Dissertation
Dissertation > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metal corrosion protection,metal surface treatment > Corrosion control and protection > Metal surface protection technology

Research on the Mechanism of Electrochemically Induced Surface Annealing in Stainless Steel and Improvement of the Technique

Author WuZong
Tutor LiZhiLin
School Beijing University of Chemical Technology
Course Materials Science and Engineering
Keywords Electrochemically induced annealing Stainless steel Hydrogen Cathode / anode time pH value Deal with media Corrosion resistance
CLC TG174.4
Type Master's thesis
Year 2011
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Electrochemically induced annealing (Electrochemically Induced Surface Annealing, EISA) is positive and negative alternating pulse processing a metastable austenitic stainless steel to improve its corrosion resistance . Since the phenomenon is found for its mechanism has never stopped , but it has not come to a definitive conclusion , and a single processing medium sodium nitrite limit the actual engineering of the process , the liquid waste treatment will lead to environmental pollution . This article by cathode hydrogen charging method of observation to the course of the reaction of hydrogen in the process of EISA , show that the hydrogen to penetrate into the surface layer of the stainless steel cathode in the electrical pulse stage and the anode phase is re-oxidized back to the processing medium , partially confirmed Burstein et al hypotheses about the the phenomenon mechanism of EISA . Also studied the influence of the cathode / anode time , pH of the medium , the cathode potential , and other factors on the EISA treatment effect , determine the long the cathode / short anode electric pulse processing method , the phase change of the processing time is shorter than the three hours the EISA , improve the processing efficiency . In addition, different medium stainless steel processing of positive and negative alternating pulses of XRD , metallographic observation , cyclic voltammetry , potentiodynamic scanning the organization before and after the change in the method of processing , corrosion resistance change mechanism, the results show that : the EISA phase change medium can be other than the sodium nitrite , such as sodium carbonate solution , nitrogen does not occur EISA phase change necessary conditions . Sodium carbonate in the EISA phase transition can also reduce the sensitivity of the pitting corrosion of stainless steel in NaCl solution ; the electrical pulse processing sodium sulfite , sodium silicate , sodium acetate and sodium hydroxide solution easily lead to martensite is priority corrosion .

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