Bushelled Iron
After heating a mixture of thin sheet or other soft steel and wrought iron scrap to a welding heat in a reverberatory furnace, it may be balled and put through the squeezer, muck rolls, etc., as was the true wrought iron made by puddling. This manipulation of scrap is known as the bushelling process and the product as “bushelled iron” or “scrap bar.” By using scrap bar for the outer layers and old wrought iron bars cut to length for the interior, box piles are made, which, heated and rolled, make very good material, though not as good as puddled iron. Certain grades on the market, e. g., common bar iron, contain more or less of this bushelled iron, but the better grades, refined wrought iron, double refined wrought iron, engine and stay-bolt iron, are usually the pure puddled product.
As with the latter, repeated shearing, piling, and rolling improve the quality.
Bushelled iron is largely the result of an endeavor to reduce the cost of production of wrought iron. The material has a legitimate place and considerable of it is used.
CHAPTER VII
CEMENTATION AND CRUCIBLE STEELS
In the early days practically the only steels recognized—certainly the only ones desired—were of the high carbon or hardening variety. These were required for the manufacture of swords and other implements of war, for tools, etc., most of which had to have hard and sharp cutting edges.
When softer and less brittle metal was desired, wrought iron was available, but in all probability high carbon steel was the material most largely used.
Having but the two iron alloys and these of very different properties, it was not difficult to distinguish between them. A piece of metal could be heated to redness and plunged into cold water. If it became glass hard when cooled in this way it was thereby proved to be steel; if still soft, it was iron.
But the problem is not so simple to-day. Medium, mild and yet softer steels, and other alloys which have steel characteristics have appeared and are used in immense quantities. Their advent introduced considerable complication.
It will be well, therefore, before taking up our subject, “Cementation and Crucible Steel,” and the several steels which are to follow, to make sure that we all understand, as well as we may, what is “steel” as defined to-day, what are the best known varieties, and what are their characteristics?