A generic term describing a family of iron alloys containing 1.8–4.5% carbon. Cast iron usually is made into specified shapes, called castings, for direct use or for processing by machining, heat treating, or assembly. In special cases it may be forged or rolled moderately. Generally, it is unsuitable for drawing into rods or wire, although to a limited extent it has been continuously cast into rods and shapes from a liquid bath or swaged from bars into smaller-dimensional units. Silicon usually is present in amounts up to 3%, but special compositions are made containing up to 6% (Silal) and up to 12% (Duriron).