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Doug Lester

Triple quenching

4 posts in this topic

I have read different opinions on triple quenching. I have read Ed Fowler's articles on it and he thinks it the thing to do to make a superior blade. Other people feel that not only is it unnecessary but that it can damange the steel. What have people who have actually tried this process found? I have kind of settled in on using 9260 and 5160 for blades and I might give L6 a try in the future.

 

Doug Lester

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If by triple quenching you mean to induce grain refinement into a piece of steel and thereby improve the material, before the final heat treatment, it's a good thing to do.

 

But, if that's the sole heat treatment regimen alone, then it remains a confusing process with no clear defined role in the improvement of the blade. It's being done, because someone said to do it, or your teacher did it that way. It's not done because you've thought this through for yourself, or tried experimenting with several of your favorite steels to see what works for you, given your shop tools.

 

Thermal cycling, multiple normalizing cycles, triple quenching are names for essentially the same process: grain refinement. The reason three keeps coming up all the time is that after about three cycles, there is no further benefit in grain reduction when compared to the amount of grain growth from a fourth heating cycle. However, there continues to be misapplication of the name of the process and continued misunderstanding of what the process actually provides the maker. Grain refinement can improve the heat treatment character of a blade. It can improve hardness to some degree, improve the toughness and fracture resistance of the steel, and provide a known starting point for a regular, consistent heat treatment regimen that will promote a consistent product.

 

Each steel has a temperature range that will respond better to this practice.

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Len Landrum and Ron Claiborne told me (and I have found it to be true in my own work) that it is best applied to 52100 and 5160. Dunno about other alloys. Their experiments produced a blade that, though proper forging, occasional grain refinement through thermal cycling, and the final triple-quench in hot oil, had grain so fine it didn't register on the normal chart and withstood a bend to 180 degrees without breaking. I myself have not tried this, but I do find the triple quench for those two steels produces a fine edge, and withstand a good standard flex test before finishing.

 

Good luck with it!

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Don't forget to include in this equation the HEAT SOURCE!

Ed is using a Oxy Acetylene set up and heating only the working portion of the blade with FLAME for NOT long soak times. Part of his process includes the gradual and repeated pulling of carbides into "solution" and three times helps achieve this.

If you are using an oven and can SOAK 5160 and 52100 for 20 minutes to pull all of the carbon and chromium loose prior to a good DUNK in the proper oil, a triple quench is not necessary.

Edited by kbaknife

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