Stainless Bolster Material???

KnuckleDownKnives

KnuckleDownKnives

Time to make the doughnuts..
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What type of stainless is good for making bolsters? Is 316/316L suitable? I see usknifemaker carries 416 is that preferable?
 
I've used 416 couple times and liked it. Machined well and polished well


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303 and 416 are the readily machinable types, 416 being hardenable and 303 not.

304 and 316 work fine, make nice bolsters or guards but are harder to grind and machine. They get hot fast when grinding and are generally miserable to work with. They are less expensive than 416 but you're much better off using 416 in my opinion.

303 can be had from McMaster but 416 is harder to find outside of the knife suppliers in flat stock.
 
For bolsters would I need to harden? I would have to outsource that now as it is and would rather not just for bolsters.

Do you know what the difference is in cold drawn vs hot rolled is if I were to go with 303? I found a supplier for both flat and round in the sizes I'd want and the prices are seem really good. The round they only have the size I want in "COLD FINISH STAINLESS ROUND 303 ANNEALED" the flat comes the exact size I want in the cold drawn. It's quite a lot cheaper than the 416 and 303 pin I can get like 8' for less than $3.00. That much pin stock would last me a long long time, and 4' of the flat I want for $50 less than 4' of 416 the same size. If this would make a suitable choice that would be great, I'd have enough bolster materials for a couple years for less than $100.
 
I think going with 303 sounds like a good option. If you use 303 pins they'll disappear when you peen and grind. Cold or hot rolled doesn't really matter much in the grand scheme of things. Cold rolled has a little more stress in it and can move as it's machined more than hot rolled but for bolsters I don't see that causing much problem.


416 I think you want to harden because it doesn't reach it's full corrosion resistance annealed but I could very well be wrong.
 
416 I think you want to harden because it doesn't reach it's full corrosion resistance annealed but I could very well be wrong.
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It will be interesting to see responses to that statement - I do not know the answer, but had not considered hardening bolster or end cap. Maybe it needs to be?

Ken H>
 
I don't know that it needs to be. I've used it on bolsters in the annealed state as well. I'm trying to recall a discussion here where I believe it was said that it should be hardened to reach it's full corrosion resistance but like I said, I might be wrong. I don't know if that makes sense chemically or not. I'm thinking that if it comes fully spheroid annealed, then some of it's chromium is just balled up in their own little spheroids and not in full distribution, and hardening it helps distribute the chromium appropriately?
 
I've read as where kuraki said it doesn't reach its full potential in corrosion resistance without being hardened. That being said
I have friends that do harden 416. I have made literally hundreds of folders without hardening with no bad effects.
Ken.
 
kuraki said:
I don't know that it needs to be. I've used it on bolsters in the annealed state as well. I'm trying to recall a discussion here where I believe it was said that it should be hardened to reach it's full corrosion resistance but like I said, I might be wrong. I don't know if that makes sense chemically or not. I'm thinking that if it comes fully spheroid annealed, then some of it's chromium is just balled up in their own little spheroids and not in full distribution, and hardening it helps distribute the chromium appropriately?
Click to expand...

What makes 416 machinable is the added sulfur - not that it's spheroidal. Without the sulfur, it's basically 410.
Same thing with the 303. It has added sulfur to give it machinability. That's the difference between it and 304. (304 is worthless for us).
 
I don't think that 416 needs to be hardened to realize full corrosion resistance potential.

The following link may be of some useful information:
http://www.azom.com/article.aspx?ArticleID=971
Concerning HT and Corrosion resistance:
Corrosion Resistance
Grade 416 steels are highly resistant to acids, alkalis, fresh water and dry air. However, they are less corrosion resistant than non-free-machining steels, austenitic grades and grade 430 Ferritic alloys with 17% chromium. These steels are hardened to obtain maximum corrosion resistance and smooth surface. 416 free-machining grades with high sulphur content are inappropriate for chloride and marine environments.
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Seems to imply that non free machining grades, austenitic grades, or 430 ferritic alloys are the grades that need heat treatment for additional resistance, but maybe I'm reading that wrong? It's just a little ambiguous.


As for CRA for HR finishes, I agree that it probably won't matter much in the grand scheme for something as easy to machine as 303 or 416. The fact that it's annealed should keep it from moving too much as that should relieve most of any stresses from the drawing/rolling process. The nice thing about CRA is that it's typically a little tighter on tolerances, and you don't have to do as much surface prep as there's no mill scale to remove. (For something as small as a bolster, this really isn't that much extra prep time.) On higher carbon steels is particularly nice as you shouldn't have any hard spots to worry about while drilling and machining.

Whatever you get, just make sure you grab the same material for pin stock IF you want them to blend.
 
Hold the phone:

Corrosion Resistance:
•Demonstrates corrosion resistance to natural food acids, waste products, basic and neutral salts, natural waters, and most atmospheric conditions
•Less resistant that the austenitic grades of stainless steel and also the 17% chromium ferritic alloys
•High sulfur, free-machining grades like Alloy 416 are unsuitable for marine or other chloride exposure
•Maximum corrosion resistance is achieved in the hardened condition, with a smooth surface finish
Click to expand...

Taken from here:
http://www.pennstainless.com/stainless-grades/400-series-stainless/416-stainless-steel/

Perhaps hardening DOES increase resistance, but whether it's that much of a difference for knife making applications, it's hard to say. I'd like to see some tests.
 
I've used 304 pin material and I have some 304 flat stock to match it and so far it seems easy to work. I know everyone cusses it but I think light pressure and sharp tools it does ok. Supposedly more corrosion resistant than 303


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416 is what you want. The downside in recent years has been that it is impossible to find really thin 416 stock, so you have to use 410 whihcis an adventure when trying to cut it on the bandsaw. 416 is a dream to drill, mill and finish.
 
Karl B. Andersen said:
What makes 416 machinable is the added sulfur - not that it's spheroidal. Without the sulfur, it's basically 410.
Same thing with the 303. It has added sulfur to give it machinability. That's the difference between it and 304. (304 is worthless for us).
Click to expand...

Yes I understand about the sulfur, I was just speculating on why hardening would effect corrosion resistence. I use 304 and 316 quite often because it's practically free to me since we scrap so much at work. I wouldn't way it's useless. It makes excellent damascus and san mai.
 
kuraki said:
Yes I understand about the sulfur, I was just speculating on why hardening would effect corrosion resistence. I use 304 and 316 quite often because it's practically free to me since we scrap so much at work. I wouldn't way it's useless. It makes excellent damascus and san mai.
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Good point - it's not useless. For fittings, 304 is like milling and drill glue.
With the availability of so many other steels, I have no use for them. But that's just me.
If I had 316 free, I might have a different opinion.
 
Thank you all for your input. I'll be going with 303 as of now after reading some of the comments here and some other posts I finally located with the same question asked and great results came from their use of 303. I do not have the ability to HT stainless at this time and do not want to have to source it out just for stainless bolsters. If I could HT it myself and could find the stock sizes I want currently and at a better price, I see where 416 has it's advantages, but all things considered I am working with 1084 currently and only plan on expanding to 1074 soon to experiment with hamons the anti corrosion properties of 303 should be suitable enough with those blade materials. I'm not making diving knives and explain to the people that receive a knife from me that if they do not want corrosion they must use some care with the knife as a preventative measure.
 
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