Triple Quench Question

i4Marc

i4Marc

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Oct 19, 2011
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I know there are different schools of thought about triple quench vs. single quench. I don't want to start another Chevy vs. Ford type of thread. I am getting ready to HT a large bowie forged from 1075. I will be claying the blade for a hamon. Other clayed blades I've heat treated have been single quenched. I am CONSIDERING triple quenching this one but I'm not sure how that would work with the clay. It seems obvious that I would need to re-clay the blade after each quench. I can only attempt to make the same clay pattern each time but surely it won't be exactly the same. Will subsequent clay patterns that differ from the previous pass muddy the resulting hamon or will they add increasing layers of complexity to it? Has anyone here triple quenched with clay?
 
Sometimes you will see the results of previous clay layouts in the finished hamon, sometimes not. You will be more likely to get extra wierdness (sometimes utsuri-looking phenomena) if your clay is significantly different each time.

I have quenched the same blade up to four times, re-claying each time. Only because each time the hamon was not how I wanted it.

Watch out though for radically increasing downward sori with each quench, if you are using oil.

Here's a shot of a blade with four clay quenches.
DSC03209.JPG
 
Thanks Salem. I will be using Parks 50. In your experience would you say it is beneficial to attempt to match the previous clay patterns as closely as possible? And, knowing you would be doing multiple quenches, would you compensate for the possibility of increasing sori by keeping the ashi in the clay pattern abbreviated? Also, because I am still trying to remember all the metallurgy, can you remind me of the benefits of the multiple quench?
 
There really isn't any benefit to multiple quenches. There is a benefit to grain refinement cycling, but once at austentizing temperature, with everything in solution, you have basically erased the previous quench process. With lower temps (such as when trying to get a hamon) and thicker cross sections, you might not get everything into solution, which is where you will see remnants from previous quenches. There is a PDF book by Verhoeven that explains this well, and it is a free download. Its a heavy read, but covers everything we need related to knife steel metallurgy.
 
The only reason to do more than one quench on a clayed up blade is because the first attempt didn't get you what you wanted, just like Salem mentioned.


The downward curve is unavoidable with multiple, differentially hardening, oil quenches. I have gotten it so severe on NO CLAY blades that it ruined them. I turned a W2 Khuk into a boomerang with 3 quenches--- just trying to get the hamon right.

I very rarely say this---- Don't do it.


:)
 
OK, single quench it is. I just downloaded the Verhoeven pdf. Looks like I have some reading to do. The blade I'll be heat treating is 1075, forged as I mentioned earlier. 12" from tip to ricasso. 2" wide. 1/4" thick at the ricasso, 3/16" in the middle and 1/16" at the tip in a constant taper. It has already been normalized (1600˚, 1400˚, 1250˚). The blade will be clayed with high temp furnace cement. I was planning on austenitizing at 1465˚ with a 5 minute soak in an Evenheat oven. Quench would be in Parks 50 at ambient temperature, approximately 80˚F. With this information can you suggest a good HT recipe? Do I need to adjust any part of my process? How thick would you apply the clay for the most dramatic hamon?




 
That's a nice blade! :thumbup: I will default to others with more experience with 1075. I have only dome two blades and wasn't thrilled with my Hamons. I used 1475f with thin clay (lower carbon raises austentizing temp.) I tried 1450f and it didn't fully harden along the edge. I was thinking 1465 on my next one, but was going to ask for advice here first. Thicker cross sections of simple steels have difficulty through hardening, as do hypo euctoid steels and with a wedge shape as in a knife, martensite will form in the thinner sections (There's a diagram in the PDF on this) first. Beyond that theoretical bit, I have no experience with optimum temp with this steel. I got a great Hamon in 15N20 with 1465, but the nickel lowers the austentizing temp. :confused:
 
Hmmmmm. I typically austenitize my 1084 and 80CrV2 blades around 1485˚ but I thought that the lower carbon in 1075 might need a lower temp. I hope someone with 1075 experience will weigh in.
 
Stacy, any recommendations on time and temp based on the information I gave earlier?
 
zaph1 said:
What type of 1075 is it? What's the make-up of it? Manganese, chromium, nickel, all need to be known to get your optimum HT.
Click to expand...


From Aldo's website:

Chemistry/Certification
Certification: C- .760 Si- .240 Mn- .350 P- .0100 S-.0010 Annealed Structure: 92% spherodized carbides.
 
Ok Stacy. I have already normalized at 1600˚, 1400˚, 1250˚. What kind of Rc hardness can I expect @400˚? I checked Kevin's site but I didn't see any HT information for 1075.

Also, you don't subscribe to the practice of doing a third temper cycle to temper the untempered martensite formed in the second temper cycle?
 
Last edited:
Since you already did a 1200 cycle. Clay up, try 1500, then temper @400f. Increase temper temperature as needed.
 
Assuming full hardening in the quench - 400°F temper should give you Rc59. As Willie said, try 400° first and if it seems too chippy go to 425°F which should yield Rc58.

As I pointed out recently, the actual Rockwell reading on a knife isn't important....It is just a number.
It is the performance that matters. A well performing Rc58 blade is far better than a Rc61 blade that chips out in a few cuts and then stops cutting.
 
Sure, I agree with that. I'm not hung up on Rc numbers. Obviously performance is the goal. I just wanted a ballpark number for comparison. Thanks.
 
I am looking forward to my next 1075 knife now! Thanks everyone for contributing to the discussion.
 
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