Chapter 11 Iron and Steel Ironmaking • Steelmaking
Elements present in pig iron must be refined to allowable amounts to meet steelmaking specifications.
The microstructure of wrought iron consists of ferrite grains incorporating a large quantity of silicate slag elongated in the working direction.
In the basic oxygen furnace, oxygen is lanced into the molten pig iron and scrap steel.
The electric-arc furnace is the most common furnace used in making many alloys of steel.
Each level of deoxidation practice exhibits a significant influence on the macrostructure of the ingot.
A shroud is used to protect the molten steel from picking up atmospheric gases as it is poured from the ladle into the mold.
The four types of semifinished forms (blooms, billets, slabs, and rounds) are defined by shape and dimensions.
The ingot mold is tapered to facilitate its removal from the steel ingot after solidification.
The macrostructure of a cast ingot consists of a chill zone of fine equiaxed grains adjacent to the mold wall, columnar grains that grow perpendicular to the wall, and equiaxed grains toward the center.
Primary rolling reduces the ingot to semifinished forms of desired cross section.
Continuous casting is a direct and continuous method of producing blooms, billets, slabs, and rounds.
Heavy press forging is performed in a large hydraulic press in order to reduce the size of the ingot to a semifinishedform larger than a standard bloom.
Structural shapes are formed in several rolling sequences, known as roughing, intermediate rolling, and finishing.
Wire is drawn in several stages, known as drafts, on a wire drawing machine. After each draft the wire is coiled.
Inclusions become elongated in the working direction of the steel and lead to directional mechanical properties, known as anisotropy.
The AISI-SAE designation system indicates the alloying elements and the partial chemical composition.
The end use of carbon steel is strongly influenced by the carbon content.
Generic ASTM specifications indicate common characteristics of families of product forms and prevent excessive repetition in the individual product specifications.
Quality descriptors in ASTM standards are used to distinguish products well suited to specific applications.