DE 3711451 A UPAB: 19970307 Rolls with a wavy surface for use in the mfr. of currugated cardboard receive a partially hardened surface structure with a hardened zone in the shape of a circular segment on each wave crest. The max.thickness of this zone is 0.35 mm. Its width is bounded by a tangent at 45 deg. to the radial plane through the crest. The pref. surface hardening method is based on a CO2 laser beam of under 500 W output. ADVANTAGE - The thickness of the hardened zone is now such that it has been removed completely, on reaching the max. permissible wear. It is not necessary, to soft anneal the roll before reconditioning its surface.