本文選題：高氮鋼 + 晶間腐蝕　； 參考：《東北石油大學》2017年碩士論文

【摘要】：高氮不銹鋼是耐蝕鋼材中比較突出的材料之一,氮元素價格低廉,可以將大部分昂貴鎳元素替換掉,能穩(wěn)定鋼中奧氏體,更能改善不銹鋼局部腐蝕。固溶處理使氮元素在不銹鋼中均勻分布,阻礙貧鉻區(qū)出現,起降低晶間腐蝕的作用。本文采用真空感應熔煉方法,制備高氮奧氏體不銹鋼。對制備所得材料的成分、組織和結構進行檢測,并在3%(wt)的Na Cl溶液中對其常態(tài)以及固溶處理后的極化曲線及阻抗譜進行測試。采用電化學動電位再活化法(EPR)以及草酸侵蝕試驗對固溶處理后敏化處理的材料的晶間腐蝕性能進行研究,能夠較準確的反映固溶處理對高氮鋼的耐晶間腐蝕性能的影響。常態(tài)下,升高溶液溫度使鈍化區(qū)間縮小,鈍化膜層電阻降低,腐蝕越容易。腐蝕介質由酸性逐漸變?yōu)閴A性,膜層電阻增大,鈍化穩(wěn)定性能變好。隨著固溶溫度升高及保溫時間增長,使最初為骨架狀鐵素體轉變?yōu)楣饣膱A形。電化學實驗表明,保溫時間較短時,隨溫度升高,鈍化電流密度縮小,腐蝕減緩,膜層耐蝕性提高,試樣鈍化穩(wěn)定性提高;時間過長時,膜層電阻降低,抗腐蝕能力變差,鈍化膜均勻性降低導致腐蝕性能變差。經1050℃保溫20min可以得到耐蝕性能較好的試樣。EPR測試選用H2SO4+Na2S4O6溶液體系適合檢測高氮奧氏體不銹鋼。測試表明,保溫時間較短,固溶溫度升高,再活化率R值降低,電量比Qr/Qa降低;保溫時間過長,R值增大,電量比Qr/Qa變大。在草酸浸蝕實驗中,選取10%草酸溶液作為電解液,在1A的恒電流下對材料侵蝕90s,結論與EPR實驗相一致。保溫時間較短,隨固溶溫度升高,晶粒長大,晶界面積減小,耐晶間腐蝕性強;保溫時間過長,析出物等出現,晶間腐蝕沿晶界發(fā)生,耐晶間腐蝕性能變差;在1050℃下保溫20min試樣的耐晶間腐蝕性能優(yōu)良。
[Abstract]:High nitrogen stainless steel is one of the most prominent materials in corrosion resistant steel. The low price of nitrogen element can replace most expensive nickel elements, which can stabilize austenite in steel and improve local corrosion of stainless steel. The solution treatment makes the nitrogen element distribute uniformly in stainless steel, which hinders the appearance of chromium-poor zone, and plays the role of reducing intergranular corrosion. In this paper, high nitrogen austenitic stainless steel was prepared by vacuum induction melting. The composition, microstructure and structure of the prepared materials were determined, and the polarization curves and impedance spectra of the prepared materials were measured in NaCl solution of 3 wts. The electrochemical potentiodynamic reactivation method (EPRR) and oxalic acid erosion test were used to study the intergranular corrosion properties of the materials sensitized by solid solution treatment, which can accurately reflect the effect of solid solution treatment on the intergranular corrosion resistance of high nitrogen steel. Under normal condition, increasing the solution temperature reduces the passivation interval and decreases the resistance of the passivation film, which makes corrosion easier. The corrosion medium changed from acidic to alkaline, the film resistance increased and the passivation stability improved. With the increase of solution temperature and holding time, the initial skeleton ferrite is transformed into a smooth circle. The electrochemical experiments show that when the holding time is short, the passivation current density decreases with the increase of temperature, the corrosion slows down, the corrosion resistance of the film increases, and the passivation stability of the sample increases, and when the holding time is too long, the resistance of the film decreases and the corrosion resistance becomes worse. The decrease of the uniformity of passivation film leads to the deterioration of corrosion performance. The sample with good corrosion resistance can be obtained by holding 20min at 1050 鈩，

本文編號：1949578