Effect of heating by electric current and external heating on the structure of aluminum wire

Conclusions

• 1. A change in the structure over the length of the wire, beginning at the terminal, is a basic structural indication of current overload; there is no coarse-grain segment in the vicinity of the burn zone.

• 2. The magnitude of the overload can be estimated by comparing the distances from the terminal to the segments with the recrystallized structure and (or) burn; the higher the overload, the smaller these distances.

• 3. A coarse recrystallized grain near the burn zone and an extended region with a partially recrystallized structure are indications of local external heating.

• 4. A finer grain in the burn zone as compared with the coarse-grain structure of the recrystallization zone is an indication of an overload that precedes heating to 600°C.