高溫成長氧化膜增進410不銹鋼抵抗應力腐蝕破裂

Improving Stress Corrosion Cracking Resistance of AISI 410 Stainless Steel By Thermally Grown Oxide Films S. K. Yen and S. L. Ging

本研究係將AISI 410麻田散鐵型不銹鋼經各種不同熱氧化條件，形成以鐵或以鉻為主之氧化物膜，其中富鉻氧化膜則被認為是較具保護性之氧化物膜；經由浸泡實驗、氫擴散實驗及慢速拉伸之應力腐蝕試驗，發現試片在300℃經20分鐘氧化後，其在1N H2SO4或0.6 M NaCl溶液中具有較優異之抗蝕性（比未處理者）；同時在0.6 M NaCl + 10-2M Na2S溶液中能提高抵抗應力腐蝕之能力；在氫擴散方面，此氧化物膜亦能減緩氧之擴散，而降低金屬中之氫濃度，使氫脆不易發生。而此性能之提高，我們認為主要是由於經如此處理之試片能在表層富鐵氧化物及基材金屬間形成一層富鉻層，當鐵氧化物面臨腐蝕環境而被侵蝕後，此富鉻層便暴露於環境中，展現其保護之特性，使腐蝕因子或氫擴散受到阻擋，達到抗蝕、抗應力腐蝕及抗氫脆之效果。

In this study , the AIS 410 martensitic stainless steel was oxidized to form an iron or chromium rich oxide film. The latter has been considered to be protective in some corrosive environment. Through immersion tests, hydrogen permeation tests, and slow—strain rate tests(SSRT), it was found that the specimen oxidized at 300℃ for 20min was protective in 1 N H2SO4 or 0.6 M NaCl solutions and the elongation was increased in 0.6 M NaCl + 10-2 M Na2S solutions under the SSRT. The oxide film also showed the retarding effect on hydrogen entry and reduced the hydrogen concentration in the metal substrate. It is suggested that those protective effects are due to some chromium-rich layer formed between the iron-rich oxide film and the metal substrate. After iron-rich oxide was etched by the corrosive solution, the chromium rich layer will face environments and show protective.