Every part of the process, even the pouring, must be done with extreme skill and care or the product suffers.
After liberation from their molds, the ingots are heated and either rolled or hammered down to the sizes desired for tools, etc.
As stated before, crucible steel necessarily is an expensive material both on account of high labor and crucible costs. For this reason, many have resorted to the process used in the very small way mentioned for the manufacture of Wootz steel—the melting of wrought iron bar or soft steel in a crucible with carbon.
In the Wootz process chopped wood and green leaves were used. Nowadays charcoal is substituted or there is added the proper amount of cast iron to give the desired amount of carbon to the wrought iron or soft steel charged. During the melting the iron takes up the charcoal and alloys with it.
“Teeming” or Pouring into Ingots. The Ingots Later Are Forged or Rolled into Bars from Which the Tools Are Made
Proper amounts of silicon, manganese, and other beneficial materials are also charged, which become either part of the alloy itself or have a cleaning or fluxing action upon it.
Steels made in this way are practically, though perhaps not quite, as good as steels made by melting together the properly selected cementation bars. The method has come to be very generally used on account of its directness and because it eliminates the long and expensive preliminary cementation process.
When Bessemer and open-hearth steels made their appearance in the market an attempt was made to use them instead of wrought iron as the base for high grade crucible steels. Though seemingly pure enough, apparently purer even than wrought iron, these metals were not able to compete with wrought iron for this purpose. For some reason, not yet satisfactorily explained, these new materials which are made in 15, 35 and 50–ton batches, when used as a base, do not give as high quality tool steel as puddled wrought iron, which is slowly and laboriously made in 500–pound lots. Considerable of these materials are utilized but it is for a somewhat lower grade of crucible steel.
For many years mild steels for castings have been quite largely made by the crucible process. They are among the best but the crucible and labor costs are usually too great to allow crucible steel castings to compete in present markets.