If I move a file from a bitlocker enabled drive/partition to a non bitlocker drive/partition what happens to the file?
Does it stay encrypted but unreadable?
Does encryption disappear?
The encryption only applies to the disk that is BitLocker encrypted. Just as the files are automatically decrypted when you open them, they are decrypted before moving them to the non-BitLocker drive.
According to Microsoft on their Help protect your files using BitLocker Drive Encryption page:
However, if you copy these files to another drive or a different PC, they're automatically decrypted.