Thread: Are these cast steel blades any good

Swedish or french origin or something where the alloying probably naturally included chromium, nickel or trace amounts of vanadium.

I haven't done as much historical reading about the stuff as I should, but I have heat treated some really low hardenability steels and it's clear that if natural ore had something in it that pinned grain size a little bit and slowed the needed transition time, that is the only way to get good results.

this became a quick fascination of mine when a discussion was going on in the blue forum in the US about how we use A2 now because we now have good steel and before then, everyone was guessing and the quality was poor and hardness inconsistent. This turns out to be nonsense, and with a fair amount of hobbyist hand heat treatment, I can hit a very narrow range of tested hardness even with water hardening. With oil hardening, it comes down to a small fraction of a point.

Someone doing this all day would have ended up with results that were absurdly consistent because people don't do habitual things drastically different when they are in automatic mode.

And then I got a metallurgical scope and took a picture of a buck iron worn heavily in a plane made around 1830, and unused (maker JT brown in the US).

The uniformity of the steel was far finer than anything else, finer even than O1. I've come to learn why this is now and can identify carbide volume and size - similar to what O1 would be in terms of carbon content and hardness, but fewer carbides. It looks like 1084 after it wears - by no means contaminated with anything meaningful.

AS time goes on, you start to realize that irons like these mathiesons are generally almost identical from one to the next. If I think about it this weekend, I'll get a picture similar to that above - it only takes about five minutes of planing to get the carbides to show themselves and see how stable the edge is. Hardness varies between makers, but not much within during a same area, so an old wives tale is created that all chisels varied a lot as if someone was hardening drunk in the middle of a clown routine (actually, it could probably be done very well and consistently drunk, but maybe not while juggling and applying clown paint).

It's true that chemistry wasn't well understood, but that statement offers a false problem - that outcomes can only be gotten consistently if every single thing about them is understood. The reality when results counted and aren't understood is that there is a premium on natural sources of good ore or ores with specific characteristics (high nickel or other alloying content in some cases creating a naturally stainless steel), and then the makers use the same source and do the same thing and at times, the variation is less than that within a large commercial oven.

But as you say, the ore was sourced elsewhere if manipulating it wasn't understood. Even once chemistry was understood in the 1920s or 1930s, sometimes characteristics were attributed to additions and later found not to be properly linked (perhaps something like tungsten was assumed to make steel more hardenable by a metallurgist in a patent, but did something else).

Not that there aren't very useful additions - air hardening steel makes a slow transition stable steel for making dies - and it through hardens in thick cross sections. Additions of molybdenum and cobalt and others create higher hot hardness and suddenly metalwork can be done faster.

But the "people were dumb long ago, had no idea what they were doing and just survived while we thrive with better modern stuff" is a very dippy view. One that's pretty common.

Prior to the 1860s, Sheffield was the primary source of cast iron to th USA. It was a very established and mature industry, the opinions about the quality of their production are just guesses out of ignorance.

This book is a very interesting read regarding the history of tool steel. There's a preview, not 100% of the book is accessible, but there's plenty of interesting history in it. If I remember correctly, somewhere in there says that the ores for steel manufacture came from Sweden.

Google Books

Rafael

Albeit in this case, I didn't do my best to check the edge before planing - this plane was probably doing rough work last. there's still enough detail here to see how fine the steel is. The worn edge is to the right, and it looks like fudge or clay compared to the chunky peanut butter look that many steels now have due to carbides.

https://i.imgur.com/mtrTWr4.jpg

If you look at the picture, this may be hard to follow, but anything that looks like a discontinuity at the edge generally originated from a scratch from the india stone and you can see some are still there and some worth off.

most of my other pictures are more carefully sharpened and checked so that these don't show up (picture later of 1.25% carbon showing this).

But, compare the carbides in the XHP (V11) picture vs. this steel. it is exceptionally fine. I'd guess that it's very plain, 0.8-0.9% carbon. Above that level, you start to see iron carbides standing proud in the matrix. Add chromium and the iron carbide formation increases as it combines with it.

It's probably worth having a few of these run through XRF as the steel isn't quite like anything now. 1084 may be close, but subjectively, 1084 isn't quite as good, and 1095 has enough carbon to create a pretty strong visible matrix of carbides like the ones in the hollow on the picture of O1.

All in all, excellent stuff. the picture would be even better if I'd done my job to get the edge finer instead of just whipping the plane out and sharpening in a minute and a half before this.

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A little more about what you're seeing in this picture. it's at true 300x optical. you can see things (like carbides) down to about 1 micron in size. there's some speculation that you can't see things smaller than 3 microns, but that's false. I think that's based on misinterpretation that a polish is reasonably bright off of a 3 micron waterstone. A 1 micron polish is brighter by a good bit.

So, you're seeing about .009" of iron length in the photo. The edge goes from looking like more prominent scratches to smudged - that smudge is wear from the wood passing over the back of the iron (this is the flat side) and rubbing the metal as it runs into the cap iron. The cap iron holds the wood down and permits this , otherwise you don't get the same smooth area. this is the wear from planing about 210 feet of cherry. Further planing would mkae the edge more worn but more uniform.

i turned the light down and didn't see anything. For comparison to this iron is W2, a steel I have made a few irons from (very plain, but does have some additions and carbon is about 0.96% in the melt that the steel came from - translation, we expect to see carbides.

With bright light, the W2 looks like this.
https://i.imgur.com/i1Qr58A.jpg (note some of the waviness is because this was a newly manufactured iron that I made and the scratches are from a rotary lap - they were at least partially honed out).

Back to the point - hard to see the carbides. Turn down the light to get some shadows so that the light isn't washed out.
https://i.imgur.com/0Oixoyp.jpg

you begin to see little dots at the edge. turn it down much further (different part of the iron, but same iron):
https://i.imgur.com/BluwKKW.jpg

Suddenly, you can see the carbides prominently. When I turned the light down on the mathieson iron, these don't show up.

That leads us to guess that they very intentionally made and used a steel that had little excess carbide over the eutectoid limit where carbides start to form visibly between the grains. and there is good reason for this if your heat treat process will be accurate but simple - no carbides, nothing to dissolve into the steel matrix and you can more or less heat the steel to nonmagnetic plus very little and then quench in water and get a relatively hard sample and a very stable edge.

As you add carbon (but not much else) well beyond 1%, the carbides become more prominent and larger, but at least in some cases, do not lead to a ragged edge. This is 1.25% carbon steel that has small amounts of manganese and chromium for hardenability. The iron carbides are prominent enough to show up well in very bright light.

https://i.imgur.com/z4QRWVU.jpg


so, I can't offer a chemical analysis, but I can show comparisons of the fineness to 1084 and we can get a sense of about what the carbon content is. If it's below my estimate, the edge begins to become stable (for example, a 0.6% carbon steel will start to have stability problems at the edge and would also not have the same tempered hardness as the mathieson iron shown here.

I have not yet found a really old iron that shows prominent carbides - I don't believe the trade in sheffield had much appreciation for driving up hardness because when the carbides are iron only, the edge life doesn't really increase. It starts to increase only when other elements (V11 as a lot of carbon but pairs an enormous amount of chromium with it- it's almost stainless. Which I believe is why Lee Valley could use XHP and not have it present elsewhere in spades - I think it was intended to be stainless, and it doesn't rust much in knives in regular use unless water is left on them on purpose, but it does take stains from food. This is apparently unacceptable to the prissy. I've made a couple of kitchen knives out of it and the discoloration from food acids is minor, and it doesn't rust at all with regular care)

I purchased a hardness tester a couple of days ago. it's a portable type, but is a 150kg dial scale diamond indent type - the same thing the large stationary testers do to test hardness, and same amount of weight, just in a portable version so the user has to operate the screw and do it accurately vs. allowing the machine to slowly lower weights to hit the test target.

Long story short, I mentioned my iron was perceptibly hard compared to many other vintage irons, and my sample tested at 63 hardness rockwell C.

this tester is not a superficial tester (it indents deeply and there's no need to convert the measurement to what it maybe if done under the full 150kg load). And from what i gather so far, is within about 0.5 points of stationary testers when used on chisels and plane irons.

Another nice, but perceptibly not quite as hard Ward and Payne iron (just tested) - 61.5 rockwell C.

if anything, the ward's hardness may make it a little nicer to use day to day for anything but very fine smoothing, but that assumes that a user is competent enough to generate the edge fineness that would differentiate the two.

Another surprise - 1950s stanley 61.5 hardness. Same generation of iron after I rehardened the iron in question and tempered only around 350F - 63.5 hardness. both of these work well.

I can test earlier irons, but I don't trust the results from laminated stanley irons because the lamination is soft and the hard layer is thinner than the minimum thickness required. I suspect that the hard layer springs back enough to throw off the test as a sweetheart laminated iron shows at 63. Same with an early laminated block plane iron (also definitely not 63).

All other numbers here gotten only on irons or chisels with layers thick enough to not be affected based on physical tester requirements.

I tested a second mathieson laminated iron from a jack plane. may or may not have been the same era - but both are relatively old.

It is also 63 hardness.

A ward parallel iron (for infill planes) also tested 63, and a pair of ward tapered irons for wooden planes were just under and just over 61 hardness.

if sharpening freehand with touch, there's a very obvious difference between an iron 61 and one 63, which is why i was able to make an accurate initial comment about the hardness of the mathieson iron. The 63 hardness ward parallel iron feels identical. If the ore came from the same place and the carbon content was identical or close, I wouldn't be surprised.