Paring Chisels May Break Me

[D_W]

I was looking into 'Crucible' steel the other night. Mainly down to sudden thought/boredom.

I was wondering if the blades in some of my older planes that have Finest Crucible Steel stamped on them would display the patternation often seen on Damascus or Wootz steels.And if treating the blades with light acids like acetic would bring it out. But I'm not sure as I think its down to the cooling process rather than just the steel itself, and those steels are different in their make up, and also the original recipe is something thats been lost

You shouldn't see any layers with crucible steel - it's high quality cast steel that's then taken and rolled or forged to refine the grain and get the carbides (Through later normalization and hardening) where they're wanted in the grain and get good microstructure.

My understanding of the pattern, and my apologies for having never had too much interest in this (I know how the modern patterned steel is made by just layering and pattern welding different alloys, but not necessarily homogenizing them)...anyway, my understanding is originally, the layering was done to remove contaminants, and if there was an addition of carbon at that point, it would've been done then.

Prior to fast steelmaking, I'm guessing that a lot of the alloying was determined by getting good ore, and some of the better steel had natural alloying elements in the ore. For example, nickel will improve steel somewhat (how much for different attributes, I don't know) and probably improve hardenability. Chromium and manganese obviously will, and small amounts of vanadium will, too, and a little silica. Whether or not larger amounts of those does is up to the preference of the user (I don't like free vanadium carbides, but knife guys looking for maximum wear resistance with minimum carbide volume seem to love vanadium carbides and will probably soon love niobium).

Long story short, the only patterning you should see in any steel made in the last 250 years will be intentional pattern welding with alloys like 15n20 and 1095 in combination. These can make very good billets, but not better than good uniform steel (which is what the crucible steel would've been).

 

[dannyr]

I was looking into 'Crucible' steel the other night. Mainly down to sudden thought/boredom.

I was wondering if the blades in some of my older planes that have Finest Crucible Steel stamped on them would display the patternation often seen on Damascus or Wootz steels.And if treating the blades with light acids like acetic would bring it out. But I'm not sure as I think its down to the cooling process rather than just the steel itself, and those steels are different in their make up, and also the original recipe is something thats been lost

interesting

However, the crucible steel itself (the hard cutting edge) will not show this as it is a refined, homogenised high carbon (.8 - 1.5%) steel --- where you often see a good pattern is the wrought iron backing (more visible on heavy chisels) this is caused by the directional rolling and forging of the silica stringers in wrought iron. If the blade is of solid crucible steel you should not see any pattern other than random surface corrosion.

Japanese chisels for the western market are often forged like samurai swords, with a back of layered 'damascus' steel and the edge of the Japanese equivalent to crucible steel (eg best white steel). In fact I understand those most sought after by Japanese craftspeople are made with the white steel blade of pure carbon steel with a backing of old wrought iron which is simpler and possibly more effective than the showy damascus type. If there has been any etching by the action of chemical, environment, age etc this may show up as a wood-like grain on the wrought iron part which can be very attractive but serves no purpose other than to show the classic construction.

There were other edge steels used before crucible and even after as cheaper, including 'German' (like wootz and damascus, probably referring to where they were traded, not always where invented or made) and shear blister steel which can be quite good but also show the unevenness of layered steel, also the pattern if visible is not so attractive.

as you probably know, an edge of Damascus steel is a variable thing - for a good tool it really should include an edge of your chosen tool steel forge welded centrally or to one side/edge.

started writing this before dw's reply .. in general terms, i think we agree7

 

[D_W]

yes, we do - the pattern welded steel now is generally 15n20 (nickel causes it to etch less) combined with something that corrodes easily (1095 is what I used as an example, but there are probably others).

Some knife makers made it into the razoring community a few years ago and the pattern welded stuff showed up everywhere. what makes a good razor is about 1.1 carbon steel without much else in it. The 26c3 i used here is a bit above that (there's no 1.1 or 1.15% carbon equivalent here, or I would be using it instead of 26c3 as 1.25% is a bit much for chisels), but is apparently a razor steel. Who makes razors from it, I don't know.

Long story short, 15n20 isn't ideal for razors and the notion even among amateurs was that the razors shaved, but they weren't a match for decent homogenized single alloys. I never bought one - they were expensive and I was skeptical about much made recently given my experience with some later razors that were popular in my estimation more because they could be easily found in unused condition (like filarmonicas, etc) and in big sizes. I had a few filarmonicas and also found them decent, but not as well finished and no better than a german razor from 1915 or so - not as good as the best of the latter (but more expensive).

The layering in japanese tools is, as you say, always confined to the backer in my travels. I had a set of mokume (acid etched wrought backed) chisels. they were nice, but not because of the visuals - rather because the wrought was relatively soft and easy to sharpen whereas mild steel or iron backing of some cheaper chisels can be harder than it should be (possibly to make the chisels stronger). The annular ring chisels sold in catalogues for high dollars don't likely have any performance attribute that can't be had in a die-pressed chisel like koyamaichi (which at one point from stu tierney were about $65-$70 each, and the ones I had from LV - who sold a special profile of them - as well as parers from stu, were great chisels. Not that pretty (just ground in dies from the looks), but great performing and not short of their hardness spec.

In planes, since the bevel of the tools is so thick, it's nice to have very soft iron just to make the honing easier - along with a thin lamination of harder steel. There are still wrought acid etched versions of those ,too, with the etch on the front of the iron being very drastic sometimes.

 

[baldkev]

Fantastic looking chisels david..... ive got mine on display

You'll have to excuse the wiring.... its functional

 

[D_W]

Hopefully, they still work!! I've got at least 4 extension cords and low wires hanging around in my garage shop. At some point they could be replaced with additional circuits, but at no point will it probably be needed. None are near the forge, though! Already burned through a loose extension cord laying around a few months ago.