Abstract: Metallic bodies having discontinuously contacting sheet surfaces such as convolute-wound corrugated/non-corrugated metal sheet auto catalyst supports having metal-to-metal diffusion bonds formed at the contacting surfaces are provided. The diffusion bonds formed at the contacting surfaces are provided. The diffusion bonds are produced by heating the body in a non-oxidizing atmosphere, whereby metal from one surface diffuses into the metal from an adjacent surface. Some bonds may also be formed by welding. The bond-formation step may be performed in tandem with a subsequent step of oxidizing the sheet surfaces where they are not bonded, e.g. for making them into a more effectively-adhesive substrate for the catalyst they are to bear.