# Question about TUNGSTEN HSS for Cutlery and Breakdown knives



## KDuncan (Nov 11, 2016)

First technical question posting- I have been given a box of old (1960's vintage) "Tungsten HSS" industrial hacksaw blades. These are .050 thick, 1.5" wide and 14 inches in length.

The local meat packing guys use HSS blades for their "breakdown" knives and they seem to keep a wicked edge with minimal stropping throughout the day- Unknown what the specific alloy is for their HSS.

Any hazards or pitfalls with making a fillet or boning style knife I should be aware of? Does the Tungsten HSS flex well or is it brittle?

Thanks and I look forward to hearing what you guys think!

Kerri


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## jessf (Nov 11, 2016)

I dont think you can forge tungsten into a new shape. Isnt it sintered in a way?


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## KDuncan (Nov 11, 2016)

Wont be forging these- they are already thin and waterjet will profile them-


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## LifeByA1000Cuts (Nov 11, 2016)

Would "Tungsten HSS" not be more likely to signify, well a hot working steel rich in tungsten, than pure tungsten?

BTW, there are interesting reads about tungsten (and other not knife related metallurgy) in old books (some of them can be found online) on vacuum tube design (yep, electronics)....


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## jessf (Nov 11, 2016)

jessf said:


> I dont think you can forge tungsten into a new shape. Isnt it sintered in a way?



Oh i misread your post thinking you said bits, not saw blades. Is the whole blade tungsten or just the teeth?


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## RDalman (Nov 12, 2016)

My advice is to not bother with mystery steel, or make a small blade by cold working it as it's currently HT(or you can actually grind pretty aggressively with hss, but anyway) and test it. You're not going to want to guess a new heat treatment without knowing composition.

If you want to make with hss, there are some available easily sourced, that are popular for blades, like m4.


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## merlijny2k (Nov 12, 2016)

With sawblades often only the tips are Tungsten carbides in a steel matrix. If it is in the whole blade i would say it is probably quite brittle. If you have a boxfull then what is stopping you from bending one until it breaks. Just based on the bend radius at breaking point you can find decent approximations for steel strength, which translates to hardness. Mechanical engineering and metallurgy books have charts for that. If you can hold it by one end and hit the edge of a table hard with the flat side of the opposite end without breaking it you are good with the brittleness. If you can bend it to a right angle permanently without heating it, it is softsteel with hardened teeth and essentially useless for knifemaking. If it doesnt snap when you hit it but it breaks when you bend it then it can potentially make a pretty sweet knife. Back in Suriname where i used to live old sawblades were the only source of metal stock available. Only stock removak work though never seen anyone do heat or forging on it.


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## Matus (Nov 12, 2016)

I would not waste my time and effort in a piece of steelbI can not identify unless you have large quantity of it and plan to use it regularly (thinking if guys like bloodroot blades)


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## KDuncan (Nov 12, 2016)

LifeByA1000Cuts said:


> Would "Tungsten HSS" not be more likely to signify, well a hot working steel rich in tungsten, than pure tungsten?
> 
> BTW, there are interesting reads about tungsten (and other not knife related metallurgy) in old books (some of them can be found online) on vacuum tube design (yep, electronics)....



True- the 1950's through mid 1960's HSS with Wo was usually a 1095 base with about 18% Wo added from what I can gather- and the "Tungsten" filament was the standard of "Flash" photography for many years- it has a warm cast yellow-orange in the visible spectrum.

I have downloaded several of these texts as well as found a company in Italy that decries a 70 Rockwell hardness to their Tungsten Carbide blades... Thanks for the info and Ill keep reading too!


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## KDuncan (Nov 12, 2016)

jessf said:


> Oh i misread your post thinking you said bits, not saw blades. Is the whole blade tungsten or just the teeth?



No worries Jessf- whole blade is tungsten "silver steel" according to the marketing materials- and based on my initial testing.


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## KDuncan (Nov 12, 2016)

RDalman said:


> My advice is to not bother with mystery steel, or make a small blade by cold working it as it's currently HT(or you can actually grind pretty aggressively with hss, but anyway) and test it. You're not going to want to guess a new heat treatment without knowing composition.
> 
> If you want to make with hss, there are some available easily sourced, that are popular for blades, like m4.



Thanks RD- I already have some M4 and M2 on order- these are a bit nostalgic as they were from an older gent that was a mentor. His family is the one who gave me the box after they were cleaning out his tool shed. I as well "inherited a variety of known steels for other uses as well.

True on the HT if it is a guessing game! I'm chatting with a materials science guy in my area with an XRF- problem is Wo doesn't show up easily on some machines. If he can get the spectrum analysis profile I need I will definitely have a alloy profile (at least within 2% +- accurate) to use for a HT in the oven. I have some Moly HSS I have forged and do not like the results initially (but will be re-visiting after tweaking the burners)


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## KDuncan (Nov 12, 2016)

merlijny2k said:


> With sawblades often only the tips are Tungsten carbides in a steel matrix. If it is in the whole blade i would say it is probably quite brittle. If you have a boxfull then what is stopping you from bending one until it breaks. Just based on the bend radius at breaking point you can find decent approximations for steel strength, which translates to hardness. Mechanical engineering and metallurgy books have charts for that. If you can hold it by one end and hit the edge of a table hard with the flat side of the opposite end without breaking it you are good with the brittleness. If you can bend it to a right angle permanently without heating it, it is softsteel with hardened teeth and essentially useless for knifemaking. If it doesnt snap when you hit it but it breaks when you bend it then it can potentially make a pretty sweet knife. Back in Suriname where i used to live old sawblades were the only source of metal stock available. Only stock removak work though never seen anyone do heat or forging on it.



Thanks for the testing specs Merlin- I did the bend/beat/snap test and think the Tungsten is throughout the steel- not just the teeth- the grain structure is fairly fine with specks of what I think are carbides throughout the fracture plane. 

The blade snapped fairly cleanly without ragged edges and there are "chipouts" along the margin where the bend began- little scalloped edges. And as for the smacking it edge wise along things- that I have not tried before- so I did and it gouged and hacked a decent portion of a cedar stump out as well as showed no wallow or mushrooming along the edge- I did get a spark when hitting a nail in the stump which produced a fairly decent scratch along the surface- but otherwise no real damage.


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## KDuncan (Nov 12, 2016)

So in my reading I'm seeing cutlery generally goes for a higher Rockwell versus EDC knives- My normal hunting knives run 60 Rc- should I shoot for 64 and then "tune" it from there on subsequent blades?


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## jessf (Nov 12, 2016)

Youve got thre material. Give it a try.


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## merlijny2k (Nov 13, 2016)

Do you know the bend radius at which it snapped? Or the amount of force/ moment applied?

If it has holes at the end you can hang weights from it. To avoid having to hang too much weight you can reduce the cross section in the middle area. Strength should run somewhere from 1200 to 3000 /mm2. 1200 is the highest strength used for bolts as they must still have some impact resistance. 1400 used to be made but is now forbidden for most applications. 1200-2400 is strength range for prestress steel. Prestress steel is quite clean carbon steel and some hobbyists forge knives from leftover prestress bars and wires. 3200 is high-tone piano wire and the strongest steel can possibly get. As far as i know the 1200N/mm2 to 3200N/mm2 corresponds roughly with 55-67HRC, although not exactly linear. I should really dig up my metallurgy course books sometime.


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## merlijny2k (Nov 13, 2016)

This text could be of interest
http://www.crucibleservice.com/eselector/general/generalpart1.html

The chart runs HRC 50-65 as 300-400 ksi which is 2067-2756N/mm2 although you may be more familiar with the unit.


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## LifeByA1000Cuts (Nov 13, 2016)

The "Tungsram" flash bulbs used quite a different material - flammable light metal wire and oxygen


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