1084- Thermal cycling/normalizing and heat treating.

C

creature

Member
I've been making knives for a while now but have outsourced my heat treating. I've come into a small propane forge and figured I should take the opportunity to learn how to heat treat some basic steels. Since I already have a few bars of 1084 from Aldo, I figured it'd be best to start with. I have some McMaster-Carr 11 second quench oil arriving tomorrow. My main question is about normalizing/heat cycling.

Before posting this thread I've done a ton of search on the net looking for a straight-up list of the process of thermal cycling/normalizing and hardening in a propane forge, but haven't found anything. I've found a very detailed step-by-step by Kevin Cashen( http://www.knivesby.com/knifemaking-Kevin-Cashen-treating-1084.html ) but the normalizing process requires accurate temperatures and 10min soak times. These are things I'm not sure I'll be able to accurately perform with my propane forge(with no thermocouple). Also, I've heard some folks say to oil quench when heat cycling, others say no. What do you all think?

Now, this isn't forged-worked 1084 I'll be heat treating. Just stock removal. I know grinding can grow grain structure so I bet I could benefit from normalizing. Since I'm not able to assure the temperature(other than being non-magnetic), how can I normalize without the precise steps?

Also, I've read that it's best(w/1084), during hardening, to heat to magnetic and hold for a couple minutes. Is that something I should do even though I can't control temp precisely?

I think I have annealing figured out based on information on the web. 400f for one hour, three times.

Any information you folks could provide me would be greatly appreciated.
 
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creature said:
I've been making knives for a while now but have outsourced my heat treating. I've come into a small propane forge and figured I should take the opportunity to learn how to heat treat some basic steels. Since I already have a few bars of 1084 from Aldo, I figured it'd be best to start with. I have some McMaster-Carr 11 second quench oil arriving tomorrow.

Before posting this thread I've done a ton of search on the net looking for a straight-up list of the process of thermal cycling/normalizing and hardening in a propane forge, but haven't found anything. I've found a very detailed step-by-step by Kevin Cashen( http://www.knivesby.com/knifemaking-Kevin-Cashen-treating-1084.html ) but the normalizing process requires accurate temperatures and 10min soak times. These are things I'm not sure I'll be able to accurately perform with my propane forge(with no thermocouple).

Now, this isn't forged-worked 1084 I'll be heat treating. Just stock removal. I know grinding can grow grain structure so I bet I could benefit from normalizing. Since I'm not able to assure the temperature(other than being non-magnetic), how can I normalize without the precise steps?

Also, I've read that it's best(w/1084), during hardening, to heat to magnetic and hold for a couple minutes. Is that something I should do even though I can't control temp precisely?

I think I have annealing figured out based on information on the web. 400f for one hour, three times.

Any information you folks could provide me would be greatly appreciated.
Click to expand...

ok, lets start at the top. 1084 is considered one of the easier steels to heat treat. first, read the label and heat quench oil to temperature. heat blade to NON-magnetic, hold for 5-10 minutes, quench. wipe clean. temper at 325F for an hour. quench in cold water. use this time to scrub off any scale. temper at 375F for an hour and you are done. if you check your hardness will probably be Rc60-62.
if using Aldo's 1084 it is already annealed. 400f for an hour times 3 would be a temper.
hope this helps
 
scott.livesey said:
ok, lets start at the top. 1084 is considered one of the easier steels to heat treat. first, read the label and heat quench oil to temperature. heat blade to NON-magnetic, hold for 5-10 minutes, quench. wipe clean. temper at 325F for an hour. quench in cold water. use this time to scrub off any scale. temper at 375F for an hour and you are done. if you check your hardness will probably be Rc60-62.
if using Aldo's 1084 it is already annealed. 400f for an hour times 3 would be a temper.
hope this helps
Click to expand...

Thanks for your response.

I understand the gist of hardening and annealing. What my question was mainly in regards to was the need to normalize/thermal cycle prior to hardening. Aldo's steel IS annealed but from my understanding, part of that process increases grain growth in the steel. That grain growth can lead to cracking or excessive warping.

What I'm mainly trying to figure out is if I should heat cycle before hardening. If so, how and whether I should oil quench or air cool?
 
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creature said:
Thanks for your response.

I understand the gist of hardening and annealing. What my question was mainly in regards to was the need to normalize/thermal cycle prior to hardening. Aldo's steel IS annealed but from my understanding, part of that process increases grain growth in the steel. That grain growth can lead to cracking or excessive warping.

What I'm mainly trying to figure out is if I should heat cycle before hardening. If so, how and whether I should oil quench or air cool?
Click to expand...

Unless you are forging, or lamellar annealing, normalizing at higher temps etc... you do not need to worry about grain size. Most bladesmiths are unnecesarily obsessed with grain size, but stock removers normally are spared this neurosis. Unless you are catching your belts on fire and need to wear a proximity suit while grinding there is no way you are affecting aus-grain. Well I guess if you have a habit of turning blades blue and getting your edges to 1600F+ you could at the edge but that would be very poor grinding technique indeed. This steel should be in pretty good shape just as you received it, grind it (carefully:3:) and then heat it up, using the magnet if you like, and quench into your oil heated to 130F. 1084 has a range from below 1450F all the way to 1500F to work in, the widest range of any steel, so you are pretty safe and the magnet will help you stay safely lower yet. Soak times are not as critical with this steel particularly if you heat it in the 1475F-1500F range. Aldo's 1084 is a special formula with a pinch of added things to help keep the grain size stable. Normal 1084 will start to move up one ASTM grain size at around 1525F but this stuff should be stable even higher.
 
Note the color of the steel once it's non-magnetic and try to hold it at that color during the soak. As Kevin said, it's not that critical in 1084 as some other alloys. I've done just a 2-3 minutes and it seems to work as far as I'm able to test it. Of course it's nice when you can spot decalesence, which is like a shadow that passes across the steel as the phase changes, but a magnet should get you by.

Doug
 
Kevin- Thanks a bunch for the help, and thanks for all the work you've free sourced out on the internet. I've learned a ton reading your works.

Doug- Thanks. I was thinking about going off of color but I'm concerned about whether I'd be doing more harm than good by going for the soak. I wouldn't want to cause issues by going over 1500F.
 
Kevin R. Cashen said:
Unless you are forging, or lamellar annealing, normalizing at higher temps etc... you do not need to worry about grain size. Most bladesmiths are unnecesarily obsessed with grain size, but stock removers normally are spared this neurosis. Unless you are catching your belts on fire and need to wear a proximity suit while grinding there is no way you are affecting aus-grain. Well I guess if you have a habit of turning blades blue and getting your edges to 1600F+ you could at the edge but that would be very poor grinding technique indeed. This steel should be in pretty good shape just as you received it, grind it (carefully:3:) and then heat it up, using the magnet if you like, and quench into your oil heated to 130F. 1084 has a range from below 1450F all the way to 1500F to work in, the widest range of any steel, so you are pretty safe and the magnet will help you stay safely lower yet. Soak times are not as critical with this steel particularly if you heat it in the 1475F-1500F range. Aldo's 1084 is a special formula with a pinch of added things to help keep the grain size stable. Normal 1084 will start to move up one ASTM grain size at around 1525F but this stuff should be stable even higher.
Click to expand...
With regards to stock removal blades, normalization then, is an unnecessary step prior to austentization/quench. Am I understanding this correctly?
 
4CIW said:
With regards to stock removal blades, normalization then, is an unnecessary step prior to austentization/quench. Am I understanding this correctly?
Click to expand...
It is not necessary. Kind of. If the steel is spherodized, normalizing will put it into a better state than the spherodized structure. However, you could also make it worse. Check out “knife steel nerds” (Larrin Thomas) on YouTube. He has quite a few videos that explain the whole thing pretty well, and I know he has at least one video on heat treating in a forge.
 
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