Photos 2 Swedish Air Force survival knives

Blade hand reground to it's original full convex blade shape on a Foss 7205 black/green silicon carbide stone used with oil, then refined on 400 grit and 1000 grit SiC wet & dry paper used with oil on glass, and the tiny burr stropped off on hard cardboard with 1.0 micron diamond paste.
The new apex measures between 20 and 22,5 degrees inclusive.
Very hard (guesstimate 64-65 HRC) and also very wear resistant steel.
Handle reassembled, now with all washers glued and pommel repolished, then treated to a few coats of warm Granger's wax.
Sheath waxed and hand restitched.





 
I have one of these with a stag handle and a pouch sheath I think very highly of. The pattern originally came out of Sheffield but many other cutlery companies made it over the years. Kinfolks made them under their own name and under contract for several other big names of the period.
 
That looks to be a very useful knife. Anyone know the type of steel used?
 
Both Pontus Holmberg knives are made from iron ore from the Dannemora mine, which resulted in very pure steel due to it being rich in manganese.
In earlier centuries it was known as "oregrounds iron": https://en.wikipedia.org/wiki/Oregrounds_iron
However i don't know if that name was still being used by the time these knives were made in the late '40's or early '50's of the 20th century.

Sheffield also used a lot of this same ore to make their famous crucible cast steel from ~1740 up until ~1960.
These two Swedish knives however are noticeably harder as well as much more wear resistant when compared to the vintage English crucible steel knives that i've hand reground/sharpened over the years.
 
Enjoying this thread immensely and learning too!
Love your work Kwakster and picking up tips from you too.
I use some old Finnish puukkos on the grounds and also notice great edge holding despite the full scandi edges. I wonder did they have a greater degree of understanding of heat treating than most of that time period?
 
ed_is_dead ed_is_dead :

At this point i'm quite certain that the steel in these 2 knives is an entirely different type when compared to the standard Sheffield made crucible cast steel.
One reason is that Pontus Holmberg classifies it as a stainless steel, where the Sheffield made crucible cast steel was a carbon steel.
See this detail picture of the sheath of knife #2, and "Rostfri" is the Swedish word for stainless.

ibb.co

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Image GEDC4173 hosted in ImgBB
ibb.co ibb.co

The second reason is the very high wear resistance of this Swedish steel: using whatever grit of black silicon carbide on it is extremely slow, be it waterproof SiC paper or the coarse black SiC side of the Foss 7205 combination stone.
The green silicon carbide side of that stone however, even though much finer than the black side, cuts the steel noticeably faster, better, and also with great feedback.
Based on this i'm beginning to suspect there might be quite a lot of tungsten carbides in it, also because the steel is able to take & hold a thin ~20 degree inclusive edge angle while whittling an old piece of hard beechwood cutting board (tested with knife #1)

A possible third reason is a little piece of info i found on this website with mining data: https://www.mindat.org/loc-3153.html
According to this there could be (traces of) silver in the Dannemora iron ore, which made me remember what Faraday wrote about the alloy of steel with silver in this thread: https://www.bladeforums.com/threads...cus-wootz-other-alloys.1666437/#post-20358902
Problems might be that Faraday wrote about his findings around 1822, he doesn't talk about silver in ore but about lab made alloys, and i'm no metallurgist.

Maybe Larrin Larrin can tell us more about the validity of Faraday's claims about steel alloyed with silver, and maybe his thoughts about the type of steel in these two Swedish knives.
 
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20° inclusive is what I was taught to sharpen a knife to, about 62 years ago.
Great job on both knives. đź‘Ť
 
Currently experimenting a bit with different grits of diamond paste on thin cardboard to see what gives both a nice blade finish as well as a good apex.

Already found that only removing the burr is not enough to get the sharpest of edges on this steel, i have to continue stropping a bit to also get the (presumed tungsten) carbides into the right shape.
I also have to tinker some more with the appearance of the blade finish (now it's a bit too shiny for my taste), but the current apex is reverse hairwhittling sharp (chest hair) @ ~20 degrees inclusive.



 
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