What term describes the decrease in a material's strength due to environmental effects over time?

The term that describes the decrease in a material's strength due to environmental effects over time is degradation. This concept encompasses a variety of processes that can lead to the weakening of materials, including chemical reactions with the environment, such as exposure to moisture, temperature fluctuations, or harmful chemicals. Over time, these interactions can alter the material's microstructure or mechanical properties, resulting in reduced strength and performance.

Degradation is a broad term that could include various specific phenomena like corrosion, which is a chemical process where materials, typically metals, react with their environment leading to deterioration. However, degradation refers more generally to any kind of reduction in the material's capabilities and includes other factors like UV exposure, fatigue due to cyclic loading, and thermal effects.

By contrast, fatigue generally refers specifically to the progressive and localized structural damage that occurs when a material is subjected to cyclic loading over time, which is different from environmental degradation. Creep is associated with the time-dependent deformation of materials under constant stress, particularly at elevated temperatures, and does not encompass the broader range of environmental effects. Corrosion specifically pertains to the chemical degradation typically involving metals reacting with their environment, but not all degradation processes involve corrosion alone.