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totalnewbie
Nov 13, 2005

I was born and raised in China, lived in Japan, and now hold a US passport.

I am wrong in every way, all the damn time.

Ask me about my tattoos.


Wroughtirony posted:

What's the deal with vanadium? Does it just sound cool or does it actually make a blade better? If so, how? All I know about vanadium is its use in batteries for storing solar power.

Yes, vanadium is a common alloying element for steel to increase hardness. But just as important as composition is the processing of steel. If it's not processed properly, you can have a steel that's too soft or too brittle.

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totalnewbie
Nov 13, 2005

I was born and raised in China, lived in Japan, and now hold a US passport.

I am wrong in every way, all the damn time.

Ask me about my tattoos.


Rotten Cookies posted:

Or at least a resurgence in marketing it.

It's this. Most people who buy knives (and probably don't read this thread) couldn't tell the difference between a cheap stamped piece of sheet metal from a nice forging.

BTW I'm a material science guy :P

totalnewbie
Nov 13, 2005

I was born and raised in China, lived in Japan, and now hold a US passport.

I am wrong in every way, all the damn time.

Ask me about my tattoos.


301 stainless is austenitic but is also high work-hardening. Austenitic stainless steels can gain magnetism through work-hardening.

This is due to partial transformation of austenite in the annealed condition to martensite after strain.

If you stick it in the oven during its self-clean cycle (or an 800 C furnace if you've got one) you can probably anneal it and make it lose its magnetism.

301 stainless is a natural choice for your speed opener because you want something that's relatively hard but minimize heat treat for hardness. Work hardening is a good process to achieve this because you'll roll out your plates to make plates of the correct thickness, but 301 retains enough ductility to be stamped or otherwise formed into the final shape.

But 301 stainless hardness tops out at 40ish HRC while 420 stainless can achieve up to 50 with proper heat treat, etc. You sacrifice corrosion resistance in the 420 but you don't need all that much corrosion resistance in a knife (against water, and mild acids is really what you need, especially if you keep your knives clean and don't let food sit on it).

Something like a 440C is even better for hardness, with 60HRC achievable in those.

But you can hit even higher hardnesses by switching away from stainless steels altogether, though I'm not really sure what steels are used in carbon steel or if any tool steel knives exist (maybe/probably?).

totalnewbie fucked around with this message at Apr 11, 2018 around 18:16

totalnewbie
Nov 13, 2005

I was born and raised in China, lived in Japan, and now hold a US passport.

I am wrong in every way, all the damn time.

Ask me about my tattoos.


mekilljoydammit posted:

A lot of tool steels ("stainless" or not) get used for higher end pocket knives and stuff. Good points on work hardening with 300-series steels - I was trying to give a high-level, pre-coffee overview.

Oh for sure, but people love to generalize (e.g. "magnetic = ferritic = hard!") so I really wanted to steer people away from that generalization. Non-magnetic knives are probably guaranteed crap, though.

SymmetryrtemmyS posted:

Tool steel and carbon steel knives are pretty common up to 63HRC or so, 65+ in some extremely well tempered knives. ZDP189 knives are getting more common for instance, and offer high hardness (on par with Blue Super or White #2) along with good durability (comparable with or better than VG10). Tool steels offer the best of both worlds, but the price is accordingly higher.


Yeah, I meant I don't know which grades of those particular steels are used. It's annoying that the knife industry hides their compositions behind proprietary steel grades because it makes it difficult to judge which knives are even worth testing for the high end stuff. Also, there's so much dependence on heat treat, etc. that maybe it's not even worth worrying about it and the real test should just be microhardness testing on the blade. That said, I'm not entirely confident in the ability of knife reviewers to properly assess the hardness of knife blades, as you really want to test the knife edge (not the bulk of the blade), but microharness testing is sensitive to specimen preparation, etc that people who aren't familiar (or aren't in a qualified lab) wouldn't necessarily know or be able to do properly.

For example, see here for an article about proper microhardness testing of cutting blades: https://www.qualitymag.com/articles...ardness-testing

Steve Yun posted:

Most mismatched username/post combo

I know a few things. Just a few.

totalnewbie fucked around with this message at Apr 12, 2018 around 15:09

totalnewbie
Nov 13, 2005

I was born and raised in China, lived in Japan, and now hold a US passport.

I am wrong in every way, all the damn time.

Ask me about my tattoos.


mekilljoydammit posted:

What's your industry? I'm a mechanical engineer doing testing stuff in small engines, but knives are interesting to me.

You're completely right about some of the "proprietary" grades, but truth to tell if you do some digging, most of the really high end knife makers are using off-the-shelf grades. A lot of the CPM tool steels are popular for various uses - some of the blends may be proprietary to Crucible but they publish heat treat guides. If you're know about microhardness testing and stuff, I'm willing to bet that you know where to dig for alloy composition - Rockwell C around 60-62 after tempering, various carbide forming alloying elements help with wear resistance, some balance to avoid too low of toughness. And yeah, heat treat is going to be a bugaboo... some of the steels that people are trying to make knives out of end up with such a fiddly heat treat schedule that it's probably pointless.

It's fun to figure out though.

I work for an automotive supplier but have a degree in materials engineering.

But I'm an engineer, so things like doing HRC testing on the blade bulk rather than the knife edge annoys me, because it leaves open the possibility of poor heat dissipation/cooling during grinding causing your edge to lose a lot of the hardness it would otherwise have. While I'm willing to be that it's NOT the case that the edge is significantly softer than the bulk material, I hate leaving open that possibility, right?

FYI for others: Grinding causes heat and insufficient cooling means the edge of your blade gets hot; hot = transformation of hard martensite to soft austenite. Therefore, it's possible for bulk blade to be harder than the edge.

totalnewbie
Nov 13, 2005

I was born and raised in China, lived in Japan, and now hold a US passport.

I am wrong in every way, all the damn time.

Ask me about my tattoos.


CrazyLittle posted:

Nah the kanji is different. But it's still a gyuto. It's an older tojiro of a different model

https://www.amazon.com/Tojiro-Finis...u/dp/B00G5HBRW2

totalnewbie
Nov 13, 2005

I was born and raised in China, lived in Japan, and now hold a US passport.

I am wrong in every way, all the damn time.

Ask me about my tattoos.


I left for a couple weeks and my parents left my admittedly cheapo knife dull as gently caress.

What is a good 2-3 stones I can buy to get my knives to a reasonable sharpness? I don't need it sharp enough to split atoms or anything, just to cut comfortably.

totalnewbie
Nov 13, 2005

I was born and raised in China, lived in Japan, and now hold a US passport.

I am wrong in every way, all the damn time.

Ask me about my tattoos.


Babylon Astronaut posted:

Honestly, if you're just doing fruits and veg and basic meat cutting and you don't need to split atoms, you can get a $10 accusharp v sharpener and be completely fine. It removes waaaay too much metal for something you want to last a life time, and will make one kind of bevel, but if you're using "wedding present" knives, they work great. The cons are they wear your knives, you won't be able to shave with it, and you need to be aware of metal filings. It will also permanently ruin high carbon steel, or anything with a custom bevel. A 10 dollar accusharp and a 12 dollar greben 8 inch chef knife is enough for even most professional cooks.

I do want something a little better than a V sharpener. I want one day to get some better knives and take care of them nicely, so I want this to be a first step.

wormil posted:

I use a Spyderco Sharpmaker. Does the job for me but you have to be careful not to round over the tip.

Same as above, I'd like to see if I can get a couple real stones to use? I'm not sure how keen I am on this type of sharpening motion :/

totalnewbie
Nov 13, 2005

I was born and raised in China, lived in Japan, and now hold a US passport.

I am wrong in every way, all the damn time.

Ask me about my tattoos.


Well that's the second time Shapton's been mentioned, so I guess I'll get some of their stones.

I don't mind picking up 2-3 stones instead of just one. Shapton recommends 1000 + 5000 for chef's knifes - I guess I can just go with these two and call it a day? Any reason to pick up a more coarse or fine grit?

totalnewbie fucked around with this message at Aug 14, 2018 around 17:28

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totalnewbie
Nov 13, 2005

I was born and raised in China, lived in Japan, and now hold a US passport.

I am wrong in every way, all the damn time.

Ask me about my tattoos.




I bought a thing.

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