Tempering Question

[Alex Topfer]

Maybe test quenching a coupon in warm water? The 3/16ths one could be getting to the limits of W2 in Parks 50. Probably not something you want to get into for blades, but will be a useful data point

 

[ScarFoot]

Maybe test quenching a coupon in warm water? The 3/16ths one could be getting to the limits of W2 in Parks 50. Probably not something you want to get into for blades, but will be a useful data point

I wondered about this. I do pre-grind my blades so I feel like with a big part of the cross section removed I’m close where I’m at but it’s just a little off for my liking. How warm would you recommend the water be?

 

[Alex Topfer]

I shoot for about 50-60c for the bioquench I use
Unless you're planning to start water quenching i don't think it matters that much. The point is to get a data point in a faster quenchant, not refine a water quenching process.
I also agree it wouldn't matter for an actual knife, if the edge is about a millimeter (1/24th) the you'll be close to the spine by the time it's 3/16ths / 4.5mm

 

[tattooedfreak]

Why not put them in the freezer until they are all ready for tempering? Aside from 52100, the majority of non-stainless carbon steels can benefit from a cryo/sub-zero/freeze period. leave them for an hour or so while your oven comes to temp. You can also use a tray of sand which will hold temp better than ambient air.

 

[Larrin]

The 3/16” looks like it didn’t harden

 

[ScarFoot]

The 3/16” looks like it didn’t harden

It didn’t. I ran it again at 1465 but soaked for 20 minutes and quenched one piece in water and the rest in Parks 50. Each broke cleanly and the grain looked good in both. My guess is 10 minutes just wasn’t a long enough soak on the first round. I’ll try to post pictures from the second run before the weekend is over.

 

[ScarFoot]

I intended to follow up with results sooner but illness ran rampant through my house last week so I’ve been behind. Everyone is better now so that’s good. Anyway below are a few more pics under 250x magnification. The water quenched 3/16 looks the best by far. The parks 50 quench looked okay but the grain was a little larger than the water quenched piece. To the naked eye they both looked good but the water quenched piece was significantly better under magnification. Since I pre-grind my blanks and the thinner pieces looked good I felt comfortable quenching them in Parks 50. I was concerned water quenching might be a bit too abrupt with the grinds mostly finished. If I hadn’t pre-ground them I’d probably water quench the 3/16” stuff.
The pieces I tempered at 405F came out in the 60-61 HRc range. The pieces I tempered at 375F came out in the 61-62 HRc range. Untempered I was getting around 65 HRc.
W2 3/16” thick held at 1465F for 20 minutes and water quenched:

W2 3/16” thick held at 1465F for 20 minutes and quenched in Parks 50: