The microstructure and electrochemical properties of 316L stainless steel were investigated after two conditions: aged at 640°C for 100,700 h and solution annealed at 1050°C for 2 h. While the aged samples were obtained from a pipe of a petrochemical reactor plant that was in service, the solution annealing was carried out in a conventional laboratory furnace. After aging, the precipitates present in decreasing order of quantity were sigma, Laves phase, and M₂₃C₆. After solution annealing, the microstructure was full austenitic. These results were in agreement with equilibria phase simulation with Thermo-Calc software. Intergranular corrosion susceptibility, evaluated by means of the single loop electrochemical potentiokinetic reactivation technique and Practice A of ASTM 262, indicated a preponderant role for the sigma precipitate. The pitting potential (E_pit) was evaluated through potentiodynamic polarization curves in 0.6 M NaCl and electrochemical impedance spectroscopy was performed at the corrosion potential to complement the information about the corrosion resistance.

中文翻译：

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某石油化工厂在 640°C 下暴露 100,700 小时的 AISI 316L 钢管道微观结构与腐蚀行为的相关性

在两种条件下研究了 316L 不锈钢的微观结构和电化学性能：在 640°C 下时效 100,700 小时和在 1050°C 下固溶退火 2 小时。虽然老化样品是从正在使用的石化反应器工厂的管道中获得的，但固溶退火是在传统的实验室炉中进行的。时效后，析出物的数量递减顺序为 sigma、Laves 相和 M ₂₃ C ₆. 固溶退火后，显微组织为全奥氏体。这些结果与使用 Thermo-Calc 软件进行的平衡相模拟一致。通过单回路电化学动电位再活化技术和 ASTM 262 的实践 A 评估的晶间腐蚀敏感性表明西格玛沉淀物起主要作用。通过在 0.6 M NaCl 中的动电位极化曲线评估点蚀电位 ( E _pit )，并在腐蚀电位下进行电化学阻抗谱以补充有关耐腐蚀性的信息。