Farklı Miktarlarda Niyobyum ile Alaşımlandırılmış Ferritik Paslanmaz Çeliğin Sülfürik Asitte Elektrokimyasal Sentezi

Bu çalışmada, Nb miktarının etkisini belirlemek için belirli oranlarda Nb elementine sahip üç tip paslanmaz çelik alaşımın korozyon davranışları sentezlenmiştir. Niyobyum, çelikler için stabilize edici elementtir. Ayrıca niyobyum, kromdan daha yüksek afiniteye sahiptir. Bu yüzden niyobyum, niyobyum karbür yaparak tane içinde krom fakirleşmesini önler. Niyobyum mikroalaşım, çeliğin yeniden kristalleşmesini kontrol etmek için kullanılan yararlı bir prosedürdür. Niyobyum mikroalaşım, tane inceltme ile de ilgilidir. FSS numuneleri alaşımsızdır ve %0.5 ve %1 Nb numuneleri ile alaşımlanmıştır. Alaşımsız numune, referans numunedir. Numuneler döküm ve dövme ürünüdür. Homojenizasyon elde etmek için numunelere farklı ısıl işlemler uygulanmıştır. Numuneler sülfürik asit çözeltisine maruz bırakılmıştır. Ferritik paslanmaz çelik (FSS) elektrotları, elektrokimyasal empedans spektroskopisi (EIS) kullanılarak analiz edilmiştir. Testler, oda sıcaklığında üç elektrotlu sistem kullanılarak yapılmıştır. Numune yüzeylerindeki korozyon ürünlerinin morfolojisi SEM ile incelenmiştir. SEM mikrografları, numunelerin çözelti içinde çukurcuk korozyonuna uğradığı görülmüştür. Korozyon hızları Stearn-Geary denklemi ile hesaplanmıştır. Hem niyobyum alaşımının hem de 30 dakikalık ısıl işlemin, ferritik paslanmaz çeliğin çukurcuk korozyonuna karşı korozyon direncini arttırdığı gözlemlenmiştir. Sonuçlar, niyobyumun pasif tabakayı güçlendirdiğini göstermiştir.Anahtar kelimeler: Ferritic paslanmaz çelik, niyobyum, korozyon, ferritik paslanmaz çelik.

The Electrochemical Synthesis of Ferritic Stainless Steel Alloyed With Nb in H2SO4 Environment

The current paper, the corrosion behaviors of three types stainless steel alloys with particular Nb element rates synthesized to determine the influence of Nb amount. Niobium is stabilizing element for steels. Besides niobium has higher affinity than chromium. So niobium prevents chromium depletion by making niobium carbide. Niobium microalloying is helpful procedure in order to control recrystallization of steel. Niobium microalloying is related on grain refinement. FSS samples were unalloyed and alloyed with 0.5 and 1% Nb samples. Unalloyed sample is referance sample. The specimens are casting and then forging products. Different heat treatments were applied to samples because of homogenization. The samples were exposed the sulphric acid solution. Ferritic stainless steel (FSS) electrodes were analyzed using electrochemical impedance spectroscopy (EIS). The experiments were performed using with three electrodes system at room temperature. The corrosion product morpholgy on the surface tests of specimens was investigated with SEM. SEM micrographs showed that the samples exposed the generalized pitting in the solution. Corrosion rate was accounted by Stearn-Geary equation. It was observed that both niobium alloying and heat treatment for 30 minutes is increased oxidation resistance of ferritic stainless steel to pitting corrosion. The results indicated that niobium reinforced the passif layer.Keywords: Ferritic stainless steel, niobium, corrosion, electrochemical synthesis.

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[1] Beck T.R. 1974. Reactions and Electrochemical Kinetics of Freshly Generated Metal Surfaces. Corrosion, 30: 408-411.
[2] Scully J.C. 1975. The role of hydrogen in stress corrosion cracking. In: A.W. Thompson and I.M. Bernstein, Editors, Effect of Hydrogen on Behavior of Materials, Proceedings of an International Conference, AIME.
[3] Yu Y., Shironita S., Souma, K., Umeda, M. 2018. Effect of Chromium Content on the corrosion resistance of ferritic stainless steel in sulfuric acid solutions. Heliyon, ,4 (11): 1-13.
[4] Zhang X.J., Gao F., Liu Z., 2016. Effect of Sn on the Pitting Corrosion Behavior of Ultra‐Purified 17% Cr Ferritic Stainless Steel. J. of Iron and Steel Research, 2310: 1044-1053.
[5] Stemp M., Mischler S., Landolt D. 2003. The effect of mechanical and electrochemical parameters on the tribocorrosion rate of stainless steel in sulphuric acid. Wear, 255: 466-475.
[6] Nam N.D., Kim J.K. 2010. Effect of Niobium on the corrosion behaviour of low alloy steel in sulfuric acid solution. Corrosion Science, 52: 3377-3384.
[7] Bojinov M.,Fabricius G., Laitine T.,Makela K.,Saario T., Sundholm G. 2001. Influence of molybdenum on the conduction mechanism in passive films on iron-chromium alloys in sulphuric acid solution, Electrochimica Acta, 46: 1339-1358.
[8] Baia G., Lu S., Lia D., Lia Y. 2016. Influences of niobium and solution treatment temperature on pitting corrosion behaviour of stabilised austenitic stainless steels. Corrosion Science, 108: 111- 124.
[9] Idiri M., Boubeker B., Sabot R., Goudeau J-F., Dinhut J-L. GrosseauP. 1999. Structure and related corrosion behavior in 1M H2SO4 of bcc 304L films prepared by ion beam sputtering. Surface and Coatings Technology, 122: 230-234.
[10] Irani H., Ghazani M.S. 2020. Effect of grain refinement on tensile properties and electrochemical behavior of Fe-18.5%Cr ferritic stainless steel. Mat Chem and Phys, 251: 123089.
[11] Luon H., Su H., Dong C., Xiao K, Li X. 2015. Data in Brief, 5: 171-178.
[12] Kim Y.J., Oh S.K., Ahn S., Oh K., Jung K., Kwon H. 2018. Electrochemical Analysis on the potential decay behavior of Fe-20Cr stainless steels in sulfuric acid solutions. Electrochimica Acta, 266: 1-6.
[13] Luo H., Su H., Dong C., Li X. 2017. Passivation and electrochemical behavior of 316L stainless steel in chlorinated simulated concrete pore solution. App Surface Science, 400: 38-48.
[14] Xu J., Wu X., Han E. 2012. The evolution of electrochemical behavior and oxide film properties of 304 stainless steel in high temperature aques environment. Electrochimica Acta, 71: 219-226.
[15] El-Shenawy EH, El-bitar T, Anchev V. 2005. EIS as a Non Destructive Technique to Investigate the Corrosion Behavior of Some Nb-bearing 304L Stainless Steel in NaCl Solution. The 9th International Mining, Petroleum and Metallurgical Engineering Conference, Cairo University, February 21-24.
[16] Hamdy A.S., El-Shenawy E., El-Bitar T. 2006. Electrochemical Impedance Spectroscopy Study of the Corrosion Behavior of Some Niobium Bearing Stainless Steels in 3.5% NaCl J. Electrochem. Sci.,1: 171-180.
[17] Cowan R.L., Tedmon C.S. 1973. Advances in Corrosion Science and Technology. in: M.G. Fontana and R.W. Staehle Eds., Vol. 3, New York, NY, Plenum.
[18] Sedriks A.J. 1996. Corrosion of Stainless Steels. 2nd ed., John Wiley, New York, NY.
[19] Kain V., Prasad R.C., De P.K. 2002. Testing sensitization and predicting ... corrosion and intergranular stress corrosion cracking. Corrosion, 58: 15-38.
[20] Kain V., Chandra K., Adhe K.N., De P.K. 2004. Effect of cold work on low-temperature sensitization behavior of austenitic stainless steel. J. of Nuclear Materials, 334: 115-132.
[21] Lee J.B. 2006. Effects of alloying elements, Cr, Mo and N on repassivation characteristics of stainless steels using the abrading electrode technique. Materials Chemistry and Physics, 99: 224.
[22] Demiroren H. 2009. Corrosion behavior of ferritic stainless steel alloyed with different amounts of niobium in hydrochloric acid solution. Journal of Applied Electrochemistry, 39: 761-767.
[23] Walter G.W. 1986. A rewiev of impedance plot methods used for corrosion performance analysis of painted metals. Corrosion Science, 26 (9): 681-703.
[24] Asselin E., Ahmed T.M., Alfantazi N.A. 2007. Corrosion of niobium in sulfuric and hydrochloric acid solution at 75 and 95 C. Corr. Sci., 49: 694.
[25] Bockris J., Reddy K.N. 1976. Modern Electrochemistry, John Wiley and Sons, New York.
[26] Erbil M. 1988. The determination of corrosion rates by analysis of AC impedance diagrams. Chimica Acta Turcica, 1: 59-70.
[27] Alonso-Falleiros N., Wolynec S. 1998. Effect of niobium on corrosion resistance to sulfuric acid of 430 ferritic stainless steel Materials Research, 1-39: 39-45
[28] Seo M., Hultquist G., Leygraf S.N. 1986. The influence of minor alloying elements (Nb, Ti and Cu) on the corrosion resistivity of ferritic stainless steel in sulfuric acid solution Corr. Sci., 20- 271: 949-960.
[29] Alonso-Falleiros N, Wolynec Stephan,1998, Effect of Niobium on Corrosion Resistance to Sulfuric Acid of 430 Ferritic Stainless Steel, Mat. Res. 1: 466-472.
[30] Uhlig H.H. 1963. Corrosion and Corrosion Control. An Introduction to Corrosion Science and Engineering. John Wiley and Sons, London.
[31] Pourbaix M. 1974. Atlas of Electrochemical Equilibrium in Aqua Solutions. NACE International, Cebelcor, Houston, Texas, USA