SHEET-METAL -

[folkda]

I want to flatten the attached.

Notice the thick red line that depicts an open edge - the point is to have the corners bent and physically welded and polished (for stainless steel)
But Catia will not keep the geometry where the three radii meet.

 

[JeniaL]

Catia won't bend this radius. How will you physically fabricate this part? Brake press won't help you. The way to go is to switch to GSD.
Trim corners / fillets as necessary and use unfold command to get flat pattern. Not perfect and you'll definitely correct flat pattern.

 

[jackk]

Instead of modeling it with Part Design and converting it to Sheetmetal, model it directly in Sheetmetal. I think there is an option for corners like this.