"cast steel" timeframe

[Bill Haumann]

I know this is very general, but is there an approximate time frame when "cast steel" was stamped on plane irons and chisels?
Also, what are the significant qualities of "cast steel"?

- Bill

[Mike Henderson]

Cast steel, also called crucible steel, is iron with a certain percentage, by weight, of carbon that has been completely melted. In the west, it was invented by Benjamin Huntsman in about 1740.

Prior to Huntsman, steel was made in a number of ways, with mixed results. Iron ore was melted in a furnace using charcoal to produce a spongy mass of iron and slag, called a bloom. The carbon was generally oxidized out of the bloom so the result was iron. The bloom was processed by hammering to produce wrought iron. Occasionally, and very difficult to control, some of the bloom would have sufficient carbon to qualify as steel.

Again, prior to cast steel, a method of making steel from wrought iron was to take thin bars of wrought iron and pack them in a case with carbon rich material, such as powdered charcoal. The box was then heated for up to a week allowing the carbon to diffuse into the iron. The problem was that the outside had more carbon than the inside. To spread the carbon, the bars were heated, folded, hammered, folded again, etc. This was called the cementation process (also called "blister steel") and the folded steel was called shear steel.

But for many applications, the irregular carbon content was a problem. Huntsman developed a method of melting wrought iron in a crucible with carbon material to create steel. By melting the iron/steel, it produced a homogeneous material. Later, the charge consisted of cast iron (high carbon) and wrought iron.

The way the furnace was constructed, the crucible had to be pulled upward to remove it from the furnace. Since everything at that time was manual, it was a man who pulled the crucible out by hand - a crucible that was glowing hot at the temperature of liquid steel. So the whole thing, the crucible and the charge, couldn't weight more than maybe 50-90 pounds. The man who pulled those out was known as the "puller-out". The liquid steel was then poured into a mold to produce a small bar of steel. The man who poured the steel was known as a "Teemer"

This made crucible steel very expensive, which is why you see laminated tools from that era. Only the cutting edge would be made of cast steel, the rest of the tool was made from wrought iron.

Crucible steel began to be eclipsed by the invention of Bessemer steel (around 1860) and then open hearth steel. But even then, crucible steel was better and was used for cutting tools. The electric furnace put the nail in the coffin of crucible steel. The last crucible steel foundry closed in the late 1960's - in England, I believe. But towards the end, I believe the crucible process was used for certain specialty steels with low volume demand, and not regular carbon steel which was much cheaper from the electric furnace.

This is all from memory so some of the info may be incorrect. I'm sure others will correct me if I made errors.

A very good reference is the two volume set "Steelmaking before Bessemer" by K. C. Barraclough, here and here.

Mike

[Once steel from electric furnaces were used, most tool makers started marking their tools as "Best Tool Steel" rather than "Best Cast Steel". The electric furnace began to be used in volume in the early 1900's, I think, maybe around the time of WWI.]

[george wilson]

The British were making crucible steel like Mike described well into the 20th.C.. I mentioned in another thread that in the 70's I purchased a NEW Marples wooden plane with a new made bitted blade in it.

The cast steel you see stamped on tools could span a great many years,especially English tools.

[David Weaver]

Speaking totally away from whether or not the term cast steel on a tool meant that the steel used was crucible steel (hopefully it was not stamped on modern bessemer steel), usually tools that say "cast steel" have a very plain fine grained steel at the cutting edge. It may not be universally true, but to this point through all of the buck, butcher, etc. that I have gotten my hands on, I have yet to get a tool marked "cast steel" that I didn't like the fineness of the steel. That doesn't mean it's as hard as I'd like, in some cases it's not ( buck chisels are often a little soft, as are a lot of the older tanged chisels that are not laminated - that may be a concession to sharpening ease ), but the steel itself is fine grained and holds up well and is predictable for its level of hardness.

I can't say the same thing for everything that says warranted on it, which may have been nothing more than continuation of a prior practice when it meant more.

[george wilson]

These days,you might see "cast pot metal" on tools.

[Jim Koepke]

These days,you might see "cast pot metal" on tools.

Or "Best Crap Steel."

jtk

[Mike Henderson]

To be fair, good steel today is far superior to the steel made back in the 18th and 19th Centuries. When crucible steel was made, for example, people didn't fully understand the chemistry of steel and making it was hit or miss. Each steelmaker had their "formulas" for making steel but they didn't have control over their inputs. They might receive an ore that had more of a certain impurity than their previous batch, for example, and the steel would come out different. They also had minimal control over their process, which also caused variations in the steel. I've seen letters (in books) sent by steel users to makers complaining about the variation in steel in different deliveries. For example, they might say, "That last batch of steel you went us was unusable. We need more good steel like you sent us in the previous shipment. Please send us another shipment of good steel."

The amount of carbon in the steel was also very difficult to control, being the result of the materials put into the pot, the impurities in the material, the temperature of the process, and any leaks of air that would cause reduced carbon in the melt. It was also dependent on the skill of the maker, which varied, and the care put into the process, which also varied because of pressure to produce more steel.

Then, the making of the tool and the hardening and tempering was also dependent on the skill and care of the worker.

We should rejoice that steel today is as good as it is. We're spoiled.

Mike

[george wilson]

Of course,I was joking. Of course we have better steels. It's more like; do they use it,or,do they harden and temper it properly? Frequently drawn too soft to not splinter in someone's eye and cause the ambulance chasers to get on them. Sometimes,just the lowest carbon steel that they can get by with is used. A Fine Woodworking article years ago found that Sears chisels,made in Holland,were made from .50% carbon. JUST enough that they would harden,but extremely low on edge durability.

[David Weaver]

White steel #1, or even #2 from a good blacksmith. Fantastic stuff. Same with swedish high carbon (as in 1.2%+).

For all of the talk about old steels, I haven't seen any that match those.

[Ray Gardiner]

This is all from memory so some of the info may be incorrect. I'm sure others will correct me if I made errors.

Hi Mike,
Excellent summary, and it's not easy to write "the history of steel" in a few sentences. I would have perhaps put "pig iron" and "cast iron" in there as pre-cursors to "wrought iron" but that's minor correction.

Nice summary.

Regards
Ray