Depth Corrosion Characteristics of Borided Layer Produced on AISI 321 Stainless Steel
K. Jagielska-Wiaderek
Czestochowa University of Technology, Faculty of Production Engineering and Materials Technology, Department of Chemistry, al. Armii Krajowej 19, 42-201 Czestochowa, Poland
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This paper presents the results of effects of boronizing process of AISI 321 austenitic stainless steel on its electrochemical corrosion resistance. The steel samples were boronized at a temperature of 900° for 6 h. In this process, a mixture powder (B4C, SiC, borax), alumina (Al2O3) and potassium fluoroborate (KBF4) was used. The evaluation of the corrosion resistance of boronized stainless steel was carried out by using the so-called progressive thinning method, consisting in determination of polarisation characteristics on increasingly-deeper situated regions of the top layer. This method made it possible to determine changes in particular corrosion parameters read out from potentiodynamic polarisation curves, thus enabling the depth profiles of these parameters. Potentiodynamic polarization tests were carried out in an 0.5 M sulphate solution acidified to pH = 2.0. It is shown that unlike unmodified steel, the boron-rich outer layer does not passivate but undergoes fast dissolution both in active- and transpassive regions in the corrosion solution.

DOI:10.12693/APhysPolA.135.252
topics: corrosion, stainless steel, boronizing