from a different point of view than some expressed here......
case hardening is a surface treatment done as a final process.It is not to create some other steel
And what is the method of "deep carburized"?
actually the most widely used method of making steel for centuries in fact used a similar process to pack case hardening in order to "deep carburize it" - it was called blister steel........this was then often further processed into shear steel (a random pattern "Damascus") and later crucible or "cast" steel
1) Blister-steel: Steel formed by roasting wrought iron bars in contact with carbon in a cementing furnace. It is so called from the blistered appearance of it's outer skin. To improve the quality, it was subjected to two subsequent processes, which converted it into shear-steel and cast-steel.
Blister steel was NOT a one off method for individual blades, but rather a method of making large amounts of steel - this method was developed circa the 1500's. James Hanson mentions in his Fur Trade Cutlery Sketch Book, that the bars of wrought iron used for making blister steel were 2" x 4" x 20 feet.
2) Shear-steel: Blister-steel was sheared into shorter, manageable lengths, heated, and tilt hammered to homogenize the steel which improved the quality. Several bars are welded together and drawn out. Shear-steel is named from its applicability to the manufacture of cutting instruments, shears, knives, scythes, etc. The bar is sometimes cut, fagoted, reheated, and again tilted. This may be repeated. The terms single shear and double shear indicate the extent to which the process is carried.
This is in fact a type/form of random pattern pattern welded Damascus first introduced into England circa 1690. It was widely used for blades of all types through the end of the 19th Century. Unlike modern times when Damascus is generally etched to accentuate the grain/pattern, shear steel blades were polished during the 18th/19th century, so one cannot tell just by looking, unless one does an etch or other test.
Was raw shear steel stock imported to the New World? Possibly, but so far I've come across no documentation of such importation. On the other hand finished blades of shear steel were IMO most likely imported, since until the 1760-70's, when crucible steel production was well on it's way, it was the most widely used cutlery steel in Sheffield, Eng. and thousands of English knives were imported. IMO documentation for such importation, if it exists would most likley be in the form of invoices to cutlers/makers/dealers in the large trade centers - documentation for it's use on the frontiere would be negligible at best.
3) Cast-steel (aka crucible steel - I believe this is the steel Mike Ameling alluded to above): Blister steel which has been broken up, fused in a crucible, cast into ingots, and rolled. The blocks of steel are melted in crucibles of re fractory clay, and the molten metal is poured into ingot-molds of cast-iron. These are opened, to let out the red-hot ingot, which is then passed to the rolls.
The process of making cast/crucible steel was developed by Benjamin Huntsman, of Sheffield, England, circa 1745. Oddly, crucible steel at first was not greeted well by the Sheffield makers while the French cutlers soon recognized it's qualities. The Sheffield makers even went so far as to ask the government for an embargo on the raw steel.
By 1840 the English had developed the cast steel method to the point that English steel made in this way became 40% (about 20,000 tons a year - up from the 200 tons a year produced by the English using all previous methods) of all steel produced in Europe (other steel centers of note during the period were: Germany (manganese and other trace minerals in the local ore made it a better than normal alloy), Spain, and Sweden). A few years later, in the 1850's, the Bessemer process was developed which increased steel production immensely.
and FWIW and with all due respect to many of my learned colleagues here -there are many folks (the world is after all MUCH wider than the "custom knife world") who are interested in re-producing those methods in the interest of historical re-productions/study. And while they do not make a knife or sword or ax "better" in technological terms, for those interested in such things it is a way of "touching" the past (and it it's own way making it "better" for them) that CAN NOT be duplicated by using modern methods or materials.....
as always others mileage will vary.......
PS this of course does not mean that everybody should "return to the past", only that there are different reasons for building knives, etc - of course if ones choice is to make modern pieces than one should use modern materials..........
