On the role of grain size and carbon content on the sensitization and desensitization behavior of 301 austenitic stainless steel

Abstract

<div lang="en" class="abs"><p class="abs_header">Abstract</p><p>The effect of grain size in the range 72 to 190 μm and carbon content in the range 0.105–0.073 wt.% on the intergranular corrosion of the austenitic stainless steel 301 has been investigated. Grain boundary chromium depletion has been studied directly using energy dispersive X-ray spectroscopy combined with scanning transmission electron microscopy and indirectly using double loop electrochemical potentiokinetic reactivation tests. In addition, chromium depletion has been modelled using the CALPHAD Thermo-Calc software TC-DICTRA. It is shown that the degree of sensitization measured using the double loop electrochemical potentiokinetic reactivation tests can be successfully predicted with the aid of a depletion parameter based on the modelled chromium depletion profiles for heat treatment times covering both the sensitization and de-sensitization or self-healing. Additionally, along with intergranular M₂₃C₆ carbides, intragranular M₂₃C₆ and Cr₂N nitrides that affect the available Cr for grain boundary carbide precipitation were also observed.</p></div>