If you must identify the weakest among billet, cast, and forged based on the given scores, which material is weakest?

• A. Cast metal
• B. Billet metal
• C. Forged metal
• D. Unknown

Answer: (A)

When evaluating strength based on how the material is processed, the form most prone to weakness is cast metal. Casting creates parts by pouring molten metal into a mold, which often traps porosity, shrinkage cavities, and other defects. The resulting microstructure tends to be coarse and randomly oriented, which lowers yield strength, tensile strength, and fatigue resistance compared with work‑shaped forms. Forging, on the other hand, deforms the metal under heat, breaking up and realigning grains, closing voids, and producing a directional grain flow that greatly enhances strength and toughness. A billet is just a starting stock that will typically be further worked; its properties can be substantially improved through forging or other deformation, but in its basic cast state, casting generally yields the weakest material among the three.