Just looked at Kia's exclusions
www.kia.com
and they include
'Normal deterioration
Normal wear, tear or deterioration such as discolouration, fading or deformation
Surface corrosion on any part other than the sheet metal panels on the exterior body'
and
'Damage due to factors beyond the manufacturer's control
Examples of this could include:
Damage or surface corrosion from the environment such as acid rain, airborne fallout (chemicals, bird lime, tree sap, etc),
salt, road hazards, hail, wind, storm, lightning, floods and other acts of God'.
My underline and italics.
I think Kia will say 'no' as an automatic response to this but they have responded with recalls if it can be shown to be a manufacturing defect. Your call Elaine. Brake pipes are not that expensive to have replaced and they will need repair whilst you argue the toss with Kia (via the dealer who will need convincing first). Kia Customer Services do have a presence on this forum so it may be worth giving them the heads up as they can get involved if a dealer is not following the procedure.
Good luck with it anyway as this should not be happening on a 6yr old car these days.