Pickling in Weak Acid Exposes the “Fibers” of Wrought Iron
As pig iron contains 3½% or more of carbon, while wrought iron has none or comparatively little of this embrittling element, any process for converting the pig iron into wrought iron must eliminate the carbon.
Following the advent of pig iron as a commercial product several furnaces and processes were developed to turn it into wrought iron. All of these were based upon the elimination of the carbon by oxidation, which means the burning of the carbon in presence of oxygen of the air.
The best known ones were the Walloon or Swedish Lancashire process, the South Wales process, the Finery Fire, the Running-Out Fire and the Charcoal Finery or Knobbling process. The Walloon furnace, largely used in Sweden, is shown in the illustration on page [94].
While by the process generally used to-day wrought iron is more easily and cheaply produced, it must be said that by the processes above named has been made as fine iron as has ever been produced. The Sheffield manufacturers, whose high grade steel made by the crucible process, is so widely and favorably known for cutlery, tools, etc., in many cases yet demand the Walloon process iron made from high grade Swedish ores as the starting point for their product.
Bar Iron Will Stand Severe Bending Even After It Has Been Nicked
Swedish Walloon Furnace
One of several types of furnaces that preceded the Reverberatory. Some of them are still used.