Any GREAT Deals on BILLET AR Lowers?

[KevinBLC]

I guess my question was... why is a forged lower stronger than a billet? I thought they were both aluminum? What am I missing?

[Hatter]

Your question revolves around understanding material properties and the effects of processes on those material properties. This involves heat treatments, forging, cold working, casting etc.

Forged aluminum has material and mechanical properties on par with some low to mid grade steels. The "ballpark" answer would be that this is a result of grain structure in the material after the forging process is complete. This is why machining processes can actually temper materials by heating them and allowing them to cool slowly as compared to a quench and temper process with a much faster cooling rate (for example this provides different martensitic grain structures in steels, resulting in different strengths).

A deeper answer could be obtained from a literature search (I recommend Shigley's Mechanical Engineering Design) regarding work processes of materials. The key characteristics being material ultimate and yield strength.