Can I somehow convert .part files to .mp3 format?
It is unfortunately not possible to directly convert Partially Downloaded Files to MP3 Audio Files (.part to .mp3 conversion).
Try renaming the file's suffix from PART to MP3. The file might be playable via some modern media player. In most cases, however, such files will be corrupted.
Your only option is to download the file again. In best-case scenario, the system will allow you to resume downloading the already partially downloaded PART file.
In a word, direct part to mp3 conversion is not possible.
So don't expect any so-called part to mp3 converter or part to mp3 free online conversion tool available.
The database currently does not contain any part software converter.