5160 Hatchet Heat Treat

[AZtrapper]

This is actually my first forge project I've ever done. It is a hatchet made from a 5160 Leaf Spring. With my current tools, I couldn't really obtain a very smooth forge finish, so please excuse its roughness. I also understand that because the blade is not directly center with the eye, that there will be balance issues. Since I have such little experience, I did not want to attempt a forge weld. Feel free to critique.





I am very close to being ready to heat treat it, but I have some questions. First, I'll list my currently available quenchants. I have water, brine solution, dish soap solution, 2-stroke motor oil, and chainsaw bar lubricant.

My current understanding is to austenitize the steel by heating it to its critical temperature in the forge, which I have read is approximately 800 degrees C. The steel should be the color of unfanned wood coals. I have magnets for checking to make sure. Once having reached critical temp, I am to quench the edge in whatever quenchant I decide to use. This begs the following questions:

For how long?
Do I rapidly submerge the steel, or slowly?
How far up past the edge should I quench for a hatchet?

Next, I am to temper it. This is the part I am most unclear on. From what I understand, I can buy a toaster oven from the thrift store, wrap the blade in foil, and heat for however long I need to at whatever temp. I am sure that there are charts online that will aid me in knowing this. This also begs a question:

What is the desired hardness for a hatchet or axe? 55 rc?

I also wonder how important it is that I relieve the stress in it first. From what I can tell, this is done by annealing. I plan on doing this by lighting a wood fire in my 55 forge, and letting the blade sit in the coals until the fire burns itself out. How many times should I do this?

[Maillemaker]

Without a very expensive machine to test hardness, getting an exact reading is next to impossible.

There is a great variety of hardnesses from the different quenchants. Generally, water gives a hard, fast quench with a greater risk of cracking, while oil gives a slower quench that doesn't produce as much hardness, with brine in-between.

When you quench, move the steel around in the fluid, as well as up and down. This prevents the fluid from superheating and not cooling the steel as fast.

When you temper, first shine the steel with sandpaper or emery cloth. Then, take a slow heat from the eye, and watch for a band of color to spread toward the blade. This is an oxide layer that gives a very good approximation to the heat of the steel. It starts at a very pale yellow, then straw, bronze, purple, deep blue, and then a grey green. Pale yellow is still very hard, and bronze or purple is hard enough for most blades without being brittle.

If you temper in a forge, be careful that you don't heat the eye above critical, or it will harden and become brittle when you quench.

You can use the stovetop element on a range, or a toaster oven as well.

[jmccustomknives]

A friend who metal detects on old sights give me a bunch of scraps he had found. Many were ax heads (most broke) and a few were made just the way yours is. It was interesting to study how those made from wrought iron and steel are done. As far as heating and quenching, you can do it two ways. The easy way is to heat just the edge to nonmagnetic and quench just the edge in motor oil. Don't use water, I have succesfully quenched 5160 in water and also had them crack. You can do the whole thing, that just makes it harder to get an even heat. 5160 tends to air harden to somewhat of a spring temper on its own anyway. The old method of heating the back of the ax up and letting the color run is very difficult. Most of the time I end up having to re-harden because I let to much heat to the end. Better to pollish up a bit of the blade and put it in a toaster oven at between 425 and 450F. The polished section should be a dark brown. For insurance you can do it three times. That should be a good temper for the ax.

[Rich Hale]

Az forgive me for being as blunt as I normally tend to be: You are asking us to type information in a little box that has been done many times in this site and is ready for you to read. I know it is not a fun thing to sit and read all of that data and not get bogged down in it. But then again a readers digest tyype of an answer in here will just be a stop gap fix. Matt qave you great info and that may be all you need to get this one done. By the way I wouild not use heat treat foil, Its real value is to prevent scale from forming while at temp. Your blade has scale already. A simply trick you may try is rather than use sandpaper to clean it for seeing heat colors run is to use a piece of sandstone or old red brick. Shine it up enough that you can see colors when heated. Woody just posted a video on heat treat tha is worth the short time it takes to watch

[AZtrapper]

Generally, water gives a hard, fast quench with a greater risk of cracking, while oil gives a slower quench that doesn't produce as much hardness, with brine in-between.

How does the type or weight of the oil affect the quench? Will lighter oils produce a greater hardness? Does it matter if I quickly submerge the edge all at once, or should I do it slowly? How long should I submerge the steel, until it is cool enough to touch with bare hands?

Az forgive me for being as blunt as I normally tend to be: You are asking us to type information in a little box that has been done many times in this site and is ready for you to read. I know it is not a fun thing to sit and read all of that data and not get bogged down in it. But then again a readers digest tyype of an answer in here will just be a stop gap fix. Matt qave you great info and that may be all you need to get this one done. By the way I wouild not use heat treat foil, Its real value is to prevent scale from forming while at temp. Your blade has scale already. A simply trick you may try is rather than use sandpaper to clean it for seeing heat colors run is to use a piece of sandstone or old red brick. Shine it up enough that you can see colors when heated. Woody just posted a video on heat treat tha is worth the short time it takes to watch

I did multiple searches on the site not yielding the answers I was searching for. If you could suggest some keywords that would produce better results, or provide me with a link to another thread, I would be more than happy to search for my answers there. I try to avoid asking questions on a forum that are asked constantly and answered the same. My homework yielded multiple 5160 heat treat charts, tempering methods, and much else. What I could not find, however, was how it all applied to axes. I appreciate the info given thus far and intend to implement it.

I had not heard of the rockwell hardness scale until I started forging, which was less than a month ago. As a result, I do not have any hands on experience with how hard things are in correlation to the scale. I know that 60rc is very hard and is desired in knives, but I have not actually tried to sharpen a 60rc knife. This is why I question what is the desired or targeted hardness for a blade of axe-type implications. It shouldn't be too hard, but also not too soft. If you supply me with ya'lls preferred hardness, I can use online heat treat tables to try and obtain it.

Better to pollish up a bit of the blade and put it in a toaster oven at between 425 and 450F. The polished section should be a dark brown. For insurance you can do it three times. That should be a good temper for the ax.

According to the tables I have looked at thus far, this will likely yield a hardness of 58rc. Does that sound right?

[Rich Hale]

Ok shop method to determine the proper hardness for an axe, hatchet or knife: Easy enough to do! Get an axe that holds and edge like you wish your new one to do. Use a file to see how it feels when youi try and sharpen it. Then see wot yours feels like, Make them the same. Knfe same thing file a knife that you know does wot you wish it to do, test your blade. Have you read the heat treat stickies? Did you look at the video I suggested? I cannot show yoiu how to search for items on this site as I cannot do it mmyownsself. When I post about anything on here it is only in areas I can do and have done and found working methods. That does not include locating things here.

[Steve Sells]

Quote : I did multiple searches on the site not yielding the answers I was searching for. If you could suggest some keywords that would produce better results, or provide me with a link to another thread, I would be more than happy to search for my answers there. I try to avoid asking questions on a forum that are asked constantly and answered the same. My homework yielded multiple 5160 heat treat charts, tempering methods, and much else. What I could not find, however, was how it all applied to axes. I appreciate the info given thus far and intend to implement it.

So you did not see the heat treat section for blades, nor the sticky's that explain most of this in detail?
http://www.iforgeiron.com/forum/56-knife-stickies-here/

[pkrankow]

In google you can use

"5160 steel specifications"

or "YYYY steel specifications" where YYYY is the ansi number for the steel you are interested in.

I also like using the "site:iforgeiron.com" tag in google to search ONLY within IFI.

You can check temperature with a magnet because when steel becomes non-magnetic it is a similar temperature to your hardening temperature for many steels. You are really interested in slightly hotter than non-magnetic for 5160, so you find non-magnetic and memorize the color, then let the blade air cool to normalize. Repeat the heating to your memorized color, then quench. I use a ceramic donut magnet from Radio Shack on a thin copper wire, hanging as a pendulum. When the magnet swings freely when the steel is brought near it is non-magnetic. Make sure your lighting is the same for all cases.

I do recommend reading the link Steve provided.

Tempering by running the colors is easy and was described above by Maillemaker. Rich talked about checking hardness with a file. You can check if it hardened adequately by testing with a file before tempering - the file should skate instead of cutting. You can take temper softer in a second tempering operation, but have to re-harden to get harder.

Phil