Want to normalize?

J

jtwodogs

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Feb 1, 2009
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I was reading in the "Stickies" about Normalizing to prevent warpage when heat treating via Bladsmith.
Since my set up is rather simple, and I will be using 1084 and a simple magnet test to determine when to quench is there a color I can look for in the metal when it reaches 1200 before I heat treat for normalizing the metal?
When 1200 is reached it also explained that I needed to let soak for 10 mins., is this possible in a simple coal/wood forge?
 
Please use either a F or C following temperature since this is an international forum.
Are you sure you have your definitions correct ?
There is a stress relief/ subcritical anneal at 1200 F used to take out stress , turn martensite or pearlite into spheroidized carbides .No significant scale will form or decarb at this temperature.
Normalize - heating above critical and air cool .
An infrared thermometer or perhaps temperature sticks [crayons] might be used.
 
Get a color chart vs temperature for steel off of the net. Take your steel to just non magnetic and note the color on the chart. This is your visual calibration. Slowly cool until the color indicates about a 200 - 250F drop from your calibration color. Try as best you can to hold at that color. The color you see might be different than the color on the chart so assume non magnetic is 1425F. Don't get frustrated, it isn't as easy as it sounds. Also, a muffle pipe might make things a little easier.
 
I apologize. I did use the wrong term.
Here is the excerpt I was speaking of.
) Stress relieve the steel before Heat Treatment. (Actually, stress relief is part of heat treatment).
There are several methods of cycling steel to get a fine grain and evenly distributed carbides, but simple methods will also relieve stress.
Sub-critical annealing is the simplest. Heat the steel to 1200°F and hold for two hours. Cool at 100° per hour to 800°F and then quench (or let air cool) to room temp.
For any steel, stainless, hypo, or hyper eutectoid...it will remove any stresses in the steel.

Thanks Bo T for the helpful info. I appreciate you helping a newbie
 
You are going to play hell doing that with a forge. Your 10 minute soak will be tough enough. An oven is needed for that level of temperature control.
 
Thats what I was thinking. I may just go with the annealed 1084 that Aldos offers, grind and then do the heat treat, and hope it does not warp.
 
You can get good results with a simple forge as long as it will evenly heat the blade.

Simplest basic softening - Heat to a bit hotter than non-magnetic ( most steel has a curie point around 1414F, so heat to about 1450-1500F) and hold for a minute or two. Let cool in air until it turns black (900F) and then water quench. Repeat a time or two if desired. This works very with simple carbon steels. 5160, O-1, and 52100 will work fairly well this way. More complex steels will require better equipment and processes.

Best Grindability - Heat to 1200-1250F and hold for any period you can that won't go above 1400F. After at least a few minutes ( 10 minutes is great, but hard in a non-controlled forge), let air cool to black and water quench. Most any steel will form spheroidized carbides this way.

Best overall - Oven heat to 1200F for two to ten hours and then cool to black,... water quench. The cooling rate is steel dependent, and can be anything from air cooling for simple carbon steel to a rate of 25F/Hr for complex stainless.




Tip and nerd info,
A way to know what color sub-critical temp looks like is to heat the steel about 100F above non-magnetic and then let it cool down in still air..... watch it closely...... At the descending/cooling transformation point, it will suddenly increase a bit in brightness ( called recalescence...or the shadow dance) and become magnetic again.

The descending transformation of phase temperature is called the Ar ( Arcm, Ar1, Ar3). The "r" is for refroidissant, which means cooling in French. this happens at about 1200-1250F for most steels.
Note that it is around 200F lower than the non-magnetic point (curie point) on increasing/climbing heat, called the Ac ( Ac1, Accm, Ac3) - the "c" is for "chauffant", which is French for "heating".
 
bladsmth said:
You can get good results with a simple forge as long as it will evenly heat the blade.

Simplest basic softening - Heat to a bit hotter than non-magnetic ( most steel has a curie point around 1414F, so heat to about 1450-1500F) and hold for a minute or two. Let cool in air until it turns black (900F) and then water quench. Repeat a time or two if desired. This works very with simple carbon steels. 5160, O-1, and 52100 will work fairly well this way. More complex steels will require better equipment and processes.

Best Grindability - Heat to 1200-1250F and hold for any period you can that won't go above 1400F. After at least a few minutes ( 10 minutes is great, but hard in a non-controlled forge), let air cool to black and water quench. Most any steel will form spheroidized carbides this way.

Best overall - Oven heat to 1200F for two to ten hours and then cool to black,... water quench. The cooling rate is steel dependent, and can be anything from air cooling for simple carbon steel to a rate of 25F/Hr for complex stainless.




Tip and nerd info,
A way to know what color sub-critical temp looks like is to heat the steel about 100F above non-magnetic and then let it cool down in still air..... watch it closely...... At the descending/cooling transformation point, it will suddenly increase a bit in brightness ( called recalescence...or the shadow dance) and become magnetic again.

The descending transformation of phase temperature is called the Ar ( Arcm, Ar1, Ar3). The "r" is for refroidissant, which means cooling in French. this happens at about 1200-1250F for most steels.
Note that it is around 200F lower than the non-magnetic point (curie point) on increasing/climbing heat, called the Ac ( Ac1, Accm, Ac3) - the "c" is for "chauffant", which is French for "heating".
Click to expand...

There is a video of that in the Youtube video sticky thread
 
It likely goes without saying, but when using color to tell temp, use dim lighting. Bright lighting, especially direct sunlight will make it extremely difficult to see what color you actually have.

Chris
 
Yes, indeed.

I try and do any HT where I am using color judgment by eye at night. I have a 75 watt light that is behind me as the only light on in the smithy when doing HT that way. If doing it during the day, do it in full shade, preferably on a cloudy day. Direct sunlight will make your color judgment off by as much as several hundred degrees. This can be disastrous in HT.

I have a funny habit of doing sword HT during thunderstorms....I even did one during a hurricane.
 
I'm under the smithy roof....so it's OK :)

If the wind is blowing hard from the east the rain will blow through, though.
 
32 years working outside and 6 Unusually close lighting strikes, one so close I felt the static charge just leaning on a garage door frame of the partially finished house we ran into for cover, when the weather man says lightening I run inside like a little girl ;0)
 
Here's what the inside of Aldo's 1084 looks like after three rounds of normalization(1550, 1550, 1500; quenched at 1525):

Top piece is part of a Nicholson file, bottom pieces are both halves of the 1084

tcAcJ2o.jpg


I do not hold at temp for any length of time. Air cool to black between cycles. I use a simple gas forge with a cheap ebay pyrometer/multimeter(with k type thermocouple input) setup. I quench in canola oil.
 
I mostly agree with Stacy except that there is no need to water quench after "black" if you intend to do another normalizing cycle. Once the steel becomes magnetic again, you are good to heat it back up for the next cycle. Only after you are done the LAST cycle would a water quench after black be needed(to avoid coarse pearlite and other unwanted precipitations).... unless you oil quench from the last heat to achieve a fully martensitic structure from which to spheroidize(Which I do).
 
You are correct, Rick.
I give the full procedure for each step because it gets half-read and mis-quoted on the internet so often. I can just see someone saying, "Rick says you don't need to quench in water."
 
True... very true. I try to word that as carefully as I can. Your explanation is much safer. You only stand to save a bit of time by not quenching before ramping back up. However, you DO risk getting a less than optimal structure if you don't quench on the final cycle.
 
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