Early modern steel included Blister Steel manufactured by the cementation process which was first made around the 16th century in Italy and soon after in England were it was produced in Coalbrookdale by Basil Brooke around 1610.Â Wrought iron bars was the raw material used in the process, and was still used up till the 19th century.
Another early modern steel was Crucible Steel which was melted in a crucible rather then being forged.Â This resulted in a more uniform structure with better composition throughout.Â Earlier furnaces could not reach high enough temperatures to melt steel.Â Modern crucible steel resulted from the invention of Benjamin Huntsman in the 1740’s. Blister Steel (same as above) was melted in a crucible in side a furnace, & cast into ingots normally.
Early modern steel era ended and Modern steel making era began with the Bessemer Process named after it’s inventor Henry Bessemer who took out a patent on the process in 1855. although this process had already been used centuries before in china and other countries it was not used on an industrial scale before.Â The process was independently discovered in 1851 by William Kelly. The Bessemer process was the first inexpensive industrial process for mass production of steel from molten pig iron.Â The key to the process is the removal of impurities from the iron by oxidation by air being blown through the molten iron.
the Bessemer Process which revolutionized steel manufacture by cutting cost and increasing production speed and decreasing labor requirements.Â this brought the price of steel down to a similar priced wrought iron, which for the first time in history made steel an affordable material for building bridges or to be used in the frame work for buildings, most manufactures switched from wrought iron to steel after this.Â
With the introduction of the Bessemer process in 1858 the modern steel making era began. The Bessemer process allowed for large quantities of steel to be produced cheaply, effectively replacing wrought iron with steel, however this was just the first of many production methods used in modern steel making most were just improvements on the Bessemer process one of these was the Gilchrist-Thomas process created by Sidney Gilchrist Thomas and cousinPercy Gilchrist devised in 1876-77 this process was widely used in Europe there after.
The Gilchrist-Thomas process of manufacturing in Bessemer converters a kind of low-phosphorus steel known as Thomas steel. In the Thomas – Gilchrist process the lining used in the converter is basic rather than acidic, and it captures the acidic phosphorus oxides formed upon blowing air through molten iron. the Gilchrist-Thomas process was an improvement on the Bessemer process.
Another improvement on the Bessemer process was the Siemens-Martin process, In 1865, the french engineer Pierre-Emile Martin took out a licence from Carl Wilhelm Siemens and first applied his furnace for making steel. Their process was known as the Siemens-Martin process, and the furnace as an "open-hearth" furnace. The most appealing characteristic of the Siemens regenerative furnace is the rapid production of large quantities of basic steel, used for example to construct high-rise buildings. The usual size of furnaces is 50 to 100 tons, but for some special processes they may have a capacity of 250 or even 500 tons. The Siemens-Martin process complemented rather than replaced the Bessemer process. It is slower and thus easier to control.
Both the Gilchrist-Thomas process and Siemens-Martin process complemented, rather than replaced the original Bessemer process
Siemens-Martin Oven below
The Bessemer process was rendered obsolete by the Linz-Donawitz process of basic oxygen steel making developed in the 1950’s, by 1968 most all commercial steel producers stopped using the Bessemer process and replaced it with the Linz-Donawitz process which offered better control of final chemistry. The Bessemer process was so fast (10-20 minutes for a heat) that it allowed little time for chemical analysis or adjustment of the alloying elements in the steel. Bessemer converters did not remove phosphorus efficiently from the molten steel; as low-phosphorus ores became more expensive, conversion costs increased. The process only permitted a limited amount of scrap steel to be charged, further increasing costs, especially when scrap was inexpensive. Certain grades of steel were sensitive to the nitrogen which was part of the air blast passing through the steel.
Linz Donawitz Oven below
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