Re heat treating high alloy?

[shqxk]

I got 59HRC with RWL-34 and want to re-hardening it to 61-62HRC. Does it really necessary to do full annealing before HT it gain? What will be the problem if I do re-heat treating with out annealing?

 

[HSC ///]

Following this, I’ve wanted to know this answer as well

 

[Natlek]

Let's see if I've learned anything all these years hanging at BF .
No , you don t need to do full annealing , just do new HT protocol .........

 

[Stacy E. Apelt - Bladesmith]

Correct.

 

[shqxk]

Let's see if I've learned anything all these years hanging at BF .
No , you don t need to do full annealing , just do new HT protocol .........

Would be great to do so. But I have seen somewhere about duplex grain you might got from multiple quenching high alloy? May be it would be nice if Larrin or @DevinT might chime in.

 

[Ken H>]

Darn, I've spent the last hr looking for the source of my note on need to anneal AEB-L before re-HT'ing but can't find it. Somewhere I got the idea of the following from either Hoss or Larrin (I think anyway).
"To anneal AEB-L wrap blades in foil, soak at 1350⁰F for 12 hours – does not require slow cooling. This is a very good condition to re-harden from. This is a simple sub-critical anneal to allow straightening before re-heat treating in cases of warpage. Once the sub-critical anneal is complete, ramp oven to 1725F, then place blade in oven for 20 minute soak. Remove blade, clamp in quench plates to cool, ramp oven to 1975F for final HT. "

I hope Hoss or Larrin will chime in to comment if there is really any need to anneal before re-HT'ing a high alloy steel, or AEB-L.

Ken H>

 

[Stacy E. Apelt - Bladesmith]

I could be wrong, but with RWL-34 being a powder metallurgy steel, It should re-heat treat OK. Larrin? any thoughts?

 

[Larrin]

With high alloy steels I prefer to re-anneal first.

 

[Ken H>]

With high alloy steels I prefer to re-anneal first.

I was pretty sure that's what I'd read you saying. Larrin, could you elaborate a bit - advantages of re-annealing vs possible problems of simply doing the normal 1725°F pre-quench, then 1975°F Quench?

 

[Larrin]

When you dissolve a bunch of carbide to heat treat the first time then those carbides aren't there to pin the grain boundaries any more.

 

[Stacy E. Apelt - Bladesmith]

There you go folks. An answer from the expert. - Thanks Larrin.

Larrin, I didn't know id the particle metallurgy somewhat eliminated the issue of carbide distribution and grain boundaries.

 

[Larrin]

The smallest carbides are dissolved first which typically have the highest density for pinning grain boundaries. Depending on the specific steel and austenitizing temperature it may not lead to excessive grain growth. But the hardening response will also be different the second time. So just simplify everything and ensure good properties by annealing.

 

[Stacy E. Apelt - Bladesmith]

Thanks. Always good to learn things.

 

[A.McPherson]

Larrin are you talking a full anneal, or sub-critical?

 

[Larrin]

Larrin are you talking a full anneal, or sub-critical?

Different paths to the same result, generally speaking.

 

[A.McPherson]

Cool, just curious. Thanks!

 

[JTknives]

I have found that if a blade produces lower then expected hardness a second heat treat at the same temp will bring the hardness back up to what’s expected. This is if your using the corect temps for that steel. Every once in a blue moon an alloy will show low hardness with the proper heat treat.

 

[shqxk]

I have found that if a blade produces lower then expected hardness a second heat treat at the same temp will bring the hardness back up to what’s expected. This is if your using the corect temps for that steel. Every once in a blue moon an alloy will show low hardness with the proper heat treat.

Great to know! do you prefer full annealing or sub-critical when re-HTing high alloy?

 

[Storm W]

With high alloy steels I prefer to re-anneal first.

I have a Benchmade pocket knife that I like but they did an awful job on the M4 and I think my AEB-L holds a better edge. What is the best way to handle a high speed steel? Is there anything more complicated?

 

[samuraistuart]

I think you have a couple options. Crucible's data sheet for annealing M4: Heat to 1600°F, hold 2 hours, then down to 1000°F at 30° an hour. This is quite a bit of time.
Larrin mentions the temper anneal for higher alloy steels, and is a lot faster. Heat to 1650°F, hold 1 hour, quench with plates, then temper at 1450°F for 2 hours.