Rockwell Hardness Question

Outdoor Gear Dad

Outdoor Gear Dad

Joined
Jun 1, 2019
Messages
211
I recently got a PHR-1 and am trying to learn how to use it. I have read through everything and got it down. I did a couple tests on the testing samples, and it was more or less accurate....I tested a couple of my blades and they were where they should be.

I am in the middle of rehandling a blade from a better known maker, and I tested the tang, and its like a 24 HRC. Granted this is on the tang but its S35VN so I would imagine the entire blade would have been treated....Any reason why this blade is giving me such a low read?
 
Possible the decarb wasn't ground through on the tang, because totally unnecessary.
 
S35vn should have no or little decarb, test on the blade. maybe a missed h/t.
 
Make sure the indenter and anvil are screwed all the way in. You will get low readings if they are loose. Rc24 is the annealed hardness.
 
daizee said:
Possible the decarb wasn't ground through on the tang, because totally unnecessary.
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How much do you have to grind toT
Willie71 said:
Make sure the indenter and anvil are screwed all the way in. You will get low readings if they are loose. Rc24 is the annealed hardness.
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hey are screwed in all the way, and right before I am testing them, I am testing on a calibrated block and getting a +/- 1.
 
Outdoor Gear Dad said:
How much do you have to grind toT

hey are screwed in all the way, and right before I am testing them, I am testing on a calibrated block and getting a +/- 1.
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Just something to check, that I found out by accident. Probably a mislabeled steel or bad heat treat.
 
Try the brass rod test on the edge to see if it deforms. That's the least destructive test I can think of. Next would be a needle file on the edge but it will have to be sharpened out if it is soft or chips. Then again if the blade is soft it's useless anyways.

If if wasn't heat treated wouldnt the customer have noticed if it's in for a rehandle?
 
Willie71 said:
Just something to check, that I found out by accident. Probably a mislabeled steel or bad heat treat.
Click to expand...

Larrin said:
If the tang is beveled that could also affect the reading. Flat is best.
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scott kozub said:
Try the brass rod test on the edge to see if it deforms. That's the least destructive test I can think of. Next would be a needle file on the edge but it will have to be sharpened out if it is soft or chips. Then again if the blade is soft it's useless anyways.

If if wasn't heat treated wouldnt the customer have noticed if it's in for a rehandle?
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After speaking with the maker he says he only HT the blade with a special forge....I haven’t been making knives long enough to cast an opinion, but it would seem to me that S35VN would be a steel you would want to wrap and HT in a kiln. Seems like there are certain variables that could really effect the performance if done wrong. Am I in the wrong for assuming that?
 
Ask the maker for his whole heat treat regimen, if it doesn't involve a kiln and specific temperature and time then there is most likely the problem.
S35vn requires pretty specific temperature and time to properly harden.
 
Outdoor Gear Dad said:
After speaking with the maker he says he only HT the blade with a special forge....I haven’t been making knives long enough to cast an opinion, but it would seem to me that S35VN would be a steel you would want to wrap and HT in a kiln. Seems like there are certain variables that could really effect the performance if done wrong. Am I in the wrong for assuming that?
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Heat treat involves holding the exact temp for 30-45 min, wrapped in foil. Typically 1950f-1975f depending on hardness desired. Cryo or sub zero, then two tempers.
 
Outdoor Gear Dad said:
After speaking with the maker he says he only HT the blade with a special forge....I haven’t been making knives long enough to cast an opinion, but it would seem to me that S35VN would be a steel you would want to wrap and HT in a kiln. Seems like there are certain variables that could really effect the performance if done wrong. Am I in the wrong for assuming that?
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Sounds like he might be using an electric induction heater/forge allowing only the blade to be inserted inside heating portion with tang left outside. There could be N2/argon purge in forge so wrapping in SS foil wouldn't be required. Is there a flat spot on blade you could test? The small dimple left from testing is a mark of assurance, not a screwup {g}.

Since this is a rehandling job, has the knife been used a good bit? How did edge hold up? Good? Then it's most likely ok. As mentioned the brass rod test is good to try.
 
Ken H> said:
Sounds like he might be using an electric induction heater/forge allowing only the blade to be inserted inside heating portion with tang left outside. There could be N2/argon purge in forge so wrapping in SS foil wouldn't be required. Is there a flat spot on blade you could test? The small dimple left from testing is a mark of assurance, not a screwup {g}.

Since this is a rehandling job, has the knife been used a good bit? How did edge hold up? Good? Then it's most likely ok. As mentioned the brass rod test is good to try.
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I at first tested the tang....And got an annealed reading of 24HRC. So I started researching....I assumed that even if the blade was getting the heat, that the tang would heat up enough to the point that it wouldn't be giving an annealed reading. So then I asked the customer if I could to the blade...I did the flat spot on the blade and the grind (flat grind), both in the 40s. So I moved up towards the tip of the knife. That was at 50. The knifes edge was able to roll on a softer piece of aluminum....granted I was whacking the aluminum.
 
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Talked to the maker, he explained the process, and I realized I was testing wrong....go figure. New guy mistake. Thanks for all the commentary.
 
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