Nondestructive Microstructural Characterization of Superduplex Stainless Steel by Double Loop Electrochemical Polarization Reactivation Portable Test

Superduplex stainless steels (SDSS) are frequently employed in the petrochemical industries where is required high mechanical strength, toughness, and corrosion resistance. However, these properties can be affected by deleterious phases formation due thermomechanical processes applied in the field during pipes and vessels construction. This work propose the nondestructive microstructural characterization of deleterious phases precipitated in SDSS isothermally treated in 800 and 850ºC using portable double loop electrochemical polarization reactivation tests (DL-EPR). The results obtained in this nondestructive test are quite close to those obtained by conventional test, and can be correlated with the amount of deleterious phases precipitated. It can be concluded that the microstructural degradation of superduplex stainless steel can be evaluated by portable DL-EPR test with slow sweep rates, using a special cell and a proper electrolyte at room temperature.超级双相不锈钢（Superduplex Stainless Steels, SDSS）常被应用于对力学强度、韧性及耐蚀性有较高要求的石油化工行业。然而，在管道与容器现场施工过程中所采用的热机械加工工艺，会促使有害相生成，进而影响上述性能。本研究采用便携式双环电化学极化再活化试验（Double Loop Electrochemical Polarization Reactivation Tests, DL-EPR），对经800℃与850℃等温处理的超级双相不锈钢中析出的有害相进行无损微观结构表征。该无损检测方法所得结果与常规试验结果高度吻合，且可与析出有害相的含量建立关联。综上，在室温条件下，采用专用电解池与适配电解液、以慢速扫描速率开展便携式DL-EPR试验，即可对超级双相不锈钢的微观结构退化程度进行评估。