Hot metal is a type of steel that was developed during the late 19th century in conjunction with the development of pig iron making techniques
When pig iron is melted, it becomes molten and a great deal of energy is required to keep it at this temperature. To do this, hot-working furnaces were developed that could melt pig iron castings in order to forge them into wrought iron. These open-hearth furnaces allowed the molten metal to be heated by hot air through jets or by hot coke or coal dust being blown on top of the molten metal. This process allowed for much more control over the temperature of the molten metal and consequently made possible much higher quality finished products than those produced by traditional methods.
jpx900 hot metal vs forged