The semi-finished products, which in turn are distinguished in: square section, rectangular section, flattened, blanks for profiles, for seamless tubes. The finished pieces are obtained: percolate of steel in sand, from semi-finished products for further plastic processing and through removal of material. Carpentry products, called sections or girders, have a double cross-section. They can be variously combined for the formation of composite structures as shown by Tool and Die Technology.
The term steel indicates in a generic way an alloy between 2 main elements: iron and carbon. Other elements present in the steel are: manganese, phosphorus, sulfur, silicon and in smaller quantities nitrogen, aluminum and oxygen. Iron is a metallic element and its chemical symbol is Fe. Carbon is a non-metallic element, C is its chemical symbol; is the main binding element in steel alloys and its percentage content fluctuates between 0.002% and 2.1%, in terms of weight (in most steels it hardly exceeds 1%).