General Steel Making: The Cementation Process

The cementation process is a now-obsolete technique for making steel with the carburization of iron. Unlike modern steelmaking it increased the amount of carbon in the iron. It was apparently developed before the 17th century. The process probably originated in Bohemia in the 16th century and was in use in Bavaria in the early 1600’s. The process was patented in England by Ellyot and Meysey in about 1614.

The cementation process of making steel is also called the converting process. This process consists in impregnating bars of wrought iron or soft steel with carbon, at a temperature below its melting point, and was used (chiefly in England) for the production of high carbon bars boom beach cheats tool to be employed in the manufacture of crucible steel or shear steel. The bars were usually of pure Swedish iron made by the Walloon process. They are packed in layers, separated by charcoal (sometimes called cement) in fire-brick chambers (converting pots) heated externally by flues, and forming part of the cementing furnace. The top of the pot is closed with an arch of wheel swarf, which later frits and forms an air-tight cover. The furnace attains its full temperature in about 3 to 4 days, at which it is maintained about 7 to 8 days for mild heats, about 9 days for medium heats, and about 11 days for high carbon heats; the cooling down requires about 4 to 6 days. To test the progress of the operation, trial bars (test bars or tap bars) are drawn at intervals through a special small aperture, provided for the purpose, and examined. If wrought iron has been employed, the finished bars will be found covered with blisters formed by the reaction between the contained slag and the carbon, from which comes the name blister bar or blister steel; at one time this was sometimes termed German steel.

This phenomenon is absent when steel bars are treated; both products are known as cement (cemented) bars or cement steel. Bars desired of very high carbon may be retreated, and are known as doubly converted bars or glazed bars. Since the carbon penetrates from the outside inward, the percentage will decrease progressively to the center. In very mild bars there is an unaltered core of mild general steel called sap, and very hard bars are easily distinguished by being what is known as flaked, as on fracture they present bright cleavage planes. It is important to have the transition from one grade to the other as gradual as possible: when the line of demarcation is too abrupt, the process has been carried out too rapidly, and the bars are said to be flushed. If, owing to a leak in the pot, air has entered, the outside of the bars will be somewhat oxidized, and are called aired bars. If the temperature has been a little too high, so the outside has fused slightly, they are called glazed bars. Blister bars rolled or hammered down at a yellow heat are known as plated bars or bar steel.

The following are various methods suggested or tried from time to time: In Bink’s process compounds of cyanogen were specified, and currents of nitrogen, carbonic oxide, and ammonia, or ammonia alone, were to be passed through decarburized molten iron. In Boullet’s process iron was to be cemented with a substance consisting of sugar, horn dust or shavings, animal fat or blood, and wood charcoal dried and pulverized. In Brooman’s process iron was to be melted in pots with compounds of cyanogen; such compounds might consist of charcoal, salt, brick dust or oxide of manganese, sal ammoniac, and ferrocyanide of potash. Henry Brown’s process consisted in cementing iron in a granulated condition in close pots with carbon: iron which was being puddled was taken out of the furnace as soon as it became granulated, and before it was pasty; it was then broken up until it would pass through a 20-mesh screen, after which it was put in dominations cheats hack tool long pots with wood and cemented as usual. James Boydell’s process was to cement the product obtained by boom beach hack tool online puddling wrought iron melted in a cupola. In Holland’s process silk waste of every kind was to be torrifled, i.e., dried at a high temperature without being carbonized, and then ground to a fine powder and used for cementing.