Influence of temperature and pH on SCC assisted by H_2S susceptibility of 22 Cr duplex

摘要

Depending on environmental conditions UNS S32205 duplex stainless steel may suffer from Stress Corrosion Cracking (SCC) assisted by H_2S initiated by local corrosion processes that involve the selective dissolution of the ferritic phase or the austenitic phase. The intent of this paper is first to study the evolution of the susceptibility of SCC assisted by H_2S according temperature and pH. In a second phase, links are highlighted between the differences of cracking resistance and localized corrosion morphologies. Results show that the temperature of highest susceptibility to SCC assisted by H_2S depends on the pH of the environment, moving from 80 °C at low pH (2.8 - 3.5) to temperature between 50 - 20 °C at higher pH (4.5 - 6.0). The maximum of cracking susceptibility seems to correlate with selective corrosion of ferrite coupled with transgranular cracks of the austenite.