Set default material on several meshes at once

Hi,
I would like to know if there is a way to define a default material on mesh import.
I imported a lot of parts, and they all have the default grid material. However i want to change the material to a base material but i don’t find anyway to do this except by changing it in the mesh properties for each mesh…
I took a look into the Bulk Edit tool, i can change the Phys Mat but not the Material itself.
Plus, another problem is showing up. I edited those meshes, and when i reimport them, UE crashes if no material is assigned…