METHOD OF MAKING SURFACE LAYERS WITH IMPROVED CORROSION PROPERTIES ON ARTICLES OF IRON-CHROMIUM ALLOYS, AND A SURFACE LAYER MADE BY THE METHOD

摘要

ABSTRACT OF THE DISCLOSUREA method for making surface layers with improved cor-rosion properties on articles of iron-chromium alloys is disclosed.By enriching the surface of iron-chromium alloys, high corrosionresistance may be obtained without alloying the complete steelmatrix, The method includes heating the articles in an oxygenatmosphere having a vacuum in the range of 10-1 to 10-8 mm Hg, toa temperature at which diffusion of reactive alloy components com-bine with oxygen on a surface layer of the article, The tempe-rature is such that all the other properties of the article aremaintained, The temperature is maintained until the surface layeris oxidized to a thickness in the range of 10-9 to 10-7 m, wherebythe surface layer forms part of the matrix of the metal alloy,