it consistently.

Doug
 
Thanks, Doug. I understand the deca/reca, but thanks for those words. I appreciate the thoughts on steels that might be more difficult in a forge to heat treat, but it is what it is, i have what I have. And my goal is to eventually buy a proper kiln. I've done 52100, and the results were superb. WAY better than 1084. I can do W2 quite well also, so the CruFV shouldn't be too much of a hastle. Actually, I just finished the HT, and while I don't have proper equip to test it, you can sure tell this stuff came out rock hard. I guess my main concern was too high of heat causing grain growth, but as long as you go down a few times, the grain should shrink on down. This was what I did, temps are approximate, but close. I've done ALL heat treating, for the past two years, in a forge, in the dark, by eye. 1550 for 5 minutes, cool to black, quench. 1450 cool to black, quench. 1350 cool to black, quench. Austenitize at 1500 for 5 minutes, quench in 130F canola, 400 2hours x2

If you think that initial heat needs to be higher, in the 1650 range, I would appreciate your thoughts on that.
 
I just did the HT on this blade.......and oh my......is it a pain in the you know what to hand sand. It laughed at my file out of the quench, and after tempering, the file will barely begin to bite in.....barely. So I think I got this thing REALLY REALLY hard.......not sure if I got ALL of it that I could.....but I'm impressed!!! Slightly frustrated at the hand sanding, but, hey, lookie here, that's what we're after.....jack!!!
 
I think it's the vanadium in the CruForgV that produces a lot of hard carbides that makes grinding and sanding a chore but it should make it a little better at edge retention than the 52100. I'm in the same spot with getting a regulated kiln to heat treat in but I have to do a new roof first. I've made a good blade from 52100 that I tested to destruction and I really like the steel but there's difference between being able to consistently able to produce a good blade and just being able to produce a blade. I think that I'm going to stick with simpler and more forgiving steels until I can swing a heat treating oven.

Doug
 
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