Don’t know about the material properties but the big iron mine in Sweden is in the far north at Kiruna and made the news a couple of years back as they moved the town to expand it.

and now back to the original question…

Funny feeling it used to be used for hammer heads favoured by panel beaters as it could be easily shaped.

A bit of iron history

https://www.jernkontoret.se/en/the-steel-industry/the-history-of-swedish-steel-industry/

As above by John. Don’t waste it on a bog standard job.

If it’s that soft it’s probably not tool steel. But honestly, with the information you’re providing it’s impossible to tell.

Wot John Haine said.   Swedish Iron is ultra-pure, which gives it exceptionally valuable electro-magnetic properties. It concentrates and loses magnetic flux very quickly.   Not cheap and difficult to find.  Don’t waste it.

The alternative is Silicon-steel, not so good electromagnetically, but much cheaper.

Technically, Swedish Iron is a bog-iron.   Rain falling on upland Iron rich soil creates salts that are absorbed and cleaned by certain plants.  When the plant dies it’s concentrated Iron salts are released and picked up again by plants further downstream.  This is repeated until the Iron is trapped in a bog.  Repeated washing and biological cleaning over about 30 years progressively removes contamination and increases concentration.   Bog Iron is very pure, and Sweden’s geology produces the best of the best.

Pure ore meant Swedish steel was as good as it gets for centuries.  Up there with Toledo, Damascus, and Wootz.  In contrast, other regions produced mysteriously haphazard steel, ranging from excellent to poor.   Led to much mumbo-jumbo and mistaken notions of craftsmanship.  Good swords were associated with magic, like Excalibur.  Actually, the problem was contaminated Iron ore, chemistry rather than craftsmanship or sorcery!

What’s in Iron Ore depends on the geological process that laid it millions of years ago.   Ore containing Sulphur and Phosphorous produces poor quality steel, whereas ore containing Vanadium, Chromium and Molybdenum produces good steel.   Not understood until analytic chemists arrived in the mid 19th Century, so most early steels were some unknown alloy, that depended on local materials and suck it and see processes.   The type of wood used to make Charcoal mattered too (lucky Sweden again!), and there was trouble wjen Coal replaced Charcoal.  Even the cleanest coal is too contaminated to make steel directly; it has to be coked, and most coals are unsuitable.

Chemistry removed much of the uncertainty.  Science identified what the contamination was, where it was coming from, and suggested how to remove it.  Practical judgement was replaced by measurement.

Modern steel is produced to any specification required, and although it can go wrong it’s usually better than old steel.  Three main exceptions:

• radioactive contamination caused by atmospheric nuclear tests cannot be removed;
• stretching a steel works at end of life can result in metal contaminated with furnace lining or made with reduced attention to chemistry or heat treatment.  Cheap rebar can be quite nasty; too much Carbon, and then it’s hosed down with cold-water as it comes out of the mill.  Done so product can be moved quickly.
• the specification is unknown, or the buyer chooses unwisely, or the supplier substitutes an alternative.   No-one has made EN1A or EN3 for decades!  We order EN and hope something similar to the WW2 spec arrives!  Unknown scrap; there are thousands of different steels and many of them do not machine well.   Manufacturers buy metal to suit their needs.  We want machinability, they might have gone for rolling, grinding, welding, forging, casting, stamping, forming or shearing etc.

Dave

John and Dave above are bang on, I worked for the last years of my working life for a switchgear manufacturer, who also undertook refurb of switchgear and other HV and high current equipment. Swedish iron was specified for relay cores due to the magnetic properties, Dave has explained above why, I never knew the reason for it’s properties, very interesting. It is funny stuff to machine with the long strings of swarf and some batches can be a bit inclined to fearsome dig ins when parting off, great care being needed to clear the swarf. Must be expensive as only the very minimum was handed out from the stores for each (very small) run of components. I do remember being told that it was used for the laminations of very high end audio transformers, and transformers designed for high frequencies, where the costs could be justified above that of silicon steel. One relay that used to intrigue me was one with a cobalt steel core, once operated the current could be removed and it would maintain its magnetism and keep its contacts open or closed for years, until a current was applies to the coil which would then drive it off. We never knew what they were for (MOD job) I would love to know what the application was if anyone knows……

Having watched the above video we didn’t do too badly with our old fashioned manual machines, and what he says about the machineability varying along the bar strikes a chord. Don’t feel so bad about that broken parting toolholder now, thought it was just me being careless.

On 12 July 2025 at 13:09 JasonB Said:

Seems to be known for it’s stringy swarf and being a pain to machine

Which is why I said I suspect the OP has not got Swedish Iron as he says it machines well. It’s actually quite hard work to cut it with a hacksaw.

As the quality of interest for Swedish iron is very low magnetic remanence I suggest the OP tries to magnetise the sample and see if it remains polarised. If it does it’s no use for magnetic cores if it doesn’t then it may be one of the modern substitutes which could be Iron/nickel or Iron/silicon both of which I would imagine machine better than pure Iron.

Used to have an Inconel 625 doorstop once. Some bod came to an old workplace with a bar end  ‘lump of stainless’ for us to make him a hub for something…. It was a LOOOONG time ago. Anyway after we had destroyed several inserts at the lowest speed and feed and when we had found the material code stamped on the bar end he had brought, it held the door open from that point onwards.

Was this sort of iron called “Armco” iron?  As near to pure iron as possible.  Suitable for laminations in electrical things rather than the barriers that prevent(?) accidents on the road.

If anyone has to machine Swedish iron, and in particular part it off or groove it (in one case had to have a circlip groove) I found the best inserts for ordinary turning were the polished ones as sold by ARC and others, but one false move or suspicion of chatter and the edge is gone unfortunately. For parting after having some trouble with insert tips I ground a HSS parting blade to the design in Geo H Thomas’s book with a groove along the top of the blade and a V front cutting edge, this curled the stringy swarf into V profile coils and prevented jamming of swarf in the cut. All this was on a very rigid, old but in superb condition Holbrook lathe (heartbreakingly sent for scrap when the works shut down). The big problem I found was that as the material varies wildly in machineability along the bar length it is hard to get a feel for the cut. I’ve never milled any so can’t really advise on that, comes under the material specification Horibillium!

Often referred to as Dreadnaught Steel John.