Anyone heat treating A8 Mod?

S

Scaniaman

Joined
Jun 15, 2012
Messages
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Hi,

I have a project coming up, a larger outdoor knife, and I thought I'd give A8 Mod a try.

What are your experiences heat treating it? I actually read in a couple of places that pre heating it was a good thing even for the thin stuff we use.

Any general or specific advise on working with this steel?

I use an electronically controlled kiln.
 
Which A8 Mod do you have? There is a version being sold by AKS as "A8 Mod" which has 5% Cr but traditionally it is 8% Cr steel which is called A8 Mod. In heat treating of the normal 8% Cr version I used 1900°F for 30 minutes, plate quench, cryo, and tempered twice at 400°F. That gave about 59 Rc and high toughness. I did not use a preheat.
 
Larrin said:
Which A8 Mod do you have? There is a version being sold by AKS as "A8 Mod" which has 5% Cr but traditionally it is 8% Cr steel which is called A8 Mod. In heat treating of the normal 8% Cr version I used 1900°F for 30 minutes, plate quench, cryo, and tempered twice at 400°F. That gave about 59 Rc and high toughness. I did not use a preheat.
Click to expand...

Thanks. I was thinking 1900F/1040C and 350-400F/175-200C temper 2x2 hrs, but was unsure about the pre heat so thanks for your reply. I don't have cryo, but use a -40C freezer. I'll run a few coupons first to dial things in.

It is the 8% Cr one, I am getting it here:

https://www.nordisches-handwerk.de/...chen/stahl-nicht-rostfrei/1.2360-x50crmov8-1/
 
Larrin said:
Which A8 Mod do you have? There is a version being sold by AKS as "A8 Mod" which has 5% Cr but traditionally it is 8% Cr steel which is called A8 Mod. In heat treating of the normal 8% Cr version I used 1900°F for 30 minutes, plate quench, cryo, and tempered twice at 400°F. That gave about 59 Rc and high toughness. I did not use a preheat.
Click to expand...

I ran two coupons 4.4 mm thickness. One got aust temp 1030 C (1886 F) and the other 1038 C (1900 F), no pre-heat. Both soaked for 30 min--> plate quench and freeze -41 C (-42 F) x1 hr. Then 1x2 hrs temper at 170 C (338 F).

I checked my hardness tester with a calibration block and then tested each coupon 8 times.

1030 C coupon: average 60.5 Hrc

1038 C coupon: average 55 Hrc

I am a little surprised by both the values and their difference. I'm gonna go with 1030 C of course, but up the temper a little maybe.
 
That sounds like a crazy difference for 8° C difference. Could there have been a slight decarb or sth else?
 
We can think up a bunch of things you might check. Or you could just do it over again. You messed up somewhere.
 
Larrin said:
Which A8 Mod do you have? There is a version being sold by AKS as "A8 Mod" which has 5% Cr but traditionally it is 8% Cr steel which is called A8 Mod. In heat treating of the normal 8% Cr version I used 1900°F for 30 minutes, plate quench, cryo, and tempered twice at 400°F. That gave about 59 Rc and high toughness. I did not use a preheat.
Click to expand...
Hi Larrin, are you tool wrapping your A8MOD?

Been doing some experimentation with it and was finding I could get a higher hardness when tool wrapped? Interested in your thoughts.

Thanks a lot, Francis
 
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