Developments Self-Hardening Steel
There is little doubt but that there is considerable misunderstanding among machinists in the 1890s regarding the use of self-hardening steel. It is quite common to resort to this steel where the ordinary carbon steel used in the shop does not stand well, or refuses to cut; then if the self-hardening steel does not work it is considered that every resource has been exhausted. The fact is, however, that while it is true that self-hardening steel will often do good work where the ordinary steel fails, or is unsatisfactory, carbon steel of high grade and high carbon can be and is made and hardened in the usual way, that will readily cut metals that no self-hardening steel can make an impression upon.
It is said a number of coarse files or rasps have been piled upon each other to a height of 12 inches, bound together with wire and drilled through from top to bottom of the pile without lubricant. This was not done by a drill made of self-hardening steel, nor of such common steel as is too often supplied by purchasing agents who give far more attention to discounts and commissions than to quality of steel they buy, but by a high-grade carbon steel made especially for use in such a test.
Mushet or self-hardening steel is all right in its place, but there are places for which it is not adapted, and it is best, both for makers and users, that the proper place and uses of the different kinds of steel should be understood.
Mushet steel is typically harder than standard water quenched steel. The typical chemical composition of Mushet steel contains 9% tngsten, 2.5% manganese and 1.85% carbon. Mushet steel is hardened by air-blasting the part after forging.