1.10 to 1.50 carbon for lathe-tools, graving-tools, scribers, scrapers, little drills, and many similar purposes.
The best all-around tool-steel is found between .90 and 1.10 carbon; steel that can be adapted safely and successfully to more uses than any other temper.
At somewhere from .90 to 1.00 carbon, iron appears to be saturated with carbon, giving the highest efficiency in tools and the highest results in the testing-machine except for compressive strains. More will be said upon this point in treating of the carbon-line.
Much more could be said about the uses for the different tempers of steel; it would be easy to write out in great detail the exact carbon which experience has shown to be best adapted to any one of hundreds of different uses, but it would only be confusing and misleading to a great many people.
It is within the experience of every steel-maker that men are just as variable as steel, and the successful steel-maker must familiarize himself with the personal equations of his patrons. One man on the sunny side of a street may be making an excellent kind of tool from a certain grade and temper of steel, and be perfectly happy and prosperous in its use. His competitor on the shady side of the street may fail in trying to use the same steel for the same purpose and condemn it utterly.
The know it all agent will condemn the latter man with an intimation that his ears are too long, and so lose his trade. The tactful agent will supply him with steel a temper higher or a temper lower, until he hits upon the right one, and so will retain both men on his list; and both men will turn out equally good products.
Few men know their own personal equations, and the best way for a steel-user to do is to tell the steel-maker what he wants to accomplish, and put upon him the responsibility of selecting the best temper.
It costs no more to make and to provide one temper than another; therefore the one inducement of the steel-maker is to give his patron that which is best adapted to his use. This plan puts all of the responsibility upon the steel-maker, just where it ought to be, because he should know more about the adaptability of his steel than any other person.
BESSEMER STEEL.
Bessemer steel is probably the cheapest of all grades of steel; that is to say, it can be made so rapidly, so continuously, and in such enormous quantities that a greater output per dollar invested can be made than by either of the other processes. Again, the work is controlled and operated by machinery to a much greater extent than in the other processes; therefore the cost of labor per ton of product both for skilled and unskilled labor is less than in the crucible or the open-hearth method.