Yes, laser engraving and laser marking metal is possible. Trotec laser machines can engrave and mark different types of metal. A laser engraver enables metal marking through different methods: Annealing marking, engraving and removing. Below you can find an explanation of the processes. To achieve these finishes you need to have a laser machine with a fiber laser source. Many Trotec lasers, including laser etching machines, can can process metals.
You can find more information about different laser types here.