Warp with a differentially treated W2 blade

Carterwhopkins

Carterwhopkins

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Dec 12, 2012
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I have a 8" chef knife made of W2 that I clayed and then heat treated at 1,460F, quenched in Parks 50, and then 360F tempering 2x. The blade was intentionally left thick on both spine and edge, it has picked up a small warp along the spine. The clayed area goes from the spine 50-60% down the blade towards the edge. Can I heat the spine and try to straighten the blade....last time I tried was with a much thinner W2 blade treated as stated above and it cracked. Any suggestions would be appreciated.

Carter
 
what Don said, but the answer to your question is - yes
I use a shallow metal tray with sand (wet), place the blade edge in the sand as much as you need and then torch the spine.
 
Thanks guys, I appreciate the feedback. I thought it would be safe and that my prior mishap was with one of my early W2 blades that was quite thin. I have been leaving more meat on the blades at the HT stage since then. I did clamp it to another piece of steel and sprung it over a bolt to over correct the warp....it is back in the oven at 375F. I have been at 360F looking to end up at 63-64 Rc.
 
Are you measuring those hardness, or estimating them. You should have a harder edge than Rc62-63 at 360F. I use 400-425F and get that with 1084.

I don't understand why people thing you have to temper at 350-375, etc, for a hard edge. If you properly did the HT and quench, a blade in W2 should have come out of the quench at Rc 65-66. At 500F temper it will still be Rc 60. You-tube is telling people not to exceed 400F .. baloney. It is rare I temper as low as 400F.
 
HI Stacy, I am testing actual hardness...just chimed in on the "moving the hardness tester" thread....I have the Grizzly version of the multiple produced Chinese tester...I am going for 63-64 and get that at 360f with W2....not watching YT for this info, mainly the knife forum threads, and mostly info from the guys here like you...MANY THANKS!! I solely make kitchen knives out of 52100 & W2 (at this time) and I do my own HT...my 52100 blades are approx 62 Rc and I shoot a little higher with the W2, 63-64 Rc.

I started my temper of both steels in the 400-425f range and then found a tad better results below 400f...with W2 being the lowest at 360f. Most of my customers are professional chefs and they report good retention and no chipping.

I am always open to new ideas and the continued learning experience. Keep the info coming!

Carter
 
Yes, generally 66-67. I am a little suspect of some of my readings at present and plan on running some test blocks. My shop is not well heated and I think the mechanism of the tester is sluggish and the grease is stiffer....it does seem to work a little better after several tests.

Just ran some test blocks and the tester is accurate. Last W2 blade tested at 63Rc after 360f temper...think it could have been higher, but the Parks had heated to probably 120f after a few previous blades.....assuming that reduced the hardness a tad.
 
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Carterwhopkins said:
Yes, generally 66-67. I am a little suspect of some of my readings at present and plan on running some test blocks. My shop is not well heated and I think the mechanism of the tester is sluggish and the grease is stiffer....it does seem to work a little better after several tests.

Just ran some test blocks and the tester is accurate. Last W2 blade tested at 63Rc after 360f temper...think it could have been higher, but the Parks had heated to probably 120f after a few previous blades.....assuming that reduced the hardness a tad.
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My 1095 and w2 test 66.5/67 out of quench and 2 2hour tempers at 350/360 leaves me around 64 with a low of 63.5 and that also matches with Cashens temper chart...
425 should give you 61.5/62/62.5
-Trey
 
W2 does do very very well at high hardness! But if I were to temper one of mine at 360f, it would be around 66. I get 67.5-68.5 right out of the quench. Run a few cycles on a test block, before actual test with the hardness tester.
 
Carterwhopkins said:
Sounds like we are getting approx the same results Trey, what is your quenchant?
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I use 50-100° F parks 50 and a drum forge with thermocouple. I had a lot of issues when I was doing hamons in my evenheat, did some testing and found the drum forge I built heats much more evenly and stable.
I prefer 1095 to w2 as it has been more consistent to work with in my shop.
I find my 1095 responds best in the 1450-1475° range and w2 needs a bit more heat as the stuff currently in circulation has about .1% less C than the 1095 I use so I run my W2 between 1465 and 1485° to get decent results.
Also any reason why you run your 52100 at 62? I prefer to quench it a little hotter (1500-1525) and leave at 63-64Hrc.
-Trey
 
Thanks Don....sounds like a good plan...interested to see if there is a delta in results with that process.

Trey - interesting in the difference in heating methods...I am using Evenheat at 1460f and about a 12min soak...usually put the blades in somewhere north of 1000f, so they should be fully acclimated when oven hits 1460f. I have not worked with 1095 yet, I am only doing chef knives and my customers seem to ask for W2 that is differentially treated or 52100. Also, my thought process is to learn 1-2 steels in detail before branching out. I like 52100 at 62, I could go higher, but like to leave that as a differentiator for W2 with a higher hardness (along with a higher price/hamon etc), also 52100 has both good retention and sharpens easy at 62.
 
Carterwhopkins said:
Thanks Don....sounds like a good plan...interested to see if there is a delta in results with that process.

Trey - interesting in the difference in heating methods...I am using Evenheat at 1460f and about a 12min soak...usually put the blades in somewhere north of 1000f, so they should be fully acclimated when oven hits 1460f. I have not worked with 1095 yet, I am only doing chef knives and my customers seem to ask for W2 that is differentially treated or 52100. Also, my thought process is to learn 1-2 steels in detail before branching out. I like 52100 at 62, I could go higher, but like to leave that as a differentiator for W2 with a higher hardness (along with a higher price/hamon etc), also 52100 has both good retention and sharpens easy at 62.
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Makes sense, I learned 52100 first, then 1095 and then w2. I also use 1095 and W2 for honyaki, all of which are forged so I do normalize. If I was going to stock remove I would prefer my 1095 simply for the fact it comes ready to harden.
I think after using 52100 for so long I just prefer it harder as I see no difference in edge stability but a world of difference in retention and stone feel.
-Trey
 
I am still doing stock removal with Aldo's steel...one day hope to forge, but wanted to learn the steels and grinding before throwing in another element/variable.
 
Carterwhopkins said:
I am still doing stock removal with Aldo's steel...one day hope to forge, but wanted to learn the steels and grinding before throwing in another element/variable.
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I stock removed for well over a year before I ever tried to forge anything, just mentioned it for HT purposes.
Also I find blades with hamon take well to peen straightening if you're careful but shim tempering is the safest option.
-Trey
 
I need to get a little further down the road, but hope to forge w/in the next year or so.

I have hammered a few W2 hamon blades, but they were thin and were pretty highly stressed, several early ones were water quenches...hammering or bending led to cracks and total failure. My W2 blades now are much more resilient. BTW, my 52100 blades bend 90 degrees, cut nails, no issues, so pleased with them....just learning the differences and trying to under stand the stresses and weak points of the differentially hardened blades.
 
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