First Heat Treat - Check my recipes

H

Hypocrite

Joined
Apr 23, 2008
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As I mentioned on my "Economic Stimulus" thread, UPS just dropped off my new kiln this week. I have several ground blades waiting for HT, but I'd like to have folks review my recipes before I start baking steel.

First off... Let's talk about the steels and tools I'm working with.
I have several blades ground from Kelly Cupples 3/16" 1080 and one (longer) blade ground from Kelly Cupples 3/16" 1095. The steel seemed to be fairly well annealed when I got it; and all shaping was done on a bandsaw (rough profiling) and a KMG. Blades have been ground to 220-grit in most cases... I may have taken one or more up to 400-grit.

As mentioned earlier, I will be bringing the blades to temp in my new Sugar Creek "Big Knife Kiln" (BKK) which is outfitted with the digital controller. I will be quenching into Parks 50 (seems to be the right choice for these particular steels), and tempering in the kitchen stove (which I have equipped with an extra oven thermometer to verify accurate temps).

So here are my recipes:

1080
(taken from a post by Stacy Apelt)
  • Austenitize at 1475F (with short soak... less than 5 mins)
  • Quench in Parks 50 heated to approx. 130F. Agitate.
  • Temper at 450F for 1hr, cool to room temp... repeat.

1095
(taken from partially several posts by Kevin Cashen)
  • Austenitize at 1500F (soak for at LEAST 5 mins)
  • Quench in Parks 50 heated to approx. 130F. Agitate.
  • Temper at 425F for 1hr, cool to room temp... repeat.

Now some questions.

  1. Should I be normallizing before quench. A have the following quote saved from a post that Kevin made awhile back:
    "Now as for the lack of normalizing, I honestly don't know where knifemakers got the concept of normalizing right before the quench (perhaps from the abundance of lamellar annealing which could result in larger grain). The purpose of normalizing is to equalize and fix internal structures after very radical procedures like forging and other heavy deformation and temperatures. Industry often only does one at 1600F; this would be very unwise right before quenching. The proper thing to do for steel that has been heavily machined before hardening would be a good old stress relieve, not an all out normalization." Based on this, it seems to me that I should not need to normalize these blades prior to HT... which leads me to my next question:
  2. Should I be running a stress relieve cycle on these steels prior to HT? What does this look like in 1080 and 1095?

How do my recipes look? Are the temps OK? Am I missing anything?

Thanks in advance. Now I need to verify my fire insurance is paid up. ;)
 
Looks OK to me.
The normalizing/stress relief prior to HT is to make sure you are converting fine grain metal. The condition before HT does affect the condition post HT.
Stacy
 
Thanks Stacy. It seems that normalizing and stress relief are not necessarily the same thing. So if I did all my grinding on annealed steel, and did NOT beat on it with a hammer, it would seem that I would NOT need to run a normalizing cycle prior to HT... but should I run some sort of stress relief cycle? What is the practical difference? For stress relief should I just take the steel up to the hardening temp then air cool?

Erin
 
Take it to critical and air cool to black heat ( around 800F). Repeat to barely magnetic and cool.Once again to around 1200F and cool. The final run will be the austenitization at 1475F and quench in 130F oil.
 
Hypocrite said:
Thanks Stacy. It seems that normalizing and stress relief are not necessarily the same thing. So if I did all my grinding on annealed steel, and did NOT beat on it with a hammer, it would seem that I would NOT need to run a normalizing cycle prior to HT... but should I run some sort of stress relief cycle? What is the practical difference? For stress relief should I just take the steel up to the hardening temp then air cool?

Erin
Click to expand...

Yes you would still need to normalize if all you did was grind. I read awhile back something Kevin wrote and he made the statement that he was really surprised at how much stress was in a blade just from grinding. The few that I have done I normalize 3 times before heat treating. As far as I know there is no difference between stress relieving and normalizing, you heat to just about nonmagnetic and then let it air cool. If any of my statement are incorrect I am sure Stacey or Kevin will correct me.
 
Stress relieving does just and only that - relieves stresses.It is done below the critical temperature , usually 1200 F.
Normalizing relieves stresses but also forms new and uniform grains .
For stresses from grinding or machining stress relief is all that's necessary to remove them. To refine grain and make the grains uniform in size you would normalize .Do this after forging.
Normalizing temperature is about 75-100 F above the critical, the same as the hardening temperature.Holding for a minute or two is all you need as it doesn't take much time for transformation to occur.Air cool.
 
mete said:
Stress relieving does just and only that - relieves stresses.It is done below the critical temperature , usually 1200 F.
Normalizing relieves stresses but also forms new and uniform grains .
For stresses from grinding or machining stress relief is all that's necessary to remove them. To refine grain and make the grains uniform in size you would normalize .Do this after forging.
Click to expand...

So could you normalize after grinding just prior to heat treating or is their an advantage to normalizing after forging and then stress relieving after grinding separately?
 
mete said:
Stress relieving does just and only that - relieves stresses.It is done below the critical temperature , usually 1200 F.
Normalizing relieves stresses but also forms new and uniform grains .
For stresses from grinding or machining stress relief is all that's necessary to remove them. To refine grain and make the grains uniform in size you would normalize .Do this after forging.
Normalizing temperature is about 75-100 F above the critical, the same as the hardening temperature.Holding for a minute or two is all you need as it doesn't take much time for transformation to occur.Air cool.
Click to expand...

Thanks Mete... this is exactly what I was looking for. :thumbup: :)

Erin
 
How would the process differ for CPMD2 and CPM154? I have a kiln so I should be able to get it pretty close to the right temperatures.

I grind barehanded, but fairly aggressively. I usually work on three at a time so I can dunk them and let them fully "air-cool" when they start to get too hot to hold, and work on another one meanwhile. Incidentally the CPM154 doesn't seem to heat up nearly as quickly as other, lower-alloy steels I've ground. Is this all in my head, or is it due to the chemistry?

The steel works easily and came with the Crucible sticker on it, so I assume (I know, I know) it was properly annealed before it left the mill. I don't do any forging.

Is a stress-relief enough? I'll gladly normalize if it's helpful to refine the grain after grinding, but Im not sure it's necessary with these CPM steels. This stuff seems to be pretty sweet and I'd like to make the most of it.
 
Last edited:
If you forge make it a practice to always normalize afterwards.
Stress relieve after grinding .


Stainless steels have a significantly different heat conductivity than alloy or carbon steels.
Only Crucible makes CPM steels.
Offhand I can't remember problems with annealed CPM steels .If there is a problem they should replace the steel.
Air hardening steels like CPM154 cannot be normalized in the regular sense as they won't give you a pearlitic structure.They would have a martensitic structure which would have to be to be tempered at 1200 F.
Stress reief should be enough.
 
mete said:
If you forge make it a practice to always normalize afterwards.
Stress relieve after grinding.
Click to expand...

That is what I have always done because that's what I have always heard or read. What is the advantage of normalizing after forging rather that after grinding just prior to heat treating?
 
Convenience for one thing. You have the forge hot at the point you need to normalize.Depending on how you forge you may have different grinding results if the grain size is different from one side to another.
 
rtj1981 said:
That is what I have always done because that's what I have always heard or read. What is the advantage of normalizing after forging rather that after grinding just prior to heat treating?
Click to expand...

Rob,

If you are using eutectoid or hypoeutectoid steel and forging, normalizing after forging will create fine perlite and it is easy to grind and drill (easy enough), so annealing isn't at all necessary and the steel is set up with equal sized and small sized grain for the heat treat.

I stress relieve before quenching, mostly in an effort to reduce warping.

Mike
 
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