When is the full shear strength of an MS20470D rivet obtained?

The full shear strength of an MS20470D rivet is achieved after a period of age hardening. This process typically involves allowing the rivet to reach its optimal strength over time, which occurs as the materials undergo changes in their microstructure. Age hardening, or precipitation hardening, enhances the mechanical properties of certain alloys, particularly those made of aluminum, which is a common material for these rivets.

Immediately after installation, the rivet may not have developed its maximum strength because the alloy's microstructure has not yet undergone the transformations necessary for peak properties. High temperatures can affect rivet strength in various ways, often leading to weakening rather than strengthening. While painting a rivet may provide some level of protection against corrosion, it does not influence the mechanical strength in terms of shear capacity. Thus, the correct answer highlights the importance of age hardening in achieving the desired strength in MS20470D rivets.