The aluminum bracket is not affected at all by normal temperature fluctuations. Once you start going below negative 40 degrees Celsius, it may become quite brittle. At temperatures above 800 degrees Celsius it starts to melt.
The steel bracket may be a bit more vulnerable in expanding and contracting with heat and cold, but in our applications, it will not affect the integrity or holding strength in any way, shape, or form that we have encountered or know of.