The difference in thermal expansion and contraction rates between forged and casted/machined metallic parts can be attributed to several factors related to their microstructure and manufacturing processes:
1. Microstructure Differences
- Forged Parts: Forging involves deforming the metal under high pressure, which aligns the grain structure and results in a more uniform and denser microstructure. This can lead to more consistent thermal expansion behavior across the material.
- Casted Parts: Casting involves pouring molten metal into a mold, which can lead to irregularities in the grain structure. The cooling process can create different phases and microstructural features that may not expand or contract uniformly, resulting in varying thermal properties.
2. Density and Porosity
- Forged Parts: The forging process typically results in lower porosity and higher density, contributing to more predictable thermal expansion behavior. The absence of air pockets or voids reduces