Is slightly overheating either blade or quench oil a problem?

weo

weo

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Sep 21, 2014
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Hello all. I just heat treated 4 kitchen knives (currently in the tempering process) and wondering about the above. 3 were 15N20 and one was O1/!5N20.

My equipment is a gas forge with ribbon burner, 5 gal bucket of Parks 50 (heated with a chink of steel that I heated n the forge to try to get it up to 130-ish.

The Parks 50 was about 110F for the first blade then got up to ~ 160-170F by the time I got the second blade in. The O1 was probably closer to a brighter orange instead of a dull orange.

I was planning on trying to sell these at the county fair where I'll be demonstrating blacksmithing for the public next week

Thanks
~billyO
 
How much oil do you have, 170° is rather hot for any oil. Parks 50 should NOT be heated, it's designed to be used at normal ambient tempatures. The only time I heat mine is in the winter when its really cold and I only heat it to 70°.
 
To answer your other question, overheating the O1 probably made the grain too large. You could thermal cycle it in descending heats then quench it again. That will reduce the grain size for you.
 
Thank you for the replies, all.

For some reason, I thought I remembered reading that Parks 50 should be heated to ~130F
New info noted.
Again, thanks.
 
Slightly OT, but do you need to heat AAA or is similar to #50 and just use it at room temp? I just put in an order with Maxim and got 5 gallons of each and would rather not mess either up.
 
AAA I've read wants a preheat. I have not used to verify. Parks is more $ and in more quantity than my hobby needs at the moment, so I did research on alternative options. Basically I wanted something that I didn't have to preheat like my canola oil. Research turned up Parks is about the only thing it seems that doesn't require a preheat, so I've just stuck with canola for now.
 
As said, parks #50 is used at room temp. Quenching in 130° #50 would reduce the quench speed. Some steels would not properly harden. I can't imagine why 5 gallons of oil would rise 60° with only four blades being quenched.

The good news is that O-1 and 15N20 have a much slower cooling curve, and would clear the pearlite nose in the warm #50. I can't say what it would do to the final hardness, but I suspect it will be lower.

Overheating a blade a little ( less than 20°) will make a slight change in the as-quenched hardness, but it won't ruin things. Overheating the blade by 50-100° will make for a poor quench result. Grain will be off and hardness will be unsuitable.
 
You need to heat AAA for it to preform as it is designed. Parks 50 was designed to be used at room temp.
 
Stacy E. Apelt - Bladesmith said:
As said, parks #50 is used at room temp. Quenching in 130° #50 would reduce the quench speed. Some steels would not properly harden. I can't imagine why 5 gallons of oil would rise 60° with only four blades being quenched.

The good news is that O-1 and 15N20 have a much slower cooling curve, and would clear the pearlite nose in the warm #50. I can't say what it would do to the final hardness, but I suspect it will be lower.

Overheating a blade a little ( less than 20°) will make a slight change in the as-quenched hardness, but it won't ruin things. Overheating the blade by 50-100° will make for a poor quench result. Grain will be off and hardness will be unsuitable.
Click to expand...


15n20 will work fine slightly overheated in a medium speed oil quench. It performs much better than expected with tight temp control in fast oil. It will give you more than one would normally expect from the chemistry, much like aeb-l will.
 
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