Yes you have to declare them. Quarantine will look on an agricultural side of things, meaning are they clean, dirt/soil (which I doubt they will) attached, dust that sort of thing. Quarantine have many different types of treatments in Australia for cleaning (not just a steam clean). Regardless if they are panel beating tools I am sure if you give them a clean up they will be fine.
In regards to Customs however if you are bringing them under tools of trade you may (not 100% sure) have some customs duties & taxes to pay even if they are used, because it is not technically personal effects, they are tools of trade and you could be liable to pay some duties.
I dont know type of quantities you are bringing, but either way just check it out.
If you need contacts for moving companies over there that can assist, let me know.
All the best