Heat Treatment - Crystal Weaving Foundation

Cool thanks jpm2.

18dps has about 72.8% (36/30)^3 more volume strength than 15dps, that is why I used 15dps to get some sort of damage. What is dps & behind edge thickness on your T42? I will find a thicker can and try open(w/o pull the blade out, just steer around until 95% cut) with this s110v. Also maybe tilt blade points inward to avoid the rim.
 
You put me to work with those questions. :eek:
Had to clamp it in the lansky, hold clamp in vice, measure level of clamp, use sharpie on edge, change angles of stone till it wiped the edge, then measure stone relative to clamp.
Flip clamp in vice and do it again.
What I came up with is 14 on one side, 17 the other.
Freehand I've always known the stroke going away from me was lower angle than towards me. Never figured out why I do that.
Best I can measure, with tape and caliper, blade thickness is about .021" @ 1mm from the edge where can was cut.
Does the edge thickness really matter if the damage doesn't get close to the primary/secondary line? (stays within the sharpening angle)
________________
 
More wedge = less stress on apex. Wider angle has larger affect than thicker bevel shoulder and upper part.

jpm2 said:
You put me to work with those questions. :eek:
Had to clamp it in the lansky, hold clamp in vice, measure level of clamp, use sharpie on edge, change angles of stone till it wiped the edge, then measure stone relative to clamp.
Flip clamp in vice and do it again.
What I came up with is 14 on one side, 17 the other.
Freehand I've always known the stroke going away from me was lower angle than towards me. Never figured out why I do that.
Best I can measure, with tape and caliper, blade thickness is about .021" @ 1mm from the edge where can was cut.
Does the edge thickness really matter if the damage doesn't get close to the primary/secondary line? (stays within the sharpening angle)
Click to expand...

Found a slightly thicker can and steer cut/saw w/o taking the blade out (hence just 1 entry punch into bottom lid). I did heard 'click, click' at one of the turn/steer.
Rsskric.jpg


btw - your blade cross section at 0.023" up v-calculated out to ~0.0124" thick
 
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Not bad, looks similar to maxamet edge. It should hold up a lot better at 18 dps.

My little t42 blade is only .5" tall max, and about .4" where it cuts. Thickness is ~.075". Probably steers easier with less stress on edge. I've cut a lot of cans open with that blade when it wasn't convenient to find a proper opener . :)
 
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Good observation - true, a narrow blade can steer/turn more easily than wider blade. Similar to width of bandsaw blade. Oh, what is hrc of that t42?

jpm2 said:
Not bad, looks similar to maxamet edge. It should hold up a lot better at 18 dps.

My little t42 blade is only .5" tall max, and about .4" where it cuts. Thickness is ~.075". Probably steers easier with less stress on edge. I've cut a lot of cans open with that blade when it wasn't convenient to find a proper opener . :)
Click to expand...

I recalibrated my tester. S110v blade is 66-66.25rc.

Rex121 blade, 72rc (avg of 10 reads) ht 2.5. 15dps 600 grit diamond.
Crude tests: Passed(no visible damages) - whittle African Blackwood, dried beef rib bone, 16d nail. Opened same can as above (14 oz curry), plenty of visible chips - about 50%(estimate using 22x loupe) taller & wider than s110v chips above.
 
Don't know the hardness, but seems to be similar to my n5 maxamet, guessing high 60's. Both will easily scratch glass. It's stock removal from an early 80's parting tool.

Opening cans is a good indication what might happen to my knife at work, it's what inspired the t42.
My methods are crude. I just go by what happens with use, in ways most people can't relate. :)
 
Thanks. T42 chem composition (http://zknives.com/knives/steels/t42.shtml) could/would be better than m4/vanadis4e/4v/xwear for hot+cold works - high stress working matrix. You sure have good instinct on picking great tool steels for strong & tough & keen knives :thumbsup: Now, where in the heck, would I able to get a few 3-6mm thick bars of this steel :cool:

jpm2 said:
Don't know the hardness, but seems to be similar to my n5 maxamet, guessing high 60's. Both will easily scratch glass. It's stock removal from an early 80's parting tool.

Opening cans is a good indication what might happen to my knife at work, it's what inspired the t42.
My methods are crude. I just go by what happens with use, in ways most people can't relate. :)
Click to expand...
 
Sorry but I've never seen t42 mentioned except in parting tools.
Other names and equivalents might be HSS 3X, HSS EC500, HS10-4-3-10, SKH-57, BT42, 1.3207.

It was more than 30 years ago I ask a machinest why knives weren't made from steel like he was using to cut that hardened steel shaft in his lathe. He went to his box, got out a small flat piece of metal. It was about 4"x0.5"x0.09", tapered along the 0.5" side. The only thing I remember marked on it was "USA 10% cobalt". He gave it to me and told me to make one .
I've cried and whined ever since for folding knives with similar blade steel.
 
Well, a good substitute: cpm rex76 - http://www.nsm-ny.com/index.cfm?fuseaction=page.display&page_id=31
idk niagara carries it in 2-4mm thick or not. A strip 2-4mm thick 2.5" x 24" bar probably would cost around $200-240 shipped.


jpm2 said:
Sorry but I've never seen t42 mentioned except in parting tools.
Other names and equivalents might be HSS 3X, HSS EC500, HS10-4-3-10, SKH-57, BT42, 1.3207.

It was more than 30 years ago I ask a machinest why knives weren't made from steel like he was using to cut that hardened steel shaft in his lathe. He went to his box, got out a small flat piece of metal. It was about 4"x0.5"x0.09", tapered along the 0.5" side. The only thing I remember marked on it was "USA 10% cobalt". He gave it to me and told me to make one .
I've cried and whined ever since for folding knives with similar blade steel.
Click to expand...
 
I've also ground a few blades from 5% cobalt parting tools, m35 I think. They perform almost as well as t42.
Got a source for m35?
 
I don't have experience with neither t42 nor m35 but t42 seem to has better elem composition than m35. Since m2 is almost like m35 sans 5%Co and M2 is darn good and readily available. Also you probably could use hap40 in place of t42.

Today ht 2.5 three blades (s30v, zwear, 3v == 1.4%C, 1.15%C, 0.8%C) - hopefully 64+rc zwear, 3v can open can like your t42 & m35 knives w/o damage (dull is ok) 15dps edge.

jpm2 said:
I've also ground a few blades from 5% cobalt parting tools, m35 I think. They perform almost as well as t42.
Got a source for m35?
Click to expand...
 
S30V gave me a Monday surprise. I was expecting this last piece of s30v as a last coffin nail to ht because it & among a few other steels failed edge stability at 62+rc. It hardness tested to 66rc (peak & untempered) this morning, nah couldn't be. So took me 30 minutes to manually put an initial 15 dps sharpening bevel with waterstones & diamond plate. It passed my whittle tests (katalox, bamboo, african blackwood, bone) - a surprise! It was harder to de-burr than s110v 66rc.

pMMVpIb.jpg


As for the other 2 blades: 3V/65.5rc, zwear/67rc. I will test them at this hardness later on today.

Edge after chopped frozen cooked beef rib bone and opened a side hole in a can below

5TDbdRK.jpg


Z-wear 67rc opened a side circle hole(slightly smaller than pic above) in the can above with 15dps, 0.010" BET edge geometry. Micro ripple (under 22x loupe) and barely visible micro chips with unaided eyes. Est at 65rc this edge would 95+% be ripple instead of micro chips. 63-64rc would roll & ripple. I will 2 swipes per side 20 dps micro bevel on this 67rc and see how it fares... a good chance of chip-free.
 
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z-wear 67rc 15dps + 2 swipes/side 18dps micro
opened 1.25" dia side hole in the can - only 1 visible micro chip, micro (22x loupe) ripple.
whittled 16d nail - micro rolled and rippled.

3v 65.5rc 15dps
opened 1.25" dia side hole in the can - a few micro(22x loupe) chip, micro ripple.
whittled 16d nail - micro rolled and rippled.

s30v 66rc, 12-13dps, 0.007" BET
ready for kitchen duty this eve. *update: did great, hit sharp edges of pork chop bone a couple times = a couple flat spots (no chip) on apex. Edge sticks to cutting board a few times, I was push cutting fairly hard - not easy pinch grip a handle-less partial tang blade.

Since edge already shown to ripple at 67rc & 65.5rc, lowering hardness would end up with bigger ripples and maybe rolls. Magnitude of roll/ripple is smaller than fracture/chip, so for hard use - either lower hardness to around 64rc or increase sharpening bevel to ~18dps.
 
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Awesome testing. Very interesting. I am learning that everything I thought I knew about steel changes drastically when you change the heat treat technique. S30v??!!
 
A few posts back - I has doubt on my s110v 'too good' result, so why not throw in a lousy (was considered so by me) s30v. Probably about 4-6 months back in this thread - I incorrectly assessed s30v as having lousy composition because edge was not stable at 63+rc. Well, I got another 'too good' out of s30v ;)

When time permits (or couldn't wait) I will try ht 2.5 on 20cv & s90v.

foofie said:
Awesome testing. Very interesting. I am learning that everything I thought I knew about steel changes drastically when you change the heat treat technique. S30v??!!
Click to expand...
 
* 3v doesn't has tiny 18dps micro bevel as niolox and zwear but maybe doesn't matter much, since micro chips from all three are at least 5x larger than the micro bevel height.

If all these edges start with apex ~10um to 16um (aluminum foil thickness), they should pass this test with maybe slightly dull/flatten to start-width + 2-4um.

ZKmTHTA.jpg
 
Latest HT 2.5 peak/max HRC#:
  • 2x S110V 66.5rc - readings between 66.5-67rc.
  • S90V 66rc - not sure how many times this blade been re-ht but at least 3 times total. Reluctantly due to hollow ground blade 66rc, 15dps, 0.012" bet, 0.030" 1/4" up from apex. Similar damaged magnitude as niolox 65rc above, except along damaged apex are fractured away rather than niolox ripples.
  • 10V 70rc - highest hardness for 10v I ever produced. Tested 69.75rc, 15dps - similar damaged magnitude as niolox 65rc above.
  • 2x 20cv 65rc. - because of ht in a batch and time sensitive, 20cv is under soaked by 5-10 minutes, so hardness is ~1rc lower. Tested 65.5rc with similar damaged magnitude as niolox 65rc above.
Test: Opened side hole in the curry can (pic above). Whittle dried cooked beef rib bone.

I am out of empty curry can and recycle bin is also empty.

Edit 19:00
s90v 66rc hacks katalox, african blackwood, dried cooked beef rib bone (crunchy/hard side) - passed (well, at least can't see any damage).
 
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10V 69.75rc 15 dps, 0.012"BET (600 grit diamond plate finished)

Chopped katalox, african blackwood, bone: Passed.

Whittled 40D nail (0.24" dia):
DVuX9tq.jpg


Well, now I have a dilemma... what to do with all the finished knives and blades with ht prior to version 2.5? :confused:
 
D6 ht 2.4 is more brittle than rex121 ht 1.5 & 2.5. Getting ready to h.25 d6, I plugged it into my steels composition spreadsheet and some calculation numbers poke my eyes

Calc fields: [steel | carbide_count | cementite_count | free_Cr_wt%]. Where 'count' is related to 'volume * factor'
  1. 52100 | 11.3 | 8.6 | 0.0%
  2. Blue Super | 23.5 | 39.2 | 0.0%
  3. D6 | 82.5 | 42.4 | 0.0% * 60/40 ratio of Cr7C3 and Cr23C6. If calc#s are correct, d6 is a carbon steel with high carbide volume (with coarse carbide diameter).
  4. D2 | 79.1 | 0.0 | 5.27% * 95/5% ratio of Cr7C3 and Cr23C6. 5.27% of free Cr for decent corrosion resistant
Edit 20170721 16:45
I tried to avoid large primary carbides (10-100 microns diameter) - succeeded in this area but penalized with bloated grain diameter. Peak hardness around 68.5-68.75rc, which is about 1rc higher than my projected hrc - perhaps due to large grain size. In spite of large grain, ht 2.5 edge tested shown more stable than ht 2.4 65rc + avg grain size. It has corrosion resistance similar to steels at 4% free Cr. Micrograph shows a lot of cementite precipitated in grain boundaries - undesirable property.

Just refilled my dewar. These 3 d6 blades will be re-ht 2.5.
 
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