# Hardening A2 Tool Steel



## jpfabricator (Oct 6, 2016)

So I bought a piece of .750" A2 tool steel on Ebay to try making a few cutters.
The best I can gather from the WWW is that a blast of shop air is the "quenching" process.
I don't have a heat treat oven, or pyrometers, just a cobbled together gas forge.
If anyone has any advice, I'm all ears.
Thank you.

Sent from somwhere in east Texas by Jake!


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## Uglydog (Oct 6, 2016)

Attached is an excerpt from the 28th MH.
You may find parts helpful.
I worked with A2 this summer. But, then I have an oven (permanent loan). 
I look forward to the responses  others! 

Daryl
MN


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## ex_isp (Oct 7, 2016)

The "A" series of steels normally harden in still air.  Blasts of air have to potential for cooling one side faster then the other.  This particularly becomes and issue
with thinner sections of steel.  Your work piece is thicker and may not be affected by moving air, though atmospheric air has oxygen that can de-carburize the surface,
leaving a softer "skin".  May recommend still air quench in replaced atmosphere like nitrogen.  See here:
http://www.hudsontoolsteel.com/technical-data/steelA2


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## Baithog (Oct 9, 2016)

I couldn't get the file Daryl posted to open.

It has been a long time since I made anything out of A2. As I remember, hardening A2 in small sections is pretty easy. Heat with a torch using a reducing flame to the right color. Hold to equalize and let it cool. The darned stuff hardens real nice. I wouldn't blow air on it for fear it would warp. The real tricky thing with A2 is you have to be sure you don't need to do any more machine operations. Annealing the stuff is nearly impossible without a proper furnace.

Larry


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## Billh50 (Oct 9, 2016)

All of the A2 I have heat treated through the years has been in a furnace. And then it was put in either a stainless steel bag or packed in cast iron chips to reduce the oxygen. Then left out to cool on it's own. Then put back into the oven for annealing to hardness wanted according to specs.


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## ex_isp (Oct 9, 2016)

I could not get that file to open either.  I get the specific message "The file is damaged".
Tried it 3 times to ensure it wasn't corrupted in download.


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## doc55 (Oct 9, 2016)

The process for A-2 is heated in controlled atmosphere thus the stainless wrap is used to make a bag and place a small piece of paper in bag with part being hardened it will ignite in bad and burn up the oxygen in bag. If you don't it will decarb and will scale up bad. I've worked in a tooling shop for many years and have done A-2 a lot. If I remember correctly temp should be 1775 for 1 hour per inch of cross section. Then remove from heat remove bag and let it cool without any air movement on it. It should come out 62 to 65 Rc the draw back temps I don't remember. The shop I work at we use A-2 for blank and pierce die's which I have made many of. I do have the temps in a book if you can't round them up on the net.


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## Uglydog (Oct 9, 2016)

That's what I've read!
Would it be enough to turn off the oven and open the door in a shop without air movement?
Or wouldn't that be fast enough?

Daryl
MN


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## doc55 (Oct 9, 2016)

Best to remove from oven we usually put it on a movable rack and just let cool to room temp. Not sure if the oven would cool fast enough it would almost be like normalizing if cooled to slow but you don't want to turn a fan on it or blow air on it while cooling just let it set and cool at room temp.


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