Impressions and Conclusions of the Conference on Mechanical Properties and adherence of scale layers and their influence on the oxidation of metals

✍ Scribed by D. R. Holmes; W. H. Whitlow

• Publisher: John Wiley and Sons
• Year: 1972
• Tongue: German
• Weight: 904 KB
• Volume: 23
• Category: Article
• ISSN: 0947-5117
• DOI: 10.1002/maco.19720230902

✦ Synopsis

Abstract

Review of the papers presented to the Conference and of discussions. The topics dealt with included the various ways in which growing oxide scales can deform to accommodate their growth stresses. According to that plastic deformation occurs by the following mechanisms: dislocation glide, dislocation climb, Herring‐Nabarro stress‐assisted diffusion creep, grain‐boundary sliding, mechanical twinning and viscous flow of amorphous oxides. The deformation depends on the scale configuration and the stress system; many oxide systems are rather plastic at high temperatures, but pores, defect doping elements and second phase inclusions play important parts, too. It is generally accepted that the evidence for some plastic deformation in growing oxide scales is very strong, the most favoured mechanism at high temperatures being diffusion controlled creep associated with grain boundary sliding. Factors influencing adhesion of scales include electrostatic forces at the metalloxide interface, interface irregularities, stress/strain interactions between oxide and metal, stress relaxation in metal and oxide, and the presence of stress raisers such as voids, second phase particles and pores at the metal/oxide interface. The necessity of developing new measuring methods is pointed out, too.