The method of melting steel in crucibles or pots was brought into use as a means of improving the product of the cementation furnace, as mentioned in Par. 113. The introduction of the Bessemer and the open-hearth steel-making processes left very limited need for the product of the cementation furnace, but the method of purifying steel and iron scrap by melting it in the crucible gave a means of producing a higher quality of steel than could be supplied by other processes. The crucible melting feature of the cementation process was therefore retained and turned to excellent use. The expense of the crucible process (about three times that of the open-hearth process) would soon cause the disuse of crucible-made steel if the steel made by other processes could be substituted for it.

The ingredients in crucible steel can be regulated as desired, giving full control of the kind of product turned out, and making possible the manufacture of many alloy steels containing small quantities of unusual ingredients which would not bring dependable results, by the Bessemer and open-hearth methods.

The crucible method is in many cases a method of steel refining rather than one of steel making.

The method of manufacture - melting in small pots containing about 100 lbs. - makes the crucible-steel output very small when compared with Bessemer and open-hearth outputs, and the product is disposed of entirely in making metal-cutting tools, wood-working tools, piano and other wires of high quality, highly tempered springs, armor-piercing projectiles and other steel articles demanding exceptional purity or hardness. Crucible steel is sometimes designated as cast steel, or crucible cast steel, because it may be cast into various shapes by pouring from the crucible into suitable moulds, and it is the first method by which steel castings were made.