Intergranular corrosion behavior of a 13Cr martensitic stainless steel (MSS) in tempered condition was studied. Tempering was done in the temperature range of 300-700 °C after austenitization, and microstructure was established using scanning and transmission electron microscopy. Electrochemical characterizations to establish localized corrosion susceptibility were performed in 5% HNO₃ solution. The MSS tempered at 550 °C showed sensitization and significant localized attack during tests in HNO₃. Characterization of surface film on this condition revealed an oxide with a higher defect density (through electrochemical impedance spectroscopy–Mott–Schottky analysis) and Fe content (x-ray photoelectron spectroscopy) as compared to that for the austenitized condition. The inability of sensitized MSS tempered at 550 °C to form a protective surface film was attributed to the formation of considerable nano-sized Cr-rich carbide precipitates associated with narrow Cr depletion zones. On the other hand, the MSS tempered at 300 and 700 °C did not show any localized attack in HNO₃ and this was attributed to lack of sensitization at 300 °C and de-sensitization at 700 °C.

中文翻译：

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13Cr马氏体不锈钢在硝酸溶液中的电化学行为和钝化性能

研究了回火条件下13Cr马氏体不锈钢（MSS）的晶间腐蚀行为。奥氏体化后在300-700°C的温度范围内进行回火，并使用扫描和透射电子显微镜建立显微组织。在5％HNO ₃溶液中进行电化学表征以建立局部腐蚀敏感性。在550°C下回火的MSS在HNO ₃中的测试过程中显示出敏化和明显的局部腐蚀。与在奥氏体化条件下相比，在这种条件下对表面膜的表征表明，氧化物的缺陷密度更高（通过电化学阻抗谱-莫特-肖特基分析）和铁含量（x射线光电子能谱）。在550°C下回火的敏化MSS无法形成保护性表面膜的原因是，形成了与狭窄的Cr耗尽区相关的大量纳米级富Cr碳化物沉淀。另一方面，在300和700°C回火的MSS在HNO _3中未显示任何局部侵蚀，这归因于在300°C缺乏敏化和在700°C脱敏。