Abstract: A disc-shaped nonmagnetic support body for a recording medium which can be magnetized particularly (vertically) has at least one flat side with a very smooth surface, on which at least one magnetizable storage layer can be placed. It should be possible to provide this carrier body readily with appropriate surfaces, and it should be dimensionally stable and sufficiently fracture-proof. A chemically hardened glass substrate is therefore provided which comprises, besides Na.sup.+ ions, K.sup.+ ions incorporated in zones near the surface and in addition Ag.sup.+ ions and/or Ag atoms. For hardening this glass substrate by means of an ion exchange process below the transformation temperature characteristic of the glass material, the substrate is advantageously placed for a predetermined time in a KNO.sub.3 melt, to which advantageously, maximally 10% by weight AgNO.sub.3 has been added.