ISO/TR 16060:2003 gives a non-exhaustive list of etchants that can be used for the macroscopic and microscopic examination of welds in accordance with ISO 17639 for the following groups of materials: carbon steels and low-alloy steels;stainless steels;nickel and nickel alloys;titanium and titanium alloys;copper and copper alloys;aluminium and aluminium alloys.