Castings or Forgings?
Most steel components start asCastings: metal that has been melted, poured into a mold and solidified. In the casting process at the foundry, because the mold has the shape of the desired component, all that remains to be done after casting are the various finishing operations.
Forgings, the first shape is an ingot or continuously cast billet. Ingots are large, usually rectangular in form and weigh up to several tons. Ingots or continuously cast billets are forged into shapes by hammers or presses. Extensive machining to final configuration usually is required, and welding also may be necessary before finishing operations can begin.
In forging, solid metal is forced into the die cavity.
In casting, liquid metal is poured into the mold cavity.
Forging : the practicality of forging decreases,as complexity of shape increases.
Castings can accommodate great complexity of shape.
In castings, the metal is isotropic,
In casting, mechanical properties are achieved in all directions (see Fig. 1–2).
the ductility and impact strength of steel castings generally lie between the longitudinal and transverse values of forgings.
In Forging , the metals are anisotropic.
Thus, wrought steel and forgings in particular, are anisotropic (exhibiting different values of a property in different directions). the mechanical characteristics of a forging, most forging references provide only longitudinal characteristics. However, tensile strength, elongation and impact properties decrease in the transverse and axial directions.