Normalize before forging?

D

Dolf

Joined
Nov 20, 2024
Messages
11
I'm a Newby and would like to forge myself a hammer from a blade spring.
Do I normalize the blade first before I try to forge it or can clean billits of spring be stacked and forged directly?
Please and thanks 😊
 
Hello, Dolf, and welcome to BladeForums! I am not exactly certain what you mean by "blade spring."

There is no need to normalize before forging. The process of normalization is done after forging to homogenize the grain size. Clean billets of steel may be stacked and forged as is. No real need to worry about crystal structure yet.

Best wishes with your project!
 
I think he is talking about stacking a group of pieces of leaf springs and forge welding them together to get a large billet to make a hammer form.

They would not need normalizing. Just grind the surfaces clean and forge weld as normal.
 
Stacy E. Apelt - Bladesmith said:
I think he is talking about stacking a group of pieces of leaf springs and forge welding them together to get a large billet to make a hammer form.

They would not need normalizing. Just grind the surfaces clean and forge weld as normal.
Click to expand...
Yes indeed it is a leaf spring I am referring to.
Answers much appreciated both of you!
 
fitzo said:
Hello, Dolf, and welcome to BladeForums! I am not exactly certain what you mean by "blade spring."

There is no need to normalize before forging. The process of normalization is done after forging to homogenize the grain size. Clean billets of steel may be stacked and forged as is. No real need to worry about crystal structure yet.

Best wishes with your project!
Click to expand...
I may have had my terms wrong again. I understand heating up and letting it cool down as a "softening" process, which I thought may have been required before attempting to forge.

But you have answered my question. Thank you very much
 
Dolf, fill out your profile with your location. It helps us give better answers.

Annealing and normalizing are all done to reset the structure of the steel to a particular desired state ... usually pearlite. The reasons and methods for each depend on what the next step in the steels processing will be.

Neither is needed when you are forge-welding, as the welding is done high in the austenite range. The steel is already in its softest state when forge-welding.

Upon cooling from the forging, after all work is done for the day, letting it cool slowly in vermiculite, ashes, or cooling down in the forge (gas forge) is a usual process. This leaves the steel in a softer state for drilling or cutting the next day, or for the next forging session.

While normalizing and annealing are similar processes, the terms are often used improperly. Sometimes this is a language issue.

Normalizing is done after a forging session to reduce carbides, reduce grain size, and prepare the steel for annealing or final heat treatment to harden the blade.
It involves heating the steel to around 1600°F and holding it there for about 10-20 minutes, then air cooling. If holding it for long times isn't possible, three heat and cool cycles will work well enough. If doing multiple cycles, cooling to black is sufficient before the final cooling to room temp.

Annealing is done to make the steel more machinable for drilling and cutting. set up the steel for final hardening, provide proper structures for getting the highest hardness in the quench.
The temperatures are lower than normalizing. Several types of annealing can be used, depending on what the next step will be and what the use of the steel will be. For knife blades Divorced Eutectoid Transformation (DET) annealing is the best one. It is done at or just slightly above the hardening temperatures used in quenching, cooled about 200 degrees, and held for a while before cooling to room temperature.

I highly recommend getting Larrin Thomas's book = "Knife Engineering". It has great explanations of metallurgical processes used in knifemaking amnd exact temperature and time charts and specs for most every steel used to make a knife. His site "Knife Nerds" is also a great place to read and learn about knifemaking metallurgy and heat treatment.
 
Stacy E. Apelt - Bladesmith said:
Dolf, fill out your profile with your location. It helps us give better answers.

Annealing and normalizing are all done to reset the structure of the steel to a particular desired state ... usually pearlite. The reasons and methods for each depend on what the next step in the steels processing will be.

Neither is needed when you are forge-welding, as the welding is done high in the austenite range. The steel is already in its softest state when forge-welding.

Upon cooling from the forging, after all work is done for the day, letting it cool slowly in vermiculite, ashes, or cooling down in the forge (gas forge) is a usual process. This leaves the steel in a softer state for drilling or cutting the next day, or for the next forging session.

While normalizing and annealing are similar processes, the terms are often used improperly. Sometimes this is a language issue.

Normalizing is done after a forging session to reduce carbides, reduce grain size, and prepare the steel for annealing or final heat treatment to harden the blade.
It involves heating the steel to around 1600°F and holding it there for about 10-20 minutes, then air cooling. If holding it for long times isn't possible, three heat and cool cycles will work well enough. If doing multiple cycles, cooling to black is sufficient before the final cooling to room temp.

Annealing is done to make the steel more machinable for drilling and cutting. set up the steel for final hardening, provide proper structures for getting the highest hardness in the quench.
The temperatures are lower than normalizing. Several types of annealing can be used, depending on what the next step will be and what the use of the steel will be. For knife blades Divorced Eutectoid Transformation (DET) annealing is the best one. It is done at or just slightly above the hardening temperatures used in quenching, cooled about 200 degrees, and held for a while before cooling to room temperature.

I highly recommend getting Larrin Thomas's book = "Knife Engineering". It has great explanations of metallurgical processes used in knifemaking amnd exact temperature and time charts and specs for most every steel used to make a knife. His site "Knife Nerds" is also a great place to read and learn about knifemaking metallurgy and heat treatment.
Click to expand...
Thank you very much
 
I neglected to say earlier - Welkom Dolf.

Thanks for adding your location. I had a feeling you were not in the Americas. Us old guys have to help each other out.
In some places, words like tempering and annealing have very different meanings than the USA versions of those words.
There are some great South African smiths. You should try and connect with them.
Dr. Larrin Thomas' book is a really valuable asset if you plan on getting into knifemaking and damascus. IIRC, it ships internationally and may even be available in S.A. on places like Amazon.
 
Much appreciated ;)
Yes English is not my mother tongue, but that is no excuse. I'm learning!
This old dog may well be a damascus job himself. San Mai with eager learner and bull headed experimenter all bashed together ;)
 
Since you are in S.A. I'll keep using temperature units in Fahrenheit. (for those who don't know, S.A. is metric except temperature)

I found that the baby step towards damascus was making san-mai. Once you learn to forge weld three pieces of steel together 7 pieces is easy.

TIPS:
1) Clean it up and keep it clean - Grind the matings surfaces clean with 60-80 grit belt. This degree of roughness makes solid welds. It also makes cleaning up a billet to remove scale and the weld metal from the MIG/TIG/stick.
After grinding clean, store each piece in a bucket of kerosene or a hydrocarbon cleaner like brake/parts cleaner (see below). Contrary to want some might think, oil, fingerprints, grease, and light rust will not affect a weld. Dirt and scale will. Even pretty new bars of steel will need the surface ground to remove mill scale and any other coatings. Most folks do this by hand on the grinder, but if you do a lot of billets, a surface grinder is invaluable.
When ready to make up the billet, just wipe the kerosene off and proceed with stacking and welding up the billet. Remember to properly store and dispose of the rags that are soaked with kerosene.

2) If you have a MIG/TIG/stick welder, welding the corners and several places down the sides will keep the billet tightly together during forge welding. Weld on a rebar handle or make the middle strip of the billet about 50mm longer to make a "stub" to grip with the tongs. This stub works well when hand forging. Use a rectangular box-jaw tongs.
Once welded up and cooled down below 100°F, store in a kero-tank. Multiple billets can be made up and stored under the liquid for months with no problem. This is called hydrocarbon fluxing. It removes the need to use borax (or greatly reduces it). You can read up on hydrocarbon fluxing by using the custom search engine in the Stickys.
Make up a 50-60cm tall tank by cutting off a surplus gas cylinder and fitting a top on it. This works perfect as a kerosene tank, and also is a great quench tank. Try and find one that is about 15cm wide. Most welding suppliers that refill tanks have a bunch around that didn't pass testing. They will often give you a few for free.
A #10 can makes a perfect top for a cut down 15cm wide welding gas tank. Old cooking pots work, too. Welding the tank bottom to a 30cmX30cm steel plate or other object makes the tank stable against tipping over. An old car tire rim works well.
You only need about 20cm of kerosene in the tank, which is four liters of kerosene for the sizes given above... just enough to cover the billets. Top it up as needed.

The other forge welding method that employs your MIG/TIG/stick welder is called dry welding. Weld every seam of the stack up. This keeps all oxygen away and promotes perfect welds. Dry welding requires no flux, but requires good welding technique. Some folks TIG with no filer rod.
When you have drawn the dry-weld billet out and are ready to re-stack the billet. Grind it clean, stack it up, and weld up all the seams again. Proceed as before with no flux. Once you get used to it, it does not take too long to weld up a 7-layer billet. That amounts to about 180cm of weld line 10cmX5cm billet.

3) Over hammering when welding is the biggest temptation to overcome. Start with medium blows and as it gets more sold feeling and sounding, increase the force of the blows.
Learn to listen to the steel - The sound of hitting a stack of bars of steel is easily differentiated from the sound of hitting a solid block of steel. Learn to listen to the sound as you weld up and compact the billet. When it sounds like a solid block of steel all over the billet, then you can start hard hammering and drawing the billet.

4) Strike While the Iron is HOT is the old saying about forging. Its forge welding partner should be Quit while it is still hot. You don't want to be trying to weld the billet below about 1800°F. People often hammer away down to a dull red ... or even black!!! This will shear the beginning welds and ruin a good billet fast. Keep the billet in and out of the forge and in the welding range until it is solid. Never let it cool down below cherry red. When solid, you can reduce the forging temperatures. Again, when welding it is best to never let it drop below cherry red. This avoids dropping into the temperatures where scale starts to form.
Some metallurgy about forge welding: The higher the carbon content the lower the welding point. High carbon steels forge weld at 1800-2100°F. Low carbon is between 1900-2400°F. You can drop about 100° below this range and still be OK, but never down into the cherry red or dull red colors. Forging above the range will cause the steel to crumble. In the terms of color (NOTE - judging temperature by color is very non-exact) forging temps run in the dark yellow to bright yellow range. Too high is yellow-white. Too low is orange. Red is far too low to weld. You may have to learn by trial and error what the colors look like at different temperatures and lighting conditions. There is no book or chart that will tell you what your eyes and brain will see in your own forge.

There is an interesting relationship between steel and oxygen. We all know that oxygen combines with iron to form iron oxide (there are several forms of iron oxide). But at high enough temperature it actually purifies the steel into iron and carbon dioxide (this is what a blast furnace does in smelting iron). Scale is the form of iron oxide we deal with in smithing. At welding temps, the oxygen just grabs some carbon and exits as a hot gas. So, the steel is not covered with a layer of glassy hard scale, but instead has a film of pure iron. However, at around 1700°F as the steel cools down, scale starts to form. This scale will make a weld impossible, but the atom thin pure iron layer will not hurt at all. This is the theory behind keeping the billet above 1700°F until all welds are set. If you only get a couple dozen hammer blows in before the color drops, put it back in the forge and let it heat up again before re-hammering. This is why lightly rusted steel will weld OK, but a little scale will make a bad weld (scale inclusion).

5) Another important thing to remember about working a billet is that the outer surface will reach the forging temperature before the inside does. Give the billet plenty of soak time for the first several welds and allow sufficient re-bound time during subsequent heats. Controlling the forge atmosphere (reducing atmosphere) and having the temperature in the right range will make for good damascus billets.

6) Don't try to do a whole billet and draw it out by hand in one session in the beginning. This almost always leads to poor or incomplete welds by rushing to draw it out before itis fully welded. It can also lead to sore arms or messed up shoulders.
Weld it up solid and let it cool down to black (below 900°F). Give it a bit of a normalization by heating to red for a few minutes and then letting cool to room temp. Store in the kerosene bucket until the next forging session.
The next forge session, draw out the billet into a bar. Don't draw too thin, as you will be grinding it down to clean steel. Cut the bar into stacking lengths and grind the surfaces clean of all scale, MIG/TIG/stick weld metal, and other crud. Once cleaned up, you can store them in the kero-tank, even if you will be dry welding later.
Next time you are in the forge, re-stack and weld up the billet again and repeat welding and drawing. It gets faster as you learn what to do.
7) FINAL TIP - In some way mark the billet or the handle. It can be a number or letter that corresponds to a note in your logbook. If you don't it is a guarantee that you will eventually pick up a billet of damascus and not remember what the steels were. Metal marking pens work well for this. A set of number stamps is also invaluable in the shop/forge. In the same way, mark both ends on both sides of every piece of steel in the shop. If you cut a piece off, re-mark the cut end immediately. If not, you will slowly collect a box of steel that you have no idea what it is ... ask me how I know this! Anyone who says they never mark their steel, and this has never happened, either has only one type of steel in his shop ... or is lying.



In a new thread, I'll explain the "hot cut-and-fold" technique of welding up a billet in one continuous session with never having to regrind it. It is all done by two people, using only hand tools and a propane forge, in one session that takes from one hour to two hours. It works on the "never let it get below red" principle.
At Bill Moran's hammer-in back around 2000, Jim Batson and I made a 30cm long 224-layer bar of random pattern damascus from seven 75mmX40mm bars in 60 minutes. We used only a 3#/1.5KG cross-pein hammer, box-jaw tongs, a wire brush, a hot cut hardie, a 25cm bar of L-6 and a 50cm bar of O-1 (both 6mm thick and 50mm wide). We tack welded the corners on a cheap stick welder first. Today, I would use 15N20 and 1084.
 
Stacy E. Apelt - Bladesmith said:
Since you are in S.A. I'll keep using temperature units in Fahrenheit. (for those who don't know, S.A. is metric except temperature)

I found that the baby step towards damascus was making san-mai. Once you learn to forge weld three pieces of steel together 7 pieces is easy.

TIPS:
1) Clean it up and keep it clean - Grind the matings surfaces clean with 60-80 grit belt. This degree of roughness makes solid welds. It also makes cleaning up a billet to remove scale and the weld metal from the MIG/TIG/stick.
After grinding clean, store each piece in a bucket of kerosene or a hydrocarbon cleaner like brake/parts cleaner (see below). Contrary to want some might think, oil, fingerprints, grease, and light rust will not affect a weld. Dirt and scale will. Even pretty new bars of steel will need the surface ground to remove mill scale and any other coatings. Most folks do this by hand on the grinder, but if you do a lot of billets, a surface grinder is invaluable.
When ready to make up the billet, just wipe the kerosene off and proceed with stacking and welding up the billet. Remember to properly store and dispose of the rags that are soaked with kerosene.

2) If you have a MIG/TIG/stick welder, welding the corners and several places down the sides will keep the billet tightly together during forge welding. Weld on a rebar handle or make the middle strip of the billet about 50mm longer to make a "stub" to grip with the tongs. This stub works well when hand forging. Use a rectangular box-jaw tongs.
Once welded up and cooled down below 100°F, store in a kero-tank. Multiple billets can be made up and stored under the liquid for months with no problem. This is called hydrocarbon fluxing. It removes the need to use borax (or greatly reduces it). You can read up on hydrocarbon fluxing by using the custom search engine in the Stickys.
Make up a 50-60cm tall tank by cutting off a surplus gas cylinder and fitting a top on it. This works perfect as a kerosene tank, and also is a great quench tank. Try and find one that is about 15cm wide. Most welding suppliers that refill tanks have a bunch around that didn't pass testing. They will often give you a few for free.
A #10 can makes a perfect top for a cut down 15cm wide welding gas tank. Old cooking pots work, too. Welding the tank bottom to a 30cmX30cm steel plate or other object makes the tank stable against tipping over. An old car tire rim works well.
You only need about 20cm of kerosene in the tank, which is four liters of kerosene for the sizes given above... just enough to cover the billets. Top it up as needed.

The other forge welding method that employs your MIG/TIG/stick welder is called dry welding. Weld every seam of the stack up. This keeps all oxygen away and promotes perfect welds. Dry welding requires no flux, but requires good welding technique. Some folks TIG with no filer rod.
When you have drawn the dry-weld billet out and are ready to re-stack the billet. Grind it clean, stack it up, and weld up all the seams again. Proceed as before with no flux. Once you get used to it, it does not take too long to weld up a 7-layer billet. That amounts to about 180cm of weld line 10cmX5cm billet.

3) Over hammering when welding is the biggest temptation to overcome. Start with medium blows and as it gets more sold feeling and sounding, increase the force of the blows.
Learn to listen to the steel - The sound of hitting a stack of bars of steel is easily differentiated from the sound of hitting a solid block of steel. Learn to listen to the sound as you weld up and compact the billet. When it sounds like a solid block of steel all over the billet, then you can start hard hammering and drawing the billet.

4) Strike While the Iron is HOT is the old saying about forging. Its forge welding partner should be Quit while it is still hot. You don't want to be trying to weld the billet below about 1800°F. People often hammer away down to a dull red ... or even black!!! This will shear the beginning welds and ruin a good billet fast. Keep the billet in and out of the forge and in the welding range until it is solid. Never let it cool down below cherry red. When solid, you can reduce the forging temperatures. Again, when welding it is best to never let it drop below cherry red. This avoids dropping into the temperatures where scale starts to form.
Some metallurgy about forge welding: The higher the carbon content the lower the welding point. High carbon steels forge weld at 1800-2100°F. Low carbon is between 1900-2400°F. You can drop about 100° below this range and still be OK, but never down into the cherry red or dull red colors. Forging above the range will cause the steel to crumble. In the terms of color (NOTE - judging temperature by color is very non-exact) forging temps run in the dark yellow to bright yellow range. Too high is yellow-white. Too low is orange. Red is far too low to weld. You may have to learn by trial and error what the colors look like at different temperatures and lighting conditions. There is no book or chart that will tell you what your eyes and brain will see in your own forge.

There is an interesting relationship between steel and oxygen. We all know that oxygen combines with iron to form iron oxide (there are several forms of iron oxide). But at high enough temperature it actually purifies the steel into iron and carbon dioxide (this is what a blast furnace does in smelting iron). Scale is the form of iron oxide we deal with in smithing. At welding temps, the oxygen just grabs some carbon and exits as a hot gas. So, the steel is not covered with a layer of glassy hard scale, but instead has a film of pure iron. However, at around 1700°F as the steel cools down, scale starts to form. This scale will make a weld impossible, but the atom thin pure iron layer will not hurt at all. This is the theory behind keeping the billet above 1700°F until all welds are set. If you only get a couple dozen hammer blows in before the color drops, put it back in the forge and let it heat up again before re-hammering. This is why lightly rusted steel will weld OK, but a little scale will make a bad weld (scale inclusion).

5) Another important thing to remember about working a billet is that the outer surface will reach the forging temperature before the inside does. Give the billet plenty of soak time for the first several welds and allow sufficient re-bound time during subsequent heats. Controlling the forge atmosphere (reducing atmosphere) and having the temperature in the right range will make for good damascus billets.

6) Don't try to do a whole billet and draw it out by hand in one session in the beginning. This almost always leads to poor or incomplete welds by rushing to draw it out before itis fully welded. It can also lead to sore arms or messed up shoulders.
Weld it up solid and let it cool down to black (below 900°F). Give it a bit of a normalization by heating to red for a few minutes and then letting cool to room temp. Store in the kerosene bucket until the next forging session.
The next forge session, draw out the billet into a bar. Don't draw too thin, as you will be grinding it down to clean steel. Cut the bar into stacking lengths and grind the surfaces clean of all scale, MIG/TIG/stick weld metal, and other crud. Once cleaned up, you can store them in the kero-tank, even if you will be dry welding later.
Next time you are in the forge, re-stack and weld up the billet again and repeat welding and drawing. It gets faster as you learn what to do.
7) FINAL TIP - In some way mark the billet or the handle. It can be a number or letter that corresponds to a note in your logbook. If you don't it is a guarantee that you will eventually pick up a billet of damascus and not remember what the steels were. Metal marking pens work well for this. A set of number stamps is also invaluable in the shop/forge. In the same way, mark both ends on both sides of every piece of steel in the shop. If you cut a piece off, re-mark the cut end immediately. If not, you will slowly collect a box of steel that you have no idea what it is ... ask me how I know this! Anyone who says they never mark their steel, and this has never happened, either has only one type of steel in his shop ... or is lying.



In a new thread, I'll explain the "hot cut-and-fold" technique of welding up a billet in one continuous session with never having to regrind it. It is all done by two people, using only hand tools and a propane forge, in one session that takes from one hour to two hours. It works on the "never let it get below red" principle.
At Bill Moran's hammer-in back around 2000, Jim Batson and I made a 30cm long 224-layer bar of random pattern damascus from seven 75mmX40mm bars in 60 minutes. We used only a 3#/1.5KG cross-pein hammer, box-jaw tongs, a wire brush, a hot cut hardie, a 25cm bar of L-6 and a 50cm bar of O-1 (both 6mm thick and 50mm wide). We tack welded the corners on a cheap stick welder first. Today, I would use 15N20 and 1084.
Click to expand...
That is indeed an above and beyond answer! The advice and the trouble to type it up is indeed appreciated.

(A small point in context, but we are full metric including the use of Celsius. So unless it is a South African blade custom I am not aware of, we are not using F. Not a problem though. My phone is a quick translate 🙃)
 
Your tip re the marking of the steel is a solid!! I have already fallen foul to that!:-o
 
Thanks for the update on South Africa being all metric now. I'll use metric for temperature from now on with you.
Out of curiosity, when did you change?
 
Stacy E. Apelt - Bladesmith said:
Thanks for the update on South Africa being all metric now. I'll use metric for temperature from now on with you.
Out of curiosity, when did you change?
Click to expand...
I was still at school, so that must have been 1970ish.
But doing it on paper does not change it in people's minds, so I would venture that for at least a decade after that it was still a mixed bag.

Only place I know where we are still very mixed up is in Tyre specification. A Tyre can for instance be 215/80/15 which would be a width of 215mm, 80% of width will be the "rubber radius" on top of the rim and the 15 would be a 15" rim.

Go figure ;))))
 
The US decided to go metric back in 1975. Because the act had the word "voluntary" in it ... it didn't happen. The president ordered it to happen in 1991 ... it still didn't happen. Technically, metric is the system the government authorizes as our system. You will hardly ever see a gas pump or grocery scale that reads in liters or grams, though.
Some people who do technical things learned it but probably 98% of Americans have no idea how many millimeters are in an inch or how many milliliters are in an ounce.
My quick math in my head uses 25mm=1" ; 30ml + 1oz. vol ; 28grams = 1 oz avdp. ; 31grams = 1 oz. troy

On a US game show recently, the question was "How many milliliters are in a liter" and no one got the right answer... sad!!!
 
The transition was enforced this side. No inch or combination metric/inch ruler or tape may have been sold at the time as example.

But I must admit it's easier to go one spanner size up in metric than imperial ;)

It's also easier now with mainly one system of bolts. With BSW, AN and metric all doing the rounds in the transition stage it was not always easy to just eyeball the right nut. Many times did I grab a 1/4 instead of the 6mm and visa versa.
 
Agreed, working on a car is confusing with most in the USA today having both metric and imperial parts.
 
What I find with Chinese parts is tolerance issues. Bolts and nuts that fit on things to assemble can range from super tight to stupid loose fitting.
When I order just nuts and bolts, they seem pretty close to specs, though.
 
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