80crv2 normalizing question

[Heikki]

I've got some 80crv2 from NJSB and I've been reading about the need to normalize it to prevent hardening issues. I do most of my grinding pre heat treat, so was wondering if it makes sense to normalize after I profile but prior to grinding my bevels in order to deal with the decarb. Was looking at 1600, 1400, and 1250 for 5 minutes each for the normalizing steps. Thanks.

 

[DustySerpa]

I'm certainly no expert, but I normalize 3 times after forging, then again after grinding, at 1500, then heat treat. I've never had any problems with it. I do it after forging mostly to make sure it's soft for grinding and drilling holes. You should definitely do it right before heat treating though, grinding can cause stress in the metal and cause warps when heat treating if you don't normalize first. Just my 2 cents. I believe the 1500 is what Jason Knight suggests in his Forged series.

 

[Kevin R. Cashen]

With an alloy such as this proper normalizing would be in excess of 1600°F and maybe more like 1650°F to achieve a full solution with proper carbide refinement. 1500°F and below would be simple grain refinement or annealing operations. Normalizing is best done earlier in the process, like right after forging and before any annealing. It would be overkill, and possibly counterproductive, after grinding or just before hardening. A better option for handling strain from grinding or machining just before hardening would be basic stress relieving. This would result in much leas scale or decarb.

Try a sample first and see if it will harden well from 1525°F, and you may not need the normalizing. If you find that you cannot achieve proper hardness at this temp with a 10 minute soak, then move on to the normalizing. There are suggestions floating around the internet of hardening heats at 1600°F or better that are best ignored in favor of the normalizing rather than cooking the steel alive in such a manner.

 

[Heikki]

With an alloy such as this proper normalizing would be in excess of 1600°F and maybe more like 1650°F to achieve a full solution with proper carbide refinement. 1500°F and below would be simple grain refinement or annealing operations. Normalizing is best done earlier in the process, like right after forging and before any annealing. It would be overkill, and possibly counterproductive, after grinding or just before hardening. A better option for handling strain from grinding or machining just before hardening would be basic stress relieving. This would result in much leas scale or decarb.

Try a sample first and see if it will harden well from 1525°F, and you may not need the normalizing. If you find that you cannot achieve proper hardness at this temp with a 10 minute soak, then move on to the normalizing. There are suggestions floating around the internet of hardening heats at 1600°F or better that are best ignored in favor of the normalizing rather than cooking the steel alive in such a manner.

Thanks Kevin. I'll try that route first.

 

[mpcoppin]

A better option for handling strain from grinding or machining just before hardening would be basic stress relieving.

Wait… I thought “stress relieving” was just another way to say “normalizing.”

You are all so generous with your time and knowledge, I feel greedy for asking but can someone pretend I know nothing (it shouldn’t be hard) and tell me where I’m right or wrong here?

Beginning: I buy 80CrV2 from AKS. Sometimes I forge to shape, other times (like when it’s thin stuff) I just cut/grind out a profile.

Middle: At this point I was taught to “normalize” in order to relieve stress and get a good grain structure.

End: After normalizing I heat it to about 1525° and let it soak for about 5 mins. Then I quench in warm canola oil. Then I temper it in the kitchen oven (2x at 2 hrs each).

What should this “middle” step look like?
Is this “normalizing,” “stress relief,” or “cycling?”

I feel like I’m using words without knowing what they really mean.

 

[tkroenlein]

It has been one of my great frustrations learning to make knives and seeing the repeated misnomers like "normalize 3X." It took me far too long to get to a basic working understanding of heat treating. I kept seeing the data sheets and web sites like Kevin's saying to normalize at a given temp, nothing about three times, and certainly none of this 3 step descending thermal cycling thing that is repeated so often.

So...

You can only normalize once. You can repeat the step if you wish, maybe necessarily if a higher heat is needed to complete the process, but it's still a one time thing. This is done for one reason only. To "reset" the steel to a workable condition, where all the constituent elements are evenly distributed. If I've forged a blade in 80CrV2, the last heat in the forge is at normalizing temperature, as evenly across the work as possible. That's the point is to get the whole piece in one condition. Personally, I then switch to the oven for 2 cycles at 1475F. I'd do the same in the forge if that's all I was using. This is just 2 heats that are in the low end of the austenitizing range, which seem to do the best at grain refinement. That's usually right where I stop. I do whatever work I want to do before finishing the heat treat, which I do at 1525F for 12-13 min (I set the timer at 15) followed by usually the 2x2 temper at 375F (~61.5HRC).

The stress relieving, which I don't do, is done in the 1250F range. I won't quote a time, cuz I don't know. It is below critical temp, so stuff doesn't move around too much.

 

[Kevin R. Cashen]

Normalizing: HOT! generally about 100°F higher than hardening heats. Purpose- to homogenize the internal structure of the steel, mostly carbide distribution. Normalized steel does not have to be softer, it just has to be uniform inside.

Thermal Cycling: ?? any temperature the knifemaker wants to use. Purpose- Anything from synchronizing the makers theta waves with the shakra of the steel to simple grain refinement. There is no real industrial heat treatment called "Thermal Cycling" or "Grain Refinement" instead this is a generic term used by knifemakers to describe any number of heats below Normalizing temperatures for the purpose of refining grain, and equalizing stress/strain. Yes I use "Thermal Cycling" as a grain refining treatment after normalizing, and may even utilize descending heats.

Annealing: For lamellar, above austenitizing heat with slow cool. For Spheroidal (what I use and recommend), below Ac1 (approx. 1300°F)

Stress relieving: 1100°F to 1250°F for the annihilation of strain effects within the steels crystalline lattice while affecting little else. You got a little eager with the mill, surface grinder or straightening hammer and you want the blade to sit still during subsequent heat treatments, but you do not want carbide growth, grain growth, scale, decarburization or effects on hardness- Stress relieve.

 

[Chris Railey]

Stress relieving: 1100°F to 1250°F for the annihilation of strain effects within the steels crystalline lattice while affecting little else. You got a little eager with the mill, surface grinder or straightening hammer and you want the blade to sit still during subsequent heat treatments, but you do not want carbide growth, grain growth, scale, decarburization or effects on hardness- Stress relieve.

That is gold right there, thanks Kevin.

 

[Smallshop]

Anything from synchronizing the makers theta waves with the shakra of the steel to simple grain refinement.

LOL!!

I tried it....it hurt.

 

[mpcoppin]

So... I'm a little embarrassed to admit this, but I have been doing this all wrong. I think I've got the concept of "normalizing" down but I'm way off on grain refinement. Rather than ask here, I'm going to start a more general thread so it will be easier to find.

 

[Chris Railey]

So... I'm a little embarrassed to admit this, but I have been doing this all wrong. I think I've got the concept of "normalizing" down but I'm way off on grain refinement. Rather than ask here, I'm going to start a more general thread so it will be easier to find.

We all started somewhere brother no reason for embarrassment here. If I may, I would suggest you go here and start. http://www.cashenblades.com/info.html
This is going to embarrass Kevin slightly but he will forgive me; In my opinion (based on my studies) you have to be careful where you go for information on two things near and dear to my heart, The Bible and Metallurgy. For the latter, I have searched and studied what is available on the internet and Kevin is a well trusted and knowledgeable scientist. He gives freely of his time and hard earned knowledge because he wants others to explore and learn for themselves. As we say in the south, "He alright".

 

[tkroenlein]

So... I'm a little embarrassed to admit this, but I have been doing this all wrong. I think I've got the concept of "normalizing" down but I'm way off on grain refinement. Rather than ask here, I'm going to start a more general thread so it will be easier to find.

Yup. I did it all wrong, too. And I'm sure I could do a lot of it "more right." I guess that's the point of my post. When the info you're getting doesn't match data sheets and the good info like Kevin's website, start asking what, how and why. Drill down on exactly what each thing is and what it accomplishes. Then try it and test it the best you can.

 

[mpcoppin]

... you have to be careful where you go for information on two things near and dear to my heart, The Bible and Metallurgy.

I know exactly what you mean. I have spent the better part of the last decade and a half explaining this concept to people as it relates to information about the US Constitution, US Law, and US Jurisprudence.

I agree, Kevin is incredibly generous with his time and knowledge. I am constantly surprised by how often this is the case among those who have been making knives, building forges, making tools, and bending metal (especially on forums like this). I recall one day I was asking about a burner design that has been around for decades and the individual responsible for the design logged on and answered my question.

I've spent a ton of time on Kevin's page and I've read other books, textbooks, blogs, and scientific papers. I think the problem is that I have never had a baseline understanding of the most fundamental vocabulary and concepts. As a result, I read something thinking I understand it but later find out that I was wrong about some important concept and so my understanding is flawed from the start.

 

[Chris Railey]

I think the problem is that I have never had a baseline understanding of the most fundamental vocabulary and concepts. As a result, I read something thinking I understand it but later find out that I was wrong about some important concept and so my understanding is flawed from the start.

I hate those situations

 

[MTBob]

Then I temper it in the kitchen oven (2x at 2 hrs each)

You probably should check / monitor the oven temp, kitchen ovens are notoriously inaccurate. An inexpensive BBQ temp monitor would do.

 

[mpcoppin]

You probably should check / monitor the oven temp, kitchen ovens are notoriously inaccurate. An inexpensive BBQ temp monitor would do.

True. I’ve got a BBQ probe thing. Mine has multiple probes so I can look at the temp in multiple locations (or in multiple steaks).

The biggest issue I have observed is that the temps drop significantly before the element kicks back in to bring it back up to temp. If your wife isn’t watching you can put the blade in a 9x13 pan with an inch or two of sand and the thermal mass of the sand will keep the temp fluctuations near the blade from swinging too far.

 

[Kevin R. Cashen]

For the guys who feel they have been doing it "wrong"- probably not, just doing it differently. Carbon, and simple alloy, steels are very forgiving, so unless you burnt the steel, blew the grain size or failed to harden, and the knife cuts and holds an edge, you are probably good. Over the years too many people have believed I was telling them they were doing it wrong, when most of the time what I was saying was your doing fine, but there could be a way to do it even better. When you answer the number of troubleshooting emails and phone calls that I do everyday, you develop the desire to get ahead of it with information in order to be proactive, rather than reactive. The more people I can help understand the process from the steels perspective, the sooner I may be able to hit the shop after the daily questions.

 

[KenH]

If I may, I would suggest you go here and start. http://www.cashenblades.com/info.html

There is a whole wealth of info on that link - THANK YOU for posting.

Dr Kevin Cashen, an even bigger THANK YOU for all your efforts to share knowledge with rest of us "mere mortals". You, we put on the pedestal of knowledge.

 

[romano]

i wonder in what state the steel is delivered from njsb. low carbon steels usually are normalised, high carbon steels are spheroidized (both improve machinability). sometimes 80cr2v/l2/1.2235 comes as rolled or quenched and tempered. they dont say. obviously heat treat would depend on that.

edit: i assume its hot (not cold) rolled, yes?