Normalization process

[Grandpa Jon]

I'm still new to this game and looking to ensure that I will have the results I'm looking for. As I understand the normalizing process, it's an annealing process applied to ferrous metals/alloys heating the steel to 20–50 °C (68-122 oF) above its upper critical point, then soaking it for a short period at that temperature and then allowing it to cool in air. NJSB suggests that the normalization for 80CRV2 follows a 3 cycle heat differential process prior to the hardening/quenching stage. The first cycle indicates a working temp of 1650F for 10-15 minutes (duration reflecting blade thickness). My question is, do I take a blade to 1687F soak for 2-3 minutes and allow to completely air cool then proceed with the prescribed 3 times/temps from NJSB?

 

[Rick Marchand]

What protocol you use for normalizing really depends on the state of the steel you are working with. Did you perform any forging operations? Was the steel heavily spheroidized? Do you actually know what the current internal structure is?

The purpose of normalizing is to relax the steel by breaking up unwanted carbides and making the grain structure uniform. This can be very critical if you forge your material or use bar stock that has been overly annealled or highly spheroidized. Having temperature control makes is easier. There are instances when you need to go even higher(1900F) to break up stubborn carbides. I tend to treat every piece of steel as if it is in horrible shape to begin with. Normalize high(1700F) followed by a 1500F quench and a couple sub-critical anneal cycles. The resulting internal structure is highly tempered martensite. This is the structure I prefer, prior to the final hardening.

Forge
1700F, cool to magnetic
1500F, oil quench
1250F-1300F(dull red, still magnetic), 2 cycles
Cold Work(grind, drill, file, etc...)
1475F-1500F, 5 minute soak, oil quench
Temper

Soak times and temperatures do vary a bit between steels. I am only addressing simple carbon steel, here.... stainless is a different animal.

 

[Grandpa Jon]

What protocol you use for normalizing really depends on the state of the steel you are working with. Did you perform any forging operations? Was the steel heavily spheroidized? Do you actually know what the current internal structure is?

The purpose of normalizing is to relax the steel by breaking up unwanted carbides and making the grain structure uniform. This can be very critical if you forge your material or use bar stock that has been overly annealled or highly spheroidized. Having temperature control makes is easier. There are instances when you need to go even higher(1900F) to break up stubborn carbides. I tend to treat every piece of steel as if it is in horrible shape to begin with. Normalize high(1700F) followed by a 1500F quench and a couple sub-critical anneal cycles. The resulting internal structure is highly tempered martensite. This is the structure I prefer, prior to the final hardening.

Forge
1700F, cool to magnetic
1500F, oil quench
1250F-1300F(dull red, still magnetic), 2 cycles
Cold Work(grind, drill, file, etc...)
1475F-1500F, 5 minute soak, oil quench
Temper

Soak times and temperatures do vary a bit between steels. I am only addressing simple carbon steel, here.... stainless is a different animal.

Thnx Rick for your intel.....

 

[Stacy E. Apelt - Bladesmith]

Rick has a good protocol. I'll elaborate on it a bit.

Normalizing is a process usually done after forging to make the structures uniform and in a condition that is good for final hardening.
In highly spheroidized steels, it is needed to make the steel structure capable of hardening later on. It is not usually needed until you are ready to do the final hardening, as the purpose of spheroidized steel is to make machining and cold work easier.

Annealing is a slightly different process used to soften steel to allow cold working and machining.

This is a post I made recently on the subject:

The best normalizing procedure for fully spheroidized steel will be:
Heat to 1650°F/900°C and hold for 15-20 minutes - cool to black
Heat to 1550°F/840°F and hold for 10-15 minutes - cool to black
Heat to 1450°F/790°C and hold for 10-15 minutes - Quench in Parks #50 or equivalent
Cool to room temperature (caution, the steel is very brittle at this time)

At this point the steel will be fine grain and ready for you to do your final HT at the exact target temperature for the steel.
If you are going to more cold work the steel (drilling, sawing, grinding, etc.) then do a sub-critical anneal like Rick suggested by holding for about 20-30 minutes at 1250°F/675°C.

You can read the whole explanation here: https://www.bladeforums.com/threads/njsb-w2-and-52100-heat-treat.1897945/