If you purchase from CAP Barbell or from an authorized retailer, the dumbbells have a 30-day warranty that only covers manufacturing defects. It does not cover "paint peeling, rust, rips, cuts and tears, dents, bent handles, loose heads if dropped or any other signs of misuse such as knocking dumbbells together".
There is a 1-year limited warranty against manufacturing defects and some websites offer a 30-day satisfaction guarantee.