A look into the two traditional methods of parts productions in engineering which are metal forging in the form of foundry and heat treatments and the counterpart which is metal forming in the form of machining of a solid metal into a required shape.
The principle of metal strength in toughness and hardness has a lot to do with the competiveness of the metal crystals structure. If the crystals are closely fitted together, then the metal will exhibit more toughness and hardness than the same material with their crystals loosely compacted in their structure.
Ideally, casted metals due exhibit some faults in crystals arrangement especially when the casting is carried out by an inexperienced personnel, however; the fault can always be corrected by the application of heat treatment to the cast metal, despite that the crystal arrangement of metal deeply depends on the method in which the metal in put into shape, a commercial solid iron had been properly treated to have a good crystal arrangement but this arrangement can be altered once the metal is subjected to a shaping process such as rolling, pressing, forging, and forming.
Forming has less impact to crystal structure when compared to other methods since the metal will only have some of its parts cut off to obtain a new shape of the intended part. But when the parent metal was not properly treated to have hardness and toughness the product of the formed part will exhibit the same property except when subjected to further treatment.
However, experiment revealed that cast or forged metal parts tend to exhibit more toughness and hardness with the disadvantage of being brittle due to their crystal arrangement. Meanwhile, formed metal parts may exhibit lower toughness and hardness but they have the advantage of being malleable in their properties.